Gene delivery using chitosan, trimethyl chitosan or polyethylenglycol-graft-trimethyl chitosan block copolymers: Establishment of structure–activity relationships in vitro

Formulation of siRNA nanoparticles, transfection and enhanced adhesion -penetration in nasal mucosal tissue

This study investigates the efficacy of trimethyl chitosan (TMC) nanoparticles (NPs) for the delivery of small interfering RNA (siRNA) targeting the EGFR gene, with a focus on optimizing complexation efficiency, release profiles, and transfection efficiency, as well as investigating mucoadhesion and mucopenetration properties. TMC nanoparticles were formulated at various siRNA:TMC weight-to-weight (w:w) ratios and assessed for binding efficiency, release in the presence of heparin, physical properties, cytotoxicity, and EGFR knockdown efficiency in HeLa cells. The integration of additives such as dextran sulfate (DS), tripolyphosphate (TPP), and hyaluronic acid (HA) was explored to enhance nanoparticle performance. Results demonstrated that higher TMC ratios improved siRNA binding and reduced release rates, with additives further stabilizing the nanoparticles. The optimized formulations showed high cell viability and significant EGFR silencing, indicating effective transfection. Mucoadhesion and mucopenetration two-photon microscopy studies on rabbit nasal mucosa confirmed the superior performance of TMC nanoparticles over free siRNA, highlighting their potential for non-invasive gene therapy applications.

Effect of polyphenolic dendrimers on biological and artificial lipid membranes

The use of dendrimers as nanovectors for nucleic acids or drugs requires the understanding of their interaction with biological membranes. This study investigates the impact of 1st generation polyphenolic carbosilane dendrimers on biological and model lipid membranes using several biophysical methods. While the increase in the z-average size of DMPC/DPPG liposomes correlated with the number of caffeic acid residues included in the dendrimer structure, dendrimers that contained polyethylene glycol chains generated lower zeta potential when interacting with a liposomal membrane. The increase in the fluorescence anisotropy of DPH and TMA-DPH probes incorporated into erythrocyte membranes predicted the ability of dendrimers to affect membrane fluidity in the hydrophobic interior and hydrophilic/polar region of a lipid bilayer. The presence of caffeic acid and polyethylene glycol chains in the dendrimer structure affected the thermodynamical properties of the membrane lipid matrix.

Gene Therapy with Chitosan Nanoparticles: Modern Formulation Strategies for Enhancing Cancer Cell Transfection

Gene therapy involves the introduction of exogenous genetic material into host tissues to modify gene expression or cellular properties for therapeutic purposes. Initially developed to address genetic disorders, gene therapy has expanded to encompass a wide range of conditions, notably cancer. Effective delivery of nucleic acids into target cells relies on carriers, with non-viral systems gaining prominence due to their enhanced safety profile compared to viral vectors. Chitosan, a biopolymer, is frequently utilized to fabricate nanoparticles for various biomedical applications, particularly nucleic acid delivery, with recent emphasis on targeting cancer cells. Chitosan's positively charged amino groups enable the formation of stable nanocomplexes with nucleic acids and facilitate interaction with cell membranes, thereby promoting cellular uptake. Despite these advantages, chitosan-based nanoparticles face challenges such as poor solubility at physiological pH, non-specificity for cancer cells, and inefficient endosomal escape, limiting their transfection efficiency. To address these limitations, researchers have focused on enhancing the functionality of chitosan nanoparticles. Strategies include improving stability, enhancing targeting specificity, increasing cellular uptake efficiency, and promoting endosomal escape. This review critically evaluates recent formulation approaches within these categories, aiming to provide insights into advancing chitosan-based gene delivery systems for improved efficacy, particularly in cancer therapy.

Exploring modified chitosan-based gene delivery technologies for therapeutic advancements

One of the critical steps in gene therapy is the successful delivery of the genes. Immunogenicity and toxicity are major issues for viral gene delivery systems. Thus, non-viral vectors are explored. A cationic polysaccharide like chitosan could be used as a nonviral gene delivery vector owing to its significant interaction with negatively charged nucleic acid and biomembrane, providing effective cellular uptake. However, the native chitosan has issues of targetability, unpacking ability, and solubility along with poor buffer capability, hence requiring modifications for effective use in gene delivery. Modified chitosan has shown that the "proton sponge effect" involved in buffering the endosomal pH results in osmotic swelling owing to the accumulation of a greater amount of proton and chloride along with water. The major challenges include limited exploration of chitosan as a gene carrier, the availability of high-purity chitosan for toxicity reduction, and its immunogenicity. The genetic drugs are in their infancy phase and require further exploration for effective delivery of nucleic acid molecules as FDA-approved marketed formulations soon.

Development of a PVA/PCL/CS-Based Nanofibrous Membrane for Guided Tissue Regeneration and Controlled Delivery of Doxycycline Hydrochloride in Management of Periodontitis: In Vivo Evaluation in Rats

Antibiotic administration is an adjacent therapy to guided tissue regeneration (GTR) in the management of periodontitis. This is due to the major role of pathogen biofilm in aggravating periodontal defects. This study aimed to fabricate a GTR membrane for sustained delivery of doxycycline hydrochloride (DOX) while having a space-maintaining function. The membranes were prepared using a polymeric blend of polycaprolactone/polyvinyl alcohol/chitosan by the electrospinning technique. The obtained membranes were characterized in terms of physicochemical and biological properties. Nanofibers showed a mean diameter in the submicron range of < 450 nm while having uniform randomly aligned morphology. The obtained membranes showed high strength and flexibility. A prolonged in vitro release profile during 68 h was observed for manufactured formulations. The prepared membranes showed a cell viability of > 70% at different DOX concentrations. The formulations possessed antimicrobial efficacy against common pathogens responsible for periodontitis. In vivo evaluation also showed prolonged release of DOX for 14 days. The histopathological evaluation confirmed the biocompatibility of the GTR membrane. In conclusion, the developed nanofibrous DOX-loaded GTR membranes may have beneficial characteristics in favour of both sustained antibiotic delivery and periodontal regeneration by space-maintaining function without causing any irritation and tissue damage.

Cationic Materials for Gene Therapy: A Look Back to the Birth and Development of 2,2-Bis-(hydroxymethyl)Propanoic Acid-Based Dendrimer Scaffolds

Gene therapy is extensively studied as a realistic and promising therapeutic approach for treating inherited and acquired diseases by repairing defective genes through introducing (transfection) the "healthy" genetic material in the diseased cells. To succeed, the proper DNA or RNA fragments need efficient vectors, and viruses are endowed with excellent transfection efficiency and have been extensively exploited. Due to several drawbacks related to their use, nonviral cationic materials, including lipidic, polymeric, and dendrimer vectors capable of electrostatically interacting with anionic phosphate groups of genetic material, represent appealing alternative options to viral carriers. Particularly, dendrimers are highly branched, nanosized synthetic polymers characterized by a globular structure, low polydispersity index, presence of internal cavities, and a large number of peripheral functional groups exploitable to bind cationic moieties. Dendrimers are successful in several biomedical applications and are currently extensively studied for nonviral gene delivery. Among dendrimers, those derived by 2,2-bis(hydroxymethyl)propanoic acid (b-HMPA), having, unlike PAMAMs, a neutral polyester-based scaffold, could be particularly good-looking due to their degradability in vivo. Here, an overview of gene therapy, its objectives and challenges, and the main cationic materials studied for transporting and delivering genetic materials have been reported. Subsequently, due to their high potential for application in vivo, we have focused on the biodegradable dendrimer scaffolds, telling the history of the birth and development of b-HMPA-derived dendrimers. Finally, thanks to a personal experience in the synthesis of b-HMPA-based dendrimers, our contribution to this field has been described. In particular, we have enriched this work by reporting about the b-HMPA-based derivatives peripherally functionalized with amino acids prepared by us in recent years, thus rendering this paper original and different from the existing reviews.

Fabrication of oxygen-carrying microparticles functionalized with liver ECM-proteins to improve phenotypic three-dimensional in vitro liver assembly, function, and responses

Oxygen and extracellular matrix (ECM)-derived biopolymers play vital roles in regulating many cellular functions in both the healthy and diseased liver. This study highlights the significance of synergistically tuning the internal microenvironment of three-dimensional (3D) cell aggregates composed of hepatocyte-like cells from the HepG2 human hepatocellular carcinoma cell line and hepatic stellate cells (HSCs) from the LX-2 cell line to enhance oxygen availability and phenotypic ECM ligand presentation for promoting the native metabolic functions of the human liver. First, fluorinated (PFC) chitosan microparticles (MPs) were generated with a microfluidic chip, then their oxygen transport properties were studied using a custom ruthenium-based oxygen sensing approach. Next, to allow for integrin engagements the surfaces of these MPs were functionalized using liver ECM proteins including fibronectin, laminin-111, laminin-511, and laminin-521, then they were used to assemble composite spheriods along with HepG2 cells and HSCs. After in vitro culture, liver-specific functions and cell adhesion patterns were compared between groups and cells showed enhanced liver phenotypic responses to laminin-511 and 521 as evidenced via enhanced E-cadherin and vinculin expression, as well as albumin and urea secretion. Furthermore, hepatocytes and HSCs exhibited more pronounced phenotypic arrangements when cocultured with laminin-511 and 521 modified MPs providing clear evidence that specific ECM proteins have distinctive roles in the phenotypic regulation of liver cells in engineering 3D spheroids. This study advances efforts to create more physiologically relevant organ models allowing for well-defined conditions and phenotypic cell signaling which together improve the relevance of 3D spheroid and organoid models.

Pyrene-Labeled and Quaternized Chitosan: Synthesis, Characterization, and Its Potential Application for Fluorescently Trackable Nucleic Acid Delivery into Cells

A chitosan derivative (Pyr-CS-HTAP) having pyrene (Pyr) and N-[(2-hydroxyl-3-trimethylammonium)] propyl (HTAP) units conjugated at C6 and C2 positions, respectively, was synthesized and characterized. Dynamic light scattering and scanning electron microscopy revealed that Pyr-CS-HTAP self-assembled into spherical nanoparticles with a hydrodynamic diameter of 211 ± 5 nm and a ζ-potential of +49 mV. The successful binding of Pyr-CS-HTAP with nucleic acid was ascertained by fluorescence resonance energy-transfer analysis and gel electrophoresis. Pyr-CS-HTAP facilitated the cellular uptake of nucleic acid up to 99%. Co-localization analysis using fluorescence microscopy revealed the endosomal escape of the Pyr-CS-HTAP/nucleic acid complexes and the successful release of the nucleic acid cargoes from the polyplexes into the nucleus. It is strongly believed that Pyr-CS-HTAP can potentially be developed into a fluorescently trackable gene delivery system in the future.

Green synthesis of quaternized chitosan nanogel using emulsion-photopolymerization as redox-responsive drug carrier

We report the green synthesis of trimethyl chitosan-functionalized poly(2-hydroxyethyl methacrylate) (PHEMA-TMC) nanogels via surfactant-free emulsion photopolymerization. TMC, a quaternized derivative of chitosan, was synthesized through methylation of chitosan, resulting in quaternary and tertiary amine groups as the main substitution products. TMC tertiary amine moiety and riboflavin (RF) acted as a redox photo-initiating system to generate free radicals for the polymerization under light irradiation. The effects of polymerization parameters such as irradiation time, concentrations of TMC and RF were investigated using MBA as crosslinker. Under the optimal condition of 1 % TMC, 4 % HEMA, 0.8 μM RF, 5 % MBA, and 4 h of polymerization time, the cationic PHEMA-TMC nanogel was synthesized with 76 % monomer conversion and an average diameter of about 106 nm. Moreover, the disulfide-crosslinked PHEMA-TMC nanogel was also synthesized using the disulfide dimethacrylate crosslinker, which exhibited a redox-induced degradation and release of encapsulated melatonin, potentially useful as a redox-responsive drug delivery carrier.

Mucoadhesive Nanoparticles Enhance the Therapeutic Effect of Dexamethasone on Experimental Ulcerative Colitis by the Local Administration as an Enema

Background

As the first-line drug to treat ulcerative colitis (UC), long-term use of glucocorticoids (GCs) produces severe toxic and side effects. Local administration as enema can increase the local GCs concentrations and reduce systemic exposure to high oral doses by directly delivering GCs to the inflammation site in the distal colorectum. However, UC patients are often accompanied by diarrhea, leading to the short colonic residence time of GCs and failure to exert their function fully.

Purpose

A kind of mucoadhesive nanoparticles (NPs) loading different dexamethasone derivatives (DDs) were developed, which could attach to the positively charged inflammatory colonic mucosa through electrostatic adsorption after administered by enema, thereby improving the local concentration and achieving effective targeted therapy for UC.

Methods

Two DDs, dexamethasone hemisuccinate and dexamethasone phosphate, were synthesized. In NPs preparation, The core PEI-DDs NPs were built by the electrostatic adsorption of DDs and the cationic polymer polyethyleneimine (PEI). Then, the natural polyanionic polysaccharide sodium alginate (SA) was electronically coated around NPs to construct the final SA-PEI-DDs NPs, followed by the in vitro stability and release tests, in vitro and in vivo colonic mucosal adhesion tests. In the in vivo anti-UC test, the experimental colitis mice were induced by 2,4,6-trinitrobenzenesulfonic acid. The body weight and disease activity index changes were measured, and the myeloperoxidase activity, pro-inflammatory cytokines concentration, and hematoxylin and eosin staining were also investigated to evaluate the therapeutic effect of NPs.

Results

The structures of two DDs were demonstrated by ¹H-NMR and MS. Both NPs were negatively charged and achieved high loading efficiency of DDs, while their particle sizes were significantly different. NPs showed good stability and sustained release properties in the simulated colonic environment. Moreover, the negative charge on the of NPs surface made them easier to adhere to the positively charged inflammatory colonic mucosa, thereby enhancing the enrichment and retention of DDS in the colitis site. Furthermore, the NPs exhibited better therapeutic effects than free Dex on the experimental colitis mice induced by TNBS through the enema rectal.

Conclusion

These results indicated the mucoadhesive NPs as a kind of novel nano-enema showed great potential to achieve efficient treatment on UC.

Evaluation of antimicrobial activity of thiolated methylated N-(4-N, N-dimethylaminobenzyl) chitosan as a new derivative of chitosan

Despite chitosan as a natural cationic polysaccharide derived from chitin can be applied as an antimicrobial agent, many studies are performing for enhancing its capability to fight against pathogens. The aim of this study is investigating the antibacterial effect of thiolated methylated N-(4-N,N-dimethylaminobenzyl) chitosan (TTMAC) polymer and its nanoparticles as a novel derivation of chitosan. The polymer derivative was synthetized and characterized via¹ H NMR, FT-IR and Elman test. The nanoparticles with different N/P ratios were prepared by ionic gelation method and characterized by DLS (Dynamic Light Scattering) and TEM (Transmission Electron Microscopy). The cellular toxicity of polymer and nanoparticles at different concentrations were evaluated on human MCF-7 cell line. Antimicrobial assay was performed on Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Candida albicans (ATCC 10231)as Gram negative, Gram positive and yeast pathogens, respectively. The obtained results have shown the TTMAC polymer has a higher inhibition activity against microbial pathogens and also lower cellular toxicity in comparison with chitosan polymer. Furthermore, chitosan nanoparticles in comparison with TTMAC nanoparticles have lower size and highest zeta potential in different ratio and chitosan nanoparticles have more inhibitory effects against microbial pathogens. In conclusion, TTMAC derivative in polymeric form can be a promising tool against microbial pathogens.

Amphiphilic Chitosan Bearing Double Palmitoyl Chains and Quaternary Ammonium Moieties as a Nanocarrier for Plasmid DNA

Amphiphilic chitosan, bPalm-CS-HTAP, having N-(2-((2,3-bis(palmitoyloxy)propyl)amino)-2-oxoethyl) (bPalm) groups as double hydrophobic tails and O-[(2-hydroxyl-3-trimethylammonium)] propyl (HTAP) groups as hydrophilic heads was synthesized and evaluated for its self-assembly properties and potential as a gene carrier. The degree of bis-palmitoyl group substitution (DS _bPalm) and the degree of quaternization (DQ) were approximately 2 and 56%, respectively. bPalm-CS-HTAP was found to assemble into nanosized spherical particles with a hydrodynamic diameter (D _H) of 265.5 ± 7.40 nm (PDI = 0.5) and a surface charge potential of 40.1 ± 0.04 mV. bPalm-CS-HTAP condensed the plasmid pVAX1.CoV2RBDme completely at a bPalm-CS-HTAP:pDNA ratio of 2:1. The self-assembled bPalm-CS-HTAP/pDNA complexes could enter HEK 293A and CHO cells and enabled gene expression at negligible cytotoxicity compared to commercial PEI (20 kDa). These results suggested that bPalm-CS-HTAP can be used as a promising nonviral gene carrier.

Synthesis, characterization and application of chitosan-N-(4-hydroxyphenyl)-methacrylamide derivative as a drug and gene carrier

The aim of this study was to develop a green method to fabricate a novel CS modified N-(4-hydroxyphenyl)- methacrylamide conjugate (CSNHMA) and to evaluate its biomedical potential. CSNHMA has been prepared by a simple method via aza Michael addition reaction between CS and N- (4-hydroxyphenyl)-methacrylamide (NHMA) in ethanol. Its structural and morphological properties were characterized by various analysis techniques. The obtained results confirmed that a highly porous network structure of CSNHMA was successfully synthesized via aza Michael addition reaction. Consequently, it was analyzed as a drug and gene carrier. CSNHMA/pGL3 showed an enhanced buffering capacity due to the presence of NHMA moiety leading to higher transfection efficiency in all cancer cells (A549, HeLa and HepG2) as compared to native CS and Lipofectamine®. Therefore, these findings clearly support the possibility of using CSNHMA as a good transfection agent. For in vitro drug release study, we prepared CSNHMA nanoparticles (NPs) and curcumin loaded CSNHMA NPs of size <230 nm respectively via the non-toxic ionic gelation route and the encapsulation efficiency of drug was found to be 77.03%. In vitro drug release studies demonstrated a faster and sustained release of curcumin loaded CSNHMA NPs at pH 5.0 compared to physiological pH.

Nanoparticles for local delivery of siRNA in lung therapy

An overview of the application of natural and synthetic, non-viral vectors for oligonucleotide delivery into the lung is presented in this review, with a special focus on lung cancer. Due to the specificity of the respiratory tract, its structure and natural barriers, the administration of drugs (especially those based on nucleic acids) is a particular challenge. Among widely tested non-viral drug and oligonucleotides carriers, synthetic polymers seem to be most promising. Unique properties of these nanoparticles allow for essentially unlimited possibilities regarding their design and modification. This gives hope that optimal nanoparticles with ideal nucleic acid carrier properties for lung cancer therapy will eventually emanate.

Using Chitosan or Chitosan Derivatives in Cancer Therapy

Cancer is one of the major causes of death worldwide. Chemotherapeutic drugs have become a popular choice as anticancer agents. Despite the therapeutic benefits of chemotherapeutic drugs, patients often experience side effects and drug resistance. Biopolymers could be used to overcome some of the limitations of chemotherapeutic drugs, as well as be used either as anticancer agents or drug delivery vehicles. Chitosan is a biocompatible polymer derived from chitin. Chitosan, chitosan derivatives, or chitosan nanoparticles have shown their promise as an anticancer agent. Additionally, functionally modified chitosan can be used to deliver nucleic acids, chemotherapeutic drugs, and anticancer agents. More importantly, chitosan-based drug delivery systems improved the efficacy, potency, cytotoxicity, or biocompatibility of these anticancer agents. In this review, we will investigate the properties of chitosan and chemically tuned chitosan derivatives, and their application in cancer therapy.

Quaternary ammonium N,N,N-trimethyl chitosan derivative and povidone‑iodine complex as a potent antiseptic with enhanced wound healing property

The importance of developing more potent antimicrobials and robust infection prevention practices has been highlighted recently with the increase in reports of emerging bacterial resistance mechanisms and the development of antibiotic-resistant microbes. In this study, a quaternary ammonium chitosan derivative, N,N,N-trimethyl chitosan chloride (TMC) with inherent bactericidal property was synthesized and complexed with povidone‑iodine (PVP-I) to create a potentially more potent antiseptic solution that could also significantly enhance the wound healing process. TMC, a positively charged, water-soluble derivative of chitosan, formed stable solutions with PVP-I at 5% w/v TMC concentration (TMC5/PVP-I). TMC5/PVP-I was significantly effective against multidrug-resistant bacteria S. aureus compared with PVP-I alone. TMC/PVP-I solutions also showed fungicidal property against C. albicans, with no cytotoxic effects when tested against human fibroblast cells cultured in vitro. Wound healing assessment in vivo revealed early collagen formation and re-epithelialization for TMC5/PVP-I treated wounds in rats relative to control and PVP-I only. Formulation of TMC/PVP-I solutions presented in the study can be easily adapted in the existing production of commercial PVP-I creating a new product with more potent bactericidal and enhanced wound healing properties for optimal wound care.

Application of nanotechnology in drug delivery systems for respiratory diseases (Review)

Respiratory disease is a common disease with a high incidence worldwide, which is a serious threat to human health, and is considered a societal and economic burden. The application of nanotechnology in drug delivery systems has created new treatments for respiratory diseases. Within this context, the present review systematically introduced the physicochemical properties of nanoparticles (NPs); reviewed the current research status of different nanocarriers in the treatment of respiratory diseases, including liposomes, solid lipid nanocarriers, polymeric nanocarriers, dendrimers, inorganic nanocarriers and protein nanocarriers; and discussed the main advantages and limitations of therapeutic nanomedicine in this field. The application of nanotechnology overcomes drug inherent deficiencies to a certain extent, and provides unlimited potential for the development of drugs to treat respiratory diseases. However, most of the related research work is in the preclinical experimental stage and safety assessment is still a challenging task. Future studies are needed to focus on the performance modification, molecular mechanism and potential toxicity of therapeutic nanomedicine.

Chitosan grafted/cross-linked with biodegradable polymers: A review

Public perception of polymers has been drastically changed with the improved plastic management at the end of their life. However, it is widely recognised the need of developing biodegradable polymers, as an alternative to traditional petrochemical polymers. Chitosan (CH), a biodegradable biopolymer with excellent physiological and structural properties, together with its immunostimulatory and antibacterial activity, is a good candidate to replace other polymers, mainly in biomedical applications. However, CH has also several drawbacks, which can be solved by chemical modifications to improve some of its characteristics such as solubility, biological activity, and mechanical properties. Many chemical modifications have been studied in the last decade to improve the properties of CH. This review focussed on a critical analysis of the state of the art of chemical modifications by cross-linking and graft polymerization, between CH or CH derivatives and other biodegradable polymers (polysaccharides or proteins, obtained from microorganisms, synthetized from biomonomers, or from petrochemical products). Both techniques offer the option of including a wide variety of functional groups into the CH chain. Thus, enhanced and new properties can be obtained in accordance with the requirements for different applications, such as the release of drugs, the improvement of antimicrobial properties of fabrics, the removal of dyes, or as scaffolds to develop bone tissues.

Nanocarriers in effective pulmonary delivery of siRNA: current approaches and challenges

Research on siRNA is increasing due to its wide applicability as a therapeutic agent in irreversible medical conditions. siRNA inhibits expression of the specific gene after its delivery from formulation to cytosol region of a cell. RNAi (RNA interference) is a mechanism by which siRNA is silencing gene expression for a particular disease. Numerous studies revealed that naked siRNA delivery is not preferred due to instability and poor pharmacokinetic performance. Nanocarriers based delivery of siRNA has the advantage to overcome physiological barriers and protect the integrity of siRNA from degradation by RNAase. Various diseases like lung cancer, cystic fibrosis, asthma, etc can be treated effectively by local lung delivery. The selective targeted therapeutic action in diseased organ and least off targeted cytotoxicity are the key benefits of pulmonary delivery. The current review highlights recent developments in pulmonary delivery of siRNA with novel nanosized formulation approach with the proven in vitro/in vivo applications.

Biodegradable Polymers for Gene-Delivery Applications

Gene-based therapies have emerged as a new modality for combating a myriad of currently incurable diseases. However, the fragile nature of gene therapeutics has significantly hampered their biomedical applications. Correspondingly, the development of gene-delivery vectors is of critical importance for gene-based therapies. To date, a variety of gene-delivery vectors have been created and utilized for gene delivery. In general, they can be categorized into viral- and non-viral vectors. Due to safety issues associated with viral vectors, non-viral vectors have recently attracted much more research focus. Of these non-viral vectors, polymeric vectors, which have been preferred due to their low immunogenicity, ease of production, controlled chemical composition and high chemical versatility, have constituted an ideal alternative to viral vectors. In particular, biodegradable polymers, which possess advantageous biocompatibility and biosafety, have been considered to have great potential in clinical applications. In this context, the aim of this review is to introduce the recent development and progress of biodegradable polymers for gene delivery applications, especially for their chemical structure design, gene delivery capacity and additional biological functions. Accordingly, we first define and categorize biodegradable polymers, followed by describing their corresponding degradation mechanisms. Various types of biodegradable polymers resulting from natural and synthetic polymers will be introduced and their applications in gene delivery will be examined. Finally, a future perspective regarding the development of biodegradable polymer vectors will be given.

Silencing of IL-6 and STAT3 by siRNA loaded hyaluronate-N,N,N-trimethyl chitosan nanoparticles potently reduces cancer cell progression

The immunosuppressive nature of the tumor microenvironment is a critical problem that should be considered before the design of immunotherapies. Interleukin (IL)-6 and its related downstream molecules such as signal transducer and activator of transcription (STAT)3 play an important role in the cancer progression, which can be considered as potential therapeutic targets. In the present study, we generated the active-targeted hyaluronate (HA) recoated N, N, N-trimethyl chitosan (TMC) nanoparticles (NPs) to deliver IL-6- and STAT3-specific small interfering RNAs (siRNAs) to the CD44-expressing cancer cells. We utilized the interaction between HA and CD44 to increase the specificity and efficacy of cellular uptake in NPs. The results showed that the synthesized NPs had efficient physicochemical characteristics, high transfection efficiency, low toxicity, and controlled siRNA release. siRNA-loaded NPs significantly inhibited the IL-6/STAT3 expression, which was associated with blockade of proliferation, colony formation, migration, and angiogenesis in cancer cells. These findings imply the potential of HA-TMC NPs as potent vectors in gene therapy and their application for the silencing of IL-6 and STAT3, as a novel anti-cancer combination therapeutic strategy, for the first time.

Adjuvants and delivery systems based on polymeric nanoparticles for mucosal vaccines

Most pathogens enter the body through mucosal surfaces. Therefore, vaccination through the mucosal route can greatly enhance the mucosal immune response. Vaccination via the mucosal surface is the most effective way to trigger a protective mucosal immune response, but the vast majority of vaccines used are administered by injection. Strategies to enhance the mucosal immunity have been developed by using vaccine adjuvants, delivery systems, bacterial or viral vectors, and DNA vaccines. Appropriate vaccine adjuvants and drug delivery systems can improve the immunogenicity of antigens, induce a stronger immune response, and reduce the vaccine dose and production cost. In recent years, many studies have focused on finding safe and effective vaccine adjuvants and drug delivery systems to formulate the mucosal vaccines for solving the above problems. Great progress has also been made in vaccine adjuvants and drug delivery systems based on biodegradable polymer nanoparticles. In this paper, the research progress of the mucosal vaccine and its related adjuvants and drug delivery systems in recent years was reviewed, and the application of polymers as adjuvants and drug delivery system in vaccine was prospected. This review provides a fundamental knowledge for the application of biodegradable polymer nanoparticles as adjuvants and carriers in mucosal vaccines and shows great application prospects.

Recent advances in polymeric materials for the delivery of RNA therapeutics

Introduction: The delivery of nucleic acid therapeutics through non-viral carriers face multiple biological barriers that reduce their therapeutic efficiency. Despite great progress, there remains a significant technological gap that continues to limit clinical translation of these nanocarriers. A number of polymeric materials are being exploited to efficiently deliver nucleic acids and achieve therapeutic effects. Areas covered: We discuss the recent advances in the polymeric materials for the delivery of nucleic acid therapeutics. We examine the use of common polymer architectures and highlight the challenges that exist for their development from bench side to clinic. We also provide an overview of the most notable improvements made to circumvent such challenges, including structural modification and stimuli-responsive approaches, for safe and effective nucleic acid delivery. Expert opinion: It has become apparent that a universal carrier that follows 'one-size' fits all model cannot be expected for delivery of all nucleic acid therapeutics. Carriers need to be designed to exhibit sensitivity and specificity toward individual targets diseases/indications, and relevant subcellular compartments, each of which possess their own unique challenges. The ability to devise synthetic methods that control the molecular architecture enables the future development that allow for the construction of 'intelligent' designs.

pH-Sensitive Chitosan-Heparin Nanoparticles for Effective Delivery of Genetic Drugs into Epithelial Cells

Chitosan has been extensively studied as a genetic drug delivery platform. However, its efficiency is limited by the strength of DNA and RNA binding. Expecting a reduced binding strength of cargo with chitosan, we proposed including heparin as a competing polyanion in the polyplexes. We developed chitosan–heparin nanoparticles by a one-step process for the local delivery of oligonucleotides. The size of the polyplexes was dependent on the mass ratio of polycation to polyanion. The mechanism of oligonucleotide release was pH-dependent and associated with polyplex swelling and collapse of the polysaccharide network. Inclusion of heparin enhanced the oligonucleotide release from the chitosan-based polyplexes. Furthermore, heparin reduced the toxicity of polyplexes in the cultured cells. The cell uptake of chitosan–heparin polyplexes was equal to that of chitosan polyplexes, but heparin increased the transfection efficiency of the polyplexes two-fold. The application of chitosan–heparin small interfering RNA (siRNA) targeted to vascular endothelial growth factor (VEGF) silencing of ARPE-19 cells was 25% higher. Overall, chitosan–heparin polyplexes showed a significant improvement of gene release inside the cells, transfection, and gene silencing efficiency in vitro, suggesting that this fundamental strategy can further improve the transfection efficiency with application of non-viral vectors.

Thiolated chitosan-lauric acid as a new chitosan derivative: Synthesis, characterization and cytotoxicity

Chitosan as a biopolymer is an attractive vehicle for biomedical applications due to its unique characteristics. In order to improve chitosan's physicochemical features, chemical modification has been carried out to make it more suitable for such approaches. The aim of this study was to prepare and evaluate thiolated chitosan-lauric acid as a new chitosan derivative for biomedical use. Lauric acid was introduced to chitosan via stable amide bond between carboxylic acid group of fatty acid and the amine in the chitosan and thiolation was carried out using thioglycolic acid. Resulted polymers were characterized by FTIR, ¹H NMR and TGA. Moreover, cell viability assessment of new derivative was performed using MTT method. FTIR and ¹H NMR results showed that both substitution reactions were successfully completed. Furthermore, new synthesized polymer had no significant cytotoxicity against normal gingiva human cells (HGF1-PI 1).These findings confirm that this new derivative can be introduced as a suitable polymer for biomedical purposes such as mucosal drug delivery.

Chitin/Chitosan: Versatile Ecological, Industrial, and Biomedical Applications

Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.

Novel chitosan based nanoparticles as gene delivery systems to cancerous and noncancerous cells

The present study aimed to investigate in vitro DNA transfection efficiency of three novel chitosan derivatives: thiolated trimethyl chitosan (TMC-Cys), methylated 4-N,N dimethyl aminobenzyl N,O carboxymethyl chitosan(MABCC) and thiolated trimethyl aminobenzyl chitosan(MABC-Cys). After polymer synthesis and characterization, nanoparticles were prepared using these polymers and their size, zeta potential and DNA condensing ability were measured. After that, cytotoxicity and transfection efficiency of nanocomplexes were carried out in three different cells. The results showed that all polymers could condense DNA plasmid strongly from N/P 2 and nanocomplexes had eligible sizes and zeta potentials. Moreover, the nanocomplexes had negligible cytotoxicity and MABC-Cys was the most effective vehicle for gene delivery in HEK-293T cells. In the two other cell lines, SKOV-3 and MCF-7, TMC-Cys exhibited the highest transfection efficiency. This study indicated that chemical structure of these novel chitosan derivatives in the interaction with the cell type can lead to successful gene delivery.

RGD/TAT-functionalized chitosan-graft-PEI-PEG gene nanovector for sustained delivery of NT-3 for potential application in neural regeneration

In this study, we prepared a multifunctional gene delivery nanovector containing a chitosan (CS) backbone and polyethylenimine (PEI) arms with arginine-glycine-aspartate (RGD)/twin-arginine translocation (TAT) conjugated via polyethylene glycol (PEG). Branched PEI, with a molecular weight of 2000 Da, was used to achieve a balance between biocompatibility and transfection efficiency, whereas RGD/TAT peptides were conjugated for enhanced targeting ability and cellular uptake. Synthesis of the copolymers was confirmed by characterizing the chemical structure with ¹H nuclear magnetic resonance and Fourier Transform Infrared Spectroscopy (FTIR). The nanovector was biocompatible with cells and showed excellent capability for DNA condensation; the resulting complexes with DNA were well-formed, and possessed small particle size and reasonable positive charge. Higher gene transfection efficiency, compared to that achieved with PEI (25 kDa), was confirmed in tumor (HeLa cells) and normal cells (293T and NIH 3T3 cells). More importantly, the cells transfected with the chitosan-graft-PEI-PEG/pCMV-EGFP-Ntf3 complex produced sustained neurotrophin-3 with a linear increase in cumulative concentration, which induced neuronal differentiation of neural stem cell and promoted neurite outgrowth. These findings suggested that our multifunctional copolymers might be ideal nanovectors for engineering cells via gene transfection, and could potentially be applied in tumor therapy and regenerative medicine.

STATEMENT OF SIGNIFICANCE

We successfully prepared a multifunctional gene delivery nanovector containing branched PEI with a molecular weight of 2000 Da to balance between biocompatibility and transfection efficiency, and RGD/TAT peptides for enhanced targeting ability and cellular uptake. The well-formed CPPP/DNA complexes of small particle size and reasonable positive charges potentially enhanced gene transfection in both tumor and normal cells. More importantly, the CPPP/pCMV-EGFP-Ntf3 complex-transfected 293T cells could produce sustained NT-3 with a constant ratio, which induced neuron differentiation of NSC and promoted neurite outgrowth. Therefore, our study provided an effective strategy for producing neurotrophins by engineering cells with gene delivery, which deserved wide investigation and potential application in regenerative medicine.

N-[4-(N,N,N-trimethylammonium)benzyl]chitosan chloride: Synthesis, interaction with DNA and evaluation of transfection efficiency

А novel cationic chitosan derivative, N-[4-(N,N,N-trimethylammonium)benzyl]chitosan chloride (TMAB-CS), with different degrees of substitution (DS) was synthesized by a chemoselective interaction of 4-formyl-N,N,N-trimethylanilinium iodide with chitosan amino groups using a reductive amination method. Several factors (pH, reactant ratio, reaction time, and chitosan structure) were studied for their effects on the DS of the resulting TMAB-CS. The obtained derivatives were characterized by ¹H NMR and FTIR spectroscopy. Turbidimetric titration showed enhanced solubility over a wide pH range even for low-substituted TMAB-CS. TMAB-CS provided strong DS-dependent binding of plasmid DNA. Dynamic light scattering measurements revealed the formation of stable polyplexes with hydrodynamic diameters of 200-300nm and ζ-potential of 20-30mV. TMAB-CS with relatively low DS (25%) demonstrated more pronounced transfection efficiency (up to 2000 cell/cm²) of plasmid DNA into the HEK293 cell line promoted by free TMAB-CS. The positive effects of lower DS can be related to a better polyplex dissociation within the cell. The cytotoxicity of TMAB-CS was comparable to that of the initial chitosan at concentrations up to 300ng/μL, even at high DS.

Atomic Force Microscopy as a Tool to Assess the Specificity of Targeted Nanoparticles in Biological Models of High Complexity

The ability to design nanoparticle delivery systems capable of selectively target their payloads to specific cell populations is still a major caveat in nanomedicine. One of the main hurdles is the fact that each nanoparticle formulation needs to be precisely tuned to match the specificities of the target cell and route of administration. In this work, molecular recognition force spectroscopy (MRFS) is presented as a tool to evaluate the specificity of neuron-targeted trimethyl chitosan nanoparticles to neuronal cell populations in biological samples of different complexity. The use of atomic force microscopy tips functionalized with targeted or non-targeted nanoparticles made it possible to assess the specific interaction of each formulation with determined cell surface receptors in a precise fashion. More importantly, the combination of MRFS with fluorescent microscopy allowed to probe the nanoparticles vectoring capacity in models of high complexity, such as primary mixed cultures, as well as specific subcellular regions in histological tissues. Overall, this work contributes for the establishment of MRFS as a powerful alternative technique to animal testing in vector design and opens new avenues for the development of advanced targeted nanomedicines.

Attenuation of Maladaptive Responses in Aortic Adventitial Fibroblasts through Stimuli-Triggered siRNA Release from Lipid-Polymer Nanocomplexes

Lipid-siRNA assemblies are modified with photo-responsive polymers to enable spatiotemporally-controlled silencing of interleukin 1 beta (IL1β) and cadherin 11 (CDH11), two genes that are essential drivers of maladaptive responses in human aortic adventitial fibroblasts (AoAFs). These hybrid nanocomplexes address the critical challenge of locally mitigating fibrotic actions that lead to the high rates of vascular graft failures. In particular, the lipid-polymer formulations provide potent silencing of IL1β and CDH11 that is precisely modulated by a photo-release stimulus. Moreover, a dynamic modeling framework is used to design a multi-dose siRNA regimen that sustains knockdown of both genes over clinically-relevant timescales. Multi-dose suppression illuminates a cooperative role for IL1β and CDH11 in pathogenic adventitial remodeling and is directly linked to desirable functional outcomes. Specifically, myofibroblast differentiation and cellular proliferation, two of the primary hallmarks of fibrosis, are significantly attenuated by IL1β silencing. Meanwhile, the effects of CDH11 siRNA treatment on differentiation become more pronounced at higher cell densities characteristic of constrictive adventitial remodeling in vivo. Thus, this work offers a unique formulation design for photo-responsive gene suppression in human primary cells and establishes a new dosing method to satisfy the critical need for local attenuation of fibrotic responses in the adventitium surrounding vascular grafts.

Chitosan/Hyaluronic Acid Nanoparticles: Rational Design Revisited for RNA Delivery

Chitosan/hyaluronic acid (HA) nanoparticles can be used to deliver an RNA/DNA cargo to cells overexpressing HA receptors such as CD44. For these systems, unequivocal links have not been established yet between chitosan macromolecular (molecular weight; degree of deacetylation, i.e., charge density) and nanoparticle variables (complexation strength, i.e., stability; nucleic acid protection; internalization rate) on one hand, and transfection efficiency on the other hand. Here, we have focused on the role of avidity on transfection efficiency in the CD44-expressing HCT-116 as a cellular model; we have employed two differently sized payloads (a large luciferase-encoding mRNA and a much smaller anti-Luc siRNA), and a small library of chitosans (variable molecular weight and degree of deactylation). The RNA avidity for chitosan showed-as expected-an inverse relationship: higher avidity-higher polyplex stability-lower transfection efficiency. The avidity of chitosan for RNA appears to lead to opposite effects: higher avidity-higher polyplex stability but also higher transfection efficiency. Surprisingly, the best transfecting particles were those with the lowest propensity for RNA release, although this might be a misleading relationship: for example, the same macromolecular parameters that increase avidity can also boost chitosan's endosomolytic activity, with a strong enhancement in transfection. The performance of these nonviral vectors appears therefore difficult to predict simply on the basis of carrier- or payload-related variables, and a more holistic consideration of the journey of the nanoparticle, from cell uptake to cytosolic bioavailability of payload, is needed. It is also noteworthy that the nanoparticles used in this study showed optimal performance under slightly acidic conditions (pH 6.4), which is promising for applications in a tumoral extracellular environment. It is also worth pointing out that under these conditions we have for the first time successfully delivered mRNA with chitosan/HA nanoparticles.

Polymeric Nanoparticle-Mediated Gene Delivery for Lung Cancer Treatment

In recent years, researchers have focused on targeted gene therapy for lung cancer, using nanoparticle carriers to overcome the limitations of conventional treatment methods. The main goal of targeted gene therapy is to develop more efficient therapeutic strategies by improving the bioavailability, stability, and target specificity of gene therapeutics and to reduce off-target effects. Polymer-based nanoparticles, an alternative to lipid and inorganic nanoparticles, efficiently carry nucleic acid therapeutics and are stable in vivo. Receptor-targeted delivery is a promising approach that can limit non-specific gene delivery and can be achieved by modifying the polymer nanoparticle surface with specific receptor ligands or antibodies. This review highlights the recent developments in gene delivery using synthetic and natural polymer-based nucleic acid carriers for lung cancer treatment. Various nanoparticle systems based on polymers and polymer combinations are discussed. Further, examples of targeting ligands or moieties used in targeted, polymer-based gene delivery to lung cancer are reviewed.

Multifaceted Applications of Chitosan in Cancer Drug Delivery and Therapy

Chitosan is a versatile polysaccharide of biological origin. Due to the biocompatible and biodegradable nature of chitosan, it is intensively utilized in biomedical applications in scaffold engineering as an absorption enhancer, and for bioactive and controlled drug release. In cancer therapy, chitosan has multifaceted applications, such as assisting in gene delivery and chemotherapeutic delivery, and as an immunoadjuvant for vaccines. The present review highlights the recent applications of chitosan and chitosan derivatives in cancer therapy.

History of Polymeric Gene Delivery Systems

As an option for genetic disease treatment and an alternative for traditional cancer chemotherapy, gene therapy achieves significant attention. Nucleic acid delivery, however, remains a main challenge in human gene therapy. Polymer-based delivery systems offer a safer and promising route for therapeutic gene delivery. Over the past five decades, various cationic polymers have been optimized for increasingly effective nucleic acid transfer. This resulted in a chemical evolution of cationic polymers from the first-generation polycations towards bioinspired multifunctional sequence-defined polymers and nanocomposites. With the increasing of knowledge in molecular biological processes and rapid progress of macromolecular chemistry, further improvement of polymeric nucleic acid delivery systems will provide effective tool for gene-based therapy in the near future.

Regioselective chitosan end-group activation: the triskelion approach

Non-reactive chitosan extremities are regioselectively activated with a trivalent linker, called triskelion, allowing subsequent end-group functionalization with any thiol-reactive species.