Development of a novel pH sensitive silane crosslinked injectable hydrogel for controlled release of neomycin sulfate

Chitosan/Fibroin Biopolymer-Based Hydrogels for Potential Angiogenesis in Developing Chicks and Accelerated Wound Healing in Mice

Potential therapies for wound management remain one of the most challenging affairs to date. Biopolymer hydrogels possess inherent properties that facilitate the healing of damaged tissue by creating a supportive and hydrated environment. Chitosan/fibroin hydrogels were formulated with poly (vinyl pyrrolidone) and cross-linked using 3-aminopropyl (diethoxy) methylsilane (APDEMS) for the aforementioned function. The hydrogels were characterized through Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy, and their swelling response was observed using a variety of solvents. Additionally, hydrogels were investigated for biomedical applications. As the amount of fibroin added to the hydrogels increased, the swelling ratio decreased. The analysis of chorioallantoic membrane (CAM) assay revealed that higher concentrations of fibroin in the hydrogel were directly correlated with increased angiogenesis. The intragroup comparison showed that the vascular number in the CPF5 group was significantly increased (p ≤ 0.05) compared to other hydrogel groups. The wound healing efficiency of the prepared hydrogels showed that the rate of wound reduction (99.06%) was remarkably (p ≤ 0.05) high in the hydrogel group with a greater fibroin content against control (67.03%). Histological findings of wounded tissues corroborate the abovementioned results, showing dense fibrous connective tissues in the fibroin group compared to the control. The results of this work provide thorough preclinical evidence that chitosan-fibroin biopolymers are involved in enhanced angiogenesis in growing chicks and speed up wound healing in mice without any obvious toxicity.

Biomedical potentials of alginate via physical, chemical, and biological modifications

Alginate is a linear polysaccharide with a modifiable structure and abundant functional groups, offers immense potential for tailoring diverse alginate-based materials to meet the demands of biomedical applications. Given the advancements in modification techniques, it is significant to analyze and summarize the modification of alginate by physical, chemical and biological methods. These approaches provide plentiful information on the preparation, characterization and application of alginate-based materials. Physical modification generally involves blending and physical crosslinking, while chemical modification relies on chemical reactions, mainly including acylation, sulfation, phosphorylation, carbodiimide coupling, nucleophilic substitution, graft copolymerization, terminal modification, and degradation. Chemical modified alginate contains chemically crosslinked alginate, grafted alginate and oligo-alginate. Biological modification associated with various enzymes to realize the hydrolysis or grafting. These diverse modifications hold great promise in fully harnessing the potential of alginate for its burgeoning biomedical applications in the future. In summary, this review provides a comprehensive discussion and summary of different modification methods applied to improve the properties of alginate while expanding its biomedical potentials.

Near-infrared light-actuated on-demand botanicals release and hyperthermia by an antibiotic-free polysaccharide-based hydrogel dressing for the synergistic treatment of wound infections

Bacterial infection is a key factor affecting wound healing. Conventional treatments might lead to the widespread emergence of drug-resistant bacteria due to the long-term and excessive use of antibiotics. It is necessary to develop an antibiotic-free method for effective treatment of bacterial wound infections. In this work, we constructed an antibiotic-free polysaccharide-based hydrogel dressing (ATB) with near-infrared light-actuated on-demand botanicals release and hyperthermia for the synergistic treatment of wound infections. The ATB hydrogel dressing was made up of agarose as a support matrix, berberine hydrochloride as the active botanicals and TA-Fe(III) nanoparticles as NIR laser-activated photothermal reagents. The ATB hydrogel dressing showed spatiotemporal botanicals release and excellent photothermal properties with NIR irradiation. With the results of in vitro and in vivo antibacterial experiments, the antibiotic-free ATB hydrogel could synergistically eliminate bacteria and accelerate wound healing. Overall, the near-infrared light-responsive ATB hydrogel could provide a promising antibiotic-free strategy for the treatment of bacterial wound infections.

Injectable hydrogels for cartilage and bone tissue regeneration: A review

Annually, millions of patients suffer from irreversible injury owing to the loss or failure of an organ or tissue caused by accident, aging, or disease. The combination of injectable hydrogels and the science of stem cells have emerged to address this persistent issue in society by generating minimally invasive treatments to augment tissue function. Hydrogels are composed of a cross-linked network of polymers that exhibit a high-water retention capacity, thereby mimicking the wet environment of native cells. Due to their inherent mechanical softness, hydrogels can be used as needle-injectable stem cell carrier materials to mend tissue defects. Hydrogels are made of different natural or synthetic polymers, displaying a broad portfolio of eligible properties, which include biocompatibility, low cytotoxicity, shear-thinning properties as well as tunable biological and physicochemical properties. Presently, novel ongoing developments and native-like hydrogels are increasingly being used broadly to improve the quality of life of those with disabling tissue-related diseases. The present review outlines various future and in-vitro applications of injectable hydrogel-based biomaterials, focusing on the newest ongoing developments of in-situ forming injectable hydrogels for bone and cartilage tissue engineering purposes.

Graphene oxide reinforced biopolymeric (chitosan) hydrogels for controlled cephradine release

In the current study, chitosan, poly (N-vinyl-2-pyrolidone) and polyamidoamine based hydrogels were prepared by Solution Casting Method using different quantity of graphene oxide (GO) for controlled cephradine (CPD) release. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermal analysis, scanning electron microscope and atomic force microscopy. FTIR results endorsed the presence of particular functionalities and developed interfaces in hydrogels. The thermal stability was directly proportional to the amount of GO. Antibacterial activity was investigated against gram-negative bacteria resultantly; CAD-2 exhibited maximum bactericidal activity against Escherichia coli and Psuedomonas aeruginosa. In addition, in-vitro biodegradation was examined in phosphate buffer saline solution and proteinase K for 21 and 07 days respectively. The maximum swelling was exhibited by CAD-133777 % in distilled water that was governed by quasi-Fickian diffusion. The swelling volumes were inversely proportional to the amount of GO. In the same way, pH sensitive CPD release was detected by UV visible spectrophotometer that followed zero order and Higuchi models. However, in 4 h, 89.4 % and 83.7 % of CPD was released in PBS and SIF solution correspondingly. Therefore, the chitosan-based biocompatible and biodegradable hydrogel platforms offered substantial potential for the controlled CPD release in medico-biological applications.

Controlled drug release contenders comprising starch/poly(allylamine hydrochloride) biodegradable composite films

The blending of natural polysaccharides with synthetic polymers has attracted much attention in drug delivery models owing to their remarkable biodegradable and biocompatible characteristics. This study focuses on the facile preparation of a sequence of composite films having Starch/Poly(allylamine hydrochloride) (ST/PAH) in different compositions to propose a novel drug delivery system (DDS). ST/PAH blend films were developed and characterized. FT-IR evaluation confirmed the involvement of intermolecular H-bonding between the ST and PAH counterparts in blended films. The water contact angle (WCA) ranged from 71° to 100° indicating that all the films were hydrophobic. TPH-1 (90 % ST and 10 % PAH) was evaluated for in vitro controlled drug release (CDR) at 37 ± 0.5 °C in a time-dependent fashion. CDR was recorded in phosphate buffer saline (PBS) and simulated gastric fluid (SGF). In the case of SGF (pH 1.2), the percentile drug release (DR) for TPH-1 was approximately 91 % in 110 min, while the maximum DR was 95 % in 80 min in PBS (pH 7.4) solution. Our results demonstrate that the fabricated biocompatible blend films can be a promising candidate for a sustained-release DDS for oral drug administration, tissue engineering, wound dressings, and other biomedical applications.

Chitosan-Based Polymer Blends for Drug Delivery Systems

Polymers have been widely used for the development of drug delivery systems accommodating the regulated release of therapeutic agents in consistent doses over a long period, cyclic dosing, and the adjustable release of both hydrophobic and hydrophilic drugs. Nowadays, polymer blends are increasingly employed in drug development as they generate more promising results when compared to those of homopolymers. This review article describes the recent research efforts focusing on the utilization of chitosan blends with other polymers in an attempt to enhance the properties of chitosan. Furthermore, the various applications of chitosan blends in drug delivery are thoroughly discussed herein. The literature from the past ten years was collected using various search engines such as ScienceDirect, J-Gate, Google Scholar, PubMed, and research data were compiled according to the various novel carrier systems. Nanocarriers made from chitosan and chitosan derivatives have a positive surface charge, which allows for control of the rate, duration, and location of drug release in the body, and can increase the safety and efficacy of the delivery system. Recently developed nanocarriers using chitosan blends have been shown to be cost-effective, more efficacious, and prolonged release carriers that can be incorporated into suitable dosage forms.

Chitosan based smart polymer composites: Fabrication and pH-Responsive behavior for bio-medical applications

This research aimed to synthesize Chitosan/PVA-blank and a series of Cs/PVA/Sepolite based pH-sensitive membranes using a solution casting process. The synthesized Cs/PVA-blank and Cs/PVA/Sep based membranes were investigated via SEM, FTIR, XRD, and TGA techniques. The SEM results of Cs/PVA/Sep based membrane reveal that the hydrolytic stability and strength were improved in acidic and basic media owing to the incorporation of sepiolite content into chitosan. The characteristic band at 3741 cm^-1 in the FTIR spectra of the Cs/PVA/Sep membrane confirmed the successful synthesis. The obtained XRD results showed higher d-spacing for Cs/PVA/Sep membranes as compared to the Cs/PVA-blank membranes owing to the intercalation of chitosan in the interlayer spacing of the sepiolite. The obtained TGA results show higher thermally stability for Cs/PVA/Sep membrane as compared to the Cs/PVA-blank sample due to the interaction of sepiolite content with the chitosan matrix. The obtained hydrolytic and swelling studies revealed that the Cs/PVA/Sep membrane displayed enhanced stability in basic and neutral media while showing minimum swelling in an acidic medium. The water uptake ability was checked for Cs/PVA/-blank and Cs/PVA/Sep-60% membrane and the results exhibited that the Cs/PVA/-blank membrane had maximum water uptake value as compared to the Cs/PVA/Sep-60% membrane. While those with a considerable amount of filler had the lowest water uptake values. As Sepolite content increased, the water uptake % values decreases because of weakness in H-bonding (of hydrophilic groups) and due to intercalation in Sepolite layers during polymer formation.

Polymer Gels: Classification and Recent Developments in Biomedical Applications

Polymer gels are a valuable class of polymeric materials that have recently attracted significant interest due to the exceptional properties such as versatility, soft-structure, flexibility and stimuli-responsive, biodegradability, and biocompatibility. Based on their properties, polymer gels can be used in a wide range of applications: food industry, agriculture, biomedical, and biosensors. The utilization of polymer gels in different medical and industrial applications requires a better understanding of the formation process, the factors which affect the gel's stability, and the structure-rheological properties relationship. The present review aims to give an overview of the polymer gels, the classification of polymer gels' materials to highlight their important features, and the recent development in biomedical applications. Several perspectives on future advancement of polymer hydrogel are offered.

Hybrid Hydrogels for Neomycin Delivery: Synergistic Effects of Natural/Synthetic Polymers and Proteins

This paper reports new physical hydrogels obtained by the freezing/thawing method. They include pullulan (PULL) and poly(vinyl alcohol) (PVA) as polymers, bovine serum albumin (BSA) as protein, and a tripeptide, reduced glutathione (GSH). In addition, a sample containing PULL/PVA and lysozyme was obtained in similar conditions. SEM analysis evidenced the formation of networks with porous structure. The average pore size was found to be between 15.7 μm and 24.5 μm. All samples exhibited viscoelastic behavior typical to networks, the hydrogel strength being influenced by the protein content. Infrared spectroscopy analysis revealed the presence of intermolecular hydrogen bonds and hydrophobic interactions (more pronounced for BSA content between 30% and 70%). The swelling kinetics investigated in buffer solution (pH = 7.4) at 37 °C evidenced a quasi-Fickian diffusion for all samples. The hydrogels were loaded with neomycin trisulfate salt hydrate (taken as a model drug), and the optimum formulations (samples containing 10-30% BSA or 2% lysozyme) proved a sustained drug release over 480 min in simulated physiological conditions. The experimental data were analyzed using different kinetic models in order to investigate the drug release mechanism. Among them, the semi-empirical Korsmeyer-Peppas and Peppas-Sahlin models were suitable to describe in vitro drug release mechanism of neomycin sulfate from the investigated hybrid hydrogels. The structural, viscoelastic, and swelling properties of PULL/PVA/protein hybrid hydrogels are influenced by their composition and preparation conditions, and they represent important factors for in vitro drug release behavior.

Antibacterial smart hydrogels: New hope for infectious wound management

Millions of people die annually due to uncured wound infections. Healthcare systems incur high costs to treat wound infections. Tt is predicted to become more challenging due to the rise of multidrug-resistant conditions. During the last decades, smart antibacterial hydrogels could attract attention as a promising solution, especially for skin wound infections. These antibacterial hydrogels are termed 'smart' due to their response to specific physical and chemical environmental stimuli. To deliver different drugs to particular sites in a controlled manner, various types of crosslinking strategies are used in the manufacturing process. Smart hydrogels are designed to provide antimicrobial agents to the infected sites or are built from polymers with inherent disinfectant properties. This paper aims to critically review recent pre-clinical and clinical advances in using smart hydrogels against skin wound infections and propose the next best thing for future trends. For this purpose, an introduction to skin wound healing and disease is presented and intelligent hydrogels responding to different stimuli are introduced. Finally, the most promising investigations are discussed in their related sections. These studies can pave the way for producing new biomaterials with clinical applications.

Smart Hydrogel Formed by Alginate-g-Poly(N-isopropylacrylamide) and Chitosan through Polyelectrolyte Complexation and Its Controlled Release Properties

Smart hydrogels that can respond to external stimuli such as temperature and pH have attracted tremendous interest for biological and biomedical applications. In this work, we synthesized two alginate-graft-poly(N-isopropylacrylamide) (Alg-g-PNIPAAm) copolymers and aimed to prepare smart hydrogels through formation of polyelectrolyte complex (PEC) between the negatively charged Alg-g-PNIPAAm copolymers and the positively charged chitosan (Cts) in aqueous solutions. The hydrogels were expected to be able to respond to both temperature and pH changes due to the nature of Alg-g-PNIPAAm and chitosan. The hydrogel formation was determined by a test tube inverting method and confirmed by the rheological measurements. The rheological measurements showed that the PEC hydrogels formed at room temperature could be further enhanced by increasing temperature over the lower critical solution temperature (LCST) of PNIPAAm, because PNIPAAm would change from hydrophilic to hydrophobic upon increasing temperature over its LCST, and the hydrophobic interaction between the PNIPAAm segments may act as additional physical crosslinking. The controlled release properties of the hydrogels were studied by using the organic dye rhodamine B (RB) as a model drug at different pH. The PEC hydrogels could sustain the RB release more efficiently at neutral pH. Both low pH and high pH weakened the PEC hydrogels, and resulted in less sustained release profiles. The release kinetics data were found to fit well to the Krosmyer-Peppas power law model. The analysis of the release kinetic parameters obtained by the modelling indicates that the release of RB from the PEC hydrogels followed mechanisms combining diffusion and dissolution of the hydrogels, but the release was mainly governed by diffusion with less dissolution at pH 7.4 when the PEC hydrogels were stronger and stabler than those at pH 5.0 and 10.0. Therefore, the PEC hydrogels are a kind of smart hydrogels holding great potential for drug delivery applications.

Biodegradable polyaspartamide-g-C18 /DOPA/GLY-NEO nano-adhesives for wound closure/healing with antimicrobial activity

This study was focused on the development of biodegradable nano-adhesives with efficient sealing and antibiotic effects for wound healing. Biodegradable polyaspartamide (PASPAM) was grafted with several functional groups to implement diverse roles-octadecylamine (C₁₈ ) for nano-aggregate formation, dopamine (DOPA) for adhesive function, neomycin (NEO) for inhibition of bacterial infection. Specifically, NEO was conjugated to PASPAM with a pH-sensitive glycine (GLY) linker for targeted delivery on the acidic wound site. About 60% of the drug was ramteleased at pH 6.0, while about 22% was released at pH 7.4, showing the faster drug release pattern of nano-adhesives in the acidic environment. The C₁₈ /DOPA/GLY-NEO-g-PASPAM nano-adhesives showed the bacterial viability higher than 70% at pH 7.4, but about 40% at pH 6.0. The wound breaking strength of the polymer-treated skin was much higher than that of the bare skin. According to the in vivo wound healing test using a mouse model, C₁₈ /DOPA/GLY-NEO-g-PASPAM nano-adhesives showed much faster healing performance than sutures. From those results, C₁₈ /DOPA/GLY-NEO-g-PASPAM nano-adhesives are expected to be utilized as effective adhesives that promote the wound healing with inhibition of bacterial infection.

Antiviral/antibacterial biodegradable cellulose nonwovens as environmentally friendly and bioprotective materials with potential to minimize microplastic pollution

Personal protective equipment (PPE) such as face masks is vital in battling the COVID-19 crisis, but the dominant polypropylene-based PPE are lack of antiviral/antibacterial activities and environmental friendliness, and have hazardous impact on the soil and aquatic ecosystems. The work presented herein focused on developing biodegradable, antiviral, and antibacterial cellulose nonwovens (AVAB-CNWs) as a multi-functional bioprotective layer for better protection against coronavirus SARS-CoV-2 and addressing environmental concerns raised by the piling of COVID-19 related wastes. Both guanidine-based polymer and neomycin sulfate (NEO) were reactive-modified and covalently grafted onto the surface of cellulose nonwovens, thereby conferring outstanding antiviral and antibacterial activities to the nonwovens without deteriorating the microstructure and biodegradability. Through adjusting the grafting amount of active components and selecting appropriate reagents for pretreatment, the antimicrobial activity and hydrophobicity for self-cleaning of the nonwovens can be tuned. More importantly, we demonstrated for the first time that such multi-functional nonwovens are capable of inactivating SARS-CoV-2 instantly, leading to high virucidal activity (> 99.35%), which is unachievable by conventional masks used nowadays. Meanwhile, the robust breathability and biodegradability of AVAB-CNWs were well maintained. The applications of the as-prepared nonwovens as high-performance textile can be readily extended to other areas in the fight against COVID-19.

Injectable thiol-ene hydrogel of galactoglucomannan and cellulose nanocrystals in delivery of therapeutic inorganic ions with embedded bioactive glass nanoparticles

We propose an injectable nanocomposite hydrogel that is photo-curable via light-induced thiol-ene addition between methacrylate modified O-acetyl-galactoglucomannan (GGMMA) and thiolated cellulose nanocrystal (CNC-SH). Compared to free-radical chain polymerization, the orthogonal step-growth of thiol-ene addition allows a less heterogeneous hydrogel network and more rapid crosslinking kinetics. CNC-SH reinforced the GGMMA hydrogel as both a nanofiller and a crosslinker to GGMMA resulting in an interpenetrating network via thiol-ene addition. Importantly, the mechanical stiffness of the GGMMA/CNC-SH hydrogel is mainly determined by the stoichiometric ratio between the thiol groups on CNC-SH and the methacrylate groups in GGMMA. Meanwhile, the bioactive glass nanoparticle (BaGNP)-laden hydrogels of GGMMA/CNC-SH showed a sustained release of therapeutic ions in simulated body fluid in vitro, which extended the bioactive function of hydrogel matrix. Furthermore, the suitability of the GGMMA/CNC-SH formulation as biomaterial resin to fabricate digitally designed hydrogel constructs via digital light processing (DLP) lithography printing was evaluated.

Angiogenic potential and wound healing efficacy of chitosan derived hydrogels at varied concentrations of APTES in chick and mouse models

Chitosan (Cs) based biomaterials seem to be indispensable for neovasculogenesis and angiogenesis that ensure accelerated wound healing. Cs/poly (vinyl alcohol) (PVA) bio-constructs were cross-linked and investigated with varying concentrations of aminopropyltriethoxysilane (APTES). This study comprised of three phases: fabrication of hydrogels, characterization, assessment of angiogenic potential along with toxico-pathological effects, wound healing efficacy in chick and mice, respectively. The hydrogels were characterized by FTIR, SEM and TGA and the swelling response was examined in different solvents. The hydrogels swelling ratio was decreased with increasing amount of APTES, showed the highest swelling at acidic and basic pH while low swelling at neutral pH. Chorioallantoic membranes (CAM) assay was performed to study in-vivo angiogenesis, toxicological, morphological, biochemical and histological analyses in developing chicks. The results showed remarkably improved angiogenesis with little deviations in morphological, histological features and liver enzymes of chick embryos at higher concentrations of APTES. Besides, full thickness wounds were excised on mice dorsolateral skin to assess the wound healing. The rate of wound size reduction was significantly higher after topical application of hydrogels with elevated levels of crosslinker. Hence, the hydrogels showed enhanced angiogenesis, accelerated wound healing with little or no observable in-vivo toxicity.

Development and evaluation of pH-sensitive biodegradable ternary blended hydrogel films (chitosan/guar gum/PVP) for drug delivery application

pH responsive hydrogels have gained much attraction in biomedical fields. We have formulated ternary hydrogel films as a new carrier of drug. Polyelectrolyte complex of chitosan/guar gum/polyvinyl pyrrolidone cross-linked via sodium tripolyphosphate was developed by solution casting method. Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis were conducted to examine the interactions between the polymeric chains, surface morphology and thermal stability, respectively. The swelling tests resulted that the swelling was reduced with the increase in the concentration of crosslinker due to the more entangled arrangement and less availability of pores in hydrogels. Ciprofloxacin hydrochloride was used as a model drug and its release in simulated gastric fluid, simulated intestinal fluid and phosphate buffer saline solution was studied. pH responsive behaviour of the hydrogels have subjected these hydrogels for drug release applications.

A supramolecular host-guest interaction-mediated injectable hydrogel system with enhanced stability and sustained protein release

Injectable hydrogels have been studied as drug delivery systems because of their minimal invasiveness and sustained drug release properties. Pluronic F127, consisting of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers, exhibits thermo-responsive properties and hence is injectable due to its rapid sol-gel transition. Unmodified Pluronic F127-based hydrogels, however, have limited long-term stability and controllable release of drugs entrapped within them. In this study, host-guest interactions between adamantane-conjugated Pluronic F127 (F127-Ad) and polymerized β-cyclodextrin (CDP) were employed to develop a hydrogel-based protein delivery system. Single or multiple adamantane units were successfully introduced at the termini of Pluronic F127 with a 100% conversion yield, and the synthesized F127-Ad polymer produced a physically crosslinked micelle-packing structure when mixed with CDP. As the number of adamantanes at the terminal ends of Pluronic F127 increased, the critical gelation concentration of F127-Ad/CDP hydrogel decreased from 15 to 6% (w/v). The F127/CDP hydrogel was able to maintain its structure even with lower polymer content, and its injectability improved with a reduction of the hydrogel viscosity. The long-term stability of F127/CDP hydrogels was evaluated in vitro and in vivo, and it was demonstrated that the subcutaneously injected hydrogel did not disintegrate for up to 30 d. Throughout the drug release test using gelatin and insulin as model drugs, it was demonstrated that their release rates could be regulated via complexation between the protein drugs and the β-cyclodextrin molecules inside the hydrogel. In conclusion, the F127-Ad/CDP hydrogel is expected to be a versatile protein delivery system with controllable durability and drug release characteristics. STATEMENT OF SIGNIFICANCE: Pluronic F127 is one of the widely studied polymeric materials for thermo-sensitive injectable hydrogels due to its high biocompatibility and rapid sol-gel transition. Since the Pluronic F127-based hydrogel has some limitations in its long-term stability and mechanical property, it is inevitable to modify its structure for the application to drug delivery. In this study, mono- or multi- adamantane-conjugated Pluronic F127s were synthesized and mixed with β-cyclodextrin polymers to form hydrogels with host-guest interaction-mediated micelle-packing structures. The host-guest interaction introduced into the hydrogel system endowed it a sustained protein drug release behavior as well as high durability in vitro and in vivo. By increasing the number of adamantane molecules at the end of the Pluronic F127, both the stability and injectability of the hydrogel could be also modulated.

Development and characterization of chitosan and acrylic acid-based novel biodegradable polymeric films for soil conditioning

In this study, biodegradable polymeric films (BPFs) based on chitosan and acrylic acid cross-linked with 3-aminopropyl triethoxysilane (APTES) were developed for water retention and soil-conditioning applications in areas sufferings from water scarcity. A series of BPFs were prepared by varying the amount of silica nanoparticles (SiNPs) (0.67% to 2.6%) and a correlation of the optimum amount of SiNPs with thermal stability, morphology, swellability (at various pH), degradability, and anti-microbial activity were deduced. The obtained results showed that the NP 8 (containing 2.51% of SiNPs) exhibited the maximum absorption capacity (1815%) in distilled water, whereas NP6 (including 1.88% of SiNPs) expressed the maximum thermal stability (T_50% at 375.61 °C). The microscopic images further strengthen this observation because the maximum number of micro-porous cavities was shown on the surface of NP8. The time-dependent swelling response in distilled water accomplished that hydrophilicity (percentage swelling) of films was enhanced with an increase in the concentration of SiNPs. All BPFs samples exhibited inhibitory response against both gram-positive (for Staphylococcus aureus was 2.9 cm for NP6) and gram-negative (for Escherichia coli was 0.9 cm for NP8) bacteria. The biodegradation test inferred that the degradation of BPFs in soil did not affect the soil fertility as nano-silica is proven as growth-promoting miniatures. It can be concluded that these BPFs may be efficiently employed in the agriculture sector for water retention and as a soil conditioner.

An in situ mechanical adjustable double crosslinking hyaluronic acid/poly-lysine hydrogel matrix: Fabrication, characterization and cell morphology

Cell fate and morphologies are influenced by the mechanical property of matrix. However, the relevant works about the dynamic adjustable of matrix mechanical property is rare and most of them need extra stimulation, such as the controllable of the degradation. In this study, double crosslinking (DC) hydrogels are fabricated by sequential covalent crosslinking and electrostatic interactions between hyaluronic acid and poly-lysine. Without any extra stimulation or treatment, the compressive stress of DC-hydrogels increases from 22.4 ± 9.4 kPa to 320.1 ± 6.6 kPa with the elongation of incubation time in DMEM solution. The change of compressive stress of matrix induced the morphology of L929 fibroblast cells adjusted from the distributed round shape to spheroid cell clusters and finally to spread shape. RNA sequence analysis also demonstrated that the differentially gene expression and GO enrichment between the cells seeded on the DC-hydrogel with different incubation time. In addition, by increasing the electrostatic interactions ratio of the hydrogel, the biodegradation, compressive stress and energy dissipation of the DC-hydrogels were also significantly improved. Therefore, our study provides new and critical insights into the design strategy to achieve DC-hydrogels which can in situ alter cells morphology and open up a new avenue for the application of disease therapy.

Antimicrobial/Biocompatible Hydrogels Dual-Reinforced by Cellulose as Ultrastretchable and Rapid Self-Healing Wound Dressing

Hydrogels as a wound dressing, integrated with ultrastretchability, rapid self-healing, and excellent antimicrobial activity, are in high demand, particularly for joint skin wound healing. Herein, a multifunctional and ductile composite hydrogel was developed using poly(vinyl alcohol) (PVA)-borax gel as a matrix that was synergized or dual-reinforced with dopamine-grafted oxidized carboxymethyl cellulose (OCMC-DA) and cellulose nanofibers (CNF). Moreover, neomycin (NEO), an aminoglycoside antibiotic with multifunctional groups, was incorporated into the hydrogel network as both an antibacterial agent and a cross-linker. The dynamic reversible borate ester linkages and hydrogen bonds between OCMC-DA, PVA, and CNF, along with dynamic cross-linking imine linkages between NEO and OCMC-DA, endowed the hydrogel with excellent self-healing ability and stretchability (3300%). The as-reinforced networks enhanced the mechanical properties of hydrogels significantly. More remarkably, the composite hydrogel with improved biodegradability and biocompatibility is pH-responsive and effective against a broad spectrum of bacteria, which is attributed to the controllable release of NEO for steady availability of the antibiotic on the wound location. Overall, the antimicrobial hydrogel with rapid self-healing and reliable mechanical properties holds significant promise as dressing material for wound healing.

Tetraethyl Orthosilicate-Based Hydrogels for Drug Delivery-Effects of Their Nanoparticulate Structure on Release Properties

Tetraethyl orthosilicate (TEOS)-based hydrogels, with shear stress response and drug releasing properties, can be formulated simply by TEOS hydrolysis followed by volume corrections with aqueous solvents and pH adjustments. Such basic thixotropic hydrogels (thixogels) form via the colloidal aggregation of nanoparticulate silica. Herein, we investigated the effects of the nanoparticulate building blocks on the drug release properties of these materials. Our data indicate that the age of the hydrolyzed TEOS used for the formulation impacts the nanoparticulate structure and stiffness of thixogels. Moreover, the mechanism of formation or the disturbance of the nanoparticulate network significantly affects the release profiles of the incorporated drug. Collectively, our results underline the versatility of these basic, TEOS-only hydrogels for drug delivery applications.

A Smart Drug Delivery System Based on Biodegradable Chitosan/Poly(allylamine hydrochloride) Blend Films

The amalgamation of natural polysaccharides with synthetic polymers often produces fruitful results in the area of drug delivery due to their biodegradable and biocompatible nature. In this study, a series of blend films composed of chitosan (CS)/poly(allylamine hydrochloride) (PAH) in different compositions were prepared as smart drug delivery matrices. The properties of these polymeric films were then explored. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis confirmed an intermolecular hydrogen bonding between CS and PAH. Atomic force microscopy (AFM) revealed improvements in surface morphology as the percentage of PAH in the blend films increased up to 60% (w/w). Water contact angle (WCA) ranged between 97° to 115°, exhibiting the hydrophobic nature of the films. Two films were selected, CTH-1 (90% CS and 10% PAH) and CTH-2 (80% CS and 20% PAH), to test for in vitro cumulative drug release (%) at 37 ± 0.5 °C as a function of time. It was revealed that for simulated gastric fluid (SGF) with pH 1.2, the cumulative drug release (CDR) for CTH-1 and CTH-2 was around 88% and 85% in 50 min, respectively. Both films converted into gel-like material after 30 min. On the other hand, in pH 7.4 phosphate buffer saline (PBS) solution, the maximum CDR for CTH-1 and CTH-2 was 93% in 90 min and 98% in 120 min, respectively. After 120 min, these films became fragments. Sustained drug release was observed in PBS, as compared to SGF, because of the poor stability of the films in the latter. These results demonstrate the excellent potential of blend films in sustained-release drug delivery systems for hydrophilic or unstable drugs.

Loading of Cefixime to pH sensitive chitosan based hydrogel and investigation of controlled release kinetics

Chitosan (biopolymer) and polyvinyl pyrolidone (PVP) with aminopropyletriethoxy silane (cross linker) based hydrogels were prepared and tested for controlled drug release. The drug release and kinetics were studied as a function of pH. Formulations were characterized by Fourier Transform Infrared (FTIR) and Thermogravimetric (TGA) analysis and TAP 32 hydrogel formulation was the most stable and hydrogel samples showed promising antibacterial activity against E. coli strain. The maximum swelling (4386%) was observed for TAP 32 formulation in distilled water, which was decreased with the concentration of ions. The diffusion exponent (n) values of all hydrogel formulations were recorded to be <0.5, which is an indication of Quasi-Fickian diffusion. The maximum swelling was observed at pH 2 and decreased at higher pH. The pH sensitivity of hydrogels found to be promising for their use in drug delivery, which was tested for cefixime drug. Drug release of 81.6% was observed for the period of 12 h in a simulated gastric fluid (SGF). The values of R² for zero order, first order, Higuchi, Hixson, Korsmeyer-Peppas and Baker-Lonsdale were 0.97, 0.9818, 0.99, 0.99, 0.88 and 0.80, respectively. The hydrogels based on chitosan and PVP revealed potential for controlled cefixime drug release in gastric pH medium.

Advances in injectable self-healing biomedical hydrogels

In recent years, implantable biomaterials have attracted significant interest owing to their potentials for use in the therapy of physical defects and traumas. Among the implantable biomaterials, hydrogels have received increasing attention for their tunable structures and good rheological behavior. However, the mechanical failures of traditional gel materials during normal operation remain a serious issue. To overcome this problem, hydrogel materials with self-healing and injectable abilities have been developed, with their potential for autonomous self-recovery and minimally invasive implantation. In this paper, the progress of injectable self-healing hydrogels is presented by combining developments in the fundamental knowledge of polymer designs and discussions on the practical biomedical applications of the materials. The mechanisms of different types of self-healing hydrogels are introduced first and their performances are then discussed, followed by a review of the self-healing hydrogels with injectability. The applications of the injectable self-healing hydrogels are discussed in the final section. STATEMENT OF SIGNIFICANCE: This paper provides an overview of the progress of a smart material, injectable self-healing hydrogel, during the past ten years and mainly focuses on its recent development. This paper presents developments in the fundamental knowledge in polymer designs and discussions on the practical biomedical application of the materials, which sheds more light on the advancement of injectable self-healing hydrogels. This paper should be of interest to the readers who are curious about the advances of injectable self-healing hydrogels.

Preparation of cationic polyelectrolyte grafted polyvinyl alcohol-formaldehyde macroporous hydrogels and their antibacterial properties

A series of novel antibacterial porous cationic PVF-g-PDMC hydrogels, synthesized by radical polymerization using ceric ammonium nitrate as an initiator, show excellent antibacterial properties, and can be used as biomedical materials.

Stimuli responsive biopolymer (chitosan) based blend hydrogels for wound healing application

Stimuli responsive chitosan (CS) and poly (N-vinyl-2-pyrrolidone) (PVP) have attained hydrogel properties in the presence of 74% neutralized poly acrylic acid (PAA) which can be exploited for wound healing applications. The FTIR spectra confirmed the presence of all specific functional groups and the developed interactions in the hydrogels. The thermal analysis explained that the hydrogel samples are thermally more stable than individual chitosan and PVP. The antimicrobial analysis revealed that all the samples show antibacterial activity against E. coli and the biodegradation analysis is performed to confirm the hydrogels degradation. The hydrogels showed enhanced responsive swelling behavior against different media depending upon the amount of PVP. The %age swelling in water is decreased with the increase in the amount of PVP. The most considerable swelling behavior is observed against pH, as they manifested low swelling at acidic pH and high swelling at neutral pH while at pH 8, the prominent values are obtained. This distinctive behavior of hydrogels and their biocompatibility made them pertinent to drug delivery and their release profile is examined spectrophotometrically using silver sulfadiazine (antibiotic for burnt wounds) showed 91.2% of drug release for a period of 1 h in phosphate buffer saline (PBS) in a consistent and controlled manner.

Development of a gallic acid-loaded chitosan and polyvinyl alcohol hydrogel composite: Release characteristics and antioxidant activity

The physico-chemical properties of a chitosan and polyvinyl alcohol (CS/PVA)-based hydrogel composite were investigated. Tetraethyl orthosilicate (TEOS) was employed as a crosslinking agent. The results indicated that the chitosan-based composite presented a thermal resistance up to 200°C. The structural properties, which were evaluated using FTIR and DSC, showed good miscibility between chitosan and polyvinyl alcohol. SEM presented a compact and homogeneous structure. The release profile of the chitosan-based hydrogel composite was investigated using gallic acid (GA). It showed high antioxidant activities, which were monitored using DPPH radical scavenging. Diffusion of water into the chitosan-based hydrogel was assumed to be pseudo-Fickian in PBS solution. The CS/PVA-based hydrogel composite exhibited good properties as a drug delivery system.