Recent advances in zwitterionic nanoscale drug delivery systems to overcome biological barriers

Nanoscale drug delivery systems(nDDS)have been employed widely in enhancing the therapeutic efficacy of drugs against diseases with reduced side effects.Although several nDDS have been successfully approved for clinical use up to now,biological barriers between the administration site and the target site hinder the wider clinical adoption of nDDS in disease treatment.Polyethylene glycol(PEG)-modification(or PEGylation)has been regarded as the gold standard for stabilising nDDS in complex biological environment.However,the accelerated blood clearance(ABC)of PEGylated nDDS after repeated injections becomes great challenges for their clinical applications.Zwitterionic polymer,a novel family of antifouling materials,have evolved as an alternative to PEG due to their super-hydrophilicity and biocompatibility.Zwitterionic nDDS could avoid the generation of ABC phenomenon and exhibit longer blood circulation time than the PEGylated analogues.More impressively,zwitterionic nDDS have recently been shown to overcome multiple biological barriers such as nonspecific organ distribution,pressure gradients,impermeable cell membranes and lysosomal degradation without the need of any complex chemical modifications.The realization of overcoming multiple biological barriers by zwitterionic nDDS may simplify the current overly complex design of nDDS,which could facilitate their better clinical translation.Herein,we summarise the recent progress of zwitterionic nDDS at overcoming various biological barriers and analyse their underlyingmechanisms.Finally,prospects and challenges are introduced to guide the rational design of zwitterionic nDDS for disease treatment.

The state-of-the-art of atmospheric pressure plasma for transdermal drug delivery

Plasma-enhanced transdermal drug delivery(TDD) presents advantages over traditional methods,including painless application, minimal skin damage, and rapid recovery of permeability. To harness its clinical potential, factors related to plasma’s unique properties, such as reactive species and electric fields, must be carefully considered.This review provides a concise summary of conventional TDD methods and subsequently offers a comprehensive examination of the current state-of-the-art in plasma-enhanced TDD. This includes an analysis of the impact of plasma on HaCaT human keratinocyte cells, ex vivo/in vivo studies, and clinical research on plasma-assisted TDD. Moreover, the review explores the effects of plasma on skin physical characteristics such as microhole formation, transepidermal water loss(TEWL), molecular structure of the stratum corneum(SC), and skin resistance. Additionally, it discusses the involvement of various reactive agents in plasma-enhanced TDD, encompassing electric fields,charged particles, UV/VUV radiation, heat, and reactive species. Lastly, the review briefly addresses the temporal behavior of the skin after plasma treatment, safety considerations, and potential risks associated with plasma-enhanced TDD.

Ionic liquids as the effective technology for enhancing transdermal drug delivery: Design principles, roles, mechanisms, and future challenges

Ionic liquids (ILs) have been proven to be an effective technology for enhancing drug transdermal absorption. However, due to the unique structural components of ILs, the design of efficient ILs and elucidation of action mechanisms remain to be explored. In this review, basic design principles of ideal ILs for transdermal drug delivery system (TDDS) are discussed considering melting point, skin permeability, and toxicity, which depend on the molar ratios, types, functional groups of ions and inter-ionic interactions. Secondly, the contributions of ILs to the development of TDDS through different roles are described: as novel skin penetration enhancers for enhancing transdermal absorption of drugs;as novel solvents for improving the solubility of drugs in carriers;as novel active pharmaceutical ingredients (API-ILs) for regulating skin permeability, solubility, release, and pharmacokinetic behaviors of drugs;and as novel polymers for the development of smart medical materials. Moreover, diverse action mechanisms, mainly including the interactions among ILs, drugs, polymers, and skin components, are summarized. Finally, future challenges related to ILs are discussed, including underlying quantitative structure-activity relationships, complex interaction forces between anions, drugs, polymers and skin microenvironment, long-term stability, and in vivo safety issues. In summary, this article will promote the development of TDDS based on ILs.

Smart drug delivery systems to overcome drug resistance in cancer immunotherapy

Cancer immunotherapy,a therapeutic approach that inhibits tumors by activating or strengthening anti-tumor immunity,is currently an important clinical strategy for cancer treatment;however,tumors can develop drug resistance to immune surveillance,resulting in poor response rates and low therapeutic efficacy.In addition,changes in genes and signaling pathways in tumor cells prevent susceptibility to immunotherapeutic agents.Furthermore,tumors create an immunosuppressive microenvironment via immunosuppressive cells and secrete molecules that hinder immune cell and immune modulator infiltration or induce immune cell malfunction.To address these challenges,smart drug delivery systems(SDDSs)have been developed to overcome tumor cell resistance to immunomodulators,restore or boost immune cell activity,and magnify immune responses.To combat resistance to small molecules and monoclonal antibodies,SDDSs are used to co-deliver numerous therapeutic agents to tumor cells or immunosuppressive cells,thus increasing the drug concentration at the target site and improving efficacy.Herein,we discuss how SDDSs overcome drug resistance during cancer immunotherapy,with a focus on recent SDDS advances in thwarting drug resistance in immunotherapy by combining immunogenic cell death with immunotherapy and reversing the tumor immunosuppressive microenvironment.SDDSs that modulate the interferon signaling pathway and improve the efficacy of cell therapies are also presented.Finally,we discuss potential future SDDS perspectives in overcoming drug resistance in cancer immunotherapy.We believe that this review will contribute to the rational design of SDDSs and development of novel techniques to overcome immunotherapy resistance.

Ionizable drug delivery systems for efficient and selective gene therapy

Gene therapy has shown great potential to treat various diseases by repairing the abnormal gene function.However,a great challenge in bringing the nucleic acid formulations to the market is the safe and effective delivery to the specific tissues and cells.To be excited,the development of ionizable drug delivery systems(IDDSs)has promoted a great breakthrough as evidenced by the approval of the BNT162b2 vaccine for prevention of coronavirus disease 2019(COVID-19)in 2021.Compared with conventional cationic gene vectors,IDDSs can decrease the toxicity of carriers to cell membranes,and increase cellular uptake and endosomal escape of nucleic acids by their unique pH-responsive structures.Despite the progress,there remain necessary requirements for designing more efficient IDDSs for precise gene therapy.Herein,we systematically classify the IDDSs and summarize the characteristics and advantages of IDDSs in order to explore the underlying design mechanisms.The delivery mechanisms and therapeutic applications of IDDSs are comprehensively reviewed for the delivery of plasmid DNA(pDNA)and four kinds of RNA.In particular,organ selecting considerations and high-throughput screening are highlighted to explore efficiently multifunctional ionizable nanomaterials with superior gene delivery capacity.We anticipate providing references for researchers to rationally design more efficient and accurate targeted gene delivery systems in the future,and indicate ideas for developing next generation gene vectors.

Interpeduncular cistern intrathecal targeted drug delivery for intractable postherpetic neuralgia: A case report

BACKGROUND Intractable postherpetic neuralgia(PHN)can be difficult to manage even with aggressive multimodal therapies.Patients who experience uncontrolled refractory cranial PHN despite conservative treatment may benefit from an intrathecal drug delivery system(IDDS).For craniofacial neuropathic pain,the traditional approach has been to place the intrathecal catheter tip below the level of the cranial nerve root entry zones,which may lead to insufficient analgesia.CASE SUMMARY We describe a 69-year-old man with a 1-year history of PHN after developing a vesicular rash in the ophthalmic division of cranial nerve V(trigeminal nerve)distribution.The pain was rated 7-8 at rest and 9-10 at breakthrough pain(BTP)on a numeric rating scale.Despite receiving aggressive multimodal therapies including large doses of oral analgesics(gabapentin 150 mg q12 h,oxycodone 5 mg/acetaminophen 325 mg q6 h,and lidocaine 5%patch 700 mg q12 h)and sphenopalatine ganglion block,there was no relief of pain.Subsequently,the patient elected to have an implantable IDDS with the catheter tip placed at the interpeduncular cistern.The frequency of BTP episodes decreased.The patient’s continuous daily dose was adjusted to 0.032 mg/d after 3 mo of follow-up and stopped 5 mo later.He did not report pain or other discomfort at outpatient follow-up 6 mo and 1 year after stopping intracisternal hydromorphone.CONCLUSION The use of interpeduncular cistern intrathecal infusion with low-dose hydromorphone by IDDS may be effective for severe craniofacial PHN.

Preparation and evaluation of controllable drug delivery system:A light responsive nanosphere based on β-cyclodextrin/mesoporous silica

A novel light responsive nanosphere was constructed,and it was used as a drug carrier to investigate the loading and release properties of the Quercetin(QU).In this paper,mesoporous silica nanoparticles(MSN)were used as a substrate,and 3-aminopropyl triethyoxysilane was used as a surface modification agent to introduce—NH_(2),and the azobenzene-4,4’-dicarboxylic acid(AZO)was used as light responsive agent to introduce the group of—N=N—,and thenβ-cyclodextrin(β-CD)was combined with AZO through host-guest interaction to construct light responsive nanoparticles(MSN@β-CD).The structure and properties of the carrier were analyzed by FTIR,BET,XPS,TGA,XRD,SEM and TEM.In vitro drug release studies showed the release rate of QU@MSN@β-CD(dark)was 12.19%within 72 h,but the release rate of QU@MSN@β-CD(light 10 min)was 26.09%,exhibiting a light-responsive property.The CCK8 tests demonstrated that MSN@β-CD could significantly decrease the toxicity of QU.Therefore,the controllable light-responsive drug delivery system has great application prospects.

High drug loading hydrophobic cross-linked dextran microspheres as novel drug delivery systems for the treatment of osteoarthritis

Drug delivery via intra-articular(IA)injection has proved to be effective in osteoarthritis(OA)therapy,limited by the drug efficiency and short retention time of the drug delivery systems(DDSs).Herein,a series of modified cross-linked dextran(Sephadex,S0)was fabricated by respectively grafting with linear alkyl chains,branched alkyl chains or aromatic chain,and acted as DDSs after ibuprofen(Ibu)loading for OA therapy.This DDSs expressed sustained drug release,excellent anti-inflammatory and chondroprotective effects both in IL-1βinduced chondrocytes and OA joints.Specifically,the introduction of a longer hydrophobic chain,particularly an aromatic chain,distinctly improved the hydrophobicity of S0,increased Ibu loading efficiency,and further led to significantly improving OA therapeutic effects.Therefore,hydrophobic microspheres with greatly improved drug loading ratio and prolonged degradation rates show great potential to act as DDSs for OA therapy.

Smart stimuli-responsive drug delivery systems in spotlight of COVID-19

The world has been dealing with a novel severe acute respiratory syndrome(SARS-CoV-2)since the end of 2019,which threatens the lives of many peopleworldwide.COVID-19 causes respiratory infection with different symptoms,from sneezing and coughing to pneumonia and sometimes gastric symptoms.Researchers worldwide are actively developing novel drug delivery systems(DDSs),such as stimuli-responsive DDSs.The ability of these carriers to respond to external/internal and even multiple stimuli is essential in creating“smart”DDS that can effectively control dosage,sustained release,individual variations,and targeted delivery.To conduct a comprehensive literature survey for this article,the terms“Stimuli-responsive”,“COVID-19”and“Drug delivery”were searched on databases/search engines like“Google Scholar”,“NCBI”,“PubMed”,and“Science Direct”.Many different types of DDSs have been proposed,including those responsive to various exogenous(light,heat,ultrasound andmagnetic field)or endogenous(microenvironmental changes in pH,ROS and enzymes)stimuli.Despite significant progress in DDS research,several challenging issues must be addressed to fill the gaps in the literature.Therefore,this study reviews the drug release mechanisms and applications of endogenous/exogenous stimuli-responsive DDSs while also exploring their potential with respect to COVID-19.

Contact lens as an emerging platform for ophthalmic drug delivery:A systematic review

The number of people with eye diseases has increased with the use of electronics.However,the bioavailability of eye drops remains low owing to the presence of the ocular barrier and other reasons.Although many drug delivery systems have been developed to overcome these problems,they have certain limitations.In recent years,the development of contact lenses that can deliver drugs for long periods with high bioavailability and without affecting vision has increased the interest in using contact lenses for drug delivery.Hence,a review of the current state of research on drug delivery contact lenses has become crucial.This article reviews the key physical and chemical properties of drug-laden contact lenses,development and classification of contact lenses,and features of the commonly used materials.A review of the methods commonly used in current research to create contact lenses has also been presented.An overview on how drug-laden contact lenses can overcome the problems of high burst and short release duration has been discussed.Overall,the review focuses on drug delivery methods using smart contact lenses,and predicts the future direction of research on contact lenses.

Recent progress of respiratory inhalation drug delivery systems

With the influence of many factors such as the aging of the population,the younger smokers,and the serious air pollution,the incidence of chronic respiratory diseases is increasing year by year.In the treatment of respiratory diseases,clinical intervention is still mainly based on drug control of pulmonary symptoms.However,systemic drugs have disadvantages such as many adverse reactions and severe systemic side effects.In recent years,the research and development of local drug delivery systems for the respiratory tract has brought new changes to the treatment of respiratory diseases.Locally delivered drugs can directly act on the airways and have the characteristics of fast onset,good curative effect and small side effects.It is a simple,efficient and safe treatment method,which has a very significant effect,and has become a hot topic of current research and promotion.This paper briefly reviews the development track and latest research progress of respiratory local drug delivery systems at home and abroad,in order to provide reference for clinical workers in drug selection and application.

Mesenchymal stem cells-based drug delivery systems for diabetic foot ulcer:A review

The complication of diabetes,which is known as diabetic foot ulcer(DFU),is a significant concern due to its association with high rates of disability and mortality.It not only severely affects patients’quality of life,but also imposes a substantial burden on the healthcare system.In spite of efforts made in clinical practice,treating DFU remains a challenging task.While mesenchymal stem cell(MSC)therapy has been extensively studied in treating DFU,the current efficacy of DFU healing using this method is still inadequate.However,in recent years,several MSCs-based drug delivery systems have emerged,which have shown to increase the efficacy of MSC therapy,especially in treating DFU.This review summarized the application of diverse MSCs-based drug delivery systems in treating DFU and suggested potential prospects for the future research.

Nasal implants for drug delivery:Advancements and applications

Nasal implants have emerged as a pioneering technology for nasal drug delivery systems.These are breakthrough options made of biocompatible materials that are temporarily inserted into the nasal passages for both functional and cosmetic purposes.Drug-eluting nasal implants are beneficial for improving patient compliance,reducing the need for repeated drug administration,and achieving controlled release of therapeutic agents.This article offers a comprehensive insight into nasal implants and their applications,and addresses a patent perspective in the same context.Important considerations for clinically approved implants,such as Propel,Sinuva,Sinu-Foam,and Relieva Stratus,have also been discussed.

Enhanced intestinal lymphatic absorption of saquinavir through supersaturated self-microemulsifying drug delivery systems

The therapeutic potential of saquinavir, a specific inhibitor of human immunodeficiency virus(HIV)-1 and HIV-2 protease enzymes, has been largely limited because of a low solubility and consequnt low bioavailability. Thus, we aimed to design a supersaturated selfmicroemulsifying drug delivery system(S-SMEDDS) that can maintain a high concentration of saquinavir in gastro-intestinal fluid thorugh inhibiting the drug precipitation to enhance the lymphatic transport of saquinavir and to increase the bioavailability of saquinavir considerably. Solubilizing capacity of different oils, surfactants, and cosurfactants for saquinavir was evaluated to select optimal ingredients for preparation of SMEDDS.Through the construction of pseudo-ternary phase diagram, SMEDDS formulations were established. A polymer as a precipitation inhibitor was selected based on its viscosity and drug precipitation inhibiting capacity. The S-SMEDDS and SMEDDS designed were administered at an equal dose to rats. At predetermined time points, levels of saquinavir in lymph collected from the rats were assessed. SMEDDS prepared presented a proper selfmicroemulsification efficiency and dispersion stability. The S-SMEDDS fabricated using the SMEDDS and hydroxypropyl methyl cellulose 2910 as a precipitation inhibitor exhibited a signficantly enhanced solubilizing capacity for saquinavir. The drug concentration in a simulated intestinal fluid evaluated with the S-SMEDDS was also maintained at higher levels for prolonged time than that examined with the SMEDDS. The S-SMEDDS showed a considerably enhanced lymphatic absoprtion of saquinavir in rats compared to the SMEDDS.Therefore, the S-SMEDDS would be usefully exploited to enhance the lymphatic absorption of hydrophobic drugs that need to be targeted to the lymphatic system.

Design and preparation of a new multi-targeted drug delivery system using multifunctional nanoparticles for co-delivery of siRNA and paclitaxel

Drug resistance is a great challenge in cancer therapy using chemotherapeutic agents. Administration of these drugs with siRNA is an efficacious strategy in this battle. Here, the present study tried to incorporate siRNA and paclitaxel(PTX) simultaneously into a novel nanocarrier. The selectivity of carrier to target cancer tissues was optimized through conjugation of folic acid(FA) and glucose(Glu) onto its surface. The structure of nanocarrier was formed from ternary magnetic copolymers based on FeCopolyethyleneimine(FeCo-PEI) nanoparticles and polylactic acid-polyethylene glycol(PLA-PEG) gene delivery system. Biocompatibility of FeCo-PEI-PLA-PEG-FA(NPsA), FeCo-PEI-PLA-PEG-Glu(NPsB) and FeCo-PEI-PLA-PEG-FA/Glu(NPsAB) nanoparticles and also influence of PTX-loaded nanoparticles on in vitro cytotoxicity were examined using MTT assay. Besides, siRNA-FAM internalization was investigated by fluorescence microscopy. The results showed the blank nanoparticles were significantly less cytotoxic at various concentrations. Meanwhile, siRNA-FAM/PTX encapsulated nanoparticles exhibited significant anticancer activity against MCF-7 and BT-474 cell lines. NPsAB/siRNA/PTX nanoparticles showed greater effects on MCF-7 and BT-474 cells viability than NPsA/siRNA/PTX and NPsB/siRNA/PTX.Also, they induced significantly higher anticancer effects on cancer cells compared with NPsA/siRNA/PTX and NPsB/siRNA/PTX due to their multi-targeted properties using FA and Glu. We concluded that NPsAB nanoparticles have a great potential for co-delivery of both drugs and genes for use in gene therapy and chemotherapy.

Narrative review-drug delivery in age-related macular degeneration

This narrative review highlights routes of ocular drug delivery for age-related macular degeneration(AMD).AMD is the leading cause of irreversible blindness in industrialized countries and accounts for 8.7%of blindness worldwide.Advanced AMD can be classified into two subtypes:late-stage dry AMD[known as geographic atrophy(GA)]and neovascular AMD(nAMD).GA is often bilateral and results from progressive and irreversible loss of photoreceptors and areas of the retinal pigment epithelium.Wet AMD is characterized by angiogenesis from the choroid to the normally avascular regions underneath the retinal pigment epithelium(RPE)or retina,a process known as choroidal neovascularization(CNV).Various targeted therapeutic options are currently available to reduce the progression rate and maintain vision in patients with nAMD.Intravitreal delivery of anti-VEGF protein treatments to halt CNV is currently the gold-standard of care for nAMD.Subretinal and suprachoroidal delivery approaches are also being explored for gene and molecular therapies.Advancements in nanotechnology and biomaterials have also led to the development of microscopic drug delivery systems,including hydrogels,microparticles,nanoparticles,implants,and liposomes.Gene therapy and stem cell therapy has recently emerged as a potential candidate treatment modality for AMD and other retinal degenerations.New drug targets and modalities have stimulated exciting developments in ocular drug delivery with the promise of greater efficacy and durability of AMD treatment.

A review on phospholipids and their main applications in drug delivery systems

Phospholipids have the characteristics of excellent biocompatibility and a especial amphiphilicity.These unique properties make phospholipids most appropriate to be employed as important pharmaceutical excipients and they have a very wide range of applications in drug delivery systems.The aim of this review is to summarize phospholipids and some of their related applications in drug delivery systems,and highlight the relationship between the properties and applications,and the effect of the species of phospholipids on the efficiency of drug delivery.We refer to some relevant literatures,starting from the structures,main sources and properties of phospholipids to introduce their applications in drug delivery systems.The present article focuses on introducing five types of carriers based on phospholipids,including liposomes,intravenous lipid emulsions,micelles,drug-phospholipids complexes and cochleates.

Recent progress on nanoparticle-based drug delivery systems for cancer therapy

The development of cancer nanotherapeutics has attracted great interest in the recent decade. Cancer nanotherapeutics have overcome several limitations of conventional therapies, such as nonspecific biodistribution, poor water solubility, and limited bioavailability. Nanoparticles with tuned size and surface characteristics are the key components of nanotherapeutics, and are designed to passively or actively deliver anti-cancer drugs to tumor cells. We provide an overview of nanoparticle-based drug delivery methods and cancer therapies based on tumor-targeting delivery strategies that have been developed in recent years.

Recent advances in arsenic trioxide encapsulated nanoparticles as drug delivery agents to solid cancers

Since arsenic trioxide was first approved as the front line therapy for acute promyelocytic leukemia 25 years ago,its anti-cancer properties for various malignancies have been under intense investigation.However,the clinical successes of arsenic trioxide in treating hematological cancers have not been translated to solid cancers.This is due to arsenic＇s rapid clearance by the body＇s immune system before reaching the tumor site.Several attempts have henceforth been made to increase its bioavailability toward solid cancers without increasing its dosage albeit without much success.This review summarizes the past and current utilization of arsenic trioxide in the medical field with primary focus on the implementation of nanotechnology for arsenic trioxide delivery to solid cancer cells.Different approaches that have been employed to increase arsenic＇s efficacy,specificity and bioavailability to solid cancer cells were evaluated and compared.The potential of combining different approaches or tailoring delivery vehicles to target specific types of solid cancers according to individual cancer characteristics and arsenic chemistry is proposed and discussed.

Targeting and exploitation of tumor-associated neutrophils to enhance immunotherapy and drug delivery for cancer treatment

Neutrophils,the most abundant leukocytes in human blood,are essential fighter immune cells against microbial infection.Based on the finding that neutrophils can either restrict or promote cancer progression,tumor-associated neutrophils(TAN)are classified into anti-tumor N1 and pro-tumor N2 subsets.One of the major mechanisms underlying the tumor-promoting function of N2-TANs is suppression of adaptive immune cells,in particular,cytotoxic T lymphocytes.Currently,no established methodologies are available that can unequivocally distinguish immunosuppressive TANs and granulocytic/polymorphonuclear myeloid-derived suppressor cells(G/PMN-MDSC).In view of the critical role of PMN-MDSCs in immune evasion and resistance to cancer immunotherapy,as established from data obtained with diverse cancer models,therapeutic strategies targeting these cells have been actively developed to enhance the efficacy of immunotherapy.Here,we have reviewed the available literature on strategies targeting PMN-MDSCs and summarized the findings into four categories:(1)depletion of existing PMN-MDSCs,(2)blockade of the development of PMNMDSCs,(3)blockade of PMN-MDSC recruitment,(4)inhibition of immunosuppressive function.Owing to their high mobility to inflamed organs and ability to trespass the blood-brain barrier,neutrophils are outstanding candidate carriers in nanoparticle-based therapies.Another attractive application of neutrophils in cancer therapy is the use of neutrophil membrane-derived nanovesicles as a surrogate of extracellular vesicles for more efficient and scalable drug delivery.In the second part of the review,we have highlighted recent advances in the field of neutrophil-based cancer drug delivery.Overall,we believe that neutrophil-based therapeutics are a rapidly growing area of cancer therapy with significant potential benefits.