Poly Lactic-co-Glycolic Acid (PLGA) as Biodegradable Controlled Drug Delivery Carrier

Enhanced anticancer efficacy of TRAIL-conjugated and odanacatib-loaded PLGA nanoparticles in TRAIL resistant cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) demonstrates unique characteristics in anticancer therapies as it selectively induces apoptosis in cancer cells. However, most cancer cells are TRAIL-resistant. Odanacatib (ODN), a cathepsin K inhibitor, is considered a novel sensitizer for cancer treatment. Combination therapy between TRAIL and sensitizers is considered a potent platform that improves TRAIL-based anticancer therapies beyond TRAIL monotherapy. Herein, we developed ODN loaded poly(lactic-co-glycolic) nanoparticles conjugated to GST-TRAIL (TRAIL-ODN-PLGA-NPs) to target and treat TRAIL-resistant cancer. TRAIL-ODN-PLGA-NPs demonstrated a significant increase in cellular uptake via death receptors (DR5 and DR4) on surface of cancer cells. TRAIL-ODN-PLGA-NPs exposure destroyed more TRAIL-resistant cells compared to a single treatment with free drugs. The released ODN decreased the Raptor protein, thereby increasing damage to mitochondria by elevating reactive oxygen species (ROS) generation. Additionally, Bim protein stabilization improved TRAIL-resistant cell sensitization to TRAIL-induced apoptosis. The in vivo biodistribution study revealed that TRAIL-ODN-PLGA-NPs demonstrated high location and retention in tumor sites via the intravenous route. Furthermore, TRAIL-ODN-PLGA-NPs significantly inhibited xenograft tumor models of TRAIL-resistant Caki-1 and TRAIL-sensitive MDA-MB-231 cells.The inhibition was associated with apoptosis activation, Raptor protein stabilizing Bim protein downregulation, Bax accumulation, and mitochondrial ROS generation elevation. Additionally, TRAIL-ODN-PLGA-NPs affected the tumor microenvironment by increasing tumor necrosis factor-α and reducing interleukin-6. In conclusion, we evealed that our formulation demonstrated synergistic effects against TRAIL compared with the combination of free drug in vitro and in vivo models. Therefore, TRAIL-ODN-PLGA-NPs may be a novel candidate for TRAIL-induced apoptosis in cancer treatment.

Optimization and evaluation of a chitosan-coated PLGA nanocarrier for mucosal delivery of Porphyromonas gingivalis antigens

Recent advances in understanding Alzheimer's disease (AD) suggest the possibility of an infectious etiology, with Porphyromonas gingivalis emerging as a prime suspect in contributing to AD. P. gingivalis may invade systemic circulation via weakened oral/intestinal barriers and then cross the blood-brain barrier (BBB), reaching the brain and precipitating AD pathology. Based on the proposed links between P. gingivalis and AD, a prospective approach is the development of an oral nanovaccine containing P. gingivalis antigens for mucosal delivery. Targeting the gut-associated lymphoid tissue (GALT), the nanovaccine may elicit both mucosal and systemic immunity, thereby hampering P. gingivalis ability to breach the oral/intestinal barriers and the BBB, respectively. The present study describes the optimization, characterization, and in vitro evaluation of a candidate chitosan-coated poly(lactic-co-glycolic acid) (PLGA-CS) nanovaccine containing a P. gingivalis antigen extract. The nanocarrier was prepared using the double emulsion solvent evaporation method and optimized for selected experimental factors, e.g. PLGA amount, surfactant concentration, w1/o phase ratio, applying a d-optimal statistical design to target the desired physicochemical criteria for its intended application. After nanocarrier optimization, the nanovaccine was characterized in terms of particle size, polydispersity index (PdI), ζ-potential, encapsulation efficiency (EE), drug loading (DL), morphology, and in vitro release profile, as well as for mucoadhesivity, stability under simulated gastrointestinal conditions, antigen integrity, in vitro cytotoxicity and uptake using THP-1 macrophages. The candidate PLGA-CS nanovaccine demonstrated appropriate physicochemical, mucoadhesive, and antigen release properties for oral delivery, along with acceptable levels of EE (55.3 ± 3.5 %) and DL (1.84 ± 0.12 %). The integrity of the encapsulated antigens remained uncompromised throughout NPs production and simulated gastrointestinal exposure, as confirmed by SDS-PAGE and Western blotting analyses. Furthermore, the nanovaccine showed effective in vitro uptake, while exhibiting low cytotoxicity. Taken together, these findings underscore the potential of PLGA-CS NPs as carriers for adequate antigen mucosal delivery, paving the way for further investigations into their applicability as vaccine candidates against P. gingivalis.

Evodiamine and its nano-based approaches for enhanced cancer therapy: recent advances and challenges

Evodiamine is a bioactive alkaloid extracted from the Evodia rutaecarpa plant. It has various pharmacological effects including anti-cancer, anti-bacterial, anti-obesity, anti-neurodegenerative, anti-depressant, and cardiac protective properties. Evodiamine demonstrates potent anti-cancer activity by inhibiting the proliferation of cancer cells in vitro and in vivo. Despite the health-promoting properties of evodiamine, its clinical use is hindered by low water solubility, poor bioavailability, and toxicity. Thus, there is a need to develop alternative drug delivery systems for evodiamine to enhance its solubility, permeability, and stability, as well as to facilitate targeted, prolonged, and controlled drug release. Nanocarriers can increase the therapeutic potential of evodiamine in cancer therapy while reducing adverse side effects. To date, numerous attempts have been made through the development of smart nanocarriers to overcome the drawbacks of evodiamine. This review focuses on the pharmacological applications, anti-cancer mechanisms, and limitations of evodiamine. Various nanocarriers, including lipid-based nanoparticles, polymeric nanoparticles, cyclodextrins, and so forth, have been discussed extensively for evodiamine delivery. Nano-drug delivery systems could increase the solubility, bioavailability, stability, and therapeutic efficacy of evodiamine. This review aims to present a comprehensive and critical evaluation of several nano-formulations of evodiamine for cancer therapy. © 2024 Society of Chemical Industry.

Implant dynamics, inner structure, and their impact on drug release of in situ forming implants uncovered through CT imaging

In situ forming implants (ISFIs) composed of biodegradable polymers and biocompatible solvents are generally designed for sustained drug release. In this study, a non-invasive computed tomography (CT) imaging approach is used to achieve real time imaging of ISFIs in vivo and in vitro using leuprolide acetate in situ forming implant as a model drug product. The process of implant formation, inner structure change and their impact on drug release were elucidated. Real-time drug distribution was unveiled by the CT contrast agent, iohexol, where it shows a core-shell structure of the deposition. The incorporation of leuprolide acetate (LA) led to a reduced extent of burst release, prolongated release profile, and extended implant size expansion. LA was found to interact with the solvent and slowed down the polymer phase inversion, thus significantly changed the drug distribution in the implant and reduced the drug release. The implant inner structure identified through SEM, implant size change, and polymer degradation along with the CT real time imaging all consistently support the implant formation differences and their implant on the drug release. Similar patterns of implant size expansion and iohexol distribution in the implants were observed both in vitro and in vivo for the implants with and without LA. The comprehensive understanding of the impact of implant formation on drug release through real time CT imaging facilitates the ISFI product development and evaluation.

Polymeric nanoparticles as a promising platform for treating triple-negative breast cancer: Current status and future perspectives

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer that lacks expression of estrogen, progesterone, and HER2 receptor targets for therapy. Polymeric nanoparticles help address the challenges in treating TNBC by enabling tailored and targeted drug delivery. Biocompatible polymeric nanoparticles leverage enhanced tumor permeability for site-specific accumulation and ligand-mediated active targeting to boost specificity. Controlled, sustained intratumorally release of encapsulated chemotherapies, such as paclitaxel and curcumin, improves antitumor efficacy as demonstrated through preclinical TNBC models. However, the practical application of these nanomedicines still has room for improvement. Advancing personalized nanoparticle platforms that align treatments to TNBC's expanding molecular subtypes shows promise. Expanding the polymer range through novel copolymers or drug conjugates may improve tumor penetration, stability, and drug encapsulation. Incorporating gene therapies, imaging agents, or triggering stimuli responsiveness into polymeric nanoparticles can also overcome innate and acquired drug resistance in TNBC while monitoring outcomes. This article reviews the different types of nanoparticles used to treat TNBC and the different mechanisms of nanoparticles that can deliver drugs to tumor cells. Collaboration across different disciplines aimed at developing combination therapies, immuno-oncology, tumor-targeting ligands, and translating preclinical safety/efficacy via scalable manufacturing practices is essential. Well-designed polymeric nanoparticles offer immense potential for patient-centric TNBC treatment, but continued optimization across bench to bedside efforts is critical for clinical realization and transforming patient outcomes.

Electrospinning Recombinant Spider Silk Fibroin-Reinforced PLGA Membranes: A Biocompatible Scaffold for Wound Healing Applications

Polylactide-polyglycolide (PLGA) is one of the most attractive polymeric biomaterials used to fabricate medical devices for drug delivery and tissue engineering applications. Nevertheless, the utilization of PLGA in load-bearing applications is restricted due to its inadequate mechanical properties. This study examines the potential of recombinant silk fibroin (eADF4), a readily producible biomaterial, as a reinforcing agent for PLGA. The PLGA/eADF4 composite membranes were developed by using the process of electrospinning. The spinnability of the electrospinning solutions and the physicochemical, mechanical, and thermal properties of the composite membranes were characterized. The addition of eADF4 increased the viscosity of the electrospinning solutions and enhanced both the mechanical characteristics and the thermal stability of the composites. This study demonstrates that PLGA membranes reinforced with recombinant spider silk fibroin are noncytotoxic, significantly enhance cell migration and wound closure, and do not trigger an inflammatory response, making them ideal candidates for advanced wound healing applications.

Recent Advances in Degradable Biomedical Polymers for Prevention, Diagnosis and Treatment of Diseases

Biomedical polymers play a key role in preventing, diagnosing, and treating diseases, showcasing a wide range of applications. Their unique advantages, such as rich source, good biocompatibility, and excellent modifiability, make them ideal biomaterials for drug delivery, biomedical imaging, and tissue engineering. However, conventional biomedical polymers suffer from poor degradation in vivo, increasing the risks of bioaccumulation and potential toxicity. To address these issues, degradable biomedical polymers can serve as an alternative strategy in biomedicine. Degradable biomedical polymers can efficiently relieve bioaccumulation in vivo and effectively reduce patient burden in disease management. This review comprehensively introduces the classification and properties of biomedical polymers and the recent research progress of degradable biomedical polymers in various diseases. Through an in-depth analysis of their classification, properties, and applications, we aim to provide strong guidance for promoting basic research and clinical translation of degradable biomedical polymers.

Bioengineered Nanomedicines Targeting the Intestinal Fc Receptor Achieve the Improved Glucoregulatory Effect of Semaglutide in a Type 2 Diabetic Mice Model

The oral administration of the glucagon-like peptide-1 analogue, semaglutide, remains a hurdle due to its limited bioavailability. Herein, neonatal Fc receptor (FcRn)-targeted nanoparticles (NPs) were designed to enhance the oral delivery of semaglutide. The nanocarriers were covalently linked to the FcRn-binding peptide FcBP or the affibody molecule ZFcRn that specifically binds to the human FcRn (hFcRn) in a pH-dependent manner. These FcRn-targeted ligands were selected over the endogenous ligands of the receptor (albumin and IgG) due to their smaller size and simpler structure, which could facilitate the transport of functionalized NPs through the tissues. The capacity of FcRn-targeted semaglutide-NPs in controlling the blood glucose levels was evaluated in an hFcRn transgenic mice model, where type 2 diabetes mellitus (T2DM) was induced via intraperitoneal injection of nicotinamide followed by streptozotocin. The encapsulation of semaglutide into FcRn-targeted NPs was translated in an improved glucoregulatory effect in T2DM-induced mice when compared to the oral free semaglutide or nontargeted NP groups, after daily oral administrations for 7 days. Notably, a similar glucose-lowering response was observed between both FcRn-targeted NPs and the subcutaneous semaglutide groups. An increase in insulin pancreatic content and a recovery in β cell mass were visualized in the mice treated with FcRn-targeted semaglutide-NPs. The biodistribution of fluorescently labeled NPs through the gastrointestinal tract demonstrated that the nanosystems targeting the hFcRn are retained longer in the ileum and colorectum, where the expression of FcRn is more prevalent, than nontargeted NPs. Therefore, FcRn-targeted nanocarriers proved to be an effective platform for improving the pharmacological effect of semaglutide in a T2DM-induced mice model.

Comparison of emulsion and spray methods for fabrication of rapamycin-loaded acetalated dextran microparticles

Rapamycin (rapa), an immunosuppressive medication, has demonstrated considerable effectiveness in reducing organ transplant rejection and treating select autoimmune diseases. However, the standard oral administration of rapa results in poor bioavailability, broad biodistribution, and harmful off-target effects, necessitating improved drug delivery formulations. Polymeric microparticles (MPs) are one such solution and have demonstrated promise in pre-clinical studies to improve the therapeutic efficacy of rapa. Nevertheless, MP formulations are highly diverse, and fabrication method selection is a critical consideration in formulation design. Herein, we compared common fabrication processes for the development of rapa-loaded MPs. Using the biopolymer acetalated dextran (Ace-DEX), rapa-loaded MPs were fabricated by both emulsion (homogenization and sonication) and spray (electrospray and spray drying) methods, and resultant MPs were characterized for size, morphology, surface charge, and drug release kinetics. MPs were then screened in LPS-stimulated macrophages to gauge immunosuppressive efficacy relative to soluble drug. We determined that homogenized MPs possessed the most optimal combination of sizing, tunable drug release kinetics, and immunosuppressive efficacy, and we subsequently demonstrated that these characteristics were maintained across a range of potential rapa loadings. Further, we performed in vivo trafficking studies to evaluate depot kinetics and cellular uptake at the injection site after subcutaneous injection of homogenized MPs. We observed preferential MP uptake by dendritic cells at the depot, highlighting the potential for MPs to direct more targeted drug delivery. Our results emphasize the significance of fabrication method in modulating the efficacy of MP systems and inform improved formulation design for the delivery of rapa.

Antiretroviral (ARV) Properties Dictate Long-Acting Release and Tissue Partitioning Behaviors in Multidrug Subcutaneous Implants

Subcutaneous implants can provide patients with long-acting, compliance-independent drug dosing. For this reason, subcutaneous implants have shown emerging interest in human immunodeficiency virus (HIV) prevention. However, any successful long-acting HIV-prevention device will require multidrug dosing, which poses a challenge for formulation considering the physicochemically diverse selection of antiretroviral (ARV) candidates. As a method that has shown the capacity of efficient multidrug delivery, we assessed electrospun fiber implants composed of three synergistically potent ARVs and a biodegradable polymer selected by in vitro release studies. In mice, subcutaneous electrospun fiber implants exhibit burst release of the more hydrophilic drugs maraviroc (MVC) and raltegravir (RAL), which could be reduced via simple prewash treatments of the implants. Over an extended 120 day time frame, fiber implants show drug-specific differences in release time frames and magnitudes in blood serum. However, end-point drug tissue concentrations show that the most hydrophobic drug etravirine (ETR) remains in high concentrations within the implant and in local skin tissue biopsies. Furthermore, ETR is found to be capable of significant partitioning into lymph nodes, the lower female reproductive tract, and the rectum. Topologically smooth film implants also exhibit the same drug-dependent trends. Therefore, we illustrate that drug release and drug tissue partitioning are largely dictated by drug properties. Further, we find that the properties of ETR enable significant drug quantities within the tissues most relevant to HIV protection. Evidence from this work emphasizes the need for a greater focus on drug properties and prodrug strategies to enable relevant, extended, and targeted drug release.

Erlotinib and curcumin-loaded nanoparticles embedded in thermosensitive chitosan hydrogels for enhanced treatment of head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) remain a major oncological challenge with significant morbidity and mortality rates. Erlotinib (Er) and Curcumin (Cm) are potential therapeutic agents for HNSCC, yet they are hindered by poor solubility and bioavailability. This study explored the optimization of poly(lactic-co-glycolic acid) nanoparticles co-loaded with Er and Cm (Er/Cm-NP), prepared via a D-optimal response surface design-guided nanoprecipitation process. The optimized formulation, optEr/Cm-NP, was then incorporated into chitosan/β-glycerophosphate hydrogels (optEr/Cm-NP-HG) to create an injectable intratumoral (IT) nanocomposite hydrogel (HG) delivery system. Physicochemical properties of the formulations, including gelation time, injectability, mechanical strength and drug release profiles were assessed alongside hemolytic activity. Compared to optEr/Cm-NP alone, the NP-loaded HG formulation exhibited a more pronounced modulation effect, enabling sustained and controlled drug release. The cytotoxicity of the developed formulations was evaluated using the FaDu HNSCC cancer cell line. Both optEr/Cm-NP and optEr/Cm-NP-HG21 displayed enhanced cytotoxicity compared to free drugs. Confocal laser microscopy and flow cytometry confirmed superior cellular uptake of Er and Cm when delivered via NPs or NP-loaded HG. Furthermore, a significant increase in apoptotic cell death upon treatment with optEr/Cm-NP was observed, highlighting its potential for HNSCC therapy. In vivo studies conducted on a xenograft HNSCC mouse model revealed the significant capacity of the intratumorally-injected optEr/Cm-NP-HG21 formulation to retard the tumor growth. Conclusively, the results presented herein report the successful development of a nanocomposite HG system incorporating NPs co-loaded with Er and Cm that could be efficiently utilized in the treatment of HNSCC.

Advancements in Ocular Therapy: A Review of Emerging Drug Delivery Approaches and Pharmaceutical Technologies

Eye disorders affect a substantial portion of the global population, yet the availability of efficacious ophthalmic drug products remains limited. This can be partly ascribed to a number of factors: (1) inadequate understanding of physiological barriers, treatment strategies, drug and polymer properties, and delivery systems; (2) challenges in effectively delivering drugs to the anterior and posterior segments of the eye due to anatomical and physiological constraints; and (3) manufacturing and regulatory hurdles in ocular drug product development. The present review discusses innovative ocular delivery and treatments, encompassing implants, liposomes, nanoparticles, nanomicelles, microparticles, iontophoresis, in situ gels, contact lenses, microneedles, hydrogels, bispecific antibodies, and gene delivery strategies. Furthermore, this review also introduces advanced manufacturing technologies such as 3D printing and hot-melt extrusion (HME), aimed at improving bioavailability, reducing therapeutic dosages and side effects, facilitating the design of personalized ophthalmic dosage forms, as well as enhancing patient compliance. This comprehensive review lastly offers insights into digital healthcare, market trends, and industry and regulatory perspectives pertaining to ocular product development.

Investigation of local stimulation effects of embedding PGLA at Zusanli (ST36) acupoint in rats based on TRPV2 and TRPV4 ion channels

Introduction

Acupoint Catgut Embedding (ACE) is an extended and developed form of traditional acupuncture that serves as a composite stimulation therapy for various diseases. However, its local stimulation effects on acupoints remain unclear. Acupuncture can activate mechanically sensitive calcium ion channels, TRPV2 and TRPV4, located on various cell membranes, promoting Ca2+ influx in acupoint tissues to exert effects. Whether ACE can form mechanical physical stimulation to regulate these channels and the related linkage effect requires validation.

Methods

This study investigates the influence of TRPV2 and TRPV4 ion channels on the local stimulation effects of ACE by embedding PGLA suture at the Zusanli (ST36) acupoint in rats and using TRPV2 and TRPV4 inhibitors. Flow cytometry, immunofluorescence, Western blot, and Real-time quantitative PCR were employed to detect intracellular Ca2+ fluorescence intensity, the expression of macrophage (Mac) CD68 and mast cell (MC) tryptase, as well as the protein and mRNA expression of TRPV2 and TRPV4 in acupoint tissues after PGLA embedding.

Results

The results indicate that ACE using PGLA suture significantly increases the mRNA and protein expression of TRPV2 and TRPV4, Ca2+ fluorescence intensity, and the expression of Mac CD68 and MC tryptase in acupoint tissues, with these effects diminishing over time. The increasing trends are reduced after using inhibitors, particularly when both inhibitors are used simultaneously. Furthermore, correlation analysis shows that embedding PGLA suture at the ST36 acupoint regulates Mac and MC functions through Ca2+ signaling involving not only TRPV2 and TRPV4 but multiple pathways.

Discussion

These results suggest that embedding PGLA suture at the ST36 acupoint generates mechanical physical stimulation and regulates TRPV2 and TRPV4 ion channels, which couple with Ca2+ signaling to form a linkage effect that gradually weakens over time. This provides new reference data for further studies on the stimulation effects and clinical promotion of ACE.

Mannose-Functionalized Chitosan-Coated PLGA Nanoparticles for Brain-Targeted Codelivery of CBD and BDNF for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a common neurodegenerative disease causing cognitive and memory decline. AD is characterized by the deposition of amyloid-β and hypophosphorylated forms of tau protein. AD brains are found to be associated with neurodegeneration, oxidative stress, and inflammation. Cannabidiol (CBD) shows neuroprotective, antioxidant, and anti-inflammatory properties and simultaneously reduces amyloid-β production and tau hyperphosphorylation. The brain-derived neurotrophic factor (BDNF) plays a vital role in the development and maintenance of the plasticity of the central nervous system. A decline of BDNF levels in AD patients results in reduced plasticity and neuronal cell death. Current therapeutics against AD are limited to only symptomatic relief, necessitating a therapeutic strategy that reverses cognitive decline. In this scenario, combination therapy of CBD and BDNF could be a fruitful strategy for the treatment of AD. We designed mannose-conjugated chitosan-coated poly(d,l-lactide-co-glycolide (PLGA) (CHTMAN-PLGA) nanoparticles for the codelivery of CBD and BDNF to the brain. Chitosan is modified with mannose to specifically target the glucose transporter-1 (GLUT-1) receptor abundantly present in the blood-brain barrier for selectively delivering therapeutics to the brain. The CBD-encapsulated nanoparticles showed an average hydrodynamic diameter of 306 ± 8.12 nm and a zeta potential of 31.7 ± 1.53 mV. The coated nanoparticles prolonged encapsulated CBD release from the PLGA matrix. The coated nanoparticles exhibited sustained release of CBD for up to 22 days with 91.68 ± 2.91% release of the encapsulated drug. The coated nanoparticles, which had a high positive zeta potential (31.7 ± 1.53 mV), encapsulated the plasmid DNA. The qualitative transfection efficiency was investigated using CHTMAN-PLGA-CBD/pGFP in bEND.3, primary astrocytes, and primary neurons, while the quantitative transfection efficiency of the delivery system was determined using CHTMAN-PLGA-CBD/pBDNF. In vitro, the pBDNF transfection study revealed that the BDNF expression was 4-fold higher for CHTMAN-PLGA-CBD/pBDNF than for naked pBDNF in all of the cell lines. The cytotoxicity and hemocompatibility of the designed nanoparticles were tested in bEND.3 cells and red blood cells, respectively, and the nanoparticles were found to be nontoxic and hemocompatible. Hence, mannose-conjugated chitosan-coated PLGA nanoparticles could be useful as brain-targeting delivery vehicles for the codelivery of CBD and BDNF for possible AD treatment.

Microneedles with Implantable Tip-Accumulated Therapeutics for the Long-Term Management of Psoriasis

Methotrexate is successfully used as the gold standard for managing moderate-to-severe psoriasis. However, the low bioavailability and short half-life of the oral pills and the invasiveness of the parenteral injections make these suboptimal therapeutic options. Microneedles, bridging the advantages of the former forms, are successfully used to deliver methotrexate for different therapeutic purposes. However, the utilized dissolving microneedles demand frequent administration, potentially compromising patients' compliance. Additionally, the high toxicity of methotrexate prompts a quest for safer alternatives. Phloretin, a natural compound with confirmed antipsoriatic potential, emerges as a promising candidate. Herein, microneedle patches with separable, slow-degrading tips are developed for the sustained delivery of methotrexate and phloretin, as a comprehensive solution for long-term psoriasis management. Both compounds are individually loaded at varying doses and display sustained-release profiles. The developed microneedle patches demonstrate high mechanical strength, favorable drug delivery efficiency, and remarkable antipsoriatic potential both in vitro in keratinocytes and in vivo in a psoriasis mouse model. Comparative analysis with two subcutaneous injections reveals a similar antipsoriatic efficacy with a single patch of either compound, with prominent phloretin safety. Therefore, the developed patches present a superior alternative to methotrexate's current marketed forms and provide a viable alternative (phloretin) with comparable antipsoriatic efficacy and higher safety.

Anti-aging Metabolite-Based Polymeric Microparticles for Intracellular Drug Delivery and Bone Regeneration

Alpha-ketoglutarate (AKG), a key component of the tricarboxylic acid (TCA) cycle, has attracted attention for its anti-aging properties. Our recent study indicates that locally delivered cell-permeable AKG significantly promotes osteogenic differentiation and mouse bone regeneration. However, the cytotoxicity and rapid hydrolysis of the metabolite limit its application. In this study, we synthesize novel AKG-based polymeric microparticles (PAKG MPs) for sustained release. In vitro data suggest that the chemical components, hydrophilicity, and size of the MPs can significantly affect their cytotoxicity and pro-osteogenic activity. Excitingly, these biodegradable PAKG MPs are highly phagocytosable for nonphagocytic pre-osteoblasts MC3T3-E1 and primary bone marrow mesenchymal stem cells (BMSCs), significantly promoting their osteoblastic differentiation. RNAseq data suggest that PAKG MPs strongly activate Wnt/β-catenin and PI3K-Akt pathways for osteogenic differentiation. Moreover, PAKG enables poly (L-lactic acid) and poly (lactic-co-glycolic acid) MPs (PLLA & PLGA MPs) for efficient phagocytosis. Our data indicate that PLGA-PAKG MPs-mediated intracellular drug delivery can significantly promote stronger osteoblastic differentiation compared to PLGA MPs-delivered phenamil. Notably, PAKG MPs significantly improve large bone regeneration in a mouse cranial bone defect model. Thus, the novel PAKG-based MPs show great promise to improve osteogenic differentiation, bone regeneration, and enable efficient intracellular drug delivery for broad regenerative medicine.

Biocompatibility analysis of titanium bone wedges coated by antibacterial ceramic-polymer layer

This paper presents the surface treatment results of titanium, veterinary bone wedges. The functional coating is composed of a porous oxide layer (formed by a plasma electrolytic oxidation process) and a polymer poly(sebacic anhydride) (PSBA) layer loaded with amoxicillin (formed by dip coatings). The coatings were porous and composed of Ca (4.16%-6.54%) and P (7.64%-9.89% determined by scanning electron microscopy with EDX) in the upper part of the implant. The titanium bone wedges were hydrophilic (54° water contact angle) and rough (surface area (Sa):1.16 μm) The surface tension determined using diiodomethane was 68.6 ± 2.0° for the anodized implant and was similar for hybrid coatings: 60.7 ± 2.2°. 12.87 ± 0.91 µg/mL of amoxicillin was released from the implants during the first 30 min after immersion in the phosphate-buffered saline (PBS) solution. This concentration was enough to inhibit the Staphylococcus aureus ATCC 25923, and Staphylococcus epidermidis ATCC12228 growth. The obtained inhibition zones were between 27.3 ± 2.1 mm-30.7 ± 0.6 mm when implant extract after 1 h or 4 h immersion in PBS was collected. Various implant biocompatibility analyses were performed under in vivo conditions, including pyrogen test (3 rabbits), intracutaneous reactivity (3 rabbits, 5 places by side), acute systemic toxicity (20 house mice), and local lymph node assay (LLNA) (20 house mice). The extracts from implants were collected in polar and non-polar solutions, and the tests were conducted according to ISO 10993 standards. The results from the in vivo tests showed, that the implant's extracts are not toxic (mass body change below 5%), not sensitizing (SI < 1.6), and do not show the pyrogen effect (changes in the temperature 0.15ºC). The biocompatibility tests were performed in a certificated laboratory with a good laboratory practice certificate after all the necessary permissions.

Nordihydroguaiaretic acid microparticles are effective in the treatment of osteoarthritis

Several disease-modifying osteoarthritis (OA) drugs have emerged, but none have been approved for clinical use due to their systemic side effects, short half-life, and rapid clearance from the joints. Nordihydroguaiaretic acid (NDGA), a reactive oxygen species (ROS) scavenger and autophagy inducer, could be a potential treatment for OA. In this report, we show for the first time that sustained delivery of NDGA through polymeric microparticles maintains therapeutic concentrations of drug in the joint and ameliorates post-traumatic OA (PTOA) in a mouse model. In vitro treatment of oxidatively stressed primary chondrocytes from OA patients using NDGA-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles (NDGA-MP) inhibited 15-lipoxygenase, induced autophagy, prevented chondrosenescence, and sustained matrix production. In vivo intra-articular delivery of NDGA-MP was non-toxic and had prolonged retention time (up to 35 days) in murine knee joints. Intra-articular therapy using NDGA-MP effectively reduced cartilage damage and reduced pain in the surgery-induced PTOA mouse model. Our studies open new avenues to modulate the immune environment and treat post-traumatic OA using ROS quenchers and autophagy inducers.

Enhanced strength, toughness and heat resistance of poly (lactic acid) with good transparency and biodegradability by uniaxial pre-stretching

Sustainable poly (lactic acid) (PLA) with excellent strength, toughness, heat resistance, transparency, and biodegradability was achieved by uniaxial pre-stretching at 70 °C. The effect of pre-stretched ratio (PSR) on the microstructure and properties of the PLA was investigated. The undrawn PLA was brittle. However, after pre-stretching, the elongation at break was increased significantly. The maximum value of 161.2 % was obtained at pre-stretching ratio (PSR) of 1.0. With the increase of PSR, the modulus and strength were improved obviously (from 1601 MPa and 60.2 MPa for undrawn PLA to 2932 MPa and 106.3 MPa for the ps-PLA at PSR =3.0). Meanwhile, the heat resistance of PLA was improved obviously with the increase of PSR. For the ps-PLA3.0, there were almost no deformation and shrink at 140 °C. Interestingly, after pre-stretching, the PLA still maintained the good transparency and biodegradability. The brittleness for undrawn PLA was attributed to the network structure of cohesional entanglements. After pre-stretching, the destruction of the network structure and formation of the orientation, mesophase and oriented nanosized crystalline phase lead to the increased the toughness, strength and heat resistance without sacrificing the transparency and biodegradability. This work provides a significant guidance for the fabrication of PLA material with excellent comprehensive performance including strength, toughness, heat resistance, transparency, and biodegradability.

Dissolving Microneedles Patch: A Promising Approach for Advancing Transdermal Delivery of Antischizophrenic Drug

OBJECTIVE

Microneedles (MNs) are minimally invasive transdermal drug delivery systems capable of penetrating the stratum corneum to overcome the barrier properties. The primary objective of this research was to prepare dissolving microneedle patches (DMNP) loaded with quetiapine (QTP).

METHODS

DMNP were fabricated employing the solvent casting technique, utilizing various polymer feed ratios including polyvinyl alcohol (PVA), polyvinylpyrrolidone K30 (PVP-K30), and polylactide-co-glycolide (PLGA) polymers. The loaded DMNP with QTP underwent a comprehensive characterization process encompassing assessments for compatibility, thickness, insertion potential, morphology, thermal behavior, X-ray diffraction, ex-vivo permeation, skin irritation, and histopathological changes.

RESULTS

FTIR studies confirmed the compatibility of QTP with the microneedle patch composites. The thickness of the drug-loaded DMNP ranged from 0.67 mm to 0.97 mm. These microneedles exhibited an impressive penetration depth of 480 μm, with over 80% of the needles maintaining their original shape after piercing Parafilm-M. SEM analysis of the optimized DMNP-2 revealed the formation of sharp-tipped and uniformly surfaced needles, measuring 570 μm in length. Remarkably, the microneedles did not elicit any signs of irritation upon application of the prepared DMNP. The DMNP-2 showcased an impressive cumulative ex-vivo permeation of QTP, reaching 17.82 µg/cm2/hr. Additionally, histopathological assessment of vital organs in rabbits attested to the safety profile of the formulated microneedle patches.

CONCLUSIONS

In conclusion, the developed microneedle patch represents a promising strategy for enhancing the transdermal delivery of QTP. This innovative approach has the potential to increase patient compliance, offering a more efficient and patient-friendly method of administering QTP.

Paravertebrally-Injected Multifunctional Hydrogel for Sustained Anti-Inflammation and Pain Relief in Lumbar Disc Herniation

Pain caused by lumbar disc herniation (LDH) severely compromises patients' quality of life. The combination of steroid and local anesthetics is routinely employed in clinics to alleviate LDH-induced pain. However, the approach only mediates transient efficacy and requires repeated and invasive lumbar epidural injections. Here a paravertebrally-injected multifunctional hydrogel that can efficiently co-load and controlled release glucocorticoid betamethasone and anesthetics ropivacaine for sustained anti-inflammation, reactive oxygen species (ROS)-removal and pain relief in LDH is presented. Betamethasone is conjugated to hyaluronic acid (HA) via ROS-responsive crosslinker to form amphiphilic polymer that self-assemble into particles with ropivacaine loaded into the core. Solution of drug-loaded particles and thermo-sensitive polymer rapidly forms therapeutic hydrogel in situ upon injection next to the herniated disc, thus avoiding invasive epidural injection. In a rat model of LDH, multifunctional hydrogel maintains the local drug concentration 72 times longer than free drugs and more effectively inhibits the expression of pro-inflammatory cytokines and pain-related molecules including cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2). Therapeutic hydrogel suppresses the LDH-induced pain in rats for 12 days while the equivalent dose of free drugs is only effective for 3 days. This platform is also applicable to ameliorate pain caused by other spine-related diseases.

Nanospheres as the delivery vehicle: novel application of Toxoplasma gondii ribosomal protein S2 in PLGA and chitosan nanospheres against acute toxoplasmosis

Toxoplasma gondii (T. gondii) is a zoonotic disease that poses great harm to humans and animals. So far, no effective T. gondii vaccine has been developed to provide fully protection against such parasites. Recently, numerous researches have focused on the use of poly-lactic-co-glycolic acid (PLGA) and chitosan (CS) for the vaccines against T. gondii infections. In this study, we employed PLGA and CS as the vehicles for T. gondii ribosome protein (TgRPS2) delivery. TgRPS2-PLGA and TgRPS2-CS nanospheres were synthesized by double emulsion solvent evaporation and ionic gelation technique as the nano vaccines. Before immunization in animals, the release efficacy and toxicity of the synthesized nanospheres were evaluated in vitro. Then, ICR mice were immunized intramuscularly, and immune protections of the synthesized nanospheres were assessed. The results showed that TgRPS2-PLGA and TgRPS2-CS nanospheres could induce higher levels of IgG and cytokines, activate dendritic cells, and promote the expression of histocompatibility complexes. The splenic lymphocyte proliferation and the enhancement in the proportion of CD4+ and CD8+ T lymphocytes were also observed in immunized animals. In addition, two types of nanospheres could significantly inhabit the replications of T. gondii in cardiac muscles and spleen tissues. All these obtained results in this study demonstrated that the TgRPS2 protein delivered by PLGA or CS nanospheres provided satisfactory immunoprotective effects in resisting T. gondii, and such formulations illustrated potential as prospective preventive agents for toxoplasmosis.

Nanocellulose-alginate composite beads for improving Ciprofloxacin bioavailability

Nanocellulose is a potential material utilized in numerous biomedical applications. However, its hydrophilic characteristic and uncontrolled encapsulated drug release hinders nanocellulose uses in oral drug administration. Thus, this work developed novel nanocellulose/alginate composite (CNC/Alg) beads for oral delivery and bioavailability enhancement of a model drug, Ciprofloxacin (CIP). CNC was green synthesized employing electrolysis process from sugarcane bagasse. CNC/Alg beads were formulated by dropwise adding CNC-Alg mixture in CaCl2 solution at room temperature. CIP was incorporated into CNC/Alg beads by adsorption technique. X-ray diffractometry and Fourier-transform infrared spectra images showed that the beads were effectively produced with high crystallinity of 75.5 %, and the typical bond of cellulose and alginate. Within 4 h of adsorption, CIP loading efficiency reached 45.27 %, with 87.2 % molecules in the zwitterionic state. The adsorption followed Elovich and pseudo-second-order models, indicating a multi-mechanism including both physical and chemical adsorptions. Importantly, in gastrointestinal tract, the beads could protect CIP from acidic stomach environment while releasing it sustainably in simulated intestinal condition (75.05 %). The beads also showed strong antibacterial activity against both Gram(-) and Gram(+) bacteria, as evidenced by low IC50 and minimum inhibitory concentration values. Finally, CNC/Alg beads could improve CIP bioavailability for effective oral drug delivery route.

Therapeutic potentials and targeting strategies of quercetin on cancer cells: Challenges and future prospects

BACKGROUND

Every cell in the human body is vital because it maintains equilibrium and carries out a variety of tasks, including growth and development. These activities are carried out by a set of instructions carried by many different genes and organized into DNA. It is well recognized that some lifestyle decisions, like using tobacco, alcohol, UV, or multiple sexual partners, might increase one's risk of developing cancer. The advantages of natural products for any health issue are well known, and researchers are making attempts to separate flavonoid-containing substances from plants. Various parts of plants contain a phenolic compound called flavonoid. Quercetin, which belongs to the class of compounds known as flavones with chromone skeletal structure, has anti-cancer activity.

PURPOSE

The study was aimed at investigating the therapeutic action of the flavonoid quercetin on various cancer cells.

METHODS

The phrases quercetin, anti-cancer, nanoparticles, and cell line were used to search the data using online resources such as PubMed, and Google Scholar. Several critical previous studies have been included.

RESULTS

Quercetin inhibits various dysregulated signaling pathways that cause cancer cells to undergo apoptosis to exercise its anticancer effects. Numerous signaling pathways are impacted by quercetin, such as the Hedgehog system, Akt, NF-κB pathway, downregulated mutant p53, JAK/STAT, G1 phase arrest, Wnt/β-Catenin, and MAPK. There are downsides to quercetin, like hydrophobicity, first-pass effect, instability in the gastrointestinal tract, etc., because of which it is not well-established in the pharmaceutical industry. The solution to these drawbacks in the future is using bio-nanomaterials like chitosan, PLGA, liposomes, and silk fibroin as carriers, which can enhance the target specificity of quercetin. The first section of this review covers the specifics of flavonoids and quercetin; the second section covers the anti-cancer activity of quercetin; and the third section explains the drawbacks and conjugation of quercetin with nanoparticles for drug delivery by overcoming quercetin's drawback.

CONCLUSIONS

Overall, this review presented details about quercetin, which is a plant derivative with a promising molecular mechanism of action. They inhibit cancer by various mechanisms with little or no side effects. It is anticipated that plant-based materials will become increasingly relevant in the treatment of cancer.

Stimuli-responsive magnetic silica-poly-lactic-co-glycolic acid hybrid nanoparticles for targeted cancer chemo-immunotherapy

Chemotherapy and immunotherapy are two important modalities in cancer management. However, due to multiple reasons, a monotherapy is only partially effective. Hence, if used concurrently in targeted and stimuli-responsive manner, it could have been superior therapeutically. To facilitate co-delivery of chemotherapeutic and immunotherapeutic agent to the target cancer cells, engineered nanoparticles, i.e., a pH-responsive polymer PLGA-coated magnetic silica nanoparticles (Fe3O4-SiO2-PLGA-PDA-PTX-siRNA NPs) encapsulating paclitaxel (PTX) and siRNA against programmed cell death ligand-1 (PD-L1) are synthesized and characterized. Developed nanoparticles demonstrated pH-sensitive sustained drug release up to 10 days. In vitro 4T1 cell line studies showed efficient cellular uptake, PD-L1 gene downregulation, and apoptosis. Further, in vivo efficacy studies carried out in the mice model demonstrated a significant reduction of tumor growth following treatment with dual-Fe3O4-SiO2-PLGA-PDA-PTX-siRNA NPs as compared with monotherapy with Fe3O4-SiO2-PLGA-PDA-PTX NPs. The high therapeutic efficacy observed with dual-Fe3O4-SiO2-PLGA-PDA-PTX-siRNA NPs was mainly due to the cytotoxic effect of PTX combined with targeted silencing of the gene of interest, i.e., PD-L1, which in turn improve CD8+ T cell-mediated cancer cell death as evident with increased proliferation of CD8+ T cells in co-culture experiments. Thereby, dual-Fe3O4-SiO2-PLGA-PDA-PTX-siRNA NPs may have a promising anti-cancer treatment potential against breast cancer; however, the beneficial effects of dual loading of PTX + PD-L1 siRNA may be corroborated against other cancer models such as lung and colorectal cancer models as well as in clinical trials.

Biophysical translational paradigm of polymeric nanoparticle: Embarked advancement to brain tumor therapy

Polymeric nanoparticles have emerged as promising contenders for addressing the intricate challenges encountered in brain tumor therapy due to their distinctive attributes, including adjustable size, biocompatibility, and controlled drug release kinetics. This review comprehensively delves into the latest developments in synthesizing, characterizing, and applying polymeric nanoparticles explicitly tailored for brain tumor therapy. Various synthesis methodologies, such as emulsion polymerization, nanoprecipitation, and template-assisted fabrication, are scrutinized within the context of brain tumor targeting, elucidating their advantages and limitations concerning traversing the blood-brain barrier. Furthermore, strategies pertaining to surface modification and functionalization are expounded upon to augment the stability, biocompatibility, and targeting prowess of polymeric nanoparticles amidst the intricate milieu of the brain microenvironment. Characterization techniques encompassing dynamic light scattering, transmission electron microscopy, and spectroscopic methods are scrutinized to evaluate the physicochemical attributes of polymeric nanoparticles engineered for brain tumor therapy. Moreover, a comprehensive exploration of the manifold applications of polymeric nanoparticles encompassing drug delivery, gene therapy, imaging, and combination therapies for brain tumours is undertaken. Special emphasis is placed on the encapsulation of diverse therapeutics within polymeric nanoparticles, thereby shielding them from degradation and enabling precise targeting within the brain. Additionally, recent advancements in stimuli-responsive and multifunctional polymeric nanoparticles are probed for their potential in personalized medicine and theranostics tailored for brain tumours. In essence, this review furnishes an all-encompassing overview of the recent strides made in tailoring polymeric nanoparticles for brain tumor therapy, illuminating their synthesis, characterization, and multifaceted application.

Development of poly (lactic-co-glycolic acid) (PLGA) based implants using hot melt extrusion (HME) for sustained release of drugs: The impacts of PLGA's material characteristics

Hot melt extrusion (HME) processed Poly (lactic-co-glycolic acid) (PLGA) implant is one of the commercialized drug delivery products, which has solid, well-designed shape and rigid structures that afford efficient locoregional drug delivery on the spot of interest for months. In general, there are a variety of material, processing, and physiological factors that impact the degradation rates of PLGA-based implants and concurrent drug release kinetics. The objective of this study was to investigate the impacts of PLGA's material characteristics on PLGA degradation and subsequent drug release behavior from the implants. Three model drugs (Dexamethasone, Carbamazepine, and Metformin hydrochloride) with different water solubility and property were formulated with different grades of PLGAs possessing distinct co-polymer ratios, molecular weights, end groups, and levels of residual monomer (high/ViatelTM and low/ ViatelTM Ultrapure). Physicochemical characterizations revealed that the plasticity of PLGA was inversely proportional to its molecular weight; moreover, the residual monomer could impose a plasticizing effect on PLGA, which increased its thermal plasticity and enhanced its thermal processability. Although the morphology and microstructure of the implants were affected by many factors, such as processing parameters, polymer and drug particle size and distribution, polymer properties and polymer-drug interactions, implants prepared with ViatelTM PLGA showed a smoother surface and a stronger PLGA-drug intimacy than the implants with ViatelTM Ultrapure PLGA, due to the higher plasticity of the ViatelTM PLGA. Subsequently, the implants with ViatelTM PLGA exhibited less burst release than implants with ViatelTM Ultrapure PLGA, however, their onset and progress of the lag and substantial release phases were shorter and faster than the ViatelTM Ultrapure PLGA-based implants, owing to the residual monomer accelerated the water diffusion and autocatalyzed PLGA hydrolysis. Even though the drug release profiles were also influenced by other factors, such as composition, drug properties and polymer-drug interaction, all three cases revealed that the residual monomer accelerated the swelling and degradation of PLGA and impaired the implant's integrity, which could negatively affect the subsequent drug release behavior and performance of the implants. These results provided insights to formulators on rational PLGA implant design and polymer selection.

The drug release of PLGA-based nanoparticles and their application in treatment of gastrointestinal cancers

The poly (lactic-co-glycolic acid) (PLGA) based nanoparticles have been applied for drug delivery due to their simple preparation, biodegradability, and ideal biocompatibility. In this study, the factors affecting the degradation of PLGA-based nanoparticles are reviewed, encompassing the ratio of PLA to PGA, relative molecular weight, crystallinity, and preparation process of PLGA nanoparticles. The drug release behavior of PLGA-based nanoparticles, such as the degradation environment, encapsulated drug properties of polymers, and drug loading rates, are also discussed. Since gastrointestinal cancer is one of the major global threats to human health, this paper comprehensively summarizes the application of PLGA nanoparticles in gastrointestinal cancers from diagnosis, chemotherapy, radiotherapy, and novel tumor treatment methods (immunotherapy, gene therapy, and photothermal therapy). Finally, the future application of PLGA-based drug delivery systems in treating gastrointestinal cancers is discussed. The bottleneck of application status and the prospect of PLGA-nanoparticles in gastrointestinal tumor application are presented. To truly realize the great and wide application of PLGA-based nanoparticles, collaborative progress in the field of nanomaterials and life sciences is needed.

Silk Fibroin Nanofibers: Advancements in Bioactive Dressings through Electrospinning Technology for Diabetic Wound Healing

BACKGROUND

Non-healing diabetic wounds represent a significant clinical challenge globally, necessitating innovative approaches in drug delivery to enhance wound healing. Understanding the pathogenesis of these wounds is crucial for developing effective treatments. Bioactive dressings and polymeric nanofibers have emerged as promising modalities, with silk biomaterials gaining attention for their unique properties in diabetic wound healing.

PURPOSE OF REVIEW

The purpose of this review is to examine the challenges and innovations in treating non-healing diabetic wounds, emphasizing the global burden and the need for effective solutions. This review explores the complex mechanisms of wound healing in diabetes and evaluates the therapeutic potential of bioactive dressings and polymeric nanofibers. Special focus is given to the application of silk biomaterials, particularly silk fibroin, for wound healing, detailing their properties, mechanisms, and clinical translation. This review also describes various nanofiber fabrication methods, especially electrospinning technology, and presents existing evidence on the effectiveness of electrospun silk fibroin formulations.

RECENT FINDINGS

Recent advancements highlight the potential of silk biomaterials in diabetic wound healing, owing to their biocompatibility, mechanical strength, and controlled drug release properties. Electrospun silk fibroin-based formulations have shown promising results in preclinical and clinical studies, demonstrating accelerated wound closure and tissue regeneration.

SUMMARY

Non-healing diabetic wounds present a significant healthcare burden globally, necessitating innovative therapeutic strategies. Bioactive dressings and polymeric nanofibers, particularly silk-based formulations fabricated through electrospinning, offer promising avenues for enhancing diabetic wound healing. Further research is warranted to optimize formulation parameters and validate efficacy in larger clinical trials.

Recent progress in cancer vaccines and nanovaccines

Vaccine science, nanotechnology, and immunotherapy are at the forefront of cancer treatment strategies, each offering significant potential for enhancing tumor-specific immunity and establishing long-lasting immune memory to prevent tumor recurrence. Despite the promise of these personalized and precision-based anti-cancer approaches, challenges such as immunosuppression, suboptimal immune activation, and T-cell exhaustion continue to hinder their effectiveness. The limited clinical success of cancer vaccines often stems from difficulties in identifying effective antigens, efficiently targeting immune cells, lymphoid organs, and the tumor microenvironment, overcoming immune evasion, enhancing immunogenicity, and avoiding lysosomal degradation. However, numerous studies have demonstrated that integrating nanotechnology with immunotherapeutic strategies in vaccine development can overcome these challenges, leading to potent antitumor immune responses and significant progress in the field. This review highlights the critical components of cancer vaccine and nanovaccine strategies for immunomodulatory antitumor therapy. It covers general vaccine strategies, types of vaccines, antigen forms, nanovaccine platforms, challenges faced, potential solutions, and key findings from preclinical and clinical studies, along with future perspectives. To fully unlock the potential of cancer vaccines and nanovaccines, precise immunological monitoring during early-phase trials is essential. This approach will help identify and address obstacles, ultimately expanding the available options for patients who are resistant to conventional cancer immunotherapies.

Introductory Review of Soft Implantable Bioelectronics Using Conductive and Functional Hydrogels and Hydrogel Nanocomposites

Interfaces between implantable bioelectrodes and tissues provide critical insights into the biological and pathological conditions of targeted organs, aiding diagnosis and treatment. While conventional bioelectronics, made from rigid materials like metals and silicon, have been essential for recording signals and delivering electric stimulation, they face limitations due to the mechanical mismatch between rigid devices and soft tissues. Recently, focus has shifted toward soft conductive materials, such as conductive hydrogels and hydrogel nanocomposites, known for their tissue-like softness, biocompatibility, and potential for functionalization. This review introduces these materials and provides an overview of recent advances in soft hydrogel nanocomposites for implantable electronics. It covers material strategies for conductive hydrogels, including both intrinsically conductive hydrogels and hydrogel nanocomposites, and explores key functionalization techniques like biodegradation, bioadhesiveness, injectability, and self-healing. Practical applications of these materials in implantable electronics are also highlighted, showcasing their effectiveness in real-world scenarios. Finally, we discuss emerging technologies and future needs for chronically implantable bioelectronics, offering insights into the evolving landscape of this field.

Mesenchymal stem cell-delivered paclitaxel nanoparticles exhibit enhanced efficacy against a syngeneic orthotopic mouse model of pancreatic cancer

Pancreatic cancer is considered the deadliest among various solid tumors, with a five-year survival rate of 13 %. One of the major challenges in the management of advanced pancreatic cancer is the inefficient delivery of chemotherapeutics to the tumor site. Even though nanocarriers have been developed to improve tumoral delivery of chemotherapeutics, less than 1 % of the drugs reach tumors, rendering inadequate concentration for effective inhibition of tumors. As a potential alternative, mesenchymal stem cells (MSCs) can effectively deliver their cargo to tumor sites because of their resistance to chemotherapeutics and inherent tumor tropism. In this study, we used MSCs for the delivery of dibenzocyclooctyne (DBCO)-functionalized paclitaxel (PTX)-loaded poly(lactide-co-glycolide)-b-poly (ethylene glycol) (PLGA) nanoparticles. MSCs were modified to generate artificial azide groups on their surface, allowing nanoparticle loading via endocytosis and surface conjugation via click chemistry. This dual drug loading strategy significantly improves the PTX-loading capacity of azide-expressed MSCs (MSC-Az, 55.4 pg/cell) compared to unmodified MSCs (28.1 pg/cell). The in vitro studies revealed that PTX-loaded MSC-Az, nano-MSCs, exhibited cytotoxic effects against pancreatic cancer without altering their inherent phenotype, differentiation abilities, and tumor tropism. In an orthotopic pancreatic tumor model, nano-MSCs demonstrated significant inhibition of tumor growth (p < 0.05) and improved survival (p < 0.0001) compared to PTX solution, PTX nanocarriers, and Abraxane. Thus, nano-MSCs could be an effective delivery system for targeted pancreatic cancer chemotherapy and other solid tumors.

Nanoparticles as Drug Delivery Vehicles for People with Cystic Fibrosis

Cystic Fibrosis (CF) is a life-shortening, genetic disease that affects approximately 145,000 people worldwide. CF causes a dehydrated mucus layer in the lungs, leading to damaging infection and inflammation that eventually result in death. Nanoparticles (NPs), drug delivery vehicles intended for inhalation, have become a recent source of interest for treating CF and CF-related conditions, and many formulations have been created thus far. This paper is intended to provide an overview of CF and the effect it has on the lungs, the barriers in using NP drug delivery vehicles for treatment, and three common material class choices for these NP formulations: metals, polymers, and lipids. The materials to be discussed include gold, silver, and iron oxide metallic NPs; polyethylene glycol, chitosan, poly lactic-co-glycolic acid, and alginate polymeric NPs; and lipid-based NPs. The novelty of this review comes from a less specific focus on nanoparticle examples, with the focus instead being on the general theory behind material function, why or how a material might be used, and how it may be preferable to other materials used in treating CF. Finally, this paper ends with a short discussion of the two FDA-approved NPs for treatment of CF-related conditions and a recommendation for the future usage of NPs in people with Cystic Fibrosis (pwCF).

Advanced nanomedicines for the treatment of age-related macular degeneration

The critical and unmet medical need for novel therapeutic advancements in the treatment of age-related macular degeneration (AMD) cannot be overstated, particularly given the aging global population and the increasing prevalence of this condition. Current AMD therapy involves intravitreal treatments that require monthly or bimonthly injections to maintain optimal efficacy. This underscores the necessity for improved approaches, prompting recent research into developing advanced drug delivery systems to prolong the intervals between treatments. Nanoparticle-based therapeutic approaches have enabled the controlled release of drugs, targeted delivery of therapeutic materials, and development of smart solutions for the harsh microenvironment of diseased tissues, offering a new perspective on ocular disease treatment. This review emphasizes the latest pre-clinical treatment options in ocular drug delivery to the retina and explores the advantages of nanoparticle-based therapeutic approaches, with a focus on AMD, the leading cause of irreversible blindness in the elderly.

Polymers as Efficient Non-Viral Gene Delivery Vectors: The Role of the Chemical and Physical Architecture of Macromolecules

Gene therapy is the technique of inserting foreign genetic elements into host cells to achieve a therapeutic effect. Although gene therapy was initially formulated as a potential remedy for specific genetic problems, it currently offers solutions for many diseases with varying inheritance patterns and acquired diseases. There are two major groups of vectors for gene therapy: viral vector gene therapy and non-viral vector gene therapy. This review examines the role of a macromolecule's chemical and physical architecture in non-viral gene delivery, including their design and synthesis. Polymers can boost circulation, improve delivery, and control cargo release through various methods. The prominent examples discussed include poly-L-lysine, polyethyleneimine, comb polymers, brush polymers, and star polymers, as well as hydrogels and natural polymers and their modifications. While significant progress has been made, challenges still exist in gene stabilization, targeting specificity, and cellular uptake. Overcoming cytotoxicity, improving delivery efficiency, and utilizing natural polymers and hybrid systems are vital factors for prospects. This comprehensive review provides an illuminating overview of the field, guiding the way toward innovative non-viral-based gene delivery solutions.

Matrix metalloproteinase-responsive hydrogels with tunable retention for on-demand therapy of inflammatory bowel disease

Therapeutic options for addressing inflammatory bowel disease (IBD) include the administration of an enema to reduce intestinal inflammation and alleviate associated symptoms. However, uncontrollable retention of enemas in the intestinal tract has posed a long-term challenge for improving their therapeutic efficacy and safety. Herein we have developed a protease-labile hydrogel system as an on-demand enema vehicle with tunable degradation and drug release rates in response to varying matrix metalloproteinase-9 (MMP-9) expression. The system, composed of three tailored hydrogel networks, is crosslinked by poly (ethylene glycol) (PEG) with 2-, 4- and 8-arms through dynamic hydrazone bonds to confer injectability and generate varying network connectivity. The retention time of the hydrogels can be tuned from 12 to 36 h in the intestine due to their different degradation behaviors induced by MMP-9. The drug-releasing rate of the hydrogels can be controlled from 0.0003 mg/h to 0.278 mg/h. In addition, injection of such hydrogels in vivo resulted in significant differences in therapeutic effects including MMP-9 consumption, colon tissue repair, reduced collagen deposition, and decreased macrophage cells, for treating a mouse model of acute colitis. Among them, GP-8/5-ASA exhibits the best performance. This study validates the effectiveness of the tailored design of hydrogel architecture in response to pathological microenvironment cues, representing a promising strategy for on-demand therapy of IBD. STATEMENT OF SIGNIFICANCE: The uncontrollable retention of enemas at the delivery site poses a long-term challenge for improving therapeutic efficacy in IBD patients. MMP-9 is highly expressed in IBD and correlates with disease severity. Therefore, an MMP-9-responsive GP hydrogel system was developed as an enema by linking multi-armed PEG and gelatin through hydrazone bonds. This forms a dynamic hydrogel characterized by in situ gelation, injectability, enhanced bio-adhesion, biocompatibility, controlled retention time, and regulated drug release. GP hydrogels encapsulating 5-ASA significantly improved the intestinal phenotype of acute IBD and demonstrated notable therapeutic differences with increasing PEG arms. This method represents a promising on-demand IBD therapy strategy and provides insights into treating diseases of varying severities using endogenous stimulus-responsive drug delivery systems.

Recent Applications of PLGA in Drug Delivery Systems

Poly(lactic-co-glycolic acid) (PLGA) is a widely used biodegradable and biocompatible copolymer in drug delivery systems (DDSs). In this article, we highlight the critical physicochemical properties of PLGA, including its molecular weight, intrinsic viscosity, monomer ratio, blockiness, and end caps, that significantly influence drug release profiles and degradation times. This review also covers the extensive literature on the application of PLGA in delivering small-molecule drugs, proteins, peptides, antibiotics, and antiviral drugs. Furthermore, we discuss the role of PLGA-based DDSs in the treating various diseases, including cancer, neurological disorders, pain, and inflammation. The incorporation of drugs into PLGA nanoparticles and microspheres has been shown to enhance their therapeutic efficacy, reduce toxicity, and improve patient compliance. Overall, PLGA-based DDSs holds great promise for the advancement of the treatment and management of multiple chronic conditions.

Colon-Targeted Sustained-Release Combinatorial 5-Fluorouracil and Quercetin poly(lactic-co-glycolic) Acid (PLGA) Nanoparticles Show Enhanced Apoptosis and Minimal Tumor Drug Resistance for Their Potential Use in Colon Cancer

Colorectal cancer (CRC) is the third most common cancer worldwide, acting as a significant public health problem. 5-Fluorouracil (5-FU) is a key chemotherapy for various types of cancer, due to its broad anticancer activity. However, the emergence of drug resistance is a considerable limitation in the clinical application of 5-FU. Quercetin (QC) is proposed as an adjuvant therapy to minimize drug resistance to chemotherapeutics and enhance their pharmacological efficacy. The oral delivery of 5-FU and QC is challenged by poor aqueous solubility of QC and poor cellular permeability of 5-FU. To solve this issue, novel polylactide-co-glycolide (PLGA) combinatorial nanoparticles loading 5-FU and QC were prepared to deliver them directly to the colon. These sustained-release combinatorial nanoparticles recorded a significant decrease in cancer cell proliferation, C-reactive protein (CRP) level, and Interleukin-8 (IL-8) expression by 30.08%, 40.7%, and 46.6%, respectively. The results revealed that this combination therapy may offer a new strategy for the targeted delivery of chemotherapeutics to the colon.

Nanoplatform Based Intranasal Vaccines: Current Progress and Clinical Challenges

Multiple vaccine platforms have been employed to develop the nasal SARS-CoV-2 vaccines in preclinical studies, and the dominating pipelines are viral vectored as protein-based vaccines. Among them, several viral vectored-based vaccines have entered clinical development. Nevertheless, some unsatisfactory results were reported in these clinical studies. In the face of such urgent situations, it is imperative to rapidly develop the next-generation intranasal COVID-19 vaccine utilizing other technologies. Nanobased intranasal vaccines have emerged as an approach against respiratory infectious diseases. Harnessing the power of nanotechnology, these vaccines offer a noninvasive yet potent defense against pathogens, including the threat of COVID-19. The improvements made in vaccine mucosal delivery technologies based on nanoparticles, such as lipid nanoparticles, polymeric nanoparticles, inorganic nanoparticles etc., not only provide stability and controlled release but also enhance mucosal adhesion, effectively overcoming the limitations of conventional vaccines. Hence, in this review, we overview the evaluation of intranasal vaccine and highlight the current barriers. Next, the modern delivery systems based on nanoplatforms are summarized. The challenges in clinical application of nanoplatform based intranasal vaccine are finally discussed.

Extended siponimod release via low-porosity PLGA fibres: a comprehensive three-month in vitro evaluation for neovascular ocular diseases

Neovascular ocular diseases are among the most common causes of preventable or treatable vision loss. Their management involves lifelong, intravitreal injections of anti-vascular endothelial growth factor (VEGF) therapeutics to inhibit neovascularization, the key pathological step in these diseases. Anti-VEGF products approved for ocular administration are expensive biological agents with limited stability and short half-life. Additionally, their therapeutic advantages are hindered by high treatment resistance, poor patient compliance and the need for frequent, invasive administration. Herein, we used electrospinning to develop a unique, non-porous, PLGA implant for the ocular delivery of siponimod to improve ocular neovascular disease management. Siponimod is an FDA-approved drug for multiple sclerosis with a novel indication as a potential ocular angiogenesis inhibitor. The electrospinning conditions were optimised to produce a microfibrous, PLGA matte that was cut and rolled into the desired implant size. Physical characterisation techniques (Raman, PXRD, DSC and FTIR) indicated siponimod was distributed uniformly within the electrospun fibres as a stabilised, amorphous, solid dispersion with a character modifying drug-polymer interaction. Siponimod dispersion and drug-polymer interactions contributed to the formation of smooth fibres, with reduced porous structures. The apparent reduced porosity, coupled with the drug's hydrophobic dispersion, afforded resistance to water penetration. This led to a slow, controlled, Higuchi-type drug diffusion, with ∼30% of the siponimod load released over 90 days. The released drug inhibited human retinal microvascular endothelial cell migration and did not affect the cells' metabolic activity at different time points. The electrospun implant was physically stable after incubation under stress conditions for three months. This novel siponimod intravitreal implant broadens the therapeutic possibilities for neovascular ocular diseases, representing a potential alternative to biological, anti-VEGF treatments due to lower financial and stability burdens. Additionally, siponimod interaction with PLGA provides a unique opportunity to sustain the drug release from the electrospun fibres, thereby reducing the frequency of intravitreal injection and improving patient adherence.

Dual Chemotherapeutic Loading in Oxalate Transferrin-Conjugated Polymersomes Incorporated into Chitosan Hydrogels for Site-Specific Targeting of Melanoma Cells

In this work, we developed a smart drug delivery system composed of poly (ethylene glycol)-block-poly (ε-caprolactone) (PEG-PCL)-based polymersomes (Ps) loaded with doxorubicin (DOX) and vemurafenib (VEM). To enhance targeted delivery to malignant melanoma cells, these drug-loaded nanovesicles were conjugated to the oxalate transferrin variant (oxalate Tf) and incorporated into three-dimensional chitosan hydrogels. This innovative approach represents the first application of oxalate Tf for the precision delivery of drug-loaded polymersomes within a semi-solid dosage form based on chitosan hydrogels. These resulting semi-solids exhibited a sustained release profile for both encapsulated drugs. To evaluate their potency, we compared the cytotoxicity of native Tf-Ps with oxalate Tf-Ps. Notably, the oxalate Tf-Ps demonstrated a 3-fold decrease in cell viability against melanoma cells compared to normal cells and were 1.6-fold more potent than native Tf-Ps, indicating the greater potency of this nanoformulation. These findings suggest that dual-drug delivery using an oxalate-Tf-targeting ligand significantly enhances the drug delivery efficiency of Tf-conjugated nanovesicles and offers a promising strategy to overcome the challenge of multidrug resistance in melanoma therapy.

Production of 5-fluorouracil-loaded PLGA nanoparticles with toroidal microfluidic system and optimization of process variables by design of experiments

In recent decades, microfluidics has presented new opportunities for the production of nanoparticles (NPs). However, to achieve rapid clinical translation, the production of PLGA NPs in a single microfluidic channel for both the pharmaceutical research and industry without the need for scaling is still limited. The aim of this study was to accomplish the production of reproducible and stable 5-FU loaded Poly(lactic-co-glycolic acid) (PLGA) NPs, using an innovative toroidal microfluidic system, for cancer therapy. The toroidal microfluidic system enabled the production of spherical NPs ranging from 100 to 150 nm by adjusting both the TFR within the range of 5-15 mL/min and FRR between 1:3 and 1:7. A systematic assessment of critical process variables (total flow rate; TFR, flow rate ratio; FRR) for the production of PLGA NPs was conducted using Design of Experiment (DoE). The NPs, which exhibit a uniform size distribution, remained stable even after centrifugation and storage for 3 months at 4 °C. The encapsulation efficiency of drug and the concentration of NPs were not affected by changing process parameters. The effective 5-FU encapsulation into NPs resulted in a controlled in vitro drug release. Due to the controlled release profile of the 5-FU loaded PLGA NPs, the formulation was a promising candidate for mitigating the toxic side effects of free 5-FU and improving cancer treatment. In conclusion, toroidal microfluidic system enables high-volume production of stable PLGA NPs, both with and without 5-FU.

PLGA Nanoparticles Based Mucoadhesive Nasal In Situ Gel for Enhanced Brain Delivery of Topiramate

Oral Topiramate therapy is associated with systemic adverse effects including paresthesia,abdominal pain, and fluctuations in plasma levels. The purpose of this research was to develop an intranasal in situ gel based system comprising Topiramate polymeric nanoparticles and evaluate its potential both in vitro and in vivo. Poly (lactic-co-glycolic acid) (PLGA)nanoparticles prepared by nanoprecipitation method were added into the in situ gelling system of Poloxamer 407 and HPMC K4M. Selected formulation (TG5) was evaluated for physicochemical properties, nasal permeation and in vivo pharmacokinetics in rats. PLGAnanoparticles (O1) exhibited low particle size (~ 144.4 nm), good polydispersity index (0.202), negative zeta potential (-12.7 mV), and adequate entrapment efficiency (64.7%). Developed in situ gel showed ideal pH (6.5), good gelling time (35 s), gelling temperature(37℃), suitable viscosity (1335 cP)and drug content of 96.2%. In vitro drug release conformedto Higuchi release kinetics, exhibiting a biphasic pattern of initial burst release and sustained release for 24 h. Oral administration of the drug to Sprague-Dawley rats (G3) showed higher plasma Cmax(504 ng/ml, p < 0.0001) when compared to nasal delivery of in situ gel (G4) or solution (G5). Additionally, AUC0-α of G3 (8786.82 ng/ml*h) was considerably higher than othergroups. Brain uptake data indicates a higher drug level with G4 (112.47 ng /ml) at 12 h when compared to G3. Histopathological examination of groups; G1 (intranasal saline), G2(intranasal placebo), G3, G4, and G5 did not show any lesions of pathological significance. Overall, the experimental results observed were promising and substantiated the potential of developed in situ gel for intranasal delivery.

Unlocking the potential of microfold cells for enhanced permeation of nanocarriers in oral drug delivery

The therapeutic effects of orally administered nanocarriers depend on their ability to effectively permeate the intestinal mucosa, which is one of the major challenges in oral drug delivery. Microfold cells are specialized enterocytes in the intestinal epithelium known for their high transcytosis abilities. This study aimed to compare and evaluate two targeting approaches using surface modifications of polymer-based nanocarriers, whereas one generally addresses enterocytes, and one is directed explicitly to microfold cells via targeting the sialyl LewisA motif on their surface. We characterized the resulting carriers in terms of size and charge, supplemented by scanning electron microscopy to confirm their structural properties. For predictive biological testing and to assess the intended targeting effect, we implemented two human intestinal in vitro models containing microfold-like cells. Both models were thoroughly characterized prior to permeation studies with the different nanocarriers. Our results demonstrated improved transport for both targeted formulations compared to undecorated carriers in the in vitro models. Notably, there was an enhanced uptake in the presence of microfold-like cells, particularly for the nanocarriers directed by the anti-sialyl LewisA antibody. These findings highlight the potential of microfold cell targeting to improve oral administration of drugs and emphasize the importance of using suitable and well-characterized in vitro models for testing novel drug delivery strategies.

Polymeric nanoparticles produced by electrohydrodynamic atomisation for the passive delivery of imatinib

Imatinib is a chemotherapeutic agent known to cause severe side effects when administrated systemically. Encapsulating imatinib in co-polymer poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) offers a targeted drug delivery. In this work, PLGA 50:50 and PLGA 75:25 NPs encapsulated imatinib using the electrohydrodynamic atomisation technique. All particles generated were spherical with a smooth surface with a size distribution of 455±115 nm (PLGA 50:50) and 363±147 nm (PLGA 75:25). Encapsulation of imatinib was shown to be higher than 75 % and was shown to increase the zeta potential of the loaded NPs. The release of imatinib showed an initial burst in the first 12 h, followed by different sustained releases with up to 70 %. Both types of imatinib-loaded NPs' effect on cell viability and their cellular uptake were also studied on A549 cells, and the antiproliferative effect was comparable to that of cells treated with free drugs. Finally, Rhodamine-B-loaded NP-treated cells demonstrated the cellular uptake of NPs.

Strategies for the development of metalloimmunotherapies

Metal ions play crucial roles in the regulation of immune pathways. In fact, metallodrugs have a long record of accomplishment as effective treatments for a wide range of diseases. Here we argue that the modulation of interactions of metal ions with molecules and cells involved in the immune system forms the basis of a new class of immunotherapies. By examining how metal ions modulate the innate and adaptive immune systems, as well as host-microbiota interactions, we discuss strategies for the development of such metalloimmunotherapies for the treatment of cancer and other immune-related diseases.

Nor-LAAM loaded PLGA microparticles for treating opioid use disorder

The treatment landscape for opioid use disorder (OUD) faces challenges stemming from the limited efficacy of existing medications, poor adherence to prescribed regimens, and a heightened risk of fatal overdose post-treatment cessation. Therefore, there is a pressing need for innovative therapeutic strategies that enhance the effectiveness of interventions and the overall well-being of individuals with OUD. This study explored the therapeutic potential of nor-Levo-α-acetylmethadol (nor-LAAM) to treat OUD. We developed sustained release nor-LAAM-loaded poly (lactic-co-glycolic acid) (PLGA) microparticles (MP) using a hydrophobic ion pairing (HIP) approach. The nor-LAAM-MP prepared using HIP with pamoic acid had high drug loading and exhibited minimal initial burst release and sustained release. The nor-LAAM-MP was further optimized for desirable particle size, drug loading, and release kinetics. The lead nor-LAAM-MP (F4) had a relatively high drug loading (11 wt%) and an average diameter (19 μm) and maintained a sustained drug release for 4 weeks. A single subcutaneous injection of nor-LAAM-MP (F4) provided detectable nor-LAAM levels in rabbit plasma for at least 15 days. We further evaluated the therapeutic efficacy of nor-LAAM-MP (F4) in a well-established fentanyl-addiction rat model, and revealed a marked reduction in fentanyl choice and withdrawal symptoms in fentanyl-dependent rats. These findings provide insights into further developing long-acting nor-LAAM-MP for treating OUD. It has the potential to offer a new effective medication to the existing sparse armamentarium of products available to treat OUD.

Polyester nanoparticles delivering chemotherapeutics: Learning from the past and looking to the future to enhance their clinical impact in tumor therapy

Polymeric nanoparticles (NPs), specifically those comprised of biodegradable and biocompatible polyesters, have been heralded as a game-changing drug delivery platform. In fact, poly(α-hydroxy acids) such as polylactide (PLA), poly(lactide-co-glycolide) (PLGA), and poly(ε-caprolactone) (PCL) have been heavily researched in the past three decades as the material basis of polymeric NPs for drug delivery applications. As materials, these polymers have found success in resorbable sutures, biodegradable implants, and even monolithic, biodegradable platforms for sustained release of therapeutics (e.g., proteins and small molecules) and diagnostics. Few fields have gained more attention in drug delivery through polymeric NPs than cancer therapy. However, the clinical translational of polymeric nanomedicines for treating solid tumors has not been congruent with the fervor or funding in this particular field of research. Here, we attempt to provide a comprehensive snapshot of polyester NPs in the context of chemotherapeutic delivery. This includes a preliminary exploration of the polymeric nanomedicine in the cancer research space. We examine the various processes for producing polyester NPs, including methods for surface-functionalization, and related challenges. After a detailed overview of the multiple factors involved with the delivery of NPs to solid tumors, the crosstalk between particle design and interactions with biological systems is discussed. Finally, we report state-of-the-art approaches toward effective delivery of NPs to tumors, aiming at identifying new research areas and re-evaluating the reasons why some research avenues have underdelivered. We hope our effort will contribute to a better understanding of the gap to fill and delineate the future research work needed to bring polyester-based NPs closer to clinical application. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Measuring Erosion of Biodegradable Polymers in Brimonidine Drug Delivery Implants by Quantitative Proton NMR Spectroscopy (q-HNMR)

Erosion of biodegradable polymeric excipients, such as polylactic acid (PLA) and polylactic-co-glycolic acid (PLGA), is generally characterized by microbalance for the remaining mass of PLA and/or PLGA and Gel Permeation Chromatography (GPC) for molecular weight (MW) decrease. For polymer erosion studies of intravitreal sustained release brimonidine implants, however, both microbalance and GPC present several challenges. Mass loss measurement by microbalance does not have specificity for excipient polymers and drug substances. Accuracy of the remaining mass by weighing could also be low due to sample mass loss through retrieval-drying steps, especially at later drug release (DR) time points. When measuring the decrease of polymer MW by GPC, trace amounts of polymeric degradants (oligomers and/or monomers) trapped inside the implants during DR tests may not be measurable due to sensitivity limitations of the GPC detector and column MW range. Previous efforts to measure remained PLGA weight of dexamethasone micro-implants using qNMR with external calibration have been performed, however, these measurements do not account for chemical structure changes (i.e. LA to GA ratio changes from time zero) of PLGA implants during drug release tests. Here, a qNMR method with an internal standard was developed to monitor the following changes in micro-implants during drug release tests: 1. The remaining overall PLA/PLGA mass. 2. The remaining lactic acid (LA), glycolic acid (GA) unit and PLGA's lauryl ester end group percentages. 3. The trace content of PLA/PLGA oligomers as degradants retained in the implants. Unlike microbalance analysis, qNMR has both specificity for drug substance, excipient polymer, and accuracy due to minimal implant loss during sample preparation. Compared to the overall PLA/PLGA remaining mass generally monitored in erosion studies, the percentage of remaining LA, GA, and the ester end group provide more information about the microstructure change (such as hydrophobicity) of PLA/PLGA. Additionally, the qNMR method can complement GPC methods by measuring the change of remaining PLA and PLGA oligomer concentrations in brimonidine implants, with tenfold less sample and no MW cutoff. The qNMR method can be used as a sensitive tool for both polymer excipient characterization and kinetics studies of brimonidine implant erosion.

Bioelectronics for electrical stimulation: materials, devices and biomedical applications

Bioelectronics is a hot research topic, yet an important tool, as it facilitates the creation of advanced medical devices that interact with biological systems to effectively diagnose, monitor and treat a broad spectrum of health conditions. Electrical stimulation (ES) is a pivotal technique in bioelectronics, offering a precise, non-pharmacological means to modulate and control biological processes across molecular, cellular, tissue, and organ levels. This method holds the potential to restore or enhance physiological functions compromised by diseases or injuries by integrating sophisticated electrical signals, device interfaces, and designs tailored to specific biological mechanisms. This review explains the mechanisms by which ES influences cellular behaviors, introduces the essential stimulation principles, discusses the performance requirements for optimal ES systems, and highlights the representative applications. From this review, we can realize the potential of ES based bioelectronics in therapy, regenerative medicine and rehabilitation engineering technologies, ranging from tissue engineering to neurological technologies, and the modulation of cardiovascular and cognitive functions. This review underscores the versatility of ES in various biomedical contexts and emphasizes the need to adapt to complex biological and clinical landscapes it addresses.