Preparation of Freeze-Dried Porous Chitosan Microspheres for the Removal of Hexavalent Chromium

Superporous sponge prepared by secondary network compaction with enhanced permeability and mechanical properties for non-compressible hemostasis in pigs

Developing superporous hemostatic sponges with simultaneously enhanced permeability and mechanical properties remains challenging but highly desirable to achieve rapid hemostasis for non-compressible hemorrhage. Typical approaches to improve the permeability of hemostatic sponges by increasing porosity sacrifice mechanical properties and yield limited pore interconnectivity, thereby undermining the hemostatic efficacy and subsequent tissue regeneration. Herein, we propose a temperature-assisted secondary network compaction strategy following the phase separation-induced primary compaction to fabricate the superporous chitosan sponge with highly-interconnected porous structure, enhanced blood absorption rate and capacity, and fatigue resistance. The superporous chitosan sponge exhibits rapid shape recovery after absorbing blood and maintains sufficient pressure on wounds to build a robust physical barrier to greatly improve hemostatic efficiency. Furthermore, the superporous chitosan sponge outperforms commercial gauze, gelatin sponges, and chitosan powder by enhancing hemostatic efficiency, cell infiltration, vascular regeneration, and in-situ tissue regeneration in non-compressible organ injury models, respectively. We believe the proposed secondary network compaction strategy provides a simple yet effective method to fabricate superporous hemostatic sponges for diverse clinical applications.

Freeze-drying revolution: unleashing the potential of lyophilization in advancing drug delivery systems

Lyophilization also known as freeze-drying is a technique that has been employed to enhance the long-term durability of nanoparticles (NPs) that are utilized for drug delivery applications. This method is used to prevent their instability in suspension. However, this dehydration process can cause stress to the NPs, which can be alleviated by the incorporation of excipients like cryoprotectants and lyoprotectants. Nevertheless, the freeze-drying of NPs is often based on empirical principles without considering the physical-chemical properties of the formulations and the engineering principles of freeze-drying. For this reason, it is crucial to optimize the formulations and the freeze-drying cycle to obtain a good lyophilizate and ensure the preservation of NPs stability. Moreover, proper characterization of the lyophilizate and NPs is of utmost importance in achieving these goals. This review aims to update the recent advancements, including innovative formulations and novel approaches, contributing to the progress in this field, to obtain the maximum stability of formulations. Additionally, we critically analyze the limitations of lyophilization and discuss potential future directions. It addresses the challenges faced by researchers and suggests avenues for further research to overcome these limitations. In conclusion, this review is a valuable contribution to the understanding of the parameters involved in the freeze-drying of NPs. It will definitely aid future studies in obtaining lyophilized NPs with good quality and enhanced drug delivery and therapeutic benefits.

A biohybrid nanomaterial of biosynthesized TiO2 NPs from Mangrove leaf and shrimp shell-based Chitosan: ultrasonic-assisted synthesis and its application for methylene blue removal and COD reduction of real industrial wastewater

In the present study, TiO2 NPs (particle size: 25-35 nm) were biosynthesized from the Mangrove leaf extract. These nanoparticles were used to modify chitosan, and Chitosan@TiO2 biohybrid nanomaterial was synthesized and characterized using FTIR, XRD, BET, and, EDX-FE-SEM analyses. The adsorption ability of Chitosan@TiO2 nanomaterial has been investigated for Methylene blue (MB) removal from aqueous solution. The results indicated that the amount of MB removal is high in alkaline pH (optimum pH = 9). The pseudo-second-order model was able to describe the effect of contact time on the adsorption ability. The Langmuir model well described the equilibrium manner, and one gram of Chitosan@TiO2 could attract 416.66 mg of MB. Kinetic data, values of parameters of activation energy (+57.283 kJ/mol), enthalpy (-86.8148 kJ/mol), and Gibbs free energy (-27.999 to -22.8987 kJ/mol) indicate the dominance of chemical adsorption over physical adsorption. The breakthrough curves of 3 adsorption/desorption cycles showed the acceptable ability and reusability of prepared nanomaterial. Synthesized biohybrid nanomaterial can reduce 75% COD and 79% nitrate of the effluent from industrial city no.3 of Yasouj. The results of this research show the high ability of chitosan@TiO2 biohybrid to remove dyes from wastewater and reduce the pollution load of industrial wastewater.

Oxalic acid-assisted preparation of LTO-carbon composite anode material for lithium-ion batteries

This study presents an oxalic acid-assisted method for synthesizing spinel-structured lithium titanate (Li4Ti5O12; LTO)/carbon composite materials. The Ag-doped LTO nanoparticles (NPs) are synthesized via flame spray pyrolysis (FSP). The synthesized material is used as a precursor for synthesizing the LTO-NP/C composite material with chitosan as a carbon source and oxalic acid as an additive. Oxalic acid improves the dissolution of chitosan in water as well as changes the composition and physical and chemical properties of the synthesized LTO-NP/C composite material. The oxalic acid/chitosan ratio can be optimized to improve the electrochemical performance of the LTO-NP/C composite material, and the electrode synthesized with a high mass loading ratio (5.44 mg cm-2) exhibits specific discharge capacities of 156.5 and 136 mAh g-1at 0.05 C- and 10 C-rate currents, respectively. Moreover, the synthesized composite LTO-NP/C composite material exhibits good cycling stability, and only 1.7% decrease in its specific capacity was observed after 200 charging-discharging cycles at 10 C-rate discharging current.

Chitosan: Structural and Chemical Modification, Properties, and Application

Chitosan is a polymer of natural origins that possesses many favourable properties [...].

Role and architectural significance of porous chitosan-based scaffolds in bone tissue engineering

In designing and fabricating scaffolds to fill the bone defects and stimulate new bone formation, the biomimetics of the construct is a crucial factor in invoking the bone microenvironment to promote osteogenic differentiation. Regarding structural traits, changes in porous characteristics of the scaffolds, such as pore size, pore morphology, and percentage porosity, may patronize or jeopardize their other physicochemical and biological properties. Chitosan (CS), a biodegradable naturally occurring polymer, has recently drawn considerable attention as a scaffolding material in tissue engineering and regenerative medicine. CS-based microporous scaffolds have been reported to aid osteogenesis under both in vitro and in vivo conditions by supporting cellular attachment and proliferation of osteoblast cells and the formation of mineralized bone matrix. This related notion may be found in numerous earlier research, even though the precise mechanism of action that encourages the development of new bone still needs to be understood completely. This article presents the potential correlations and the significance of the porous properties of the CS-based scaffolds to influence osteogenesis and angiogenesis during bone regeneration. This review also goes over resolving the mechanical limitations of CS by blending it with other polymers and ceramics.

Neat Chitosan Porous Materials: A Review of Preparation, Structure Characterization and Application

This review presents an overview of methods for preparing chitosan-derived porous materials and discusses their potential applications. This family of materials has garnered significant attention owing to their biocompatibility, nontoxicity, antibacterial properties, and biodegradability, which make them advantageous in a wide range of applications. Although individual porous chitosan-based materials have been widely discussed in the literature, a summary of all available methods for preparing materials based on pure chitosan, along with their structural characterization and potential applications, has not yet been presented. This review discusses five strategies for fabricating porous chitosan materials, i.e., cryogelation, freeze-drying, sol-gel, phase inversion, and extraction of a porogen agent. Each approach is described in detail with examples related to the preparation of chitosan materials. The influence of the fabrication method on the structure of the obtained material is also highlighted herein. Finally, we discuss the potential applications of the considered materials.

Synthesis and Characterization of Porous Chitosan/Saccharomycetes Adsorption Microspheres

Porous chitosan/saccharomycetes adsorption microspheres were successfully prepared by using silica gel as porogen. The morphology of porous chitosan/saccharomycetes microspheres was characterized by scanning electron microscopy, the interaction between molecules was characterized by Fourier transform infrared spectroscopy, and the crystallization property of the microspheres was characterized by X-ray diffraction. The results showed that the adsorption sites of amino and hydroxyl groups had been provided by the porous chitosan/saccharomycetes microspheres for the removal of preservatives, pigments, and other additives in food. The surface roughness of microspheres could be improved by increasing the mass ratio of saccharomycetes. The increase in silica gels could make the microsphere structure more compact. The porous chitosan/saccharomycetes microspheres could be used as adsorbents to adsorb doxycycline in wastewater.

Wastewater Treatment by Polymeric Microspheres: A Review

This review addresses polymer microspheres used as adsorbent for wastewater treatment. The removal of various pollutants (including dyes, heavy metal ions, and organic pollutants) is a prominent issue, as they can cause severe health problems. Porous microspheres can provide large specific area and active sites for adsorption or photo degradation. Enhancement in performance is achieved by various modifications, such as the introduction of nanoparticles, magnetic particles, and ZIF-8. Some microspheres were synthesized from synthetic polymers such as vinylic polymer and polydopamine (PDA) through a facile fabrication process. Natural polymers (such as cellulose, alginate, and chitosan) that are biodegradable and eco-friendly are also used. The adsorbents used in industrial application require high adsorption capacity, thermal stability, and recyclability. Batch adsorption experiments were conducted to investigate the optimal conditions, influence of related factors, and adsorption capacities. Insights regarding the adsorption mechanisms were given from the kinetic model, isotherm model, and various characterization methods. The recyclability is investigated through regeneration ratio, or their maintenance of their capability through repeated adsorption-desorption cycles. The high potential of polymer microsphere for the removal of pollutants from wastewater is shown through the high adsorption capacities, environmentally friendliness, and high stability.

Chitosan Reinforced with Kenaf Nanocrystalline Cellulose as an Effective Carrier for the Delivery of Platelet Lysate in the Acceleration of Wound Healing

The clinical use of platelet lysate (PL) in the treatment of wounds is limited by its rapid degradation by proteases at the tissue site. This research aims to develop a chitosan (CS) and kenaf nanocrystalline cellulose (NCC) hydrogel composite, which intend to stabilize PL and control its release onto the wound site for prolonged action. NCC was synthesized from raw kenaf bast fibers and incorporated into the CS hydrogel. The physicochemical properties, in vitro cytocompatibility, cell proliferation, wound scratch assay, PL release, and CS stabilizing effect of the hydrogel composites were analyzed. The study of swelling ratio (>1000%) and moisture loss (60-90%) showed the excellent water retention capacity of the CS-NCC-PL hydrogels as compared with the commercial product. In vitro release PL study (flux = 0.165 mg/cm2/h) indicated that NCC act as a nanofiller and provided the sustained release of PL compared with the CS hydrogel alone. The CS also showed the protective effect of growth factor (GF) present in PL, thereby promoting fast wound healing via the formulation. The CS-NCC hydrogels also augmented fibroblast proliferation in vitro and enhanced wound closures over 72 h. This study provides a new insight on CS with renewable source kenaf NCC as a nanofiller as a potential autologous PL wound therapy.