In Situ Forming Injectable Thermoresponsive Hydrogels for Controlled Delivery of Biomacromolecules

The Method of Direct and Reverse Phase Portraits as a Tool for Systematizing the Results of Studies of Phase Transitions in Solutions of Thermosensitive Polymers

It is shown that a more than significant amount of experimental data obtained in the field of studying systems based on thermosensitive hydrophilic polymers and reflected in the literature over the past decades makes the issue of their systematization and classification relevant. This, in turn, makes relevant the question of choosing the appropriate classification criteria. It is shown that the basic classification feature can be the number of phase transition stages, which can vary from one to four or more depending on the nature of the temperature-sensitive system. In this work, the method of inverse phase portraits is proposed for the first time. It was intended, among other things, to identify the number of phase transition stages. Moreover, the accuracy of this method significantly exceeds the accuracy of the previously used method of direct phase portraits since, for the first time, the operation of numerical differentiation is replaced by the operation of numerical integration. A specific example of the application of the proposed method for the analysis of a previously studied temperature-sensitive system is presented. It is shown that this method also allows for a quantitative comparison between the results obtained by the differential calorimetry method and the turbidimetry method. Issues related to increasing the resolution of the method of direct phase portraits are discussed.

Propelling Minimally Invasive Tissue Regeneration With Next-Era Injectable Pre-Formed Scaffolds

The growing aging population, with its associated chronic diseases, underscores the urgency for effective tissue regeneration strategies. Biomaterials play a pivotal role in the realm of tissue reconstruction and regeneration, with a distinct shift toward minimally invasive (MI) treatments. This transition, fueled by engineered biomaterials, steers away from invasive surgical procedures to embrace approaches offering reduced trauma, accelerated recovery, and cost-effectiveness. In the realm of MI tissue repair and cargo delivery, various techniques are explored. While in situ polymerization is prominent, it is not without its challenges. This narrative review explores diverse biomaterials, fabrication methods, and biofunctionalization for injectable pre-formed scaffolds, focusing on their unique advantages. The injectable pre-formed scaffolds, exhibiting compressibility, controlled injection, and maintained mechanical integrity, emerge as promising alternative solutions to in situ polymerization challenges. The conclusion of this review emphasizes the importance of interdisciplinary design facilitated by synergizing fields of materials science, advanced 3D biomanufacturing, mechanobiological studies, and innovative approaches for effective MI tissue regeneration.

Intramyocardial delivery of injectable hydrogel with arctigenin alleviated myocardial ischemia-reperfusion injury in rats

Arctigenin belongs to a major bioactive component of Fructus arctii and has been found with cardioprotective effects on rats with ischemia‒reperfusion (I/R) injury. The application of arctigenin is limited due to poor water solubility and low bioavailability. Hydrogel drug delivery systems can improve the efficacy and safety of drugs, increase drug utilization, and reduce side effects. We hypothesized that hydrogels containing arctigenin would facilitate the effect of arctigenin and alleviate I/R injury in the rat heart. Presently, adult Sprague-Dawley (SD) rats were subjected to 1 h of I/R injury, then hydrogels comprising arctigenin were implanted into the myocardium of rats. Triphenyl tetrazolium chloride staining, hematoxylin-eosin staining, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining and Western blot were performed for evaluating the infarct size, histopathological, and vital protein alterations of hearts. It was discovered that the hydrogel combined with arctigenin abated apoptosis and reduced infarct size. In addition, the results of echocardiography and Masson staining suggested that the hydrogel with arctigenin improved cardiac function, restrained myocardial fibrosis, and activated AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1). Collectively, the injectable hydrogel delivery system enhances the effect of arctigenin, which may play a protective role in I/R injury by activating AMPK and SIRT1.

ECM-mimetic, NSAIDs loaded thermo-responsive, immunomodulatory hydrogel for rheumatoid arthritis treatment

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease, and it leads to irreversible inflammation in intra-articular joints. Current treatment approaches for RA include non-steroidal anti-inflammatory drugs (NSAIDs), disease-modifying anti-rheumatic drugs (DMARDs), corticosteroids, and biological agents. To overcome the drug-associated toxicity of conventional therapy and transdermal tissue barrier, an injectable NSAID-loaded hydrogel system was developed and explored its efficacy.

RESULTS

The surface morphology and porosity of the hydrogels indicate that they mimic the natural ECM, which is greatly beneficial for tissue healing. Further, NSAIDs, i.e., diclofenac sodium, were loaded into the hydrogel, and the in vitro drug release pattern was found to be burst release for 24 h and subsequently sustainable release of 50% drug up to 10 days. The DPPH assay revealed that the hydrogels have good radical scavenging activity. The biocompatibility study carried out by MTT assay proved good biocompatibility and anti-inflammatory activity of the hydrogels was carried out by gene expression study in RAW 264.7 cells, which indicate the downregulation of several key inflammatory genes such as COX-2, TNF-α & 18s.

CONCLUSION

In summary, the proposed ECM-mimetic, thermo-sensitive in situ hydrogels may be utilized for intra-articular inflammation modulation and can be beneficial by reducing the frequency of medication and providing optimum lubrication at intra-articular joints.

Thermo-sensitive PLGA-PEG-PLGA hydrogel for sustained release of EGF to inhibit cervical cancer recurrence

Overexpression of epidermal growth factor receptor (EGFR) in cancer is a key cause of recurrence of cervical cancer (CC). Although the EGF-EGFR pathway has been studied for decades, preventing tumor growth and recurrence caused by peripheral EGF remains a great challenge. In this work, a strategy is proposed to reduce the stimulation of high concentration EGF on tumor growth by using a thermo-sensitive hydrogel. The hydrogel is a triblock copolymer composed of polyethylene glycol (PEG) and poly (lactide glycolide) (PLGA). Based on the excellent temperature sensitivity, carrier capacity, swelling property and biocompatibility, the hydrogel can absorb the liquid around the tumor by injection and release EGF continuously at low concentration. The inhibitory effect of hydrogel on tumor growth is fully confirmed by an implanted tumor mouse model with human cervical cancer cell lines (HeLa) using triple-immunodeficient NCG mice. Compared with free EGF, the EGF-loaded hydrogel can hardly induce surface plasmon resonance (SPR) response, which proves that hydrogel can effectively weaken cytoskeleton rearrangement and inhibit cell migration by continuously releasing low concentration EGF. In addition, the EGF-loaded hydrogel can reduce cell proliferation by delaying the progress of cell cycle progression. Taken together, the hydrogel can effectively protect tumor microenvironment from the stimulation of high concentration EGF, delay cancer cellular processes and tumor growth, and thus providing an approach for inhibiting tumor recurrence of CC.

Recent advances in fabricating injectable hydrogels via tunable molecular interactions for bio-applications

Hydrogels with three-dimensional structures have been widely applied in various applications because of their tunable structures, which can be easily tailored with desired functionalities. However, the application of hydrogel materials in bioengineering is still constrained by their limited dosage flexibility and the requirement of invasive surgical procedures. Compared to traditional hydrogels, injectable hydrogels, with shear-thinning and/or in situ formation properties, simplify the implantation process and reduce tissue invasion, which can be directly delivered to target sites using a syringe injection, offering distinct advantages over traditional hydrogels. These injectable hydrogels incorporate physically non-covalent and/or dynamic covalent bonds, granting them self-healing abilities to recover their structural integrity after injection. This review summarizes our recent progress in preparing injectable hydrogels and discusses their performance in various bioengineering applications. Moreover, the underlying molecular interaction mechanisms that govern the injectable and functional properties of hydrogels were characterized by using nanomechanical techniques such as surface forces apparatus (SFA) and atomic force microscopy (AFM). The remaining challenges and future perspectives on the design and application of injectable hydrogels are also discussed. This work provides useful insights and guides future research directions in the field of injectable hydrogels for bioengineering.

Programmed release of vascular endothelial growth factor and exosome from injectable chitosan nanofibrous microsphere-based PLGA-PEG-PLGA hydrogel for enhanced bone regeneration

The healing of large bone defects remains a significant challenge in clinical practice. Accelerating both angiogenesis and osteogenesis can promote effective bone healing. In the natural healing process, angiogenesis precedes osteogenesis, providing a blood supply that supports the subsequent progression of osteogenesis. Developing a biomimetic scaffold that mimics the in vivo environment and promotes the proper sequence of vascularization followed by ossification is crucial for successful bone regeneration. In this study, a novel injectable dual-drug programmed releasing chitosan nanofibrous microsphere-based poly(D, l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(D,l-lactide-co-glycolide) (PLGA-PEG-PLGA) hydrogel is fabricated by incorporating vascular endothelial growth factor (VEGF) and microspheres loaded with dental pulp stem cells-derived exosomes (DPSCs-Exo). Rapid release of VEGF promotes the swift initiation of angiogenesis, while DPSCs-Exo release ensures persistent osteogenesis. Our results demonstrate that chitosan microsphere-based PLGA-PEG-PLGA hydrogel significantly promotes angiogenesis in human umbilical vascular endothelial cells and enhances the osteogenic differentiation of pre-osteoblasts. Furthermore, in vivo transplantation of this injectable chitosan microsphere-based PLGA-PEG-PLGA hydrogel into calvarial bone defects markedly promotes bone formation. Overall, our study provides a promising approach for improving bone regeneration by temporally replicating the behavior of angiogenesis and osteogenesis.

Engineered therapeutic proteins for sustained-release drug delivery systems

Proteins play a vital role in diverse biological processes in the human body, and protein therapeutics have been applied to treat different diseases such as cancers, genetic disorders, autoimmunity, and inflammation. Protein therapeutics have demonstrated their advantages, such as specific pharmaceutical effects, low toxicity, and strong solubility. However, several disadvantages arise in clinical applications, including short half-life, immunogenicity, and low permeation, leading to reduced drug effectiveness. The structure of protein therapeutics can be modified to increase molecular size, leading to prolonged stability and increased plasma half-life. Notably, the controlled-release delivery systems for the sustained release of protein drugs and preserving the stability of cargo proteins are envisioned as a potential approach to overcome these challenges. In this review, we summarize recent research progress related to structural modifications (PEGylation, glycosylation, poly amino acid modification, and molecular biology-based strategies) and promising long-term delivery systems, such as polymer-based systems (injectable gel/implants, microparticles, nanoparticles, micro/nanogels, functional polymers), lipid-based systems (liposomes, solid lipid nanoparticles, nanostructured lipid carriers), and inorganic nanoparticles exploited for protein therapeutics. STATEMENT OF SIGNIFICANCE: In this review, we highlight recent advances concerning modifying proteins directly to enhance their stability and functionality and discuss state-of-the-art methods for the delivery and controlled long-term release of active protein therapeutics to their target site. In terms of drug modifications, four widely used strategies, including PEGylation, poly amino acid modification, glycosylation, and genetic, are discussed. As for drug delivery systems, we emphasize recent progress relating to polymer-based systems, lipid-based systems developed, and inorganic nanoparticles for protein sustained-release delivery. This review points out the areas requiring focused research attention before the full potential of protein therapeutics for human health and disease can be realized.

Stimuli-Responsive Hydrogels for Protein Delivery

Proteins and peptides are potential therapeutic agents, but their physiochemical properties make their use as drug substances challenging. Hydrogels are hydrophilic polymeric networks that can swell and retain high amounts of water or biological fluids without being dissolved. Due to their biocompatibility, their porous structure, which enables the transport of various peptides and proteins, and their protective effect against degradation, hydrogels have gained prominence as ideal carriers for these molecules' delivery. Particularly, stimuli-responsive hydrogels exhibit physicochemical transitions in response to subtle modifications in the surrounding environment, leading to the controlled release of entrapped proteins or peptides. This review is focused on the application of these hydrogels in protein and peptide delivery, including a brief overview of therapeutic proteins and types of stimuli-responsive polymers.

Recent Advances in Formulations for Long-Acting Delivery of Therapeutic Peptides

Recent preclinical and clinical studies have focused on the active area of therapeutic peptides due to their high potency, selectivity, and specificity in treating a broad range of diseases. However, therapeutic peptides suffer from multiple disadvantages, such as limited oral bioavailability, short half-life, rapid clearance from the body, and susceptibility to physiological conditions (e.g., acidic pH and enzymolysis). Therefore, high peptide dosages and dose frequencies are required for effective patient treatment. Recent innovations in pharmaceutical formulations have substantially improved therapeutic peptide administration by providing the following advantages: long-acting delivery, precise dose administration, retention of biological activity, and improvement of patient compliance. This review discusses therapeutic peptides and challenges in their delivery and explores recent peptide delivery formulations, including micro/nanoparticles (based on lipids, polymers, porous silicon, silica, and stimuli-responsive materials), (stimuli-responsive) hydrogels, particle/hydrogel composites, and (natural or synthetic) scaffolds. This review further covers the applications of these formulations for prolonged delivery and sustained release of therapeutic peptides and their impact on peptide bioactivity, loading efficiency, and (in vitro/in vivo) release parameters.

Bioactive Materials for Bone Regeneration: Biomolecules and Delivery Systems

Novel tissue regeneration strategies are constantly being developed worldwide. Research on bone regeneration is noteworthy, as many promising new approaches have been documented with novel strategies currently under investigation. Innovative biomaterials that allow the coordinated and well-controlled repair of bone fractures and bone loss are being designed to reduce the need for autologous or allogeneic bone grafts eventually. The current engineering technologies permit the construction of synthetic, complex, biomimetic biomaterials with properties nearly as good as those of natural bone with good biocompatibility. To ensure that all these requirements meet, bioactive molecules are coupled to structural scaffolding constituents to form a final product with the desired physical, chemical, and biological properties. Bioactive molecules that have been used to promote bone regeneration include protein growth factors, peptides, amino acids, hormones, lipids, and flavonoids. Various strategies have been adapted to investigate the coupling of bioactive molecules with scaffolding materials to sustain activity and allow controlled release. The current manuscript is a thorough survey of the strategies that have been exploited for the delivery of biomolecules for bone regeneration purposes, from choosing the bioactive molecule to selecting the optimal strategy to synthesize the scaffold and assessing the advantages and disadvantages of various delivery strategies.

Development of double crosslinked sodium alginate/chitosan based hydrogels for controlled release of metronidazole and its antibacterial activity

Double network sodium alginate/chitosan hydrogels were prepared using calcium chloride (CaCl2) and glutaraldehyde as the crosslinking agents by the ionotropic interaction method for controlled metronidazole release. The effect of polymer ratios and CaCl2 amount is investigated by the developing porosity, gel fraction, and extent of swelling in simulated physiological fluids. Interaction between the polymers with the formation of crosslinked structures, good stability, phase nature, and morphology of the hydrogels is revealed by Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. A sodium alginate/chitosan hydrogel (weight ratio of 75:25) crosslinked with two percent CaCl2 is chosen for the in-situ loading of 200 mg of metronidazole. The drug release kinetics using different models show that the best-fit Korsmeyer-Peppas model suggests metronidazole release from the matrix follows diffusion and swelling-controlled time-dependent non-Fickian transport related to hydrogel erosion. This composition displays enhanced antimicrobial activity against Staphylococcus aureus and Escherichia coli.

Polymeric in situ forming depots for long-acting drug delivery systems

Polymeric in situ forming depots have emerged as highly promising drug delivery systems for long-acting applications. Their effectiveness is attributed to essential characteristics such as biocompatibility, biodegradability, and the ability to form a stable gel or solid upon injection. Moreover, they provide added versatility by complementing existing polymeric drug delivery systems like micro- and nanoparticles. The formulation's low viscosity facilitates manufacturing unit operations and enhances delivery efficiency, as it can be easily administered via hypodermic needles. The release mechanism of drugs from these systems can be predetermined using various functional polymers. To enable unique depot design, numerous strategies involving physiological and chemical stimuli have been explored. Important assessment criteria for in situ forming depots include biocompatibility, gel strength and syringeability, texture, biodegradation, release profile, and sterility. This review focuses on the fabrication approaches, key evaluation parameters, and pharmaceutical applications of in situ forming depots, considering perspectives from academia and industry. Additionally, insights about the future prospects of this technology are discussed.

Emerging frontiers in drug delivery with special focus on novel techniques for targeted therapies

The management and treatment of disease are achieved via the use of pharmacologically active substances or drugs. Drugs do not, however, have an intrinsic ability to be effective; rather, how well they work depends on how they are administered or supplied. Treatment of a variety of biological illnesses, such as autoimmune disorders, cancer, and bacterial infections, requires effective drug delivery. Drug absorption, distribution, metabolism, duration of therapeutic impact, pharmacokinetics, excretion, and toxicity can all be impacted by drug administration. Improved chemistry and materials are required for the delivery of therapeutic concentration of novel treatments to the specified targets within the body, as well as for the necessary duration of time. This requirement is accompanied by the development of new therapeutics. Formulating a medication as a DDS is a promising strategy for directly addressing numerous typical barriers to adherence, such as frequent dosage, such as frequent dosage, side effects, and a delayed beginning of the action. In the current review, we give a compendium of drug delivery and controlled release and subsequently highlight some of the newest developments in the realm, with a particular emphasis on cutting-edge methods for targeted therapy. In each instance, we outline the obstacles to efficient drug administration as well as the chemical and material developments that are allowing the sector to overcome these obstacles and have a positive clinical impact.

Current Role and Potential of Polymeric Biomaterials in Clinical Obesity Treatment

The rise of obesity and associated fatal diseases has taken a massive toll worldwide. Despite the existing pharmaceuticals and bariatric surgeries, these approaches manifest limited efficacy or accompany various side effects. Therefore, researchers seek to facilitate the prolonged and specific delivery of therapeutics. Or else, to mimic the essential part of "gastric bypass" by physically blocking excessive absorption via less invasive methods. To achieve these goals, polymeric biomaterials have gained tremendous interest recently. They are known for synthesizing hydrogels, microneedle patches, mucoadhesive coatings, polymer conjugates, and so forth. In this Review, we provide insights into the current studies of polymeric biomaterials in the prevention and treatment of obesity, inspiring future improvements in this regime of study.

An Overview of Stimuli-Responsive Intelligent Antibacterial Nanomaterials

Drug-resistant bacteria and infectious diseases associated with biofilms pose a significant global health threat. The integration and advancement of nanotechnology in antibacterial research offer a promising avenue to combat bacterial resistance. Nanomaterials possess numerous advantages, such as customizable designs, adjustable shapes and sizes, and the ability to synergistically utilize multiple active components, allowing for precise targeting based on specific microenvironmental variations. They serve as a promising alternative to antibiotics with diverse medical applications. Here, we discuss the formation of bacterial resistance and antibacterial strategies, and focuses on utilizing the distinctive physicochemical properties of nanomaterials to achieve inherent antibacterial effects by investigating the mechanisms of bacterial resistance. Additionally, we discuss the advancements in developing intelligent nanoscale antibacterial agents that exhibit responsiveness to both endogenous and exogenous responsive stimuli. These nanomaterials hold potential for enhanced antibacterial efficacy by utilizing stimuli such as pH, temperature, light, or ultrasound. Finally, we provide a comprehensive outlook on the existing challenges and future clinical prospects, offering valuable insights for the development of safer and more effective antibacterial nanomaterials.

Gemcitabine and rapamycin-loaded mixed polymeric thermogel for metastatic pancreatic cancer therapy

Pancreatic ductal adenocarcinoma (PDAC) is the 4th leading cause of cancer-related death and has a poor 5-year overall survival. The superior therapeutic benefits of combination or co-administration of drugs as intraperitoneal chemotherapy have increased interest in developing strategies to deliver chemotherapeutic agents to patients safely. In this study, we prepared a gel comprising the thermosensitive poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) polymer and gemcitabine (GEM), which is currently used as the primary chemotherapy for PDAC and rapamycin (RAPA), a mammalian TOR (mTOR) inhibitor, to deliver the drug through intraperitoneal injection. We performed in vitro cytotoxicity experiments to verify the synergistic effects of the two drugs at different molar ratios and characterized the physicochemical properties of the GEM, RAPA, and GEM/RAPA-loaded thermosensitive PLGA-PEG-PLGA gels, hereafter referred to as (g(G), g(R), and g(GR)), respectively. The g(GR) comprising PLGA-PEG-PLGA polymer (25% w/v) and GEM and RAPA at a molar ratio of 11:1 showed synergism and was optimized. An in vitro cytotoxicity assay was performed by treating Panc-1-luc2 tumor spheroids with g(G), g(R), or g(GR). The g(GR) treatment group showed a 2.75-fold higher inhibition rate than the non-treated (NT) and vehicle-treated groups. Furthermore, in vivo drug release assay in mice by intraperitoneal injection of g(G), g(R), or g(GR) showed a more rapid release rate of GEM than RAPA, similar to the in vitro release pattern. The drugs in the gel were released faster in vivo than in vitro and degraded in 48 h. In addition, g(GR) showed the highest anti-tumor efficacy with no toxicity to mice. These results provide evidence for the safety and efficacy of g(GR) for intraperitoneal drug delivery. This study will assist in developing and clinically administering topical anti-cancer formulations.

Optimization of In Situ Gel-Forming Chlorhexidine-Encapsulated Polymeric Nanoparticles Using Design of Experiment for Periodontitis

Periodontitis is a chronic inflammatory disease of the gums caused by pathogenic microorganisms damaging and destroying periodontal tissues. Chlorhexidine digluconate (CHX) is a commonly used antimicrobial agent for the treatment of periodontitis. However, it has many drawbacks, such as toxicity due to the high dosage required, low prolonged release, and low adhesion in the periodontal pocket. The objective of this study was to develop and optimize CHX-encapsulated polymeric nanoparticles (NPs) loaded into in situ gel-forming (ISGF) using design of experiment (DoE) to improve the treatment of periodontitis and overcome these limitations. CHX-NPs were optimized from 0.046%w/v chitosan, 0.05%w/w gelatin, and 0.25%w/w CHX. After that, the optimized of CHX-NPs was loaded into a thermosensitive ISGF, which was a mixture of 15%w/v Poloxamer 407 and 1% hydroxypropyl methylcellulose (HPMC). The optimized CHX-NPs, loaded into ISGF, was evaluated by measuring gelling temperature and time, pH, viscosity, compatibility, in vitro drug release, antibacterial activity, cytotoxicity, and stability. The results showed that the size, PDI, and zeta potential of optimized CHX-NPs were 53.07±10.17 nm, 0.36±0.02, and 27.63±4.16 mV, respectively. Moreover, the optimized ISGF loading CHX-NPs showed a gelling temperature at 34.3±1.2°C within 120.00±17.32 s with a pH value of 4.06. The viscosity of the formulations at 4°C was 54.33±0.99 cP. The DSC and FTIR showed no interaction between ingredients. The optimal formulations showed a prolonged release of up to 7 days while providing potential antibacterial activity and were safe for normal gingival fibroblast cells. Moreover, the formulations had high stability at 4°C and 25°C for 3 months. In conclusion, the study achieved the successful development of ISGF loading CHX-NPs formulations for effectiveness use in periodontal treatment.

Erythropoietin-PLGA-PEG as a local treatment to promote functional recovery and neurovascular regeneration after peripheral nerve injury

Background

Traumatic peripheral nerve injury (TPNI) is a major medical problem with no universally accepted pharmacologic treatment. We hypothesized that encapsulation of pro-angiogenic erythropoietin (EPO) in amphiphilic PLGA-PEG block copolymers could serve as a local controlled-release drug delivery system to enhance neurovascular regeneration after nerve injury.

Methods

In this study, we synthesized an EPO-PLGA-PEG block copolymer formulation. We characterized its physiochemical and release properties and examined its effects on functional recovery, neural regeneration, and blood vessel formation after sciatic nerve crush injury in mice.

Results

EPO-PLGA-PEG underwent solution-to-gel transition within the physiologically relevant temperature window and released stable EPO for up to 18 days. EPO-PLGA-PEG significantly enhanced sciatic function index (SFI), grip strength, and withdrawal reflex post-sciatic nerve crush injury. Furthermore, EPO-PLGA-PEG significantly increased blood vessel density, number of junctions, and myelinated nerve fibers after injury.

Conclusion

This study provides promising preclinical evidence for using EPO-PLGA-PEG as a local controlled-release treatment to enhance functional outcomes and neurovascular regeneration in TPNI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01666-5.

Intracranial In Situ Thermosensitive Hydrogel Delivery of Temozolomide Accomplished by PLGA–PEG–PLGA Triblock Copolymer Blending for GBM Treatment

Glioblastoma (GBM) recurrence after surgical excision has grown to be a formidable obstacle to conquer. In this research, biodegradable thermosensitive triblock copolymer, poly(D, L–lactic acid–co–glycolic acid)–b–poly(ethylene glycol)–b–poly(D, L–lactic acid–co–glycolic acid (PLGA–PEG–PLGA) was utilized as the drug delivery system, loading with micronized temozolomide(micro-TMZ) to form an in situ drug–gel depot inside the resection cavity. The rheology studies revealed the viscoelastic profile of hydrogel under various conditions. To examine the molecular characteristics that affect gelation temperature, ¹H–NMR, inverse gated decoupling ¹³C–NMR, and GPC were utilized. Cryo-SEM and XRD were intended to disclose the appearance of the hydrogel and the micro-TMZ existence state. We worked out how to blend polymers to modify the gelation point (T_gel) and fit the correlation between T_gel and other dependent variables using linear regression. To simulate hydrogel dissolution in cerebrospinal fluid, a membraneless dissolution approach was used. In vitro, micro-TMZ@PLGA–PEG–PLGA hydrogel exhibited Korsmeyer–Peppas and zero–order release kinetics in response to varying drug loading, and in vivo, it suppressed GBM recurrence at an astoundingly high rate. Micro-TMZ@PLGA–PEG–PLGA demonstrates a safer and more effective form of chemotherapy than intraperitoneal TMZ injection, resulting in a spectacular survival rate (40%, n = 10) that is much more than intraperitoneal TMZ injection (22%, n = 9). By proving the viability and efficacy of micro-TMZ@PLGA–PEG–PLGA hydrogel, our research established a novel chemotherapeutic strategy for treating GBM recurrence.

Branched PCL-Based Thermogelling Copolymers: Controlling Polymer Architecture to Tune Drug Release Profiles

Temperature-responsive hydrogels, or thermogels, are a unique class of biomaterials that show facile and spontaneous transition from solution to gel when warmed. Their high biocompatibility, and ease of formulation with both small molecule drugs and biologics have made these materials prime candidates as injectable gel depots for sustained local drug delivery. At present, controlling the kinetics and profile of drug release from thermogels is achieved mainly by varying the ratio of hydrophobic: hydrophilic composition and the polymer molecular weight. Herein, we introduce polymer branching as a hitherto-overlooked polymer design parameter that exhibits profound influences on the rate and profile of drug release. Through a family of amphiphilic thermogelling polymers with systematic variations in degree of branching, we demonstrate that more highly-branched polymers are able to pack less efficiently with each other during thermogel formation, with implications on their physical properties and stability towards gel erosion. This in turn resulted in faster rates of release for both encapsulated small molecule hydrophobic drug and protein. Our results demonstrate the possibility of exploiting polymer branching as a hitherto-overlooked design parameter for tailoring the kinetics and profile of drug release in injectable thermogel depots.

Design, Preparation, and Evaluation of Enteric Coating Formulation of HPMC and Eudragit L100 on Carboxylated Agarose Hydrogel by Using Drug Tartrazine

Enteric-coated application on drug is used to prevent the drug from inactivation which are degraded by gastric enzyme. The present study is aimed at achieving controlled drug delivery in acidic medium of gastrointestinal tract (GIT) by enteric coating of hydroxy propyl methylcellulose (HPMC) and Eudragit L100 on carboxylated agarose hydrogel, creating a pH-dependent delivery system. Fourier-transformed infrared spectroscopy (FTIR) was for the detection of carboxylic group on agarose hydrogel, and scanning electron microscope (SEM) was used for the determination surface of prepared formulation. To check the pH sensitivity of enteric-coated formulation, different pH solution was used. It was found that the formulation was not dissolved in 1.2 but dissolve in pH 6.8 similarly; hydrogels lacking coating showed that tartrazine was more dissolved in pH 1.2, and less dissolved at pH 6.8. The release of tartrazine from the hydrogels was measured by using spectrophotometer and using a scanning electron microscope to examine the morphology and surface appearance of hydrogel capsules. This study revealed cracks on coated samples, while noncoated samples showed clear appearance with no cracks. Our findings revealed that this method could be useful for the development of an enteric coating drug delivery system.

Molecular bases for temperature sensitivity in supramolecular assemblies and their applications as thermoresponsive soft materials

Thermoresponsive supramolecular assemblies have been extensively explored in diverse formats, from injectable hydrogels to nanoscale carriers, for a variety of applications including drug delivery, tissue engineering and thermo-controlled catalysis. Understanding the molecular bases behind thermal sensitivity of materials is fundamentally important for the rational design of assemblies with optimal combination of properties and predictable tunability for specific applications. In this review, we summarize the recent advances in this area with a specific focus on the parameters and factors that influence thermoresponsive properties of soft materials. We summarize and analyze the effects of structures and architectures of molecules, hydrophilic and lipophilic balance, concentration, components and external additives upon the thermoresponsiveness of the corresponding molecular assemblies.

Injectable Composite Systems Based on Microparticles in Hydrogels for Bioactive Cargo Controlled Delivery

Engineering drug delivery systems (DDS) aim to release bioactive cargo to a specific site within the human body safely and efficiently. Hydrogels have been used as delivery matrices in different studies due to their biocompatibility, biodegradability, and versatility in biomedical purposes. Microparticles have also been used as drug delivery systems for similar reasons. The combination of microparticles and hydrogels in a composite system has been the topic of many research works. These composite systems can be injected in loco as DDS. The hydrogel will serve as a barrier to protect the particles and retard the release of any bioactive cargo within the particles. Additionally, these systems allow different release profiles, where different loads can be released sequentially, thus allowing a synergistic treatment. The reported advantages from several studies of these systems can be of great use in biomedicine for the development of more effective DDS. This review will focus on in situ injectable microparticles in hydrogel composite DDS for biomedical purposes, where a compilation of different studies will be analysed and reported herein.

Preclinical evaluation of methotrexate-loaded polyelectrolyte complexes and thermosensitive hydrogels as treatment for rheumatoid arthritis

This work proposes new methotrexate (MTX) loaded drug delivery systems (DDS) to treat rheumatoid arthritis via the intra-articular route: a poloxamer based thermosensitive hydrogel (MTX-HG), oligochitosan and hypromellose phthalate-based polyelectrolyte complexes (MTX-PEC) and their association (MTX-PEC-HG). MTX-PEC showed 470 ± 166 nm particle size, 0.298 ± 0.108 polydispersity index, +26 ± 2 mV and 74.3 ± 5.8% MTX efficiency entrapment and particle formation was confirmed by infrared spectroscopy and thermal analysis. MTX-HG and MTX-PEC-HG gelled at 36.7°C. MTX drug release profile was prolonged for MTX-HG and MTX-PEC-HG, and faster for MTX-PEC and free MTX. The in vivo effect of the MTX-DDSs systems was evaluated in induced arthritis rats as single intra-articular dose. The assessed parameters were the mechanical nociceptive threshold, the plasmatic IL-1β level and histological analysis of the tibiofemoral joint. MTX-HG and MTX-PEC-HG performance were similar to free MTX and worse than oral MTX, used as positive control. All DDSs showed some irritative effect, for which further studies are required. MTX-PEC was the best treatment on recovering cartilage damage and decreasing allodynia. Thus, MTX-PEC demonstrated potential to treat rheumatoid arthritis, with the possibility of decreasing the systemic exposure to the drug.

An overview of PLGA in-situ forming implants based on solvent exchange technique: effect of formulation components and characterization

As a result of the low oral bioavailability of several drugs, there is a renewed interest for parenteral administration to target their absorption directly into the blood bypassing the long gastrointestinal route and hepatic metabolism. In order to address the potential side effects of frequent injections, sustained release systems are the most popular approaches for achieving controlled long-acting drug delivery. Injectable in-situ forming implants (ISFIs) have gained greater popularity in comparison to other sustained systems. Their significant positive aspects are attributed to easier production, acceptable administration route, reduced dosing frequency and patient compliance achievement. ISFI systems, comprising biodegradable polymers such as poly (lactide-co-glycolide) (PLGA) based on solvent exchange mechanisms, are emerged as liquid formulations that develop solid or semisolid depots after injection and deliver drugs over extended periods. The drug release from ISFI systems is generally characterized by an initial burst during the matrix solidification, followed by diffusion processes and finally polymeric degradation and erosion. The choice of suitable solvent with satisfactory viscosity, miscibility and biocompatibility along with considerable PLGA hydrophobicity and molecular weights is fundamental for optimizing the drug release. This overview gives a particular emphasis on evaluations and the wide ranges of requirements needed to achieve reasonable physicochemical characteristics of ISFIs.

Subcutaneous Delivery of Albumin: Impact of Thermosensitive Hydrogels

Albumin demonstrates remarkable promises as a versatile carrier for therapeutic and diagnostic agents. However, noninvasive delivery of albumin-based therapeutics has been largely unexplored. In this study, injectable thermosensitive hydrogels were evaluated as sustained delivery systems for Cy5.5-labeled bovine serum albumin (BSA-Cy5.5). These hydrogels were prepared using aqueous solutions of Poloxamer 407 (P407) or poly(lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly(lactide-co-glycolide) (PLGA-PEG-PLGA), which could undergo temperature-triggered phase transition and spontaneously solidify into hydrogels near body temperature, serving as in situ depot for tunable cargo release. In vitro, these hydrogels were found to release BSA-Cy5.5 in a sustained manner with the release half-life of BSA-Cy5.5 from P407 and PLGA-PEG-PLGA hydrogels at 16 h and 105 h, respectively. Without affecting the bioavailability, subcutaneous administration of BSA-Cy5.5-laden P407 hydrogel resulted in delayed BSA-Cy5.5 absorption, which reached the maximum plasma level (T_max) at 24 h, whereas the T_max for subcutaneously administered free BSA-Cy5.5 solution was 8 h. Unexpectedly, subcutaneously injected BSA-Cy5.5-laden PLGA-PEG-PLGA hydrogel did not yield sustained BSA-Cy5.5 plasma level, the bioavailability of which was significantly lower than that of P407 hydrogel (p < 0.05). The near-infrared imaging of BSA-Cy5.5-treated mice revealed that a notable portion of BSA-Cy5.5 remained trapped within the subcutaneous tissues after 6 days following the subcutaneous administration of free solution or hydrogels, suggesting the discontinuation of BSA-Cy5.5 absorption irrespective of the formulations. These results suggest the opportunities of developing injectable thermoresponsive hydrogel formulations for subcutaneous delivery of albumin-based therapeutics.

Poly ethylene glycol (PEG)-Related controllable and sustainable antidiabetic drug delivery systems

Diabetes mellitus is one of the most challenging threats to global public health. To improve the therapy efficacy of antidiabetic drugs, numerous drug delivery systems have been developed. Polyethylene glycol (PEG) is a polymeric family sharing the same skeleton but with different molecular weights which is considered as a promising material for drug delivery. In the delivery of antidiabetic drugs, PEG captures much attention in the designing and preparation of sustainable and controllable release systems due to its unique features including hydrophilicity, biocompatibility and biodegradability. Due to the unique architecture, PEG molecules are also able to shelter delivery systems to decrease their immunogenicity and avoid undesirable enzymolysis. PEG has been applied in plenty of delivery systems such as micelles, vesicles, nanoparticles and hydrogels. In this review, we summarized several commonly used PEG-contained antidiabetic drug delivery systems and emphasized the advantages of stimuli-responsive function in these sustainable and controllable formations.

Type I Photoinitiator-Functionalized Block Copolymer Nanoparticles Prepared by RAFT-Mediated Polymerization-Induced Self-Assembly

Type I photoinitiators have been widely used in UV-vis curing technology for the fabrication of functional polymer materials such as coatings, inks, and adhesives. To overcome the drawbacks of using small molecular type I photoinitiators and expand the potential applications of UV-vis curing technology, attaching type I photoinitiators onto the surface of polymer colloids is an attractive strategy. Here we report a robust strategy for the efficient preparation of type I photoinitiator-functionalized block copolymer nanoparticles with various morphologies via aqueous reversible addition-fragmentation chain transfer (RAFT)-mediated polymerization-induced self-assembly (PISA), in which the photoinitiating ability of the type I photoinitiator end group provides a landscape for further functionalization. These block copolymer nanoparticles could also be used as heterogeneous photoinitiators to generate hydrogels with nanoparticles embedded inside. Significantly, the properties and functionalities of these hydrogels could be further controlled by using different block copolymer nanoparticles. This study provides a robust strategy toward the preparation of type I photoinitiator-functionalized block copolymer nanoparticles with the capacity to be modified with varying functionalities.