Chitin, a polysaccharide composed of β-(1–4)-linked 2-deoxy-2-acetamido-d-glucose units, is found in cell walls of different organisms, including crustaceans, fungi, insects, some algae, microorganisms, and some invertebrate animals, and its deacetylation into chitosan confers it with incredible chemical versatility allowing it to be processed into numerous products [...] Full article

Curcumin has been used in traditional medicine forages. The present study aimed to develop a curcumin-based hydrogel system and assess its antimicrobial potential and wound healing (WH) activity on an invitro and in silico basis. A topical hydrogel was prepared using chitosan, PVA, and Curcumin in varied ratios, and hydrogels were evaluated for physicochemical properties. The hydrogel showed antimicrobial activity against both gram-positive and gram-negative microorganisms. In silico studies showed good binding energy scores and significant interaction of curcumin components with key residues of inflammatory proteins that help in WH activity. Dissolution studies showed sustained release of curcumin. Overall, the results indicated wound healing potential of chitosan–PVA–curcumin hydrogel films. Further in vivo experiments are needed to evaluate the clinical efficacy of such films for wound healing. Full article

Chitosan is used in medicine, pharmaceuticals, cosmetics, agriculture, water treatment, and food due to its superior biocompatibility and biodegradability. Nevertheless, the complex and relatively expensive extraction costs hamper its exploitation and, implicitly, the recycling of marine waste, the most abundant source of chitosan. In the spirit of developing environmental-friendly and cost-effective procedures, the present study describes one method worth consideration to deliver calcium-carbonate-enriched chitosan from shrimp shell waste, which proposes to maintain the native minerals in the structure of chitin in order to improve the thermal stability and processability of chitosan. Therefore, a synthesis protocol was developed starting from an optimized deacetylation procedure using commercial chitin. The ultimate chitosan product from shrimp shells, containing native calcium carbonate, was further compared to commercial chitosan and chitosan synthesized from commercial chitin. Finally, the collected data during the study pointed out that the prospected method succeeded in delivering calcium-carbonate-enriched chitosan with high deacetylation degree (approximately 75%), low molecular weight (Mn ≈ 10.000 g/ mol), a crystallinity above 59 calculated in the (020) plane, high thermal stability (maximum decomposition temperature over 300 °C), and constant viscosity on a wide range of share rates (quasi-Newtonian behavior), becoming a viable candidate for future chitosan-based materials that can expand the application horizon. Full article

Chitosan-based hydrogels possess numerous advantages, such as biocompatibility and non-toxicity, and it is considered a proper material to be used in biomedical and pharmaceutical applications. Vaginal administration of progesterone represents a viable alternative for maintaining pregnancy and reducing the risk of miscarriage and in supporting the corpus luteum during fertilization cycles. This study aimed to develop new formulations for vaginal administration of progesterone (PGT). A previously synthesized responsive chitosan-grafted-poly (N-isopropylacrylamide) (CS-g-PNIPAAm) was formulated in various compositions with polyvinyl alcohol (PVA) as external crosslinking agent to obtain pH- and temperature-dependent hydrogels; the hydrogels had the capacity to withstand shear forces encountered in the vagina due to its mechanism of swelling once in contact with vaginal fluids. Three different hydrogels based on grafted chitosan were analyzed via Fourier-transform infrared spectroscopy (FTIR), swelling tests, in vitro drug release, and bioadhesion properties by TA.XTplus texture analysis. A higher amount of PVA decreased the swelling and the bioadhesion capacities of the hydrogel. All hydrogels showed sensitivity to temperature and pH in terms of swelling and in vitro delivery characteristics. By loading progesterone, the studied hydrogels seemed to possess even higher sensitivity than drug–free matrices. The release profile of the active substance and the bioadhesion characteristics recommended the CS-g-PNIPAAm/PVA 80/20 +PGT (P1) hydrogel as a proper constituent for the vaginal formulation for progesterone administration. Full article

(1) Background: Chitosan-gelatin-based thermosensitive hydrogel containing 5FU-alginate nanoparticles was formulated for the effective and sustained delivery of 5FU to the skin. (2) Methods: Alginate, a polysaccharide was used for the formulation of nanoparticles using a spray drying technique. Size, zeta potential, and surface morphology were investigated using a zetasizer and scanning electron microscope. The hydrogel was fabricated using chitosan and gelatin. Several important analyses were used to characterize these prepared topical hydrogels. The pH, visual transparency, rheological behavior, and swelling index of the prepared hydrogels were evaluated. The in vitro release studies were performed at different pH (5.5 and 7.4) and temperature (32 and 37 °C) conditions using a Franz diffusion cell. Ex vivo permeation and in vivo studies were performed using Sprague Dawley rats. (3) Results: Results show that spherical nanoparticles were produced at sizes of 202–254 nm and with zeta potentials of −43 to −38 mV. The prepared nanoparticles were successfully incorporated into chitosan-gelatin-based hydrogels using a glycerol 2-phosphate disodium salt hydrates crosslinker. Drug polymers and excipients compatibility and formulation of hydrogels was confirmed by ATR-FTIR results. The pH of the prepared hydrogels was in accordance with the skin pH. The viscosity of prepared hydrogel increased with temperature increase and phase transition (sol-gel transition) occurred at 34 °C. The release of drug was sustained in case of nanoparticles incorporated hydrogels (5FU-Alg-Np-HG) as compared to nanoparticles (5FU-Alg-Np) and simple hydrogels (5FU-HG) (ANOVA; p < 0.05). The premature and initial burst release of 5FU was prevented using 5FU-Alg-Np-HG. The release mechanism of 5FU from the 5FU-Alg-Np-HG diffusion was followed by swelling and erosion, as suggested by Korsmeyer-Peppas model. The prepared hydrogel proved to be non-irritant. Ex vivo permeation study across rat’s skin suggests that permeability of nanoparticles (5FU-Alg-Np) was higher than the 5FU-Alg-Np-HG (ANOVA; p < 0.05). However, skin-related drug retention of 5FU-Alg-Np-HG was significantly higher than the 5FU solution, 5FU-Alg-Np, and 5FU-HG (ANOVA; p < 0.05). This was due to swelling of hydrogels in the lower layers of skin where the temperature is 37 °C. The higher concentration of 5FU in the skin is helpful for treatment of local skin cancer, such as melanoma, and actinic keratosis. In vivo results also confirmed maximum AUC, t_1/2, and skin-related drug retention of 5FU-Alg-Np-HG. (4) Conclusions: Chitosan-gelatin-based hydrogels containing 5FU-Alg-Np possess exceptional properties, and can be used for the sustained delivery of 5FU for the treatment of local skin cancers. Full article

Chitosan (CS) crosslinking has been thoroughly investigated, but the chemical reactions leading to submicronic hydrogel formulations pose problems due to various physical/chemical interactions that limit chitosan processability. The current study employs the chemical modification of chitosan by Michael addition of poly (ethylene glycol) methyl ether acrylate (PEGA) to the amine groups to further prepare chitosan particulate hydrogels (CPH). Thus, modified CS is subjected to a double crosslinking, ionic and covalent, in water/oil emulsion. The studied process parameters are polymer concentration, stirring speed, and quantity of ionic crosslinker. The CPH were structurally and morphologically characterized through infrared spectroscopy, scanning electron microscopy, light scattering granulometry, and zeta potential, showing that modified CS allows better control of dimensional properties and morphology as compared with neat CS. Swelling properties were studied in acidic and neutral pH conditions, showing that pH-dependent behavior was maintained after grafting and double crosslinking. The applicability of the prepared materials was further tested for drug loading and in vitro delivery of levofloxacin (LEV), showing excellent capacity. CPH were found to be cyto- and hemocompatible demonstrating their potential for effective use as a controlled release system for different biomedical applications. Full article

Chitosan-capped silver nanoparticle (CS-capped AgNPs)-incorporated Poly(vinyl alcohol) (PVA) hybrid membranes were prepared by a solution-casting technique for ethanol dehydration via pervaporation. The incorporation of CS-capped AgNPs into the PVA membrane and its influence on membrane properties and pervaporation-separation process of azeotropic water/ethanol mixture was studied. The addition of CS-capped AgNPs into the PVA membrane reduced the crystallinity, thereby increasing the hydrophilicity and swelling degree of the hybrid membrane, supported by contact angle (CA) analyzer and swelling degree experiments, respectively. Fourier transform infrared spectroscopy (FTIR) demonstrated the formation of polymeric matrix between PVA and CS and also the binding of AgNPs onto the functional group of CS and PVA, which was also reflected in the microstructure images demonstrated by scanning electron microscopy (SEM) and by 2θ angle of wide-angle X-ray diffraction (WAXD). The effect of CS-capped AgNPs on the thermal stability of the hybrid membrane was demonstrated by differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA). These characteristics of the hybrid membrane positively impact the efficiency of the dehydration of ethanol, as indicated by pervaporation experiments. The best performances in total flux (12.40 ± 0.20 × 10⁻² kg/m² h) and selectivity (3612.33 ± 6.03) at 30 °C were shown for CS-capped AgNPs PVA hybrid membrane containing 2 wt.% CS-capped AgNPs (M-4). This confirms that the developed hybrid membranes can be efficiently used to separate water from azeotropic aqueous ethanol. Full article

Hydrogel conjugates based on chitosan and an essential oil were synthetized by an ultrasound-assisted emulsification approach. Rheology studies revealed a gel-type structure with pronounced compactness and flexibility while SEM showed the formation of a two-level ordered network with highly interconnected pores. The swelling studies indicated a pH-dependent behavior with a significant overshooting effect. The synergistic effects of the components in clove essential oil led to a strong antioxidant character and an enhanced antimicrobial activity of the conjugate hydrogels. The bioactivity was maintained for 6 months, despite a slight decrease in the antimicrobial effect. Hydrogel conjugates were found to be very stable even after two months immersed in acidic solutions that would otherwise dissolve the chitosan matrix. Ultrasound emulsification was proved as an efficient one-step loading method of hydrophobic clove essential oil into hydrophilic chitosan matrix. It was found that clove oil and its components have a double role. Besides providing bioactivity, they also behave as gelation-inducing agents, acting as an alternative to the classical chemical cross-linkers to ensure the good physical and chemical stabilization of chitosan. Full article

Three-dimensional chitosan-gallic acid complexes were proposed and prepared for the first time by a simple adsorption process of gallic acid (GA) on three-dimensional chitosan structures (3D chitosan). Highly porous 3D devices facilitate a high GA load, up to 2015 mmol/kg at pH 4.0. The preservation of the redox state of GA released from 3D chitosan was confirmed by spectroscopic analyses. The antioxidant activity of 3D chitosan-GA complexes was assessed using the DPPH radical scavenging assay and was found to be dramatically higher than that of free chitosan. The mechanical property of 3D chitosan–GA complexes was also evaluated using a compression test. Finally, 3D chitosan–GA complexes showed a significant antimicrobial capacity against E. coli and S. aureus, selected, respectively, as a model strain for Gram-negative and Gram-positive bacteria. Our study demonstrated a new, simple, and eco-friendly approach to prepare functional chitosan-based complexes for nutraceutical, cosmeceutical, and pharmaceutical applications. Full article

The development of biodegradable polysaccharide hydrogel matrices for cytostatic delivery can improve the therapeutic results of patients by prolonging the action of the drug, reducing its toxicity and providing additional biological activity by polysaccharides. In this work, N-succinyl chitosan/hyaluronic acid dialdehyde/cytostatic formulations have been prepared using two different chitosan grades (30 kDa and 150 kDa) and hyaluronic acid dialdehyde. The interaction of amino groups of N-succinyl chitosan and aldehydes of hyaluronic acid resulted in the formation of azomethine bonds and was demonstrated using ¹³C NMR. The elastic properties of the obtained hydrogels determine their use as implants. Two cytostatics—5-fluorouracil and mitomycin C were chosen as drugs because of their using both in oncology and in ophthalmology for the surgical treatment of glaucoma. Hydrogel formulations containing cytostatic were prepared and drug release was studied using in vitro dialysis method. It was established that the molecular weight of N-succinyl chitosan and rheological properties of hydrogel influenced the drug release behavior of the gelling delivery system. Formulations prepared from N-succinyl chitosan with greatest molecular weight and mitomycin C were found to be the most promising for medical application due to their rheological properties and prolonged drug release. Mild preparation conditions, simplicity of the technique, short gelation time (within a minute), 100% yield of hydrogel, suitability for drug release applications are the main advantages of the obtained hydrogels. Full article

Mixtures of aqueous solutions of chitosan hydrochloride (CS·HCl, 1–4 wt.%) and Pluronic F-127 (Pl F-127, 25 wt.%) were studied using vibrational and rotational viscometry; the optimal aminopolysaccharide concentration (3 wt.%) and the CS·HCl:Pl F-127 ratio (30:70) to obtain a thermosensitive hydrogel were found. It was shown that at 4 °C, such mixed compositions were viscous liquids, while at 37 °C for 1–2 min, they undergo a thermally reversible transition to a shape-stable hydrogel with a developed level of structure formation, satisfactory viscosity and high mucoadhesive parameters (maximum pull-off force F_max = 1.5 kN/m²; work of adhesion W = 66.6 × 10⁻³ J). Adding D-ascorbic acid to the hydrogel led to orientational ordering of the supramolecular structure of the mixed system and significantly improved mucoadhesion (F_max = 4.1 kN/m², W = 145.1 × 10⁻³ J). A microbiological study revealed the high antibacterial activity of the hydrogel against Gram-negative and Gram-positive bacterial strains. The treatment of mixed bacterial infection in cows demonstrated the possibility of the in situ formation of a viscoelastic gel and revealed its high therapeutic effect. It has been suggested that our thermosensitive mucoadhesive CS·HCl:Pl F-127 hydrogels could be considered as independent veterinary drugs and pharmaceuticals. Full article

Chitosan, a copolymer of glucosamine and N-acetyl glucosamine, is derived from chitin. Chitin is found in cell walls of crustaceans, fungi, insects and in some algae, microorganisms, and some invertebrate animals. Chitosan is emerging as a very important raw material for the synthesis of a wide range of products used for food, medical, pharmaceutical, health care, agriculture, industry, and environmental pollution protection. This review, in line with the focus of this special issue, provides the reader with (1) an overview on different sources of chitin, (2) advances in techniques used to extract chitin and converting it into chitosan, (3) the importance of the inherent characteristics of the chitosan from different sources that makes them suitable for specific applications and, finally, (4) briefly summarizes ways of tailoring chitosan for specific applications. The review also presents the influence of the degree of acetylation (DA) and degree of deacetylation (DDA), molecular weight (M_w) on the physicochemical and biological properties of chitosan, acid-base behavior, biodegradability, solubility, reactivity, among many other properties that determine processability and suitability for specific applications. This is intended to help guide researchers select the right chitosan raw material for their specific applications. Full article

Cardiovascular diseases are a leading cause of mortality across the globe, and transplant surgeries are not always successful since it is not always possible to replace most of the damaged heart tissues, for example in myocardial infarction. Chitosan, a natural polysaccharide, is an important biomaterial for many biomedical and pharmaceutical industries. Based on the origin, degree of deacetylation, structure, and biological functions, chitosan has emerged for vital tissue engineering applications. Recent studies reported that chitosan coupled with innovative technologies helped to load or deliver drugs or stem cells to repair the damaged heart tissue not just in a myocardial infarction but even in other cardiac therapies. Herein, we outlined the latest advances in cardiac tissue engineering mediated by chitosan overcoming the barriers in cardiac diseases. We reviewed in vitro and in vivo data reported dealing with drug delivery systems, scaffolds, or carriers fabricated using chitosan for stem cell therapy essential in cardiac tissue engineering. This comprehensive review also summarizes the properties of chitosan as a biomaterial substrate having sufficient mechanical stability that can stimulate the native collagen fibril structure for differentiating pluripotent stem cells and mesenchymal stem cells into cardiomyocytes for cardiac tissue engineering. Full article