The effect of hyperbranched polyglycerol coatings on drug delivery using degradable polymer nanoparticles

Softening the tumor matrix through cholesterol depletion breaks the physical barrier for enhanced antitumor therapy

The tumor develops defense tactics, including conversing the mechanical characteristics of tumor cells and their surrounding environment. A recent study reported that cholesterol depletion stiffens tumor cells, which could enhance adaptive T-cell immunotherapy. However, it remains unclear whether reducing the cholesterol in tumor cells contributes to re-educating the stiff tumor matrix, which serves as a physical barrier against drug penetration. Herein, we found that depleting cholesterol from tumor cells can demolish the intratumor physical barrier by disrupting the mechanical signal transduction between tumor cells and the extracellular matrix through the destruction of lipid rafts. This disruption allows nanoparticles (H/S@hNP) to penetrate deeply, resulting in improved photodynamic treatment. Our research also indicates that cholesterol depletion can inhibit the epithelial-mesenchymal transition and repolarize tumor-associated macrophages from M2 to M1, demonstrating the essential role of cholesterol in tumor progression. Overall, this study reveals that a cholesterol-depleted, softened tumor matrix reduces the difficulty of drug penetration, leading to enhanced antitumor therapeutics.

Study of the Structure of Hyperbranched Polyglycerol Coatings and Their Antibiofouling and Antithrombotic Applications

While blood-contacting materials are widely deployed in medicine in vascular stents, catheters, and cannulas, devices fail in situ because of thrombosis and restenosis. Furthermore, microbial attachment and biofilm formation is not an uncommon problem for medical devices. Even incremental improvements in hemocompatible materials can provide significant benefits for patients in terms of safety and patency as well as substantial cost savings. Herein, a novel but simple strategy is described for coating a range of medical materials, that can be applied to objects of complex geometry, involving plasma-grafting of an ultrathin hyperbranched polyglycerol coating (HPG). Plasma activation creates highly reactive surface oxygen moieties that readily react with glycidol. Irrespective of the substrate, coatings are uniform and pinhole free, comprising O─C─O repeats, with HPG chains packing in a fashion that holds reversibly binding proteins at the coating surface. In vitro assays with planar test samples show that HPG prevents platelet adhesion and activation, as well as reducing (>3 log) bacterial attachment and preventing biofilm formation. Ex vivo and preclinical studies show that HPG-coated nitinol stents do not elicit thrombosis or restenosis, nor complement or neutrophil activation. Subcutaneous implantation of HPG coated disks under the skin of mice shows no evidence of toxicity nor inflammation.

In Vitro Biocompatibility and Endothelial Permeability of Branched Polyglycidols Generated by Ring-Opening Polymerization of Glycidol with B(C6F5)3 under Dry and Wet Conditions

Polyglycidol or polyglycerol (PG), a polyether widely used in biomedical applications, has not been extensively studied in its branched cyclic form (bcPG), despite extensive research on hyperbranched PG (HPG). This study explores the biomedical promise of bcPG, particularly its ability to cross the blood-brain barrier (BBB). We evaluate in vitro biocompatibility, endothelial permeability, and formation of branched linear PG (blPG) as topological impurities in the presence of water. Small angle X-ray scattering in solution revealed a fractal dimension of approximately two for bcPG and the mixture bc+blPG, suggesting random branching. Comparisons of cytotoxicity and endothelial permeability between bcPG, bc+blPG, and HPG in a BBB model using hCMEC/D3 cells showed different biocompatibility profiles and higher endothelial permeability for HPG. bcPG showed a tendency to accumulate around cell nuclei, in contrast to the behavior of HPG. This study contributes to the understanding of the influence of polymer topology on biological behavior.

Convergence of nanomedicine and neutrophils for drug delivery

Neutrophils have recently emerged as promising carriers for drug delivery due to their unique properties including rapid response toward inflammation, chemotaxis, and transmigration. When integrated with nanotechnology that has enormous advantages in improving treatment efficacy and reducing side effects, neutrophil-based nano-drug delivery systems have expanded the repertoire of nanoparticles employed in precise therapeutic interventions by either coating nanoparticles with their membranes, loading nanoparticles inside living cells, or engineering chimeric antigen receptor (CAR)-neutrophils. These neutrophil-inspired therapies have shown superior biocompatibility, targeting ability, and therapeutic robustness. In this review, we summarized the benefits of combining neutrophils and nanotechnologies, the design principles and underlying mechanisms, and various applications in disease treatments. The challenges and prospects for neutrophil-based drug delivery systems were also discussed.

Novel approach for enhancing skin allograft survival by bioadhesive nanoparticles loaded with rapamycin

Skin graft rejection is a significant challenge in skin allografts for skin defects, particularly in extensive burn injury patients when autografts are insufficient. Enhancing the survival duration of allogeneic skin grafts can improve the success rate of subsequent autologous skin grafting, thereby promoting the therapeutic efficacy for wound healing. Rapamycin (Rapa), a potent immunosuppressant with favorable efficacy in organ transplantation, is limited by its systemic administration-associated toxicity and side effects. Therefore, addressing the short survival time of allogeneic skin grafts and minimizing the toxicity related to systemic application of immunosuppressive agents is an urgent requirement. Here, we present a topical formulation based on bioadhesive poly (lactic acid)-hyperbranched polyglycerol nanoparticles (BNPs) with surface-modified encapsulation of Rapamycin (Rapa/BNPs), applied for local immunosuppression in a murine model of allogeneic skin grafts. Our Rapa/BNPs significantly prolong nanoparticle retention, reduce infiltration of T lymphocytes and macrophages, decrease the level of pro-inflammatory cytokines and ultimately extend skin allograft survival with little systemic toxicity compared to free Rapa or Rapamycin-loaded non-bioadhesive nanoparticles (Rapa/NNPs) administration. In conclusion, Rapa/BNPs effectively deliver local immunosuppression and demonstrate potential for enhancing skin allograft survival while minimizing localized inflammation, thus potentially increasing patient survival rates for various types of skin defects.

A nanocomposite hydrogel for co-delivery of multiple anti-biofilm therapeutics to enhance the treatment of bacterial biofilm-related infections

The characteristics of biofilms have exacerbated the issue of clinical antibiotic resistance, rendering it a pressing challenge in need of resolution. The combination of biofilm-dispersing agents and antibiotics can eliminate biofilms and promote healing synergistically in infected wounds. In this study, we developed a novel nanocomposite hydrogel (NC gel) comprised of the poly(lactic acid)-hyperbranched polyglycerol (PLA-HPG) based bioadhesive nanoparticles (BNPs) and a hydrophilic carboxymethyl chitosan (CS) network. The NC gel was designed to co-deliver two biofilm-dispersing agents (an NO-donor SNO, and an α-amylase Am) and an antibiotic, cefepime (Cef), utilizing a synergistic anti-biofilm mechanism in which Am loosens the matrix structure and NO promotes the release of biofilm bacteria via quorum sensing, and Cef kills bacteria. The drug-loaded NC gel (SNO/BNP/CS@Am-Cef) demonstrated sustained drug release, minimal cytotoxicity, and increased drug-bacterial interactions at the site of infection. When applied to mice infected with methicillin-resistant Staphylococcus aureus (MRSA) biofilms in vivo, SNO/BNP/CS@Am-Cef enhanced biofilm elimination and promoted wound healing compared to traditional antibiotic treatments. Our work demonstrates the feasibility of the co-delivery of biofilm-dispersing agents and antibiotics using the NC gel and presents a promising approach for the polytherapy of bacterial biofilm-related infections.

Breath Biopsy Reveals Systemic Immunothrombosis and Its Resolution through Bioorthogonal Dendritic Nanoprobes

Immunothrombosis, an inflammation-dependent activation of the coagulation cascade, leads to microthrombi formations in small vessels. It is a dreaded complication of COVID-19 and a major cause of respiratory failure. Due to their size and disseminated nature, microthrombi are currently undetectable. Here, noninvasive detection of a volatile reporter in the exhaled air is introduced for assessment of systemic immunothrombosis. A dendritic nanoprobe, containing high loading of a thrombin-sensitive substrate, is selectively cleaved by thrombin, resulting in release of a synthetic bioorthogonal volatile organic compound (VOC). The VOC is quantitated in the exhaled air biopsies via gas chromatography-mass spectrometry (GC-MS), allowing near real-time assessment of systemic immunothrombosis. The VOC detection can be further improved with more rapid and sensitive MS-based technologies. The amount of the VOC in the exhaled air decreases with resolution of the microvascular inflammation and intravascular fibrin depositions. Through conjugation of the thrombin-sensitive peptide with a rhodol derivative, a novel thrombin-sensitive fluorescent nanoprobe is developed for intravital visualization of thrombin activity in actively growing thrombi. These results establish unprecedented detection of thrombin activity in vivo, addressing this unmet medical need. This novel approach facilitates diagnosis of immunothrombosis in diseases such as diabetic complications, disseminated intravascular coagulation, and COVID-19.

Intrathecal delivery of nanoparticle PARP inhibitor to the cerebrospinal fluid for the treatment of metastatic medulloblastoma

The morbidity associated with pediatric medulloblastoma, in particular in patients who develop leptomeningeal metastases, remains high in the absence of effective therapies. Administration of substances directly into the cerebrospinal fluid (CSF) is one approach to circumvent the blood-brain barrier and focus delivery of drugs to the site of tumor. However, high rates of CSF turnover prevent adequate drug accumulation and lead to rapid systemic clearance and toxicity. Here, we show that PLA-HPG nanoparticles, made with a single-emulsion, solvent evaporation process, can encapsulate talazoparib, a PARP inhibitor (BMN-673). These degradable polymer nanoparticles improve the therapeutic index when delivered intrathecally and lead to sustained drug retention in the tumor as measured with PET imaging and fluorescence microscopy. We demonstrate that administration of these particles into the CSF, alone or in combination with systemically administered temozolomide, is a highly effective therapy for tumor regression and prevention of leptomeningeal spread in xenograft mouse models of medulloblastoma. These results provide a rationale for harnessing nanoparticles for the delivery of drugs limited by brain penetration and therapeutic index and demonstrate important advantages in tolerability and efficacy for encapsulated drugs delivered locoregionally.

Hydration-induced Void-containing Hydrogels for Encapsulation and Sustained Release of Small Hydrophilic Molecules

Efficient encapsulation and sustained release of small hydrophilic molecules from traditional hydrogel systems have been challenging due to the large mesh size of 3D networks and high water content. Furthermore, the encapsulated molecules are prone to early release from the hydrogel prior to use, resulting in a short shelf life of the formulation. Here, we present a hydration-induced void-containing hydrogel (HVH) based on hyperbranched polyglycerol-poly(propylene oxide)-hyperbranched polyglycerol (HPG-PPG-HPG) as a robust and efficient delivery system for small hydrophilic molecules. Specifically, after the HPG-PPG-HPG is incubated overnight at 4 °C in the drug solution, it is hydrated into a hydrogel containing micron-sized voids, which could encapsulate hydrophilic drugs and achieve 100% drug encapsulation efficiency. In addition, the voids are surrounded by a densely packed polymer matrix, which restricts drug transport to achieve sustained drug release. The hydrogel/drug formulation can be stored for several months without changing the drug encapsulation and release properties. HVH hydrogels are injectable due to shear thinning properties. In rats, a single injection of the HPG-PPG-HPG hydrogel containing 8 μg of tetrodotoxin (TTX) produced sciatic nerve block lasting up to 10 hours without any TTX-related systemic toxicity nor local toxicity to nerves and muscles.

PLA-HPG based coating enhanced anti-biofilm and wound healing of Shikonin in MRSA-infected burn wound

Burn wounds are susceptible to bacterial infections, including Methicillin-resistant Staphylococcus aureus (MRSA), which typically form biofilms and exhibit drug resistance. They also have specific feature of abundant exudate, necessitating frequent drug administration. Shikonin (SKN) has been reported to reverse MRSA drug resistance and possesses anti-biofilm and wound healing properties, however, it suffers from drawbacks of low solubility and instability. In this study, we developed PLA-HPG based bioadhesive nanoparticles SKN/BNP, which demonstrated a drug loading capacity of about 3.6%, and exhibited sustained-release behavior of SKN. The aldehyde groups present on the surface of BNP improved the local adhesion of SKN/BNP both in vitro and in vivo, thereby reducing the frequency of drug dosing in exudate-rich burn wounds. BNP alone enhanced proliferation and migration of the fibroblast, while SKN/BNP promoted fibroblast proliferation and migration as well as angiogenesis. Due to its bioadhesive property, BNP directly interacted with biofilm and enhanced the efficacy of SKN against MRSA biofilm in vitro. In a mouse model of MRSA-infected burn wounds, SKN/BNP demonstrated improved anti-biofilm and wound healing efficiency. Overall, our findings suggest that SKN/BNP holds great promise as a novel and effective treatment option for clinical applications in MRSA-infected burn wounds.

Nanoparticle Strategies to Improve the Delivery of Anticancer Drugs across the Blood-Brain Barrier to Treat Brain Tumors

Primary brain and central nervous system (CNS) tumors are a diverse group of neoplasms that occur within the brain and spinal cord. Although significant advances in our understanding of the intricate biological underpinnings of CNS neoplasm tumorigenesis and progression have been made, the translation of these discoveries into effective therapies has been stymied by the unique challenges presented by these tumors' exquisitely sensitive location and the body's own defense mechanisms (e.g., the brain-CSF barrier and blood-brain barrier), which normally protect the CNS from toxic insult. These barriers effectively prevent the delivery of therapeutics to the site of disease. To overcome these obstacles, new methods for therapeutic delivery are being developed, with one such approach being the utilization of nanoparticles. Here, we will cover the current state of the field with a particular focus on the challenges posed by the BBB, the different nanoparticle classes which are under development for targeted CNS tumor therapeutics delivery, and strategies which have been developed to bypass the BBB and enable effective therapeutics delivery to the site of disease.

Microneedle-Assisted Topical Delivery of Idebenone-Loaded Bioadhesive Nanoparticles Protect against UV-Induced Skin Damage

Ultraviolet (UV) radiation can penetrate the basal layer of the skin and induce profound alterations in the underlying dermal tissues, including skin pigmentation, oxidative stress, photoaging, glycation, and skin cancer. Idebenone (IDB), an effective antioxidant that suppresses melanin biosynthesis and glycation, can protect the skin from UV-induced damage, accounting for its use in commercial anti-aging formulations. Ideally, IDB formulations should retain IDB inside the skin for a sufficient period, despite disturbances such as sweating or swimming. Herein, we present an IDB topical formulation based on Tris (tris(hydroxymethyl)-aminomethane)-modified bioadhesive nanoparticles (Tris-BNPs) and microneedle-assisted delivery. We found that Tris-BNPs loaded with IDB (IDB/Tris-BNPs) effectively reached the basal layer of the skin and were retained for at least 4 days with a slow and continuous drug release profile, unlike non-bioadhesive nanoparticles (NNPs) and bioadhesive nanoparticles (BNPs) of similar sizes (ranging from 120-142 nm) and zeta-potentials (above -20 mV), which experienced a significant reduction in concentration within 24 h. Notably, IDB/Tris-BNPs showed superior performance against UV-induced damage relative to IDB/NNPs and IDB/BNPs. This effect was demonstrated by lower levels of reactive oxygen species and advanced glycation end-products in skin tissues, as well as suppressed melanogenesis. Therefore, the proposed IDB delivery strategy provided long-term protective effects against UV-induced skin damage.

Effective Treatment of Haemophilus influenzae-Induced Bacterial Conjunctivitis by a Bioadhesive Nanoparticle Reticulate Structure

Ocular formulations should provide an effective antibiotic concentration at the site of infection to treat bacterial eye infections. However, tears and frequent blinking accelerate the drug clearance rate and limit drug residence time on the ocular surface. This study describes a biological adhesion reticulate structure (BNP/CA-PEG) consisting of antibiotic-loaded bioadhesion nanoparticles (BNP/CA), with an average 500-600 nm diameter, and eight-arm NH₂-PEG-NH₂ for local and extended ocular drug delivery. This retention-prolonging effect is a function of the Schiff base reaction between groups on the surface of BNP and amidogen on PEG. BNP/CA-PEG showed significantly higher adhesion properties and better treatment efficacy in an ocular rat model with conjunctivitis in comparison to non-adhesive nanoparticles, BNP, or free antibiotics. Both in vivo safety experiment and in vitro cytotoxicity test verified the biocompatibility and biosafety of the biological adhesion reticulate structure, indicating a promising translational prospect for further clinical use.

Synthesis of hyperbranched polymer films via electrodeposition and oxygen-tolerant surface-initiated photoinduced polymerization

HYPOTHESIS

Hyperbranched polymers, not only possess higher functionality, but are also easier to prepare compared to dendrimers and dendric polymers. Combining electrodeposition and surface-initiated photoinduced electron transfer-reversible addition-fragmentation chain transfer (SI-PET-RAFT) polymerization is hypothesized to be a novel strategy for preparing hyperbranched polymer films on conductive surfaces without degassing.

EXPERIMENTS

Polymer brush grafted films with four different architectures (i.e. linear, branched, linear-block-branched, and branched-block-linear) were prepared on gold-coated glass substrates using electrodeposition, followed by SI-PET-RAFT polymerization. The resulting film structure and thickness, surface topology, absorption property, and electrochemical behavior were confirmed by spectroscopy, microscopy, microbalance technique, and impedance measurement.

FINDINGS

These hyperbranched polymer brushes were capable of forming a thicker but more uniformly covered films compared to linear polymer brush films, demonstrating that hyperbranched polymer films can be potentially useful for fabricating protective polymer coatings on various conductive surfaces.

In Situ Separable Nanovaccines with Stealthy Bioadhesive Capability for Durable Cancer Immunotherapy

Because of tumor heterogeneity and the immunosuppressive tumor microenvironment, most cancer vaccines typically do not elicit robust antitumor immunological responses in clinical trials. In this paper, we report findings about a bioadhesive nanoparticle (BNP)-based separable cancer vaccine, FeSHK@B-ovalbumin (OVA), to target multi-epitope antigens and exert effective cancer immunotherapy. After the FeSHK@B-OVA "nanorocket" initiates the "satellite-rocket separation" procedure in the acidic tumor microenvironment, the FeSHK@B "launch vehicle" can amplify intracellular oxidative stress persistently. This procedure allows for bioadhesiveness-mediated prolonged drug retention within the tumor tissue and triggers the immunogenic death of tumor cells that transforms the primary tumors into antigen depots, which acts synergistically with the OVA "satellite" to trigger robust antigen-specific antitumor immunity. The cooperation of these two immunostimulants not only efficiently inhibits the primary tumor growth and provokes durable antigen-specific immune activation in vivo but also activates a long-term and robust immune memory effect to resist tumor rechallenge and metastasis. These results highlight the enormous potential of FeSHK@B-OVA to serve as an excellent therapeutic and prophylactic cancer nanovaccine. By leveraging the antigen depots in situ and the synergistic effect among multi-epitope antigens, such a nanovaccine strategy with stealthy bioadhesion may offer a straightforward and efficient approach to developing various cancer vaccines for different types of tumors.

Anti-seed PNAs targeting multiple oncomiRs for brain tumor therapy

Glioblastoma (GBM) is one of the most lethal malignancies with poor survival and high recurrence rates. Here, we aimed to simultaneously target oncomiRs 10b and 21, reported to drive GBM progression and invasiveness. We designed short (8-mer) γ-modified peptide nucleic acids (sγPNAs), targeting the seed region of oncomiRs 10b and 21. We entrapped these anti-miR sγPNAs in nanoparticles (NPs) formed from a block copolymer of poly(lactic acid) and hyperbranched polyglycerol (PLA-HPG). The surface of the NPs was functionalized with aldehydes to produce bioadhesive NPs (BNPs) with superior transfection efficiency and tropism for tumor cells. When combined with temozolomide, sγPNA BNPs administered via convection-enhanced delivery (CED) markedly increased the survival (>120 days) of two orthotopic (intracranial) mouse models of GBM. Hence, we established that BNPs loaded with anti-seed sγPNAs targeting multiple oncomiRs are a promising approach to improve the treatment of GBM, with a potential to personalize treatment based on tumor-specific oncomiRs.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Emulsion-induced polymersomes taming tetrodotoxin for prolonged duration local anesthesia

Injectable local anesthetics that can provide a continuous nerve block approximating the duration of a pain state would be a life-changing solution for patients experiencing post-operative pain or chronic pain. Tetrodotoxin (TTX) is a site 1 sodium channel blocker that is extremely potent compared to clinically used local anesthetics. Challengingly, TTX doses are limited by its associated systemic toxicity, thus shortening the achievable duration of nerve blocks. Here, we explore emulsion-induced polymersomes (EIP) as a drug delivery system to safely use TTX for local anesthesia. By emulsifying hyperbranched polyglycerol-poly (propylene glycol)-hyperbranched polyglycerol (HPG-PPG-HPG) in TTX aqueous solution, HPG-PPG-HPG self-assembled into micrometer-sized polymersomes within seconds. The formed polymersomes have microscopically visible internal aqueous pockets that encapsulate TTX with an encapsulation efficiency of up to 94%. Moreover, the polymersomes are structurally stable, enabling sustained TTX release. In vivo, the freshly prepared EIP/TTX formulation can be directly injected and increased the tolerated dose of TTX in Sprague-Dawley rats to 11.5 μg without causing any TTX-related systemic toxicity. In the presence of the chemical penetration enhancer (CPE) sodium octyl sulfate (SOS), a single perineural injection of EIP/TTX/SOS formulation produced a reliable sciatic nerve block for 22 days with minimal local toxicity.

Pervaporation Polyurethane Membranes Based on Hyperbranched Organoboron Polyols

On the basis of aminoethers of boric acid (AEBA), polyurethane vapor-permeable and pervaporative membranes were obtained. AEBAs, the structure of which is modified by bulk adducts (EM) of diphenylol propane diglycidyl ether and ethanolamine, were studied. It turned out that AEBA exists in the form of clusters, and the use of EM as a result of partial destruction of associative interactions leads to a significant decrease in the size of AEBA-EM particles and their viscosity compared to unmodified AEBA. The introduction of EM into the composition of AEBA leads to a threefold increase in the vapor permeability of polyurethanes obtained on their basis. The observed effect is explained by the fact that a decrease in the size of clusters leads to loosening of their dense packing. Areas of clustering due to associative interactions of hydroxyl groups, together with the hydrophilic nature of polyoxyethylene glycol, create channels through which water molecules can penetrate. The increase in vapor permeability is accompanied by a multiple increase in the permeability coefficients in the pervaporative dehydration of isopropanol.

Polymer nanocarriers for targeted local delivery of agents in treating brain tumors

Glioblastoma (GBM), the deadliest brain cancer, presents a multitude of challenges to the development of new therapies. The standard of care has only changed marginally in the past 17 years, and few new chemotherapies have emerged to supplant or effectively combine with temozolomide. Concurrently, new technologies and techniques are being investigated to overcome the pharmacokinetic challenges associated with brain delivery, such as the blood brain barrier (BBB), tissue penetration, diffusion, and clearance in order to allow for potent agents to successful engage in tumor killing. Alternative delivery modalities such as focused ultrasound and convection enhanced delivery allow for the local disruption of the BBB, and the latter in particular has shown promise in achieving broad distribution of agents in the brain. Furthermore, the development of polymeric nanocarriers to encapsulate a variety of cargo, including small molecules, proteins, and nucleic acids, have allowed for formulations that protect and control the release of said cargo to extend its half-life. The combination of local delivery and nanocarriers presents an exciting opportunity to address the limitations of current chemotherapies for GBM toward the goal of improving safety and efficacy of treatment. However, much work remains to establish standard criteria for selection and implementation of these modalities before they can be widely implemented in the clinic. Ultimately, engineering principles and nanotechnology have opened the door to a new wave of research that may soon advance the stagnant state of GBM treatment development.

Strategies to overcome/penetrate the BBB for systemic nanoparticle delivery to the brain/brain tumor

Despite its prevalence in the management of peripheral tumors, compared to surgery and radiation therapy, chemotherapy is still a suboptimal intervention in fighting against brain cancer and cancer brain metastases. This discrepancy is mainly derived from the complicatedly physiological characteristic of intracranial tumors, including the presence of blood-brain barrier (BBB) and limited enhanced permeability and retention (EPR) effect attributed to blood-brain tumor barrier (BBTB), which largely lead to insufficient therapeutics penetrating to tumor lesions to produce pharmacological effects. Therefore, dependable methodologies that can boost the efficacy of chemotherapy for brain tumors are urgently needed. Recently, nanomedicines have shown great therapeutic potential in brain tumors by employing various transcellular strategies, paracellular strategies, and their hybrids, such as adsorptive-mediated transcytosis, receptor-mediated transcytosis, BBB disruption technology, and so on. It is compulsory to comprehensively summarize these practices to shed light on future directions in developing therapeutic regimens for brain tumors. In this review, the biological and pathological characteristics of brain tumors, including BBB and BBTB, are illustrated. After that, the emerging delivery strategies for brain tumor management are summarized into different classifications and supported with detailed examples. Finally, the potential challenges and prospects for developing and clinical application of brain tumor-oriented nanomedicine are discussed.

Polyglycerol and Poly(ethylene glycol) exhibit different effects on pharmacokinetics and antibody generation when grafted to nanoparticle surfaces

Poly(ethylene glycol) (PEG) is widely employed for passivating nanoparticle (NP) surfaces to prolong blood circulation and enhance localization of NPs to target tissue. However, the immune response of PEGylated NPs-including anti-PEG antibody generation, accelerated blood clearance (ABC), and loss of delivery efficacy-is of some concern, especially for treatments that require repeat administrations. Although polyglycerol (PG), which has the same ethylene oxide backbone as PEG, has received attention as an alternative to PEG for NP coatings, the pharmacokinetic and immunogenic impact of PG has not been studied systematically. Here, linear PG, hyperbranched PG (hPG), and PEG-coated polylactide (PLA) NPs with varying surface densities were studied in parallel to determine the pharmacokinetics and immunogenicity of PG and hPG grafting, in comparison with PEG. We found that linear PG imparted the NPs a stealth property comparable to PEG, while hPG-grafted NPs needed a higher surface density to achieve the same pharmacokinetic impact. While linear PG-grafted NPs induced anti-PEG antibody production in mice, they exhibited minimal accelerated blood clearance (ABC) effects due to the poor interaction with anti-PEG immunoglobulin M (IgM). Further, we observed no anti-polymer IgM responses or ABC effects for hPG-grafted NPs.

Topical formulation based on disease-specific nanoparticles for single-dose cure of psoriasis

First-line treatments for mild to moderate psoriasis are typically topical formulations containing corticosteroids, however, the therapeutic efficacy of these formulations is compromised by limited penetration and skin retention. Even more challenging, off-target corticosteroids are known to adversely affect healthy skin, including induction of epidermal and dermal atrophy. Here, we report a nanoparticle-based topical formulation that cures psoriasis in a single dose, but leaves healthy skin intact. Specifically, we developed tris(hydroxymethyl)aminomethane-modified bioadhesive nanoparticles (Tris-BNPs) that exploit the high permeability characteristic of psoriasis to penetrate only psoriatic skin but not the healthy skin. Furthermore, as Tris-BNPs diffuse and penetrate into the epidermis, the Tris molecules slowly diffuse away, exposing the aldehyde groups of BNPs, which can bind to amine groups present within lesional skin, leading to long local retention of BNPs in lesions of psoriatic skin. The accumulated BNPs within lesions release corticosteroids over a ~ 3 day period to maintain local drug concentration above the therapeutic level. In addition to deeper penetration and longer retention compared with commercial psoriasis treatments, the topical applied Tris-BNPs were not affected by sweating, humidity, or active wiping due to their preferential accumulation between the stratum corneum and the basal cells of the epidermis. Overall, Tris-BNP as a topical formulation hold promise to overcome the limitations of current psoriasis treatment.

Poly(lactic acid)-hyperbranched polyglycerol nanoparticles enhance bioadhesive treatment of esophageal disease and reduce systemic drug exposure

The effective treatment of esophageal disease represents a significant unmet clinical need, as existing treatments often lead to unnecessary systemic drug exposure and suboptimal concentrations at the disease site. Here, surface-modified bioadhesive poly(lactic acid)-hyperbranched polyglycerol nanoparticles (BNPs), with an average 100-200 nm diameter, were developed for local and sustained esophageal drug delivery. BNPs showed significantly higher adhesion and permeation into ex vivo human and rat esophageal tissue than non-adhesive nanoparticles (NNPs) and had longer residence times within the rat esophagus in vivo. Incubation with human esophagus (Het-1A) cells confirmed BNPs' biocompatibility at clinically relevant concentrations. In a rat model of achalasia, nifedipine-loaded BNPs significantly enhanced esophageal drug exposure, increased therapeutic efficacy, and reduced systemic drug exposure compared to NNPs and free drug. The safety of BNPs was demonstrated by an absence of intestinal, hepatic, and splenic toxicity following administration. This study is the first to demonstrate the efficacy of BNPs for esophageal drug delivery and highlight their potential for improving the lives of patients suffering with esophageal conditions.

In Vivo Evaluation of Cefuroxime Axetil-Loaded Bioadhesive Nanoparticles to Treat Haemophilus influenzae-Induced Otitis Media

Otitis media (OM) is a common disease in children. One of the most common pathogens causing OM is non-typeable Haemophilus influenzae (NTHi). NTHi in the middle ear can be successfully eradicated by a regimen of oral antibiotics sustained for 7–10 days (e.g., cefuroxime axetil 250 mg/day for patients aged 3 months to 2 years and 500 mg/day for patients ages ≥2 years). However, lack of compliance is relevant to treatment failure or early relapse. In order to overcome these challenges, we have developed antibiotics-loaded bioadhesive nanoparticles (BNPs) that can adhere to the epidermis of the middle ear after local administration and significantly prolong the release time of antibiotics in the middle ear. Compared with oral administration of CA, local delivery of free antibiotic cefuroxime axetil (CA), and CA loaded non-bioadhesive nanoparticles (CA/NNPs), BNPs loaded with cefuroxime axetil (CA/BNPs) showed significantly longer retention time in the middle ear, resulting in continuous release of the drug and higher therapeutic efficacy against OM with only a single dosage. CA concentrations were maintained above the minimum inhibitory concentration (MIC) for NTHi throughout 7 days’ treatment. NTHi OM in a mouse model was successfully eradicated without causing tissue toxicity. CA/BNPs minimize systemic drug exposure through local administration, as demonstrated by undetectable levels in the blood.

Untangling Mucosal Drug Delivery: Engineering, Designing, and Testing Nanoparticles to Overcome the Mucus Barrier

Mucus is a complex viscoelastic gel and acts as a barrier covering much of the soft tissue in the human body. High vascularization and accessibility have motivated drug delivery to various mucosal surfaces; however, these benefits are hindered by the mucus layer. To overcome the mucus barrier, many nanomedicines have been developed, with the goal of improving the efficacy and bioavailability of drug payloads. Two major nanoparticle-based strategies have emerged to facilitate mucosal drug delivery, namely, mucoadhesion and mucopenetration. Generally, mucoadhesive nanoparticles promote interactions with mucus for immobilization and sustained drug release, whereas mucopenetrating nanoparticles diffuse through the mucus and enhance drug uptake. The choice of strategy depends on many factors pertaining to the structural and compositional characteristics of the target mucus and mucosa. While there have been promising results in preclinical studies, mucus-nanoparticle interactions remain poorly understood, thus limiting effective clinical translation. This article reviews nanomedicines designed with mucoadhesive or mucopenetrating properties for mucosal delivery, explores the influence of site-dependent physiological variation among mucosal surfaces on efficacy, transport, and bioavailability, and discusses the techniques and models used to investigate mucus-nanoparticle interactions. The effects of non-homeostatic perturbations on protein corona formation, mucus composition, and nanoparticle performance are discussed in the context of mucosal delivery. The complexity of the mucosal barrier necessitates consideration of the interplay between nanoparticle design, tissue-specific differences in mucus structure and composition, and homeostatic or disease-related changes to the mucus barrier to develop effective nanomedicines for mucosal delivery.

Bioadhesive Nanoparticles for Local Drug Delivery

Local drug delivery is an effective strategy for achieving direct and instant therapeutic effects. Current clinical treatments have fallen short and are limited by traditional technologies. Bioadhesive nanoparticles (NPs), however, may be a promising carrier for optimized local drug delivery, offering prolonged drug retention time and steadily maintained therapeutic concentrations. In addition, the possibility of clinical applications of this platform are abundant, as most polymers used for bioadhesion are both biodegradable and biocompatible. This review highlights the major advances in the investigations of polymer-based bioadhesive nanoparticles and their innumerable applications in local drug delivery.

Linear Polyglycerol for N-terminal-selective Modification of Interleukin-4

Polymer conjugation to biologics is of key interest to the pharmaceutical industry for the development of potent and long acting biotherapeutics, with poly(ethylene glycol) (PEG) being the gold standard. Within the last years, unwanted PEG-related side effects (immunological reactions, antibody formation) arose, therefore creating several attempts to establish alternative polymers with similar potential to PEG. In this article, we synthesized N-terminal bioconjugates of the potential therapeutic human interleukin-4 (hIL-4 WT) with linear polyglycerol (LPG) of 10 and 40 kDa and compared it with its PEG analogs of same nominal weights. Polyglycerol is a highly hydrophilic polymer with good biocompatibility and therefore represents an alternative polymer to PEG. Both polymer types resulted in similar conjugation yields, comparable hydrodynamic sizes and an unaltered secondary structure of the protein after modification. LPG- and PEG-bioconjugates remained stable in human plasma, whereas binding to human serum albumin (HSA) decreased after polymer modification. Furthermore, only minor differences in bioactivity were observed between LPG- and PEG-bioconjugates of same nominal weights. The presented findings are promising for future pharmacokinetic evaluation of hIL-4-polymer bioconjugates.

Direct targeting of amplified gene loci for proapoptotic anticancer therapy

Gene amplification drives oncogenesis in a broad spectrum of cancers. A number of drugs have been developed to inhibit the protein products of amplified driver genes, but their clinical efficacy is often hampered by drug resistance. Here, we introduce a therapeutic strategy for targeting cancer-associated gene amplifications by activating the DNA damage response with triplex-forming oligonucleotides (TFOs), which drives induction of apoptosis in tumors, whereas cells without amplifications process lower levels of DNA damage. Focusing on cancers driven by HER2-amplification, we find that TFOs targeting HER2 induce copy number-dependent DNA double strand breaks and activate p53-independent apoptosis in HER2-positive cancer cells and human tumor xenografts via a mechanism that is independent of HER2 cellular function. This strategy has demonstrated in vivo efficacy comparable with current precision medicines and provided a feasible alternative to combat drug resistance in HER-positive breast and ovarian cancer models. These findings offer a general strategy for targeting tumors with amplified genomic loci.

Linear and Branched Lactide Polymers for Targeted Drug Delivery Systems

Abstract

The review presents modern advances in the synthesis of biodegradable polymers based on lactide of various topologies and also analyzes the main methods for preparation of nanoparticles that show promise for the creation of targeted drug delivery systems.

Nanoparticles for delivery of agents to fetal lungs

Fetal treatment of congenital lung disease, such as cystic fibrosis, surfactant protein syndromes, and congenital diaphragmatic hernia, has been made possible by improvements in prenatal diagnostic and interventional technology. Delivery of therapeutic agents to fetal lungs in nanoparticles improves cellular uptake. The efficacy and safety of nanoparticle-based fetal lung therapy depends on targeting of necessary cell populations. This study aimed to determine the relative distribution of nanoparticles of a variety of compositions and sizes in the lungs of fetal mice delivered through intravenous and intra-amniotic routes. Intravenous delivery of particles was more effective than intra-amniotic delivery for epithelial, endothelial and hematopoietic cells in the fetal lung. The most effective targeting of lung tissue was with 250nm Poly-Amine-co-Ester (PACE) particles accumulating in 50% and 44% of epithelial and endothelial cells. This study demonstrated that route of delivery and particle composition impacts relative cellular uptake in fetal lung, which will inform future studies in particle-based fetal therapy.

Nonsurgical treatment of skin cancer with local delivery of bioadhesive nanoparticles

Keratinocyte-derived carcinomas, including squamous cell carcinoma (SCC), comprise the most common malignancies. Surgical excision is the therapeutic standard but is not always clinically feasible, and currently available alternatives are limited to superficial tumors. To address the need for a nonsurgical treatment for nodular skin cancers like SCC, we developed a bioadhesive nanoparticle (BNP) drug delivery system composed of biodegradable polymer, poly(lactic acid)-hyperbranched polyglycerol (PLA-HPG), encapsulating camptothecin (CPT). Nanoparticles (NPs) of PLA-HPG are nonadhesive NPs (NNPs), which are stealthy in their native state, but we have previously shown that conversion of the vicinal diols of HPG to aldehydes conferred NPs the ability to form strong covalent bonds with amine-rich surfaces. Herein, we show that these BNPs have significantly enhanced binding to SCC tumor cell surfaces and matrix proteins, thereby significantly enhancing the therapeutic efficacy of intratumoral drug delivery. Tumor injection of BNP-CPT resulted in tumor retention of CPT at ∼50% at 10 d postinjection, while CPT was undetectable in NNP-CPT or free (intralipid) CPT-injected tumors at that time. BNP-CPT also significantly reduced tumor burden, with a portion (∼20%) of BNP-CPT-treated established tumors showing histologic cure. Larger, more fully established PDV SCC tumors treated with a combination of BNP-CPT and immunostimulating CpG oligodeoxynucleotides exhibited enhanced survival relative to controls, revealing the potential for BNP delivery to be used along with local tumor immunotherapy. Taken together, these results indicate that percutaneous delivery of a chemotherapeutic agent via BNPs, with or without adjuvant immunostimulation, represents a viable, nonsurgical alternative for treating cutaneous malignancy.

Multi-responsive poly(oligo(ethylene glycol)methyl methacrylate)-co-poly(2-(diisopropylamino)ethyl methacrylate) hyperbranched copolymers via reversible addition fragmentation chain transfer polymerization

Multi-responsive P(OEGMA-co-DIPAEMA) hyperbranched copolymers are synthesized via RAFT polymerization. The copolymers form different aggregates in aqueous media depending on solution pH, temperature and copolymer composition.

Challenges and opportunities in the delivery of cancer therapeutics: update on recent progress

Global cancer prevalence has continuously increased in the last decades despite substantial progress achieved for patient care. Cancer is no longer recognized as a singular disease but as a plurality of different ones, leading to the important choice of the drug administration route and promoting the development of novel drug-delivery systems (DDS). Due to their structural diversity, therapeutic cancer drugs present specific challenges in physicochemical properties that can adversely affect their efficacy and toxicity profile. These challenges are addressed by innovative DDS to improve bioavailability, pharmacokinetics and biodistribution profiles. Here, we define the drug delivery challenges related to oral, intravenous, subcutaneous or alternative routes of administration, and review innovative DDS, marketed or in development, that answer those challenges.

Addressing the challenges to increase the efficiency of translating nanomedicine formulations to patients

INTRODUCTION

Nanotechnology is in a growth phase for drug delivery and medical imaging. Nanomaterials with unique properties present opportunities for encapsulation of therapeutics and imaging agents, along with conjugation to ligands for targeting. Favorable chemistry of nanomaterials can create formulations that address critical challenges for therapeutics, such as insolubility and a low capacity to cross the blood-brain-barrier (BBB) and intestinal wall.

AREAS COVERED

The authors investigate challenges faced during translation of nanomedicines while suggesting reasons as to why some nanoformulations have under-performed in clinical trials. They assess physiological barriers such as the BBB and gut mucus that nanomedicines must overcome to deliver cargos. They also provide an overview with examples of how nanomedicines can be designed to improve localization and site-specific delivery (e.g., encapsulation, bioconjugation, and triggered-release).

EXPERT OPINION

There are examples where nanomedicines have demonstrated improved efficacy of payload in humans; however, most of the advantages conferred were in improved pharmacokinetics and reduced toxicity. Problematic data show susceptibility of nanoformulations against natural protective mechanisms present in the body, including distribution impediment by physiological barriers and activation of the reticuloendothelial system. Further initiatives should address current challenges while expanding the scope of nanomedicine into advanced biomedical imaging and antibiotic delivery.

Zein-Polyglycerol Conjugates with Enhanced Water Solubility and Stabilization of High Oil Loading Emulsion

To increase the water solubility of zein as a stabilizing agent for oil-in-water (O/W) emulsions, three zein-polyglycerol (Zein-PG) conjugates, Zein-PG-2, Zein-PG-6, and Zein-PG-10, were prepared by dehydration between zein and polyglycerol aldehydes obtained by NaIO₄ oxidation of polyglycerol-2, -6, and -10 and characterized by free amine content, grafting degree, Fourier transform infrared spectroscopy, and fluorescence spectra. All conjugates dispersed in water as nanoparticles were verified by transmission electron microscopy. Conjugation with PG changed the isoelectric point of zein from 6.2 to 6.8 and to 4.0. Zein-PG-6 and Zein-PG-10 showed strong stabilization on the O/W emulsions with 18-fold loading of soybean oil on the basis of conjugate mass, displaying high oil loading capacity. Confocal laser scanning microscopy (CLSM) confirmed the O/W structure of emulsions and that the absorption of Zein-PG-10 on the oil droplet surface offered the driving force to be stable. The present Zein-PG conjugates thus produced an enticing resource for use as nanocarriers or bioemulsifiers in food or pharmaceutical industries.

Polymeric vehicles for nucleic acid delivery

Polymeric vehicles are versatile tools for therapeutic gene delivery. Many polymers-when assembled with nucleic acids into vehicles-can protect the cargo from degradation and clearance in vivo, and facilitate its transport into intracellular compartments. Design options in polymer synthesis yield a comprehensive range of molecules and resulting vehicle formulations. These properties can be manipulated to achieve stronger association with nucleic acid cargo and cells, improved endosomal escape, or sustained delivery depending on the application. Here, we describe current approaches for polymer use and related strategies for gene delivery in preclinical and clinical applications. Polymer vehicles delivering genetic material have already achieved significant therapeutic endpoints in vitro and in animal models. From our perspective, with preclincal assays that better mimic the in vivo environment, improved strategies for target specificity, and scalable techniques for polymer synthesis, the impact of this therapeutic approach will continue to expand.

The effect of phenylalanine ligands on the chiral-selective oxidation of glucose on Au(111)

As typical glucose oxidase nanozymes, gold nanoparticles (Au NPs) have attracted much attention due to their wide-ranging applications. Ligand caps, as the "cure-all solution" for NPs, not only play important roles in the size and shape control of Au NPs but also influence their catalytic activity and selectivity. A deep understanding of the catalytic mechanism and precise description of the important role of ligands can provide possible ways to design functional Au NPs. Here, with the specific example of Au(111) capped with chiral phenylalanine (Phe), the chiral selective oxidation mechanism of glucose and the important role of the ligands were studied via first-principles calculations. All results show that the dehydrogenation of glucose to form glucono delta-lactone (GDL) is favored on clean Au(111), while the subsequent hydrolysis of GDL is the rate-limiting step for glucose oxidation. The flat and nonchiral Au(111) surface shows negligible selectivity in relation to the oxidation of d- and l-glucose, while chiral Phe-Au(111) shows selective adsorption towards d- and l-glucose. l-Phe-capped Au(111) prefers to adsorb d-glucose, while d-Phe-capped Au(111) prefers to adsorb l-glucose. Considering the three steps in the capped ligand catalysis (adsorption, replacement and reaction), we propose that the ligands play key roles in selectively adsorbing reactants before the subsequent exchange and reaction steps.

High-throughput quantitative microscopy-based half-life measurements of intravenously injected agents

Accurate analysis of blood concentration and circulation half-life is an important consideration for any intravenously administered agent in preclinical development or for therapeutic application. However, the currently available tools to measure these parameters are laborious, expensive, and inefficient for handling multiple samples from complex multivariable experiments. Here we describe a robust high-throughput quantitative microscopy-based method to measure the blood concentration and circulation half-life of any fluorescently labeled agent using only a small (2 µL) amount of blood volume, enabling additional end-point measurements to be assessed in the same subject. To validate this method, we demonstrate its use to measure the circulation half-life in mice of two types of fluorescently labeled polymeric nanoparticles of different sizes and surface chemistries and of a much smaller fluorescently labeled monoclonal antibody. Furthermore, we demonstrate the improved accuracy of this method compared to previously described methods.

Investigation of Combination Effect Between 6 MV X-Ray Radiation and Polyglycerol Coated Superparamagnetic Iron Oxide Nanoparticles on U87-MG Cancer Cells

Background

Radiosensitization using nanoparticles is proposed as a novel strategy for treatment of different cancers. Superparamagnetic iron oxide nanoparticles (SPIONs) have been reported to enhance effects of radiotherapy in several researches.

Objective

The objective of this research is to investigate the radiosensitization properties of polyglycerol coated SPIONs (PG-SPIONs) on U87-MG cancer cells.

Material and Methods

In this experimental study, polyglycerol coated SPIONs were synthesized by thermal decomposition method and characterized by FTIR, TEM and VSM analysis. Cellular uptake of nanoparticles by cells was examined via AAS. Cytotoxicity and radiosensitization of nanoparticles in combination with radiation were evaluated by MTT and colony assay, respectively.

Results

Mean size of nanoparticles was 17.9±2.85 nm. FTIR verified SPIONs coating by Polyglycerol and VSM showed that they have superparamagnetic behaviour. Viability significantly (P < 0.001) decreased at concentrations above 100µg/ml for SPIONs but not for PG-SPIONs (P > 0.05). Dose verification results by TLD for doses of 2 and 4 Gy were 2±0.19 and 4±0.12 Gy respectively. The combination index for all situations was less than 1 and the effect is antagonism.

Conclusion

However, PG-SPIONs combination with 6 MV X-ray reduced survival of U87-MG cells compared to radiation alone but the effect is antagonism.

Polyglycerol Hyperbranched Polyesters: Synthesis, Properties and Pharmaceutical and Biomedical Applications

In a century when environmental pollution is a major issue, polymers issued from bio-based monomers have gained important interest, as they are expected to be environment-friendly, and biocompatible, with non-toxic degradation products. In parallel, hyperbranched polymers have emerged as an easily accessible alternative to dendrimers with numerous potential applications. Glycerol (Gly) is a natural, low-cost, trifunctional monomer, with a production expected to grow significantly, and thus an excellent candidate for the synthesis of hyperbranched polyesters for pharmaceutical and biomedical applications. In the present article, we review the synthesis, properties, and applications of glycerol polyesters of aliphatic dicarboxylic acids (from succinic to sebacic acids) as well as the copolymers of glycerol or hyperbranched polyglycerol with poly(lactic acid) and poly(ε-caprolactone). Emphasis was given to summarize the synthetic procedures (monomer molar ratio, used catalysts, temperatures, etc.,) and their effect on the molecular weight, solubility, and thermal and mechanical properties of the prepared hyperbranched polymers. Their applications in pharmaceutical technology as drug carries and in biomedical applications focusing on regenerative medicine are highlighted.

Optimizing biodegradable nanoparticle size for tissue-specific delivery

Nanoparticles (NPs) are promising vehicles for drug delivery because of their potential to target specific tissues [1]. Although it is known that NP size plays a critical role in determining their biological activity, there are few quantitative studies of the role of NP size in determining biodistribution after systemic administration. Here, we engineered fluorescent, biodegradable poly(lactic-co-glycolic acid) (PLGA) NPs in a range of sizes (120-440nm) utilizing a microfluidic platform and used these NPs to determine the effect of diameter on bulk tissue and cellular distribution after systemic administration. We demonstrate that small NPs (∼120nm) exhibit enhanced uptake in bulk lung and bone marrow, while larger NPs are sequestered in the liver and spleen. We also show that small NPs (∼120nm) access specific alveolar cell populations and hematopoietic stem and progenitor cells more readily than larger NPs. Our results suggest that size of PLGA NPs can be used to tune delivery to certain tissues and cell populations in vivo.