Synthesis and characterization of hydrogels based on grafted chitosan for the controlled drug release

Biopolymer hydrogels and synergistic blends for tailored wound healing

Biopolymers have a transformative role in wound repair due to their biocompatibility, ability to stimulate collagen production, and controlled drug and growth factor delivery. This article delves into the biological parameters critical to wound healing emphasizing how combinations of hydrogels with reparative properties can be strategically designed to create matrices that stimulate targeted cellular responses at the wound site to facilitate tissue repair and recovery. Beyond a detailed examination of various biopolymer types and their functionalities in wound dressings acknowledging that the optimal choice depends on the specific wound type and application, this evaluation provides concepts for developing synergistic biopolymer blends to create next-generation dressings with enhanced efficiencies. Furthermore, the incorporation of therapeutic agents such as medications and wound healing accelerators into dressings to enhance their efficacy is examined. These agents often possess desirable properties such as antibacterial activity, antioxidant effects, and the ability to promote collagen synthesis and tissue regeneration. Finally, recent advancements in conductive hydrogels are explored, highlighting their capabilities in treatment and real-time wound monitoring. This comprehensive resource emphasizes the importance of optimizing ingredient efficiency besides assisting researchers in selecting suitable materials for personalized wound dressings, ultimately leading to more sophisticated and effective wound management strategies.

Locust bean gum-based silver nanocomposite hydrogel as a drug delivery system and an antibacterial agent

Effective drug release is of utmost importance in the medical field for treating various diseases, particularly cancer. Nanocomposite hydrogels remain the best materials for enhancing the bioavailability and therapeutic levels of drugs as they enable sustained, targeted, or controlled drug release. In this work, a nanocomposite hydrogel containing locust bean gum (LBG), poly(4-acryloylmorpholine) (PAcM), and silver nanoparticles (SN) has been made using an eco-friendly microwave (MW)-assisted method and characterized by various advanced techniques. The material is evaluated for its potential as a polymer matrix towards delivering 5-fluorouracil (5-FU), an anticancer drug in the gastrointestinal tract, and inhibiting bacterial growth. The pH-dependency of the nanocomposite material towards swelling and drug release and its antibacterial characteristics have been compared with the neat gel in order to understand the role of SN in enhancing the performance of the materials. The results indicated both polymer materials exhibit a pH-dependent release of 5-FU with a higher release at pH 1.2, simulated gastric fluid, than at pH 7.4, simulated intestinal fluid. About 72 % of the loaded drug was released from the nanocomposite, as compared to 44 % from the neat gel at pH 1.2 during the observation period of 3 h. The drug release process could be best explained by the first-order kinetic model and Fickian diffusion transport mechanism. The nanocomposite exhibited remarkable antibacterial activity against Staphylococcus aureus and Escherichia coli. The biocompatibility of the drug-loaded nanocomposite was demonstrated by a cytotoxicity study, which showed higher than 80 % viability of healthy IEC-6 cells. The results indicate the suitability of the developed nanocomposite material as a polymer matrix for sustained release of 5-FU for cancer therapy and also as an antibacterial agent to fight against bacterial infections.

Trends in sustainable chitosan-based hydrogel technology for circular biomedical engineering: A review

Eco-friendly materials have emerged in biomedical engineering, driving major advances in chitosan-based hydrogels. These hydrogels offer a promising green alternative to conventional polymers due to their non-toxicity, biodegradability, biocompatibility, environmental friendliness, affordability, and easy accessibility. Known for their remarkable properties such as drug encapsulation, delivery capabilities, biosensing, functional scaffolding, and antimicrobial behavior, chitosan hydrogels are at the forefront of biomedical research. This paper explores the fabrication and modification methods of chitosan hydrogels for diverse applications, highlighting their role in advancing climate-neutral healthcare technologies. It reviews significant scientific advancements and trends chitosan hydrogels focusing on cancer diagnosis, drug delivery, and wound care. Additionally, it addresses current challenges and green synthesis practices that support a circular economy, enhancing biomedical sustainability. By providing an in-depth analysis of the latest evidence on climate-neutral management, this review aims to facilitate informed decision-making and foster the development of sustainable strategies leveraging chitosan hydrogel technology. The insights from this comprehensive examination are pivotal for steering future research and applications in sustainable biomedical solutions.

Design and Characterization of Chitosan-Based Smart Injectable Hydrogel for Improved Sustained Release of Antinarcotics

The treatment adherence of narcotics-addicted individuals with reduced incidences of relapse can be enhanced by a sustained drug release formulation of antinarcotics. So far, different drug formulations have been reported with sustained drug release periods of 28 and 35 days. To further enhance this duration, different formulations of injectable hydrogels (IHs) have been developed by combining low molecular weight (LMW) and high molecular weight (HMW) chitosan (CS) with guar gum (GG) and crosslinking them by sodium bi phosphate dibasic. The structural, morphological, and physicochemical properties of LMW-CS IH, and HMW-CS IH were evaluated using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), and rheological, swelling, and biodegradation analysis. The HMW-CS IH showed high crosslinking, increased thermal stability, high mechanical strength, elevated swelling, and low biodegradation. The antinarcotic drugs naltrexone (NTX) and disulfiram (DSF) were loaded separately into the HMW-CS IH and LMW-CS IH. The release of NTX and DSF was investigated in phosphate buffer saline (PBS) and ethanol (0.3%, 0.4%, and 0.5%) over a 56-day period using an UV spectrophotometer. The drug release data were tested in zero-order, first-order, and Korsemeyer-Peppas mathematical models. In PBS, all prepared formulations followed non-Fickian drug release, while in ethanol, only NTX HMW-CS IH followed non-Fickian release in all three different concentrations of ethanol.

Evaluation of drug release efficiency and antibacterial property of a pH-responsive dextran-based silver nanocomposite hydrogel

The bioavailability of curcumin (CUR), a highly lipophilic and commonly used anticancer drug, is mainly affected by its poor solubility in aqueous environment and quick metabolism. These challenges can be met by employing delivery systems. Nanocomposite materials have been used as delivery systems to enhance the solubility and dissolution rate of the drug. This study aims to develop dextran-graft-poly(4-acryloylmorpholine) silver nanocomposite using a microwave-assisted method to evaluate its drug-release efficiency and antimicrobial activity. The materials were characterized by FT-IR, FE-SEM, EDS, XRD, HR-TEM, TGA, and BET techniques. Drug loading and release efficiency were evaluated using CUR as the model drug. The swelling and drug release studies were conducted in buffer solutions of pH 1.2 and 7.4. Staphylococcus aureus and Escherichia coli were employed to evaluate the antibacterial activity. The cytotoxicity was assessed by MTT assay against the breast MCF-10. Higher swelling and drug release were observed at pH 1.2 than 7.4. Nanocomposite hydrogel exhibited antibacterial activity against the tested bacterial strains. Cytotoxicity study proved the safety of the developed matrix. The results suggest the developed nanocomposite hydrogel to be a promising polymer matrix for the sustained release of CUR for cancer treatment that requires infectious control.

Chondrogenic Potential of Human Adipose-Derived Mesenchymal Stromal Cells in Steam Sterilized Gelatin/Chitosan/Polyvinyl Alcohol Hydrogels

Cross-linked polymer blends from natural compounds, namely gelatin (Gel), chitosan (CS), and synthetic poly (vinyl alcohol) (PVA), have received increasing scrutiny because of their versatility, biocompatibility, and ease of use for tissue engineering. Previously, Gel/CS/PVA [1:1:1] hydrogel produced via the freeze-drying process presented enhanced mechanical properties. This study aimed to investigate the biocompatibility and chondrogenic potential of a steam-sterilized Gel/CS/PVA hydrogel using differentiation of human adipose-derived mesenchymal stromal cells (AD-hMSC) and cartilage marker expression. AD-hMSC displayed fibroblast-like morphology, 90% viability, and 69% proliferative potential. Mesenchymal profiles CD73 (98.3%), CD90 (98.6%), CD105 (97.0%), CD34 (1.11%), CD45 (0.27%), HLA-DR (0.24%); as well as multilineage potential, were confirmed. Chondrogenic differentiation of AD-hMSC in monolayer revealed the formation of cartilaginous nodules composed of glycosaminoglycans after 21 days. Compared to nonstimulated cells, hMSC-derived chondrocytes shifted the expression of CD49a from 2.82% to 40.6%, CD49e from 51.4% to 92.2%, CD54 from 9.66 to 37.2%, and CD151 from 45.1% to 75.8%. When cultured onto Gel/CS/PVA hydrogel during chondrogenic stimulation, AD-hMSC changed to polygonal morphology, and chondrogenic nodules increased by day 15, six days earlier than monolayer-differentiated cells. SEM analysis showed that hMSC-derived chondrocytes adhered to the surface with extended filopodia and abundant ECM formation. Chondrogenic nodules were positive for aggrecan and type II collagen, two of the most abundant components in cartilage. This study supports the biocompatibility of AD-hMSC onto steam-sterilized GE/CS/PVA hydrogels and its improved potential for chondrocyte differentiation. Hydrogel properties were not altered after steam sterilization, which is relevant for biosafety and biomedical purposes.

Thermo-Responsive Hydrogels Encapsulating Targeted Core-Shell Nanoparticles as Injectable Drug Delivery Systems

As therapeutic agents that allow for minimally invasive administration, injectable biomaterials stand out as effective tools with tunable properties. Furthermore, hydrogels with responsive features present potential platforms for delivering therapeutics to desired sites in the body. Herein, temperature-responsive hydrogel scaffolds with embedded targeted nanoparticles were utilized to achieve controlled drug delivery via local drug administration. Poly(N-isopropylacrylamide) (pNIPAM) hydrogels, prepared with an ethylene-glycol-based cross-linker, demonstrated thermo-sensitive gelation ability upon injection into environments at body temperature. This hydrogel network was engineered to provide a slow and controlled drug release profile by being incorporated with curcumin-loaded nanoparticles bearing high encapsulation efficiency. A core (alginate)-shell (chitosan) nanoparticle design was preferred to ensure the stability of the drug molecules encapsulated in the core and to provide slower drug release. Nanoparticle-embedded hydrogels were shown to release curcumin at least four times slower compared to the free nanoparticle itself and to possess high water uptake capacity and more mechanically stable viscoelastic behavior. Moreover, this therapy has the potential to specifically address tumor tissues over-expressing folate receptors like ovaries, as the nanoparticles target the receptors by folic acid conjugation to the periphery. Together with its temperature-driven injectability, it can be concluded that this hydrogel scaffold with drug-loaded and embedded folate-targeting nanoparticles would provide effective therapy for tumor tissues accessible via minimally invasive routes and be beneficial for post-operative drug administration after tumor resection.

Development and Evaluation of Sodium Alginate/Carbopol 934P-Co-Poly (Methacrylate) Hydrogels for Localized Drug Delivery

This research was carried out to create a pH-responsive polymeric system for the targeted drug delivery of Diloxanide furoate. It relied on sodium alginate (Na-Alg) and Carbopol 934P as building blocks. Using an aqueous free radical polymerization method, SCH1-SCH12 was created with varying polymer, MAA, and MBA input ratios. Positive outcomes were seen in the swelling and release profiles at higher pH levels. Hydrogel formation, as well as component compatibility, thermal stability, and Diloxanide furoate loading, were all validated by instrumental characterization. A drug loading percentage of 83.56% was determined, with the swelling reaching 743.19%. For the formulation with MBA, the gel fraction was 94.58%. The release of diloxanide furoate increased to 91.77% at neutral pH. The formulation containing Carbopol 934P provided the highest mucoadhesion force (3993.42 dynes/cm²). The created hydrogel has been shown to be biocompatible by toxicological testing of the network. Based on the findings, the created polymeric nexus proved promising for pH-dependent localized and regulated delivery of Diloxanide furoate.

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.

CMC-based hydrogels loaded with Hypericum perforatum nanoemulsion for potential wound dressing applications

Wound healing is a complicated process requiring appropriate environment to accelerate healing process. In the recent years, many wound dressings have been developed for treating various kinds of wounds. In this study, we aimed to develop a novel dressing with high ability of burn wound healing and minimum side effects. Carboxymethyl cellulose (CMC) based hydrogels containing Hypericum perforatum were developed by grafting methacrylic acid and acrylamide onto CMC to produce a good mechanical strength dressing. Covalent crosslinking, which is responsible for stable mechanical structure, led to a 3D structure with appropriate water vapor transmission rate (2950 g/m2/day), controlled drug release (33% in 78 h), and great burn healing ability (almost complete healing in 10 day). The hydrogel has proper antimicrobial activity against the tested microorganisms. Zone of inhibition against E.coli was the higher in comparison with S. aureus and Candida. Minimum inhibitory concentration (MIC) for C. albicans, S. aureus, and E. coli were as 6, 4, and 5 mg/ml of H. perforatum. In vivo experiments on rats revealed that wound healing process by loaded hydrogels was faster in comparison with control group. All the results indicated that prepared hydrogel has the capability to accelerate burn wound healing process.

Systems for Muscle Cell Differentiation: From Bioengineering to Future Food

In light of pressing issues, such as sustainability and climate change, future protein sources will increasingly turn from livestock to cell-based production and manufacturing activities. In the case of cell-based or cultured meat a relevant aspect would be the differentiation of muscle cells into mature muscle tissue, as well as how the microsystems that have been developed to date can be developed for larger-scale cultures. To delve into this aspect we review previous research that has been carried out on skeletal muscle tissue engineering and how various biological and physicochemical factors, mechanical and electrical stimuli, affect muscle cell differentiation on an experimental scale. Material aspects such as the different biomaterials used and 3D vs. 2D configurations in the context of muscle cell differentiation will also be discussed. Finally, the ability to translate these systems to more scalable bioreactor configurations and eventually bring them to a commercial scale will be touched upon.

Development of pH-Sensitive Chitosan-g-poly(acrylamide-co-acrylic acid) Hydrogel for Controlled Drug Delivery of Tenofovir Disoproxil Fumarate

The present study aimed to develop a pH-sensitive chitosan-based hydrogel for controlled delivery of an anti-hepatitis B drug, tenofovir disoproxil fumarate (TDF). Free radical polymerization was utilized to graft acrylamide and acrylic acid using N,N-methylene bisacrylamide as the crosslinker. Physicochemical characterization confirmed the synthesis of thermally stable chitosan-g-poly(acrylamide-co-acrylic acid) hydrogels with well-defined pores within a fibrous surface. The prepared hydrogels exhibited pH and ionic strength sensitivity, with the swelling significantly lower under acidic and strong ionic strength conditions but higher in neutral and basic solutions. In addition, cytotoxicity studies on HeLa cell lines proved the cytocompatibility of the drug delivery material and its readiness for physiological applications. The encapsulation of TDF in the hydrogels was optimized and an encapsulation efficiency and a drug loading percentage of 96% and 10% were achieved, respectively. More interestingly, in vitro release studies demonstrated a pH-dependent release of TDF from hydrogels. The release at pH 7.4 was found to be up to five times higher than at pH 1.2 within 96 h. This further suggested that the newly developed hydrogel-loaded TDF could be proposed as a smart delivery system for oral delivery of anti-hepatitis B drugs.

Binary Graft of Poly(N-vinylcaprolactam) and Poly(acrylic acid) onto Chitosan Hydrogels Using Ionizing Radiation for the Retention and Controlled Release of Therapeutic Compounds

In this study, we carried out the synthesis of a thermo- and pH-sensitive binary graft, based on N-vinylcaprolactam (NVCL) and pH sensitive acrylic acid (AAc) monomers, onto chitosan gels (net-CS) by ionizing radiation. Pre-oxidative irradiation and direct methods were examined, and materials obtained were characterized by FTIR-ATR, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and swelling tests (equilibrium swelling time, critical pH, and temperature). The best synthesis radiation method was the direct method, which resulted in the maximum grafting percentages (~40%) at low doses (10–12 kGy). The main goal of this study was the comparison of the swelling behavior and physicochemical properties of net-CS with those of the binary system (net-CS)-g-NVCL/AAc with the optimum grafting percentage (~30%). This produced a material that showed an upper critical solution temperature (UCST) of 33.5 °C and a critical pH value of 3.8, indicating the system is more hydrophilic at higher temperatures and low pH values. Load and release studies were carried out using diclofenac. The grafted system (32%) was able to load 19.3 mg g⁻¹ of diclofenac and release about 95% within 200 min, in comparison to net-CS, which only released 80% during the same period. When the grafted system was protonated before diclofenac loading, it loaded 27.6 mg g⁻¹. However, the drug was strongly retained in the material by electrostatic interactions and only released about 20%.

Gamma radiation synthesis of a novel amphiphilic terpolymer hydrogel pH-responsive based chitosan for colon cancer drug delivery

Particularly, chitosan (Cs) loaded with drug cannot pass through the colonic region, often leading in the bursting drug release in the stomach due to its solubility in gastric contents. The novelty of the current article is to solve this limitation by performing gamma irradiation cross-linking of Cs with two anionic polymers of (acrylic acid)-co-(2-acrylamido-2-methylpropane-sulfonic acid) (AAc/AMPS) to give amphiphilic hydrogel. The shifted in the characteristic FTIR peaks of Cs in the (Cs/AAc/AMPS) confirm the exits of inter-molecular interactions that make Cs and (AAc/AMPS) are miscible. Swelling experiments under different pH indicated that the (Cs/AAc/AMPS) hydrogels were significantly sensitive to pH change. The results give the possibility to use the obtained (Cs/AAc/AMPS) hydrogel on drug delivery system. The in vitro Fluorouracil (5-FU) releasing from (Cs/AAc/AMPS) matrix was examined under the influence of pH1 and pH7.The results confirmed the hydrogels capability to release 96 % of 5-FU drug at pH 7 after 7 h.

Fundamental Concepts of Hydrogels: Synthesis, Properties, and Their Applications

In the present review, we focused on the fundamental concepts of hydrogels-classification, the polymers involved, synthesis methods, types of hydrogels, properties, and applications of the hydrogel. Hydrogels can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and a combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical, and hybrid bonding. The bonding is formed via different routes, such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. These properties are substantial for electrochemical and biomedical applications. Furthermore, this review emphasizes flexible and self-healable hydrogels as electrolytes for energy storage and energy conversion applications. Insufficient adhesiveness (less interfacial interaction) between electrodes and electrolytes and mechanical strength pose serious challenges, such as delamination of the supercapacitors, batteries, and solar cells. Owing to smart and aqueous hydrogels, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability are the critical factors that can identify the reliability and robustness of the energy storage and conversion devices. These devices are highly efficient and convenient for smart, light-weight, foldable electronics and modern pollution-free transportation in the current decade.

Novel Maleic Acid, Crosslinked, Nanofibrous Chitosan/Poly (Vinylpyrrolidone) Membranes for Reverse Osmosis Desalination

Fresh and clean water is consistently depleting and becoming a serious problem with rapid increases in population, so seawater desalination technology has captured global attention. For an efficient desalination process, this work proposes a novel, nanofibrous, thin-film composite membrane (NF-TFC) based on the deposition of the nanofibrous active layer of a blend of chitosan (CS) and poly (vinylpyrrolidone) (PVP) crosslinked with maleic acid on a 3-triethoxysilylpropylamine functionalized cellulose acetate substrate. FTIR analysis demonstrated the development of chemical and physical interactions and confirmed the incorporation of functional groups present in the NF-TFC. Scanning electron microscopy (SEM) micrographs depict the fibrous structure of the active layers. The reverse osmosis (RO) desalination characteristics of NF-TFC membranes are elevated by increasing the concentration of the crosslinker in a CS/PVP blend. Cellulose acetate (CA)-S4 attained an optimal salt rejection of 98.3% and permeation flux of 42.9 L/m2h, suggesting that the NF-TFC membranes could be favorable for seawater desalination.

Translational applications of photopolymerizable hydrogels for cartilage repair

BACKGROUND

Articular cartilage lesions generated by trauma or osteoarthritis are the most common causes of pain and disability in patients. The development of photopolymerizable hydrogels has allowed for significant advances in cartilage repair procedures. Such three-dimensional (3D) networks of polymers that carry large amounts of water can be created to resemble the physical characteristics of the articular cartilage and be delivered into ill-defined cartilage defects as a liquid solution prior to polymerization in vivo for perfect fit with the surrounding native tissue. These hydrogels offer an adapted environment to encapsulate and propagate regenerative cells in 3D cultures for cartilage repair. Among them, mesenchymal stem cells and chondrocytes may represent the most adapted sources for implantation. They also represent platforms to deliver therapeutic, biologically active factors that promote 3D cell differentiation and maintenance for in vivo repair.

CONCLUSION

This review presents the benefits of photopolymerization of hydrogels and describes the photoinitiators and materials in current use for enhanced cartilage repair.

Chitosan-grafted-poly(methacrylic acid)/graphene oxide nanocomposite as a pH-responsive de novo cancer chemotherapy nanosystem

The aim of this study was the design and development of a novel de novo drug delivery system for cancer chemotherapy. For this purpose, chitosan (CS) functionalized using phthalic anhydride followed by 4-cyano, 4-[(phenylcarbothioyl) sulfanyl] pentanoic acid as a chain transfer agent (CTA) to afford CS-CTA macroinitiator. The synthesized CS-CTA macroinitiator was then copolymerized with methacrylic acid (MAA) monomer using reversible addition-fragmentation chain transfer (RAFT) polymerization technique to produce chitosan-graft-poly(methacrylic acid) (CS-g-PMAA) graft copolymer. Afterward, graphene oxide (GO) nanosheets were incorporated into the synthesized copolymer through the physical interactions. The CS-g-PMAA/GO nanocomposite was loaded with doxorubicin hydrochloride (DOX) as a universal anticancer drug. The biocompatibility, DOX-loading capacity, and pH dependent drug release behavior of the developed nanocomposite were also investigated. As the experimental results, as well as superior biological and physicochemical features of CS and GO, we envision that the developed CS-g-PMAA/GO nanocomposite may be applied as de novo drug delivery nanosystem for cancer chemotherapy.

Role of proton balance in formation of self-assembled chitosan nanoparticles

Researchers have explored the ability of chitosan to form nanoparticles, to suit varying applications, ranging from wound-healing to gene delivery. Ionic gelation is a widely used method for formulating chitosan nanoparticles, where self-assembly plays a crucial role. This self-assembly is initially promoted by hydrophilic-hydrophobic parity amongst individual chitosan residues, along with electrostatic and Van der Waals interactions with the cross-linker. However, until now the intrinsic ability of chitosan to self-assemble is not widely studied; hence, we investigate the self-assembly of chitosan, based on proton balance between its protonated and deprotonated residues, to promote facile nanoparticle synthesis. This is one of the first reports that highlights subtle but critical influence of proton balance in the chitosan polymer on the formation of chitosan nanoparticles.

Modified n-HA/PA66 scaffolds with chitosan coating for bone tissue engineering: cell stimulation and drug release

The dipping-drying procedure and cross-linking method were used to make drug-loaded chitosan (CS) coating on nano-hydroxyapatite/polyamide66 (nHA/PA66) composite porous scaffold, endowing the scaffold controlled drug release functionality. The prefabricated scaffold was immersed into an aqueous drug/CS solution in a vacuum condition and then crosslinked by vanillin. The structure, porosity, composition, compressive strength, swelling ratio, drug release and cytocompatibility of the pristine and coating scaffolds were investigated. After coating, the scaffold porosity and pore interconnection were slightly decreased. Cytocompatibility performance was observed through an in vitro experiment based on cell attachment and the MTT assay by MG63 cells which revealed positive cell viability and increasing proliferation over the 11-day period in vitro. The drug could effectively release from the coated scaffold in a controlled fashion and the release rate was sustained for a long period and highly dependent on coating swelling, suggesting the possibility of a controlled drug release. Our results demonstrate that the scaffold with drug-loaded crosslinked CS coating can be used as a simple technique to render the surfaces of synthetic scaffolds active, thus enabling them to be a promising high performance biomaterial in bone tissue engineering.

Carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing

The objective of this study was to develop a novel carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing. To prepare the crosslinked hydrogels, poly(vinyl alcohol) (PVA) was grafted with succinate acid to yield carboxyl-modified poly(vinyl alcohol) (PVA-COOH). Hydrogel films based on PVA-COOH and chitosan (CS) at different concentrations were crosslinked through the formation of amide linkages. The mechanical properties of these crosslinked hydrogel films in dry and swollen state were greatly improved with high swelling ratio. Water vapor and oxygen permeability evaluations indicated that crosslinked hydrogel films could maintain a moist environment over wound bed. Biocompatibility test showed the crosslinked hydrogels had no cytotoxicity and hemolytic potential. Gentamicin sulfate-loaded crosslinked hydrogel films showed sustained drug release profile, and could effectively suppress bacterial proliferation and protect wound from infection.

Experimental and mathematical studies on the drug release properties of aspirin loaded chitosan nanoparticles

The study of drug release dynamic is aiming at understanding the process that drugs release in human body and its dynamic characteristics. It is of great significance since these characteristics are closely related to the dose, dosage form, and effect of the drugs. The Noyes-Whitney function is used to represent how the solid material is dissolved into solution, and it is well used in study of drug dynamic. In this research, aspirin (acetylsalicylic acid (ASA)) has been encapsulated with different grades of chitosan (CS) varying in molecular weight (Mw) for the purpose of controlled release. The encapsulation was accomplished by ionic gelation technology based on assembly of positively charged chitosan and negatively charged sodium tripolyphosphate (TPP). The encapsulation efficiency, loading capacity, and drug release behavior of aspirin loaded chitosan nanoparticles (CS-NPs) were studied. It was found that the concentration of TPP and Aspirin, molecular weights of chitosan have important effect on the drug release patterns from chitosan nanoparticles. The results for simulation studies show that the Noyes-Whitney equation can be successfully used to interpret the drug release characteristics reflected by our experimental data.

Controlled release of tinidazole and theophylline from chitosan based composite hydrogels

Several composite hydrogels were synthesized by free radical crosslink copolymerization of acrylic acid (AA) and N' methylene bis-acrylamide (MBA) in the presence of chitosan (CS). During polymerization CS was incorporated in situ in the crosslinked polyacrylic acid gel to produce composite hydrogels. The structure and properties of the hydrogels were characterized by FTIR, (13)C NMR, DTA-TGA, XRD, swelling and diffusion characteristic and also network parameters. The loading and the in vitro release behaviours of theophylline and tinidazole model drugs were studied with these hydrogels. The wt% of CS and MBA and pH of the medium was found to strongly influence the drug release behaviour of the gels. Accordingly, the release rate of these two drugs was much faster at pH of 7.6 than at pH 1.5.

Miscibility of eudragit/chitosan polymer blend in water determined by physical property measurements

The interest in the preparation and application of polymeric blends is growing since they can exhibit properties of great industrial interest. The current study focuses on the preparation of polymeric blends of varying compositions of eudragit and chitosan and their miscibility studies. The preparation was carried out by using ethanol and 1% acetic acid in water. FT-IR spectra reveal the possibilities of chemical interactions between eudragit/chitosan. The miscibility of polymeric blend at different composition has been investigated by viscosity, ultrasonic velocity, density, refractive index and adiabatic compressibility values measured at two different temperatures 30 °C and 40 °C. The interaction parameters ΔB, μ and α, were determined from viscosity data. From the values observed, it is found that the blend is miscible in all compositions at 30 °C whereas at 40 °C, it seems to be immiscible in certain compositions. It is found that the blend is miscible, when the chitosan concentration is more than 70% (v/v) at both the temperatures and also observed that variation of temperature has no effect on the miscibility of eudragit/chitosan blend.