Tuning chitosan’s chemical structure for enhanced biological functions

Hydrogel-exosome system in tissue engineering: A promising therapeutic strategy

Characterized by their pivotal roles in cell-to-cell communication, cell proliferation, and immune regulation during tissue repair, exosomes have emerged as a promising avenue for "cell-free therapy" in clinical applications. Hydrogels, possessing commendable biocompatibility, degradability, adjustability, and physical properties akin to biological tissues, have also found extensive utility in tissue engineering and regenerative repair. The synergistic combination of exosomes and hydrogels holds the potential not only to enhance the efficiency of exosomes but also to collaboratively advance the tissue repair process. This review has summarized the advancements made over the past decade in the research of hydrogel-exosome systems for regenerating various tissues including skin, bone, cartilage, nerves and tendons, with a focus on the methods for encapsulating and releasing exosomes within the hydrogels. It has also critically examined the gaps and limitations in current research, whilst proposed future directions and potential applications of this innovative approach.

Advances of biological macromolecules hemostatic materials: A review

Achieving hemostasis is a necessary intervention to rapidly and effectively control bleeding. Conventional hemostatic materials currently used in clinical practice may aggravate the damage at the bleeding site due to factors such as poor adhesion and poor adaptation. Compared to most traditional hemostatic materials, polymer-based hemostatic materials have better biocompatibility and offer several advantages. They provide a more effective method of stopping bleeding and avoiding additional damage to the body in case of excessive blood loss. Various hemostatic materials with greater functionality have been developed in recent years for different organs using diverse design strategies. This article reviews the latest advances in the development of polymeric hemostatic materials. We introduce the coagulation cascade reaction after bleeding and then discuss the hemostatic mechanisms and advantages and disadvantages of various polymer materials, including natural, synthetic, and composite polymer hemostatic materials. We further focus on the design strategies, properties, and characterization of hemostatic materials, along with their applications in different organs. Finally, challenges and prospects for the application of hemostatic polymeric materials are summarized and discussed. We believe that this review can provide a reference for related research on hemostatic materials, contributing to the further development of polymer hemostatic materials.

Research progress of photo-crosslink hydrogels in ophthalmology: A comprehensive review focus on the applications

Hydrogel presents a three-dimensional polymer network with high water content. Over the past decade, hydrogel has developed from static material to intelligent material with controllable response. Various stimuli are involved in the formation of hydrogel network, among which photo-stimulation has attracted wide attention due to the advantages of controllable conditions, which has a good application prospect in the treatment of ophthalmic diseases. This paper reviews the application of photo-crosslink hydrogels in ophthalmology, focusing on the types of photo-crosslink hydrogels and their applications in ophthalmology, including drug delivery, tissue engineering and 3D printing. In addition, the limitations and future prospects of photo-crosslink hydrogels are also provided.

Dual growth factor methacrylic alginate microgels combined with chitosan-based conduits facilitate peripheral nerve repair

Treating severe peripheral nerve injuries is difficult. Nerve repair with conduit small gap tubulization is a treatment option but still needs to be improved. This study aimed to assess the use of microgels containing growth factors, along with chitosan-based conduits, for repairing nerves. Using the water-oil emulsion technique, microgels of methacrylic alginate (AlgMA) that contained vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF) were prepared. The effects on rat Schwann cells (RSC96) and human umbilical vein endothelial cells (HUVECs) were evaluated. Chitosan-based conduits were fabricated and used in conjunction with microgels containing two growth factors to treat complete neurotmesis in rats. The results showed that the utilization of dual growth factor microgels improved the migration and decreased the apoptosis of RSC96 cells while promoting the growth and formation of tubes in HUVECs. The utilization of dual growth factor microgels and chitosan-based conduits resulted in notable advancements in the regeneration and myelination of nerve fibers, recovery of neurons, alleviation of muscle atrophy and recovery of neuromotor function and nerve conduction. In conclusion, the use of dual growth factor AlgMA microgels in combination with chitosan-based conduits has the potential to significantly improve the effectiveness of nerve repair.

High-performance lung-targeted bio-responsive platform for severe colistin-resistant bacterial pneumonia therapy

Polymyxins are the last line of defense against multidrug-resistant (MDR) Gram-negative bacterial infections. However, this last resort has been threatened by the emergence of superbugs carrying the mobile colistin resistance gene-1 (mcr-1). Given the high concentration of matrix metalloproteinase 3 (MMP-3) in bacterial pneumonia, limited plasma accumulation of colistin (CST) in the lung, and potential toxicity of ionic silver (Ag+), we designed a feasible clinical transformation platform, an MMP-3 high-performance lung-targeted bio-responsive delivery system, which we named "CST&Ag@CNMS". This system exhibited excellent lung-targeting ability (>80% in lungs), MMP-3 bio-responsive release property (95% release on demand), and synergistic bactericidal activity in vitro (2-4-fold minimum inhibitory concentration reduction). In the mcr-1+ CST-resistant murine pneumonia model, treatment with CST&Ag@CNMS improved survival rates (70% vs. 20%), reduced bacteria burden (2-3 log colony-forming unit [CFU]/g tissue), and considerably mitigated inflammatory response. In this study, CST&Ag@CNMS performed better than the combination of free CST and AgNO3. We also demonstrated the superior biosafety and biodegradability of CST&Ag@CNMS both in vitro and in vivo. These findings indicate the clinical translational potential of CST&Ag@CNMS for the treatment of lung infections caused by CST-resistant bacteria carrying mcr-1.

Eco-friendly management strategies of insect pests: long-term performance of rosemary essential oil encapsulated into chitosan and gum Arabic

This study focused on encapsulation of Rosmarinus officinalis essential oil (EO) on chitosan and gum Arabic matrix in various ratios and with varying essential oil concentrations. Additionally, UV/VIS spectroscopy was used to determine cumulative-release profiles. The insecticidal activity was tested against Tribolium castaneum and Oryzaephilus surinamensis, both pests of stored products. In terms of encapsulation efficiency (EE%) and loading capacity (LC%), capsules had EE at 45.8% and LC at 2.31%. Furthermore, many minor compounds were lost after encapsulation, until identifying only 1,8-cineole, α-terpineol, and camphor after 60 d of storage. The fumigant tests demonstrated that encapsulated EO exhibited an effective control against insect pest during storage periods, namely, 30, 45, and 60 d with 99, 66, and 46% mortality for T. castaneum and 100, 84, 82% mortality for O. surinamensis.

Construction of chrysophanol loaded nanoparticles with N-octyl-O-sulfate chitosan for enhanced nephroprotective effect

Natural occurring anthraquinone like chrysophanol has been studied because of its anti-diabetic, anti-tumor, anti-inflammatory, hepatoprotective and neuroprotective properties. Nonetheless, its poor water solubility and unstable nature are big concerns in achieving efficient delivery and associated pharmacokinetic and pharmacodynamic effects. Herein, this study sought to solve the above-mentioned problem through development of chrysophanol-loaded nanoparticles to enhance the bioavailability of chrysophanol and to evaluate its anti-renal fibrosis effect in rats. After synthesis of a safe N-octyl-O-sulfate chitosan, we used it to prepare chrysophanol-loaded nanoparticles through dialysis technique before we performed and physical characterization. Also, we tested the stability of the nanoparticles for 21 days at 4 °C and room temperature (25 °C) and evaluated their pharmacokinetics and anti-renal fibrosis effect in rat model of chronic kidney disease (CKD). In terms of results, the nano-preparation demonstrated an acceptable narrow size distribution, wherein the encapsulation rate, size, polydispersed index (PDI) and electrokinetic potential at room temperature were respectively 83.41±0.89 %, 364.88±13.62 nm, 0.192±0.015 and 23.78±1.39 mV. During 21 days of storage, we observed that size of particles and electrokinetic potential altered slightly but the difference was statistically insignificant (p > 0.05). Also, in vitro release studies showed that the formulation reached 84.74 % at 24 h. Chrysophanol nanoparticles showed a 2.57-fold increase in bioavailability compared to unformulated chrysophanol. More importantly, chrysophanol nanoparticles demonstrated certain renal internalization properties and anti-renal fibrosis effects, which could ultimately result in reduced blood-urea nitrogen (BUN), kidney-injury molecule-1 (KIM-1) and serum creatinine (SCr) levels in model rats. In conclusion, the prepared chrysophanol-loaded nanoparticles potentially increased bioavailability and enhanced nephroprotective effects of chrysophanol.

Preparation, Characterization, and Anticancer Activity Assessment of Chitosan/TPP Nanoparticles Loaded with Echis carinatus Venom

AIMS AND BACKGROUND

Echis carinatus venom is a toxic substance naturally produced by special glands in this snake species. Alongside various toxic properties, this venom has been used for its therapeutic effects, which are applicable in treating various cancers (liver, breast, etc.).

OBJECTIVE

Nanotechnology-based drug delivery systems are suitable for protecting Echis carinatus venom against destruction and unwanted absorption. They can manage its controlled transfer and absorption, significantly reducing side effects.

METHODS

In the present study, chitosan nanoparticles were prepared using the ionotropic gelation method with emulsion cross-linking. The venom's encapsulation efficiency, loading capacity, and release rate were calculated at certain time points. Moreover, the nanoparticles' optimal formulation and cytotoxic effects were determined using the MTT assay.

RESULTS

The optimized nanoparticle formulation increases cell death induction in various cancerous cell lines. Moreover, chitosan nanoparticles loaded with Echis carinatus venom had a significant rate of cytotoxicity against cancer cells.

CONCLUSION

It is proposed that this formulation may act as a suitable candidate for more extensive assessments of cancer treatment using nanotechnology-based drug delivery systems.

Conversion of liquid chitosan-based nanoemulsions into inhalable solid microparticles: Process challenges with polysaccharide

Solid particles ≤5 μm are essential to allow lower lung deposition and macrophage phagocytosis of anti-tubercular drugs. Decorating liquid nanoemulsion of anti-tubercular drug with macrophage-specific chitosan and chitosan-folate conjugate and spray drying the nanoemulsion with lactose produced oversized solid particles due to polysaccharide binding effects. This study designed solid nanoemulsion using lactose as the primary solid carrier and explored additives and spray-drying variables to reduce the binding and particle growth effects of chitosan. Deposition of magnesium stearate on lactose negated chitosan-inducible excessive lactose-liquid nanoemulsion binding and solid particle growth. Moderating the adhesion of chitosan-decorated liquid nanoemulsion onto lactose produced smooth-surface solid microparticles (size: 5.45 ± 0.26 μm; roughness: ∼80 nm) with heterogeneous size (span: 1.87 ± 1.21) through plasticization of constituent materials of nanoemulsion and lactose involving OH/N-H, C-H, CONH and/or COO moieties. Smaller solid particles could attach onto the larger particles with minimal steric hindrance by smooth surfaces. Together with round solid particulate structures (circularity: 0.919 ± 0.002), good pulmonary inhalation beneficial for treatment of pulmonary tuberculosis as well as other diseases is conferred.

Biopolymer-Based Nanosystems: Potential Novel Carriers for Kidney Drug Delivery

Kidney disease has become a serious public health problem throughout the world, and its treatment and management constitute a huge global economic burden. Currently, the main clinical treatments are not sufficient to cure kidney diseases. During its development, nanotechnology has shown unprecedented potential for application to kidney diseases. However, nanotechnology has disadvantages such as high cost and poor bioavailability. In contrast, biopolymers are not only widely available but also highly bioavailable. Therefore, biopolymer-based nanosystems offer new promising solutions for the treatment of kidney diseases. This paper reviews the biopolymer-based nanosystems that have been used for renal diseases and describes strategies for the specific, targeted delivery of drugs to the kidney as well as the physicochemical properties of the nanoparticles that affect the targeting success.

Synthesis, Characterization and Biological Properties of Type I Collagen-Chitosan Mixed Hydrogels: A Review

Type I collagen and chitosan are two of the main biological macromolecules used to design scaffolds for tissue engineering. The former has the benefits of being biocompatible and provides biochemical cues for cell adhesion, proliferation and differentiation. However, collagen hydrogels usually exhibit poor mechanical properties and are difficult to functionalize. Chitosan is also often biocompatible, but is much more versatile in terms of structure and chemistry. Although it does have important biological properties, it is not a good substrate for mammalian cells. Combining of these two biomacromolecules is therefore a strategy of choice for the preparation of interesting biomaterials. The aim of this review is to describe the different protocols available to prepare Type I collagen-chitosan hydrogels for the purpose of presenting their physical and chemical properties and highlighting the benefits of mixed hydrogels over single-macromolecule ones. A critical discussion of the literature is provided to point out the poor understanding of chitosan-type I collagen interactions, in particular due to the lack of systematic studies addressing the effect of chitosan characteristics.

Mechanism of Heterogeneous Alkaline Deacetylation of Chitin: A Review

This review provides an analysis of experimental results on the study of alkaline heterogeneous deacetylation of chitin obtained by the authors and also published in the literature. A detailed analysis of the reaction kinetics was carried out considering the influence of numerous factors: reaction reversibility, crystallinity and porosity of chitin, changes in chitin morphology during washing, alkali concentration, diffusion of hydroxide ions, and hydration of reacting particles. A mechanism for the chitin deacetylation reaction is proposed, taking into account its kinetic features in which the decisive role is assigned to the effects of hydration. It has been shown that the rate of chitin deacetylation increases with a decrease in the degree of hydration of hydroxide ions in a concentrated alkali solution. When the alkali concentration is less than the limit of complete hydration, the reaction practically does not occur. Hypotheses have been put forward to explain the decrease in the rate of the reaction in the second flat portion of the kinetic curve. The first hypothesis is the formation of “free” water, leading to the hydration of chitin molecules and a decrease in the reaction rate. The second hypothesis postulates the formation of a stable amide anion of chitosan, which prevents the nucleophilic attack of the chitin macromolecule by hydroxide ions.