Structure and interactions in covalently and ionically crosslinked chitosan hydrogels for biomedical applications

Chitosan-based xerogel film incorporating Nystatin: Synthesis, structural Analysis, and biological evaluation

Wound infections are challenging to manage, requiring innovative wound dressing systems with prescribed properties. Active wound dressings should provide a moist environment, protect from secondary infections, and remove wound exudate to accelerate tissue regeneration. Hydrogels are encouraging matrices for bioactive compound encapsulation in pharmaceutical applications. The aim of the present study is to design chitosan/gelatin /polyvinyl alcohol-based xerogel film containing nystatin for wound dressing applications with antifungal properties. The xerogel film is developed using a film-casting method and evaluated for its chemical and physical characteristics using FTIR, SEM, AFM, and tensile analysis. Water barrier properties of the film, such as the moisture content (17.84 ± 3.62 %), water solubility (44.50 ± 5.55 %), gel fraction (55.50 ± 5.55 %), and water vapour transmission rate (1912.25 ± 248.12 g m-2 per day), suggest a humid microenvironment suitable for wound. The xerogel film, characterized by its robust mechanical strength, substantial swelling capacity (∼120-400 %) across various pH levels, and acceptable bio-adhesive properties, reveals as a potential antifungal wound dressing material. In vitro toxicity assessments confirm its biocompatibility towards both RBCs and NIH-3 T3 fibroblast cells. The findings confirm that the film formulation has strong antifungal properties, with a minimum inhibitory concentration of 2-8 μL/mL against Candida species, as well as outstanding antibiofilm effectiveness (∼85 %) and a significant reduction of the fungal colony count (∼100 %). Moreover, its controlled drug release capabilities, along with antifungal properties, offer it as an appealing dressing for the localized treatment of superficial fungal infections. As a result, this xerogel film can be used as a versatile platform for advanced wound care and therapeutic applications.

Chitosan-Based Gel Development: Extraction, Gelation Mechanisms, and Biomedical Applications

Chitosan (CS), a versatile biopolymer obtained through the deacetylation of chitin, has gained significant interest in biomedical and pharmaceutical applications due to its biocompatibility, biodegradability, and unique gel-forming capabilities. This review comprehensively analyzes CS-based gel development, covering its extraction from various natural sources, gelation mechanisms, and biomedical applications. Different extraction methods, including chemical, biological, and green techniques, are discussed regarding efficiency and sustainability. The review explores the physicochemical properties of CS that influence its gelation behavior, highlighting various gelation mechanisms such as physical, ionic, and chemical cross-linking. Recent advances in gel formation, including Schiff base reactions, Diels-Alder click chemistry, and thermosensitive gelation, have expanded the applicability of CS hydrogels. Furthermore, CS-based gels have demonstrated potential in wound healing, tissue engineering, drug delivery, and antimicrobial applications, offering controlled drug release, enhanced biocompatibility, and tunable mechanical properties. The incorporation of nanomaterials, bioactive molecules, and functional cross-linkers has further improved hydrogel performance. The current review underscores the growing significance of CS-based gels as innovative biomaterials in regenerative medicine and pharmaceutical sciences.

Application of Carbon Nanotubes in Breast Cancer Therapy

Conjugated single-walled carbon nanotubes (SWNT) have been shown to be promising in cancer-targeted accumulation and is biocompatible, easily excreted, and possesses little toxicity. The present study aims at reviewing the recent advancements in carbon nanotubes especially SWNT for improving the treatment of breast cancer. Nanotube drug delivery system is a potential high efficacy therapy with minimum side effects for future tumor therapy with low doses of drug.

An insight into chemically modified chitosan and their biological, pharmaceutical, and medical applications: A review

Quaternized chitosan derivatives demonstrated improved antimicrobial activity. Carboxy chitosan derivatives, resulting from carboxylation with glyoxylic acid or chloroalkanoic acid, enhance solubility and are utilized in wound healing and antitumor therapies. Modifications like acylation of chitosan alter hydrophobicity, affecting biocompatibility and drug delivery efficiency. Thiolated chitosan derivatives, with enhanced mucoadhesive properties, are advantageous for mucosal drug delivery. Sulfated chitosan derivatives mimic heparin's functions, showcasing anticoagulant, anti-sclerosis, and antiviral properties. Phosphorylated chitosan derivatives find utility in orthopedics due to their cation-exchange abilities. Heterocyclic chitosan derivatives exhibit antibacterial properties, while Schiff's base and epoxy Schiff's base chitosan derivatives display antimicrobial enhancements and improved drug delivery profiles. Aminosalicylhydrazide cross-linked Schiff's base chitosan derivatives exhibit versatility with heightened antimicrobial and biological activities. Continually exploring novel functional groups highlights the importance of staying current with ongoing research in chitosan modification. Future research should focus on developing innovative chitosan derivatives with enhanced bioactivity, physicochemical properties, and multifunctional capabilities to improve pharmaceutical applications. Additionally, studies on scalability, commercialization, and eco-friendly production methods are essential to ensure industrial viability and sustainability.

Chitosan-based biomaterials for bone tissue engineering

Common critical size bone defects encountered in clinical practice often result in inadequate bone regeneration,primarily due to the extent of damage surpassing the inherent capacity of the body for self-healing. Bone tissue engineering scaffolds possess the desirable characteristics of biomimetic bone structure, simulated extracellular matrix, optimal mechanical strength, and biological functionality, rendering them the preferred option for the treatment of bone defects. Chitosan demonstrates favorable biocompatibility, plasticity, and a range of biological activities, rendering it a highly appealing material. Chitosan and its derivatives have been found to exert an impact on bone repair through their ability to modulate macrophage polarization, angiogenesis, and the delicate equilibrium of bone remodeling. However, the efficacy of pure chitosan is constrained, necessitating its combination with other bioactive substances to achieve an optimal biomimetic scaffold that is compatible with the specific bone defect site. Chitosan is commonly utilized in the field of bone repair in four different application forms: rigid scaffold, hydrogel, membranes, and microspheres. In order to enhance comprehension of the benefits and constraints associated with chitosan, this review provides a comprehensive overview of the structure and biological properties of chitosan, the molecular mechanisms by which chitosan promotes osteogenic differentiation, the diverse methods of chitosan preparation for various applications, and the impacts of chitosan when loaded with bioactive substances.

Insights into the formation of pullulan nanofilm and its feasibility as probiotic-resided oral fast dissolving carrier

Oral fast dissolving films represent a novel dosage form for probiotics. To reduce the dependence of film preparation on synthetic materials, a polysaccharide-based oral fast dissolving nanofilm for probiotics was fabricated through pullulan (PUL) electrospinning. An electrospinnability map of PUL with varying physical properties was developed, identifying a molecular weight of 200 kDa and a concentration of 20 % as suitable conditions for achieving favorable fiber morphology. Scanning electron microscopy, Fourier-transform infrared spectroscopy, and fluorescence assays confirmed that probiotics could be effectively encapsulated in the nanofilm, with 92.6 % of viable cells retained after electrospinning. Results of thermogravimetric analysis and thermal test indicated that the heat resistance of the encapsulated bacteria was significantly improved (P < 0.05). After 28 days of storage, the loss of viable bacteria was higher at 25 °C (2.9 log) than at 4 °C (0.5 log). This observation is consistent with the results of accelerated storage test, which showed that probiotic nanofilms stored at 4 °C had a longer shelf life with an inactivation rate constant of 1.74 × 10-5. Furthermore, the dissolution study revealed that the nanofilms could disintegrate in simulated saliva within 15 s, highlighting their potential as oral fast dissolving formulation.

Directing mineralization of ZnO nanoparticles in cyanobacterial liquid crystalline polysaccharides for cancer therapies

Effective cancer therapy faces significant challenges, including non-selective toxicity, limited structural stability, inconsistent nanoparticle (NP) morphology, and instability under varying biological conditions. These issues hindering targeted delivery and therapeutic efficacy. Previous approaches using polysaccharide-based nanomaterials have shown promise; however, problems such as inconsistent NP sizes and shapes, poor mechanical stability, and limited pH resilience restrict their clinical potential. This study hypothesized that sacran, a cyanobacterial liquid crystalline (LC) polysaccharide, can stabilize ZnO NPs, allowing for controlled mineralization, enhanced stability, and selective cytotoxicity. We developed ZnO nanocomposite xerogels in an LC sacran matrix, yielding block-like ZnO NPs (25-70 nm) with high surface-area-to-volume ratios that improve cellular uptake in tumor environments. Incorporating these NPs into chemically crosslinked sacran matrices resulted in a 3-fold increase in mechanical strength and a 10-fold improvement in swelling capacity compared to physically crosslinked systems. Additionally, the sacran-ZnO nanocomposites demonstrated robust stability under various pH conditions, indicating their resilience in diverse biological environments. Cytotoxicity assays revealed that higher concentrations of ZnO NP selectively increased toxicity toward human lung cancer cells (A549), with less impact on human dermal fibroblasts (HDFa). Moreover, HDFa successfully attached to and proliferated on the smooth surfaces of the xerogels, emphasizing their compatibility with normal cells. This highlights the potential of sacran-ZnO nanocomposite xerogels as cancer-selective therapeutic materials, offering stability and effectiveness even under varying biological conditions, while addressing key challenges associated with earlier NP-based therapies.

Langmuir Monolayer Studies of Phosphatidylcholine Membranes with Naproxen on the Polysaccharide Subphase

Natural polysaccharides are biocompatible and biodegradable; therefore, they can be widely used in drug delivery, tissue engineering and wound healing. In this context, the interactions between polysaccharides, drugs and biological membranes are of great interest. In this paper, a 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) monolayer was used as a model membrane to study the interactions with polysaccharides: chitosan (Ch) and/or hyaluronic acid (HA) and a nonsteroidal anti-inflammatory drug (NSAID) naproxen (NAP). The changes in the physicochemical properties of the model membrane were characterized by means of the Langmuir monolayer technique combined with Brewster angle microscopy (BAM). Compression/adsorption isotherms and morphology images were obtained at 20 °C. They allowed us to determine the effect of the subphase type (Ch, HA, Ch-HA) on the behavior of DPPC monolayers in the absence and presence of NAP, their elasticity, morphology and stability as a function of time. A potential mode of interactions between the phospholipid, polysaccharides and drug responsible for the change in membrane properties was proposed. These interactions regulate the efficiency of drug delivery systems, being of importance for living organisms in pain relief and wound healing.

Infertility treatment using polysaccharides-based hydrogels: new strategies in tissue engineering and regenerative medicine

Infertility is a primary health issue affecting about 15% of couples of reproductive ages worldwide, leading to physical, mental, and social challenges. Advances in nanobiotechnology and regenerative medicine are opening new therapeutic horizons for infertility by developing polysaccharide-based nanostructured biomaterials. This review explores the role of tissue engineering and regenerative medicine in infertility treatment, explicitly focusing on the promising potential of polysaccharide-based hydrogels. In this context, using these biomaterials offers unique advantages, including biodegradability, biocompatibility, and the ability to mimic the natural endometrial microenvironment, making them highly effective for applications in endometrial regeneration, ovarian tissue engineering, spermatogenesis support, and controlled drug delivery. This review discusses the various properties and uses of polysaccharide-based hydrogels, like alginate, hyaluronic acid, and chitosan, in helping to restore reproductive function. While these materials hold great promise, some notable challenges to their clinical use include issues like rapid degradation, mechanical instability, and potential immune reactions. Future research should focus on developing hybrid hydrogels, investigating advanced fabrication techniques, and testing these materials in clinical settings. By combining findings from recent studies, this review aims to provide a solid foundation for researchers and clinicians looking to discover new and effective strategies for treating infertility, ultimately connecting research efforts with practical applications in healthcare.

Immunomodulatory hydrogel orchestrates pro-regenerative response of macrophages and angiogenesis for chronic wound healing

Chronic wound healing often encounters challenges characterized by prolonged inflammation and impaired angiogenesis. While the immune response plays a pivotal role in orchestrating the intricate process of wound healing, excessive inflammation can hinder tissue repair. In this study, a bilayer alginate hydrogel system encapsulating polyelectrolyte complex nanoparticles (PCNs) loaded with anti-inflammatory cytokines and angiogenic growth factors is developed to address the challenges of chronic wound healing. The alginate hydrogel is designed using two distinct crosslinking methods to achieve differential degradation, thereby enabling precise spatial and temporal controlled release of PCNs. Initially, interleukin-10 (IL-10) is released to mitigate inflammation, while unsaturated PCNs bind and remove accumulated pro-inflammatory cytokines at the wound site. Subsequently, angiogenic growth factors, including vascular endothelial growth factor and platelet-derived growth factor, are released to promote vascularization and vessel maturation. Our results demonstrate that the bilayer hydrogel exhibits distinct degradation kinetics between the two layers, facilitating the staged release of multiple signaling molecules. In vitro experiments reveal that IL-10 can activate the Jak1/STAT3 pathway, thereby suppressing pro-inflammatory cytokines and chemokines while down-regulating inflammation-related genes. In vivo studies demonstrate that application of the hydrogel in chronic wounds using diabetic murine model promotes healing by positively modulating multiple integral reparative mechanisms. These include reducing inflammation, promoting macrophage polarization towards a pro-regenerative phenotype, enhancing keratinocyte migration, stimulating angiogenesis, and expediting wound closure. In conclusion, our hydrogel system effectively mitigates inflammatory responses and provides essential physiological cues by inducing a synergistic angiogenic effect, thus offering a promising approach for the treatment of chronic wounds.

Evaluation of Physicochemical Properties of Polymeric Systems for Potential Applications in Cartilage Tissue Engineering

This study investigates the physicochemical properties of hydrogels based on PVA and PVP crosslinked with PEGDA, focusing on their swelling capacity, surface roughness, incubation behavior, and structural modifications upon bioactive component incorporation. Swelling analysis demonstrated that the amount and molecular weight of PEGDA significantly influences the hydrogels' sorption properties, with the highest swelling coefficient observed for samples with 2 mL PEGDA (575 g/mol) due to a looser network structure, while the lowest was recorded for 2.5 mL PEGDA (700 g/mol), indicating a denser network. Surface roughness analysis revealed that increasing the crosslinker amount led to higher roughness both before and after incubation, with samples containing 575 g/mol PEGDA being more susceptible to structural changes in an incubation environment. FT-IR spectroscopy confirmed the presence of characteristic functional groups, providing insight into the chemical stability and hydration properties of the hydrogels. Modification with a bioactive mixture (glucosamine, chondroitin, and MSM) was confirmed by spectral analysis, indicating successful integration without compromising the hydrogel matrix. The modified hydrogels demonstrated potential applications in regenerative medicine, particularly for joint disease treatment and cartilage tissue repair.

Flexible and Robust Piezoelectric Chitosan Films with Enhanced Bioactivity

Chitosan (CHT) is a known piezoelectric biomacromolecule; however, its usage is limited due to rapid degradation in an aqueous system. Herein, we prepared CHT film via a solvent casting method and cross-linked in an alkaline solution. Sodium hydroxide facilitated deprotonation, leading to increased intramolecular hydrogen bonding and mechanical properties. The CHT film remained intact for 30 days in aqueous environments. A systematic study revealed a gradual increase in the output voltage from 0.9 to 1.8 V under external force (1-16 N). In addition, the CHT film showed remarkable antibacterial and anti-inflammatory activities under ultrasound stimulation and inhibition of inflammatory cytokines. The CHT films also displayed enhanced cellular proliferation and ∼5-fold faster migration of NIH3T3 cells under US stimulation. Overall, this work presents a robust, biocompatible, and wearable CHT device that can transform biomechanical energy into electrical pulses for the modulation of cell fate processes and other bioactivities.

An insight into cancer nanomedicine based on polysaccharides

With cancer rates on the rise around the world, cancer treatment has dominated scientific discussions in recent years. The toxicity of cytotoxic drugs, their lack of tumor localization, and their uniform dispersion into tumor tissues are the obstacles to cancer therapy. Other cancer treatment drawbacks include short blood circulation half-lives and undesirable pharmacokinetic behavior. Low-molecular-weight drugs conjugated with macromolecular carriers are better distributed in the body. The enhanced permeation and retention (EPR) effect causes natural and synthetic polymers, such as polysaccharides, proteins, antibodies, and poly amino acids, to accumulate in tumor tissue. Many manufactured and natural polymers are attractive polymeric drug carriers, allowing the creation of prodrugs from medicinal substances. Polysaccharides are biological polymers with structural and functional variations. They are also non-toxic, hydrophilic, biodegradable, and efficiently bioactive. Polysaccharides are ideal for synthesizing many nanoparticles due to their functional groups. Their ability to adapt to their microenvironment makes them valuable. Nanoplatforms based on polysaccharides can deliver targeted anticancer drugs for personalized cancer treatment. Unique polysaccharide structures and properties offer chemical and biological advantages for novel drug delivery. Polysaccharide-drug conjugation could revolutionize cancer chemotherapy. This study investigates polysaccharide conjugates and polysaccharides as natural biomaterials for cancer drug delivery.

Development of paroxetine loaded nanotransferosomal gel for intranasal delivery with enhanced antidepressant activity in rats

The aim of this study was to develop paroxetine (PXT) loaded nanotransferosomal gel (PXT-NTFG) for intranasal brain delivery. The process involved fabricating PXT-NTFs (paroxetine-loaded nanotransferosomes) through a thin film hydration method and optimizing them based on parameters such as particle size (PS), zeta potential (ZP), polydispersity index (PDI), and entrapment efficiency (EE). The optimized PXT-NTFs exhibited uniform morphology with a PS of 158.30 ± 2.73 nm, low PDI (0.142 ± 0.072), high ZP (21.00 ± 0.75 mV), and excellent EE (88.09 ± 3.40 %). Characterization through various techniques confirmed the incorporation of PXT into the nanotransferosomes and its conversion to amorphous state. Moreover, PXT-NTFG was formulated with suitable viscosity and mucoadhesive properties. In vitro release studies demonstrated sustained drug release from PXT-NTFG at different pH levels as compared to PXT-NTFs and NTF dispersion. Similarly, ex vivo experiments showed 4 folds enhanced drug permeation from PXT-NTFG when compared with PXT conventional gel. Stability studies indicated that the optimized PXT-NTFs remained stable for four months at 4°C and 25°C. Additionally, improved behavioral outcomes, increased neuronal survival rates, and upregulated brain-derived neurotrophic factor (BDNF) expression was observed in lipopolysaccharide (LPS) induced depressed Sprague-Dawley rats after treatment with PXT-NTFG as compared to PXT-dispersion treated and untreated LPS-control groups. Notably, the formulation led to a significant reduction in brain and plasma TNF-α levels. In conclusion, intranasal PXT-NTFG is a promising formulation with sustained drug release, improved brain targeting and enhanced antidepressant activity.

Formulation development of highly stable collagenase-containing hydrogels for wound healing

Collagenases are enzymes that break down collagen and are used in wound healing and treating various disorders. Currently, collagenase is commercially available in only ointment and injectable forms and is sensitive to various environmental factors. In the present study, different hydrogel formulations of collagenase have been prepared at pH 6.5 using carboxymethylcellulose sodium and zinc acetate with and without humectants such as propylene glycol (PG) and glycerin (GL) in varying concentrations. The formulated gels were stored at room temperature (25±2°C, 60±5% RH) and refrigerator temperature (5±3°C) for six months to evaluate their physical and up to six years for chemical stability. The gels were subjected to various tests, including organoleptic studies, spreadability, moisture content, swelling index, swelling/de-swelling, syneresis, viscosity, gelation time, and weight variation. The purity and molecular weight of collagenase have been determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). At the same time, its activity during the storage period was evaluated by gelatin zymography. Casein zymography was also performed to detect any caseinase contamination in the formulations. The release of the enzyme from different gel formulations was assessed using the Franz diffusion apparatus and analyzed by gelatin zymography. The results showed some physical changes that were more prominent in gels stored at room temperature than those kept refrigerated. The difference in humectant concentration was also found to affect the stability of gels. PG was found to be a better humectant than GL, particularly in a concentration of 25%. The zymography results indicated that collagenase was stable in all formulations kept in the refrigerator. In contrast, its complete degradation was noted in the preparations stored at room temperature within a month. The data generated in this study will help the formulators to commercialize a relatively economical gel formulation of collagenase that is highly stable for up to six years at refrigerator temperature (5±3°C).

Inhibition of growth and lung metastasis of breast cancer by pH-responsive methotrexate/curcumin-loaded chitosan-stabilized nanoemulsions

Chemotherapeutic agents are widely used to combat breast cancer. However, due to their non-selective biodistribution, their usage is associated with severe adverse effects on healthy tissues. In this study, a chitosan-stabilized nanoemulsion (CSNE) was prepared for the codelivery of curcumin (CUR) and methotrexate (MTX). The mean diameter and polydispersity index of CUR-MTX-CSNEs were 194.63 ± 6.7 nm and 0.27 ± 0.06, respectively. Modifying the nanoemulsion surface with chitosan decreased the drug release at pH 7.4 compared to pH 5.8. The MTT test demonstrated that CUR-MTX-CSNEs were more successful in reducing the cell viability of 4T1 cells than both bare formulation and free drugs. Moreover, compared to the free drug-treated group, a 2.6 times reduction of the relative tumor volume was witnessed in CUR-MTX-CSNEs-receiving mice. Histopathological studies confirmed a more substantial inhibitory effect on tumor growth and pulmonary metastasis of developed nanostructures than free CUR/MTX. While there was no noticeable toxicity in the vital organs of CUR-MTX-CSNEs-receiving mice, free drugs resulted in severe toxicity in the liver, kidney, lung and spleen. Overall, the pH-dependent drug release, improved anti-tumor activity and reduced organ toxicity suggest that CUR-MTX-CSNE may be promising in breast cancer therapy.

Advances in the preparation, applications, challenges, and future trends of polysaccharide-based gels as food-grade delivery systems for probiotics: A review

Probiotics are highly regarded for their multiple functions, such as regulating gut health, enhancing the immune system, and preventing chronic diseases. However, their stability in harsh environments and targeted release remain significant challenges. Therefore, exploring effective protection and delivery strategies to ensure targeted release of probiotics is critically important. Polysaccharides, known for their non-toxicity, excellent biocompatibility, and superior biodegradability, show broad prospects in probiotic delivery by forming physical barriers to protect the probiotics. Particularly, polysaccharide-based gels (PBGs), with their unique "spider-web" like structure, capture and ensure the targeted release of probiotics, significantly enhancing their efficacy. This review discusses common polysaccharides used in PBG preparation, their classification and synthesis in food applications, and the advantages of PBGs as probiotic delivery systems. Despite their potential, challenges such as inconsistent gel properties and the need for improved stability remain. Future research should focus on developing novel PBG materials with higher biodegradability and mechanical strength, optimizing the physicochemical properties and cross-linking methods, as well as designing multilayered structures for more precise release control. Additionally, exploring the co-delivery of probiotics with prebiotics, active ingredients, or multi-strain systems could further enhance the efficacy of probiotic delivery.

Hydrogels in wearable neural interfaces

The integration of wearable neural interfaces (WNIs) with the human nervous system has marked a significant progression, enabling progress in medical treatments and technology integration. Hydrogels, distinguished by their high-water content, low interfacial impedance, conductivity, adhesion, and mechanical compliance, effectively address the rigidity and biocompatibility issues common in traditional materials. This review highlights their important parameters-biocompatibility, interfacial impedance, conductivity, and adhesiveness-that are integral to their function in WNIs. The applications of hydrogels in wearable neural recording and neurostimulation are discussed in detail. Finally, the opportunities and challenges faced by hydrogels for WNIs are summarized and prospected. This review aims to offer a thorough examination of hydrogel technology's present landscape and to encourage continued exploration and innovation. As developments progress, hydrogels are poised to revolutionize wearable neural interfaces, offering significant enhancements in healthcare and technological applications.

Graphical Abstract

To Evaluate and Compare the Microleakage of Chitosan Nano Hydrogel-Incorporated MTA and Glass Ionomer Cements When used as a Retrograde Filling Material

Background

An inadequate apical seal stands out as a primary cause of disappointment in surgical endodontic procedures. Therefore, the choice of root-end filling material should aim to prevent the leakage of potential contaminants into the periapical tissue.

Aim

To evaluate and compare microleakage of chitosan nano hydrogel-incorporated mineral trioxide aggregate (MTA) and glass ionomer cement (GIC) when used as a retrograde filling material.

Materials and Methods

Sixty single-rooted premolars were decoronated at cemento enamel junction (CEJ), and root canals were prepared and obturated, with the coronal part sealed with a composite. The dye absorption was measured by an automatic spectrophotometer.

Results

The results showed that the MTA + chitosan group had less microleakage values compared to the MTA group but was not statistically significant and GIC + chitosan had less microleakage values compared to the GIC group and was statistically significant.

Conclusion

Chitosan-incorporated MTA and chitosan-incorporated GIC can be considered as retrograde filling material; however, further in vitro and in vivo research and long-term clinical studies are required.

Engineered bio-functional material-based nerve guide conduits for optic nerve regeneration: a view from the cellular perspective, challenges and the future outlook

Nerve injuries can be tantamount to severe impairment, standard treatment such as the use of autograft or surgery comes with complications and confers a shortened relief. The mechanism relevant to the regeneration of the optic nerve seems yet to be fully uncovered. The prevailing rate of vision loss as a result of direct or indirect insult on the optic nerve is alarming. Currently, the use of nerve guide conduits (NGC) to some extent has proven reliable especially in rodents and among the peripheral nervous system, a promising ground for regeneration and functional recovery, however in the optic nerve, this NGC function seems quite unfamous. The insufficient NGC application and the unabridged regeneration of the optic nerve could be a result of the limited information on cellular and molecular activities. This review seeks to tackle two major factors (i) the cellular and molecular activity involved in traumatic optic neuropathy and (ii) the NGC application for the optic nerve regeneration. The understanding of cellular and molecular concepts encompassed, ocular inflammation, extrinsic signaling and intrinsic signaling for axon growth, mobile zinc role, Ca2+ factor associated with the optic nerve, alternative therapies from nanotechnology based on the molecular information and finally the nanotechnological outlook encompassing applicable biomaterials and the use of NGC for regeneration. The challenges and future outlook regarding optic nerve regenerations are also discussed. Upon the many approaches used, the comprehensive role of the cellular and molecular mechanism may set grounds for the efficient application of the NGC for optic nerve regeneration.

Fabrication and Optimization of a Silodosin In Situ-Forming PLGA Implants for the Treatment of Benign Prostatic Hyperplasia: In Vitro and In Vivo Study

Objectives: Lower urinary tract symptoms (LUTSs) related to benign prostatic hyperplasia (BPH) are common in older men, and alpha-adrenoceptor blockers continue to be a key part of managing these symptoms. This study aimed to formulate injectable poly (lactic-co-glycolic acid) (PLGA) in situ-forming implants (ISFIs) loaded with silodosin (SLD) to address symptoms associated with BPH. This method, which ensures prolonged therapeutic effects of SLD, is intended to decrease dosing frequency and improve treatment outcomes, leading to better patient adherence. Methods: An appropriate solvent with favorable PLGA solubility, viscosity, and in vitro release profile was selected. Additionally, an I-optimal design was employed as an optimization technique. An in vivo study in albino male rats was conducted to investigate prostate-specific antigens (PSAs), prostate weight and prostatic index, histopathology, and SLD pharmacokinetics. Results: The optimized formulation showed experimental values of 29.25% for the initial burst after 2 h and 58.23% for the cumulative release of SLD after 10 days. Pharmacokinetic data revealed that the SLD-ISFI formulation had lower Cmax and higher AUC values than subcutaneous (SC) pure SLD and oral commercial SLD capsule, indicating the controlled-release impact and improved bioavailability of the ISFI systems. SLD-ISFI produced a marked drop in the prostatic index by 2.09-fold compared to the positive control. Serum PSA level decreased significantly from 0.345 ± 0.007 to 0.145 ± 0.015 ng/mL after SLD-ISFI injection compared to the positive control. Conclusions: This study indicated that the optimized SLD-ISFI formulation proved its efficacy in managing BPH.

Probing the Effects of Chirality on Self-Assembling Peptides: Hydrogel Formation, Degradation, Antigen Release, and Adjuvancy

Introduction

Multidomain peptides (MDPs) are amino acid sequences that self-assemble to form supramolecular hydrogels under physiological conditions that have shown promise for a number of biomedical applications. K2(SL)6K2 ("K2"), a widely studied MDP, has demonstrated the ability to enhance the humoral immune response to co-delivered antigen. Herein, we sought to explore the in vitro and in vivo properties of a peptide with the same sequence but opposite chirality (D-K2) since peptides composed of D-amino acids are resistant to protease degradation and potentially more immunostimulatory than their canonical counterparts.

Methods

K2 and D-K2 hydrogels were characterized and evaluated in vitro using circular dichroism, rheology, cryo-electron microscopy, and fluorescence recovery after photobleaching studies. In vivo experiments in SKH-1 mice were conducted to evaluate both ovalbumin release from the hydrogels and hydrogel degradation. The injection site of the hydrogels was analyzed using histology and humoral immunity was assessed by ELISA.

Results

In vitro, the enantiomeric hydrogels exhibited similar rheological properties, and fluorescence recovery after photobleaching experiments demonstrated that the diffusion of ovalbumin (OVA), a model antigen, was similar within both hydrogels. In vivo, K2 and D-K2 peptide hydrogels had similar OVA release rates, both releasing 89% of the antigen within 8 days. Both hydrogels elicited a similar antigen-specific humoral immune response. However, the in vivo degradation of the D-K2 hydrogel progressed significantly slower than K2. After 4 weeks in vivo, only 23 ± 7% of the K2 hydrogel remained at the injection site compared to 94 ± 7% of the D-K2 hydrogel, likely due to their different protease susceptibilities.

Conclusion

Taken together, these data suggest that peptide chirality can be a useful tool for increasing hydrogel residence time for biomedical applications that would benefit from long persistence times and that, if an antigen releases over a sufficiently short period, release can be largely independent of degradation rate, though slower-diffusing payloads may exhibit degradation rate dependence.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-024-00806-1.

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.

Stretchable hydrogels of chitosan/hyaluronic acid induced by polyelectrolyte complexation around neutral pH

In this work, we propose the formation of stretchable hydrogels at neutral pH from the physical crosslinking of chitosan (CS) and hyaluronic acid (HA) by polyelectrolyte complexation. A mixture of CS (Mw ≈ 600 kg/mol, degree of acetylation ≈ 50 %) solution and HA (Mw ≈ 77 kg/mol) solution was prepared with an excess of salts screening the electrostatic interactions CS/HA. In a controlled manner, the polyelectrolyte complexation was induced through the progressive dialysis of the salted polymer mixture against a sodium acetate solution (AcONa, 0.01 M) for 7 days. Depending on [HA], various materials were obtained: viscous solutions at [HA] = 0.75 % (w/v); hydrogels at [HA] = 1.50-2.24 % (w/v) with Young modulus of 14 kPa and stretchable to 200 %. The small angle X-ray scattering characterization of the hydrogels revealed a multiscale organization related to the conformation of the polymers induced by the physical interactions. The dialysis process with AcONa was optimized by adding a dialysis step against a zinc acetate solution containing Zn2+. The combination of polyelectrolyte complexation between CS/HA and metal complexation between Zn2+ and the polymers led to an enhancement of the hydrogel stretchability up to 400 %.

Tuning the Properties of Xylan/Chitosan-Based Films by Temperature and Citric Acid Crosslinking Agent

Petroleum-based food packaging causes environmental problems such as waste accumulation and microplastic generation. In this work, biobased films from stable polyelectrolyte complex suspensions (PECs) of xylan and chitosan (70 Xyl/30 Ch wt% mass ratio), at different concentrations of citric acid (CA) (0, 2.5, 5, 7.5 wt%), were prepared and characterized. Films were treated at two temperatures (135 °C, 155 °C) and times (30 min, 60 min) to promote covalent crosslinking. Esterification and amidation reactions were confirmed by Fourier Transform Infrared Spectroscopy and Confocal Raman Microscopy. Water resistance and dry and wet stress-strain results were markedly increased by thermal treatment, mainly at 155 °C. The presence of 5 wt% CA tended to increase dry and wet stress-strain values further, up to 88 MPa-10% (155 °C for 60 min), and 5.6 MPa-40% (155 °C for 30 min), respectively. The UV-blocking performance of the films was improved by all treatments, as was thermal stability (up to Tonset: 230 °C). Contact angle values were between 73 and 84°, indicating partly wettable surfaces. Thus, thermal treatment at low CA concentrations represents a good alternative for improving the performance of Xyl/Ch films.

Exploring the Feasibility of Polysaccharide-Based Mulch Films with Controlled Ammonium and Phosphate Ions Release for Sustainable Agriculture

Bio-based polymers are a promising material with which to tackle the use of disposable and non-degradable plastics in agriculture, such as mulching films. However, their poor mechanical properties and the high cost of biomaterials have hindered their widespread application. Hence, in this study, we improved polysaccharide-based films and enriched them with plant nutrients to make them suitable for mulching and fertilizing. Films were produced combining sodium carboxymethyl cellulose (CMC), chitosan (CS), and sodium alginate (SA) at different weight ratios with glycerol and CaCl2 as a plasticizer and crosslinker, respectively, and enriched with ammonium phosphate monobasic (NH4H2PO4). A polysaccharide weight ratio of 1:1 generated a film with a more crosslinked structure and a lower expanded network than that featuring the 17:3 ratio, whereas CaCl2 increased the films' water resistance, thermal stability, and strength characteristics, slowing the release rates of NH4+ and PO43-. Thus, composition and crosslinking proved crucial to obtaining promising films for soil mulching.

Synthesis of biocompatible hydrogel of alginate-chitosan enriched with iron sulfide nanocrystals

This work aimed to synthesize and characterize a biocompatible hydrogel of alginate and chitosan enriched with iron sulfide nanocrystals. Three concentrations of iron sulfide nanocrystals (FeS2NCs) 0.03905, 0.0781, and 0.2343 mg/ml were used. Gel swelling was determined using phosphate-buffered saline solution at 1, 2, 4, 6, 24, 48, and 72 h. The microstructure, the morphology, and the elastic strength were determined by optical microscopy, scanning electron microscopy, and rheological studies, respectively. The functional groups were identified through Fourier Transform Infrared spectroscopy. Biocompatibility was determined in a murine model; after seven days of subdermal inoculation, histological sections stained with H&E were analyzed, and then histopathological features were evaluated. All the compounds obtained showed a loss modulus lower than the storage modulus. The 0.2343 mg/ml FeS2NCs hydrogel showed higher swelling than the control. In the in vivo evaluation, no adverse effects were found. The presence of FeS2NCs was well tolerated in the subcutaneous tissue of mice, according to histopathological analysis. The hydrogels synthesized with added FeS2NCs demonstrate a swelling ratio of 150 %, rheologically exhibiting gel-like behavior rather than viscous liquids. Furthermore, they did not present any adverse effects on the subcutaneous tissue.

Chitosan: An overview of biological activities, derivatives, properties, and current advancements in biomedical applications

The second and most often utilized natural polymer is chitosan (CS), a naturally existing amino polysaccharide that is produced by deacetylating chitin. Numerous applications have been the subject of in-depth investigation due to its non-hazardous, biologically compatible, and biodegradable qualities. Chitosan's characteristics, such as mucoadhesion, improved permeability, controlled release of drugs, in situ gelation process, and antibacterial activity, depend on its amino (-NH2) and hydroxyl groups (-OH). This study examines the latest findings in chitosan research, including its characteristics, derivatives, preliminary research, toxic effects, pharmaceutical kinetics and chitosan nanoparticles (CS-NPs) based for non-parenteral delivery of drugs. Chitosan and its derivatives have a wide range of physical and chemical properties that make them highly promising for use in the medicinal and pharmaceutical industries. The characteristics and biological activities of chitosan and its derivative-based nanomaterials for the delivery of drugs, therapeutic gene transfer, delivery of vaccine, engineering tissues, evaluations, and other applications in medicine are highlighted in detail in the current review. Together with the techniques for binding medications to nanoparticles, the application of the nanoparticles was also dictated by their physical properties that were classified and specified. The most recent research investigations on delivery of drugs chitosan nanoparticle-based medication delivery methods applied topically, through the skin, and through the eyes were considered.

Green immobilization: Enhancing enzyme stability and reusability on eco-friendly support

In the current years of heightened focus on green chemistry and sustainable materials, this study delves into the untapped potential of hyaluronic acid (HA), chitin, and chitosan-prominent polysaccharides for groundbreaking applications. The primary aim is to effectively immobilize catalase enzymes onto matrices composed of chitosan, chitin, HA/chitin, and HA/chitosan. The rigorous investigation covers a spectrum of structural enhancements encompassing pH and temperature stability, thermal resilience, half-life extension, storage durability, reusability, and comprehensive FTIR analyses of the catalase immobilization. Notably, catalase activity demonstrated remarkable resilience on HA/chitin and HA/chitosan matrices, maintaining 73.80% and 79.55% efficacy even after 25 cycles. The introduction of covalent cross-linking between catalase and HA/chitin or HA/chitosan, facilitated by a cross-linking agent, significantly amplified stability and recycling efficiency. Consequently, the immobilized catalase showcases substantial promise across a spectrum of industrial applications, spanning from food and detergent production to bioremediation and diverse commercial processes. This underscores its pivotal role as a versatile and invaluable innovation in the realm of sustainable technologies.

Propelling Minimally Invasive Tissue Regeneration With Next-Era Injectable Pre-Formed Scaffolds

The growing aging population, with its associated chronic diseases, underscores the urgency for effective tissue regeneration strategies. Biomaterials play a pivotal role in the realm of tissue reconstruction and regeneration, with a distinct shift toward minimally invasive (MI) treatments. This transition, fueled by engineered biomaterials, steers away from invasive surgical procedures to embrace approaches offering reduced trauma, accelerated recovery, and cost-effectiveness. In the realm of MI tissue repair and cargo delivery, various techniques are explored. While in situ polymerization is prominent, it is not without its challenges. This narrative review explores diverse biomaterials, fabrication methods, and biofunctionalization for injectable pre-formed scaffolds, focusing on their unique advantages. The injectable pre-formed scaffolds, exhibiting compressibility, controlled injection, and maintained mechanical integrity, emerge as promising alternative solutions to in situ polymerization challenges. The conclusion of this review emphasizes the importance of interdisciplinary design facilitated by synergizing fields of materials science, advanced 3D biomanufacturing, mechanobiological studies, and innovative approaches for effective MI tissue regeneration.

Computational Fluid Dynamics (CFD) Analysis of Bioprinting

Regenerative medicine has evolved with the rise of tissue engineering due to advancements in healthcare and technology. In recent years, bioprinting has been an upcoming approach to traditional tissue engineering practices, through the fabrication of functional tissue by its layer-by-layer deposition process. This overcomes challenges such as irregular cell distribution and limited cell density, and it can potentially address organ shortages, increasing transplant options. Bioprinting fully functional organs is a long stretch but the advancement is rapidly growing due to its precision and compatibility with complex geometries. Computational Fluid Dynamics (CFD), a carestone of computer-aided engineering, has been instrumental in assisting bioprinting research and development by cutting costs and saving time. CFD optimizes bioprinting by testing parameters such as shear stress, diffusivity, and cell viability, reducing repetitive experiments and aiding in material selection and bioprinter nozzle design. This review discusses the current application of CFD in bioprinting and its potential to enhance the technology that can contribute to the evolution of regenerative medicine.

Design of gelatin cryogel scaffolds with the ability to release simvastatin for potential bone tissue engineering applications

Tissue engineering aims to improve or restore damaged tissues by using scaffolds, cells and bioactive agents. In tissue engineering, one of the most important concepts is the scaffold because it has a key role in keeping up and promoting the growth of the cells. It is also desirable to be able to load these scaffolds with drugs that induce tissue regeneration/formation. Based on this, in our study, gelatin cryogel scaffolds were developed for potential bone tissue engineering applications and simvastatin loading and release studies were performed. Simvastatin is lipoliphic in nature and this form is called inactive simvastatin (SV). It is modified to be in hydrophilic form and converted to the active form (SVA). For our study's drug loading and release process, simvastatin was used in both inactive and active forms. The blank cryogels and drug-loaded cryogels were prepared at different glutaraldehyde concentrations (1, 2, and 3%). The effect of the crosslinking agent and the amount of drug loaded were discussed with morphological and physicochemical analysis. As the glutaraldehyde concentration increased gradually, the pores size of the cryogels decreased and the swelling ratio decreased. For the release profile of simvastatin in both forms, we can say that it depended on the form (lipophilic and hydrophilic) of the loaded simvastatin.

Graphene Oxide Nanosheets for Bone Tissue Regeneration

Bone tissue engineering is a promising alternative to repair wounds caused by cellular or physical accidents that humans face daily. In this sense, the search for new graphene oxide (GO) nanofillers related to their degree of oxidation is born as an alternative bioactive component in forming new scaffolds. In the present study, three different GOs were synthesized with varying degrees of oxidation and studied chemically and tissue-wise. The oxidation degree was determined through infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron (XPS), and Raman spectroscopy (RS). The morphology of the samples was analyzed using scanning electron microscopy (SEM). The oxygen content was deeply described using the deconvolution of RS and XPS techniques. The latter represents the oxidation degree for each of the samples and the formation of new bonds promoted by the graphitization of the material. In the RS, two characteristic bands were observed according to the degree of oxidation and the degree of graphitization of the material represented in bands D and G with different relative intensities, suggesting that the samples have different crystallite sizes. This size was described using the Tuinstra-Koenig model, ranging between 18.7 and 25.1 nm. Finally, the bone neoformation observed in the cranial defects of critical size indicates that the F1 and F2 samples, besides being compatible and resorbable, acted as a bridge for bone healing through regeneration. This promoted healing by restoring bone and tissue structure without triggering a strong immune response.

Intra-Articular Injectable Biomaterials for Cartilage Repair and Regeneration

Osteoarthritis is a degenerative joint disease characterized by cartilage deterioration and subsequent inflammatory changes in the underlying bone. Injectable hydrogels have emerged as a promising approach for controlled drug delivery in cartilage therapies. This review focuses on the latest developments in utilizing injectable hydrogels as vehicles for targeted drug delivery to promote cartilage repair and regeneration. The pathogenesis of osteoarthritis is discussed to provide a comprehensive understanding of the disease progression. Subsequently, the various types of injectable hydrogels used for intra-articular delivery are discussed. Specifically, physically and chemically crosslinked injectable hydrogels are critically analyzed, with an emphasis on their fabrication strategies and their capacity to encapsulate and release therapeutic agents in a controlled manner. Furthermore, the potential of incorporating growth factors, anti-inflammatory drugs, and cells within these injectable hydrogels are discussed. Overall, this review offers a comprehensive guide to navigating the landscape of hydrogel-based therapeutics in osteoarthritis.

A Novel Bio-Adhesive Based on Chitosan-Polydopamine-Xanthan Gum for Glass, Cardboard and Textile Commodities

The escalating environmental concerns associated with petroleum-based adhesives have spurred an urgent need for sustainable alternatives. Chitosan, a natural polysaccharide, is a promising candidate; however, its limited water resistance hinders broader application. The aim of this study is to develop a new chitosan-based adhesive with improved properties. The polydopamine association with chitosan presents a significant increase in adhesiveness compared to pure chitosan. Polydopamine is synthesized by the enzymatic action of laccase from Trametes versicolor at pH = 4.5, in the absence or presence of chitosan. This pH facilitates chitosan's solubility and the occurrence of catechol in its reduced form (pH < 5.5), thereby increasing the final adhesive properties. To further enhance the adhesive properties, various crosslinking agents were tested. A multi-technique approach was used for the characterization of formulations. The formulation based on 3% chitosan, 50% polydopamine, and 3% xanthan gum showed a spectacular increase in adhesive properties when tested on glass, cardboard and textile. This formulation increased water resistance, maintaining the adhesion of a sample soaked in water for up to 10 h. For cardboard and textile, material rapture occurred, in mechanical tests, prior to adhesive bond failure. Furthermore, all the samples showed antiflame properties, expanding the benefits of their use. Comparison with commercial glues confirms the remarkable adhesive properties of the new formulation.

Bridging Nature and Engineering: Protein-Derived Materials for Bio-Inspired Applications

The sophisticated, elegant protein-polymers designed by nature can serve as inspiration to redesign and biomanufacture protein-based materials using synthetic biology. Historically, petro-based polymeric materials have dominated industrial activities, consequently transforming our way of living. While this benefits humans, the fabrication and disposal of these materials causes environmental sustainability challenges. Fortunately, protein-based biopolymers can compete with and potentially surpass the performance of petro-based polymers because they can be biologically produced and degraded in an environmentally friendly fashion. This paper reviews four groups of protein-based polymers, including fibrous proteins (collagen, silk fibroin, fibrillin, and keratin), elastomeric proteins (elastin, resilin, and wheat glutenin), adhesive/matrix proteins (spongin and conchiolin), and cyanophycin. We discuss the connection between protein sequence, structure, function, and biomimetic applications. Protein engineering techniques, such as directed evolution and rational design, can be used to improve the functionality of natural protein-based materials. For example, the inclusion of specific protein domains, particularly those observed in structural proteins, such as silk and collagen, enables the creation of novel biomimetic materials with exceptional mechanical properties and adaptability. This review also discusses recent advancements in the production and application of new protein-based materials through the approach of synthetic biology combined biomimetics, providing insight for future research and development of cutting-edge bio-inspired products. Protein-based polymers that utilize nature's designs as a base, then modified by advancements at the intersection of biology and engineering, may provide mankind with more sustainable products.

Encapsulation of Active Substances in Natural Polymer Coatings

Already used in the food, pharmaceutical, cosmetic, and agrochemical industries, encapsulation is a strategy used to protect active ingredients from external degradation factors and to control their release kinetics. Various encapsulation techniques have been studied, both to optimise the level of protection with respect to the nature of the aggressor and to favour a release mechanism between diffusion of the active compounds and degradation of the barrier material. Biopolymers are of particular interest as wall materials because of their biocompatibility, biodegradability, and non-toxicity. By forming a stable hydrogel around the drug, they provide a 'smart' barrier whose behaviour can change in response to environmental conditions. After a comprehensive description of the concept of encapsulation and the main technologies used to achieve encapsulation, including micro- and nano-gels, the mechanisms of controlled release of active compounds are presented. A panorama of natural polymers as wall materials is then presented, highlighting the main results associated with each polymer and attempting to identify the most cost-effective and suitable methods in terms of the encapsulated drug.

Naringenin-Zinc Oxide Nanocomposites Amalgamated Polymeric Gel Augmented Drug Delivery and Attenuated Experimental Cutaneous Candidiasis in Balb/c Mice: In Vitro and In Vivo Studies

Naringenin (NRG) inhibits the fungal 17β-hydroxysteroid dehydrogenase accountable for ergosterol synthesis in Candida albicans (C. albicans), a causative agent for cutaneous candidiasis. In present research, NRG was complexed with ZnO nanomaterial (NRG-Zn2+) to synthesize NRG-Zn2+ nanocomposites. The particle size and ζ-potential of NRG-Zn2+ nanocomposites were respectively estimated to be 180.33 ± 1.22-nm and - 3.92 ± 0.35-mV. In silico data predicted the greater affinity of NRG-Zn2+ nanocomposite for 14α-demethylase and ceramide in comparison to NRG alone. Later, NRG-Zn2+ nanocomposites solution was transformed in to naringenin-zinc oxide nanocomposites loaded chitosan gel (NRG-Zn-CS-Gel) with viscosity and firmness of 854806.7 ± 52386.43 cP and 698.27 ± 10.35 g, respectively. The ex-vivo skin permeation demonstrated 70.49 ± 5.22% skin retention, significantly greater (P < 0.05) than 44.48 ± 3.06% of naringenin loaded chitosan gel (NRG-CS-Gel) and 31.24 ± 3.28% of naringenin solution (NRG Solution). NRG-Zn-CS-Gel demonstrated 6.71 ± 0.84% permeation of NRG with a flux value of 0.046 ± 0.01-µg/cm2/h. The MIC50 of NRG-Zn-CS-Gel against C. albicans was estimated to be 0.156-µg/mL with FICI (fractional inhibitory concentration index) of 0.018 that consequently exhibited synergistic efficacy. Further, NRG-Zn-CS-Gel demonstrated superior antifungal efficacy in C. albicans induced cutaneous candidiasis infection in Balb/c mice. The fungal burden in NRG-Zn-CS-Gel treated group was 109 ± 25 CFU/mL, significantly lower (P < 0.05) than positive control (2260 ± 446 CFU/mL), naringenin loaded chitosan gel (NRG-CS-Gel; 928 ± 127 CFU/mL) and chitosan gel (CS-Gel; 2116 ± 186 CFU/mL) treated mice. Further, histopathology examination and cytokine profiling of TNF-α, IL-1β and IL-10 revealed the healing of skin and inflammation associated with cutaneous candidiasis infection. In conclusion, NRG-Zn-CS-Gel may be a potential candidate for translating in to a clinical viable topical nanotherapeutic.

Insect cuticle-inspired design of sustainably sourced composite bioplastics with enhanced strength, toughness and stretch-strengthening behavior

Insect cuticles that are mainly made of chitin, chitosan and proteins provide insects with rigid, stretchable and robust skins to defend harsh external environment. The insect cuticle therefore provides inspiration for engineering biomaterials with outstanding mechanical properties but also sustainability and biocompatibility. We herein propose a design of high-performance and sustainable bioplastics via introducing CPAP3-A1, a major structural protein in insect cuticles, to specifically bind to chitosan. Simply mixing 10w/w% bioengineered CPAP3-A1 protein with chitosan enables the formation of plastics-like, sustainably sourced chitosan/CPAP3-A1 composites with significantly enhanced strength (∼90 MPa) and toughness (∼20 MJ m -3), outperforming previous chitosan-based composites and most synthetic petroleum-based plastics. Remarkably, these bioplastics exhibit a stretch-strengthening behavior similar to the training living muscles. Mechanistic investigation reveals that the introduction of CPAP3-A1 induce chitosan chains to assemble into a more coarsened fibrous network with increased crystallinity and reinforcement effect, but also enable energy dissipation via reversible chitosan-protein interactions. Further uniaxial stretch facilitates network re-orientation and increases chitosan crystallinity and mechanical anisotropy, thereby resulting in stretch-strengthening behavior. In general, this study provides an insect-cuticle inspired design of high-performance bioplastics that may serve as sustainable and bio-friendly materials for a wide range of engineering and biomedical application potentials.

Innovative technologies for the fabrication of 3D/4D smart hydrogels and its biomedical applications - A comprehensive review

Repairing and regenerating damaged tissues or organs, and restoring their functioning has been the ultimate aim of medical innovations. 'Reviving healthcare' blends tissue engineering with alternative techniques such as hydrogels, which have emerged as vital tools in modern medicine. Additive manufacturing (AM) is a practical manufacturing revolution that uses building strategies like molding as a viable solution for precise hydrogel manufacturing. Recent advances in this technology have led to the successful manufacturing of hydrogels with enhanced reproducibility, accuracy, precision, and ease of fabrication. Hydrogels continue to metamorphose as the vital compatible bio-ink matrix for AM. AM hydrogels have paved the way for complex 3D/4D hydrogels that can be loaded with drugs or cells. Bio-mimicking 3D cell cultures designed via hydrogel-based AM is a groundbreaking in-vivo assessment tool in biomedical trials. This brief review focuses on preparations and applications of additively manufactured hydrogels in the biomedical spectrum, such as targeted drug delivery, 3D-cell culture, numerous regenerative strategies, biosensing, bioprinting, and cancer therapies. Prevalent AM techniques like extrusion, inkjet, digital light processing, and stereo-lithography have been explored with their setup and methodology to yield functional hydrogels. The perspectives, limitations, and the possible prospects of AM hydrogels have been critically examined in this study.

The influence of viscosity of hydrogels on the spreading and migration of cells in 3D bioprinted skin cancer models

Various in vitro three-dimensional (3D) tissue culture models of human and diseased skin exist. Nevertheless, there is still room for the development and improvement of 3D bioprinted skin cancer models. The need for reproducible bioprinting methods, cell samples, biomaterial inks, and bioinks is becoming increasingly important. The influence of the viscosity of hydrogels on the spreading and migration of most types of cancer cells is well studied. There are however limited studies on the influence of viscosity on the spreading and migration of cells in 3D bioprinted skin cancer models. In this review, we will outline the importance of studying the various types of skin cancers by using 3D cell culture models. We will provide an overview of the advantages and disadvantages of the various 3D bioprinting technologies. We will emphasize how the viscosity of hydrogels relates to the spreading and migration of cancer cells. Lastly, we will give an overview of the specific studies on cell migration and spreading in 3D bioprinted skin cancer models.

A Review of Recent Developments in Biopolymer Nano-Based Drug Delivery Systems with Antioxidative Properties: Insights into the Last Five Years

In recent years, biopolymer-based nano-drug delivery systems with antioxidative properties have gained significant attention in the field of pharmaceutical research. These systems offer promising strategies for targeted and controlled drug delivery while also providing antioxidant effects that can mitigate oxidative stress-related diseases. Generally, the healthcare landscape is constantly evolving, necessitating the continual development of innovative therapeutic approaches and drug delivery systems (DDSs). DDSs play a pivotal role in enhancing treatment efficacy, minimizing adverse effects, and optimizing patient compliance. Among these, nanotechnology-driven delivery approaches have garnered significant attention due to their unique properties, such as improved solubility, controlled release, and targeted delivery. Nanomaterials, including nanoparticles, nanocapsules, nanotubes, etc., offer versatile platforms for drug delivery and tissue engineering applications. Additionally, biopolymer-based DDSs hold immense promise, leveraging natural or synthetic biopolymers to encapsulate drugs and enable targeted and controlled release. These systems offer numerous advantages, including biocompatibility, biodegradability, and low immunogenicity. The utilization of polysaccharides, polynucleotides, proteins, and polyesters as biopolymer matrices further enhances the versatility and applicability of DDSs. Moreover, substances with antioxidative properties have emerged as key players in combating oxidative stress-related diseases, offering protection against cellular damage and chronic illnesses. The development of biopolymer-based nanoformulations with antioxidative properties represents a burgeoning research area, with a substantial increase in publications in recent years. This review provides a comprehensive overview of the recent developments within this area over the past five years. It discusses various biopolymer materials, fabrication techniques, stabilizers, factors influencing degradation, and drug release. Additionally, it highlights emerging trends, challenges, and prospects in this rapidly evolving field.

Nanofabrication of chitosan-based dressing to treat the infected wounds: in vitro and in vivo evaluations

Aim: Here, an innovative kind of antibacterial nanocomposite film is developed by incorporating graphene oxide and zinc oxide into chitosan matrix. Materials & methods: Our dressing was fabricated using the solution casting method. Fourier transform infrared spectra and TGA-DTG clearly confirmed the structure of film dressing. Results & conclusion: Our results showed the tensile strength and elongation at the break of the films were 20.1 ± 0.7 MPa and 36 ± 10%, respectively. Our fabricated film could absorb at least three-times the fluid of its dry weight while being biocompatible, antibacterial, non-irritant and non-allergic. In addition, it accelerated the healing process of infected wounds by regulating epithelium thickness and the number of inflammatory cells, thus it may be useful for direct application to damaged infected wounds.

Lysine-Triggered Polymeric Hydrogels with Self-Adhesion, Stretchability, and Supportive Properties

Hydrogels, recognized for their flexibility and diverse characteristics, are extensively used in medical fields such as wearable sensors and soft robotics. However, many hydrogel sensors derived from biomaterials lack mechanical strength and fatigue resistance, emphasizing the necessity for enhanced formulations. In this work, we utilized acrylamide and polyacrylamide as the primary polymer network, incorporated chemically modified poly(ethylene glycol) (DF-PEG) as a physical crosslinker, and introduced varying amounts of methacrylated lysine (LysMA) to prepare a series of hydrogels. This formulation was labeled as poly(acrylamide)-DF-PEG-LysMA, abbreviated as pADLx, with x denoting the weight/volume percentage of LysMA. We observed that when the hydrogel contained 2.5% w/v LysMA (pADL2.5), compared to hydrogels without LysMA (pADL0), its stress increased by 642 ± 76%, strain increased by 1790 ± 95%, and toughness increased by 2037 ± 320%. Our speculation regarding the enhanced mechanical performance of the pADL2.5 hydrogel revolves around the synergistic effects arising from the co-polymerization of LysMA with acrylamide and the formation of multiple intermolecular hydrogen bonds within the network structures. Moreover, the acid, amine, and amide groups present in the LysMA molecules have proven to be instrumental contributors to the self-adhesion capability of the hydrogel. The validation of the pADL2.5 hydrogel's exceptional mechanical properties through rigorous tensile tests further underscores its suitability for use in strain sensors. The outstanding stretchability, adhesive strength, and fatigue resistance demonstrated by this hydrogel affirm its potential as a key component in the development of robust and reliable strain sensors that fulfill practical requirements.

Chitosan-based materials for dental implantology: A comprehensive review

Chitosan, a versatile biopolymer, has gained recognition in the discipline of dental implantology due to possessing salient properties. This comprehensive review explores the potential of chitosan in dental implants, focusing on its biocompatibility, bioactivity, and the various chitosan-based materials that have been utilized for dental implant therapy. The review also highlights the importance of surface treatment in dental implants to enhance osseointegration and inhibit bacterial biofilm formation. Additionally, the chemical structure, properties, and sources of chitosan are described, along with its different structural forms. The characteristics of chitosan particularly color, molecular weight, viscosity, and degree of deacetylation are discussed about their influence on its applications. This review provides valuable insights into the promising utilization of polymeric chitosan in enhancing the success and functionality of dental implants. This study highlights the potential applications of chitosan in oral implantology. Chitosan possesses various advantageous properties, including muco-adhesiveness, hemostatic action, biocompatibility, biodegradability, bioactivity, and antibacterial and antifungal activities, which enhance its uses in dental implantology. However, it has limited aqueous solubility at the physiological pH, which sometimes restricts its biological application, but this problem can be overcome by using modified chitosan or chitosan derivatives, which have also shown encouraging results. Recent research suggests that chitosan may act as a promising material for coating titanium-based implants, improving osteointegration together with antibacterial properties.

Harnessing Macromolecular Chemistry to Design Hydrogel Micro- and Macro-Environments

Cell encapsulation within three-dimensional hydrogels is a promising approach to mimic tissues. However, true biomimicry of the intricate microenvironment, biophysical and biochemical gradients, and the macroscale hierarchical spatial organizations of native tissues is an unmet challenge within tissue engineering. This review provides an overview of the macromolecular chemistries that have been applied toward the design of cell-friendly hydrogels, as well as their application toward controlling biophysical and biochemical bulk and gradient properties of the microenvironment. Furthermore, biofabrication technologies provide the opportunity to simultaneously replicate macroscale features of native tissues. Biofabrication strategies are reviewed in detail with a particular focus on the compatibility of these strategies with the current macromolecular toolkit described for hydrogel design and the challenges associated with their clinical translation. This review identifies that the convergence of the ever-expanding macromolecular toolkit and technological advancements within the field of biofabrication, along with an improved biological understanding, represents a promising strategy toward the successful tissue regeneration.

Preparation and Optimization of MiR-375 Nano-Vector Using Two Novel Chitosan-Coated Nano-Structured Lipid Carriers as Gene Therapy for Hepatocellular Carcinoma

Currently, there is still a lack of effective carriers with minimal side effects to deliver therapeutic miRNA. Thus, it is crucial to optimize novel drug delivery systems. MiR-375 has proven superior therapeutic potency in Hepatocellular carcinoma (HCC). The purpose of this study was to fabricate 2 novel and smart nano-carriers for the transportation efficiency of miR-375 in HCC cells and enhance its anti-tumor effects. We established the miR-375 construct through the pEGP- miR expression vector. Two nano-carriers of solid/liquid lipids and chitosan (CS) were strategically selected, prepared by high-speed homogenization, and optimized by varying nano-formulation factors. Thus, the two best nano-formulations were designated as F1 (0.5% CS) and F2 (1.5% CS) and were evaluated for miR-375 conjugation efficiency by gel electrophoresis and nanodrop assessment. Then, physio-chemical characteristics and stability tests for the miR-375 nano-plexes were all studied. Next, its efficiencies as replacement therapy in HepG2 cells have been assessed by fluorescence microscopy, flow cytometry, and cytotoxicity assay. The obtained data showed that two cationic nanostructured solid/liquid lipid carriers (NSLCs); F1 and F2 typically had the best physio-chemical parameters and long-term stability. Moreover, both F1 and F2 could form nano-plexes with the anionic miR-375 construct at weight ratios 250/1 and 50/1 via electrostatic interactions. In addition, these nano-plexes exhibited physical stability after three months and protected miR-375 from degradation in the presence of 50% fetal bovine serum (FBS). Furthermore, both nano-plexes could simultaneously deliver miR-375 into HepG2 cells and they ensure miR re-expression even in the presence of 50% FBS compared to free miR-375 (p-value < 0.001). Moreover, both F1 and F2 alone significantly exhibited minimal cytotoxicity in treated cells. In contrast, the nano-plexes significantly inhibited cell growth compared to free miR-375 or doxorubicin (DOX), respectively. More importantly, F2/miR-375 nano-plex exhibited more anti-proliferative activity in treated cells although its IC50 value was 55 times lower than DOX (p-value < 0.001). Collectively, our findings clearly emphasized the multifunctionality of the two CS-coated NSLCs in terms of their enhanced biocompatibility, biostability, conjugation, and transfection efficiency of therapeutic miR-375. Therefore, the NSLCs/miR-375 nano-plexes could serve as a novel and promising therapeutic strategy for HCC.

Colloidal Engineering of Microplastic Capture with Biodegradable Soft Dendritic "Microcleaners"

The introduction of colloidal principles that enable efficient microplastic collection from aquatic environments is a goal of great environmental importance. Here, we present a novel method of microplastic (MP) collection using biodegradable hydrogel soft dendritic colloids (hSDCs). These dendritic colloids have abundant nanofibrils and a large surface area, which provide an abundance of interfacial interactions and excellent networking capabilities, allowing for the capture of plastic particles and other contaminants. Here, we show how the polymer composition and morphology of the hSDCs can impact the capture of microplastics modeled by latex microbeads. Additionally, we use colloidal DLVO theory to interpret the capture efficiencies of microbeads of different sizes and surface functional groups. The results demonstrate the microplastic remediation efficiency of hydrogel dendricolloids and highlight the primary factors involved in the microbead interactions and adsorption. On a practical level, the results show that the development of environmentally benign microcleaners based on naturally sourced materials could present a sustainable solution for microplastic cleanup.

Exploring modified chitosan-based gene delivery technologies for therapeutic advancements

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