Search Results (6)

Carbon dioxide (CO₂) capture has been identified as a potential technology for reducing the anthropic emissions of greenhouse gases, particularly in post-combustion processes. The development of adsorbents for carbon capture and storage is expanding at a rapid rate. This article presents a novel sustainable synthesis method for the production of chitosan/activated carbon CO₂ adsorbents. Chitosan is a biopolymer that is naturally abundant and contains amino groups (–NH₂), which are required for the selective adsorption of CO₂. Spent coffee grounds have been considered as a potential feedstock for the synthesis of activated coffee grounds through carbonization and chemical activation. The chitosan/activated coffee ground composite microspheres were created using the emulsion cross-linking method with epichlorohydrin. The effects of the amount of chitosan (15, 20, and 25 g), activated coffee ground (10, 20, 30, and 40%w/w), and epichlorohydrin (2, 3, 4, 5, 6, 7 and 8 g) were examined. The CO₂ capture potential of the composite beads is superior to that of the neat biopolymer beads. The CO₂ adsorbed of synthesized materials at a standard temperature and pressure is improved by increasing the quantity of activated coffee ground and epichlorohydrin. These findings suggest that the novel composite bead has the potential to be applied in CO₂ separation applications. Full article

The exploration of efficient, low-leaching, and recyclable transition-metal-based catalysts is of great importance for the removal of pollutants from peroxymonosulfate (PMS) in water purification processes. In this study, a bimetallic CoFe@CSC-700 composite was prepared by an alkaline gel pyrolysis reduction method using chitosan as a forming agent and applied to activate PMS to degrade levofloxacin (LEV). The leaching concentration of both cobalt and iron ions in the CoFe@CSC-700 catalyst was reduced by about 8-fold compared to the monometallic composite pellet catalyst. In addition, the removal efficiency of the CoFe@CSC-700 catalyst can still reach 90% after five cycles, showing good recyclability, recoverability and stability. Both free radical pathways (SO₄·⁻, ·OH, and ·O₂⁻) and non-free radical pathways (¹O₂) were detected in the oxidation reaction, with free radical pathways as the main contributor. The possible degradation pathways of LEV were proposed by LC-MS tests. Overall, this study provides new insights into the construction of efficient and stable PMS catalysts for wastewater treatment. Full article

Bacterial infection contributes to the bioburden of wounds, which is an essential factor in determining whether a wound can heal. Wound dressings with antibacterial properties that can promote wound-healing are highly desired for the treatment of chronic wound infections. Herein, we fabricated a simple polysaccharide-based hydrogel dressing encapsulating tobramycin-loaded gelatine microspheres with good antibacterial activity and biocompatibility. We first synthesised long-chain quaternary ammonium salts (QAS) by the reaction of tertiary amines with epichlorohydrin. The amino groups of carboxymethyl chitosan were then conjugated with QAS through the ring-opening reaction and QAS-modified chitosan (CMCS) was obtained. The antibacterial analysis showed that both QAS and CMCS could kill E. coli and S. aureus at relatively low concentrations. QAS with 16 carbon atoms has a MIC of 16 μg/mL for E. coli and 2 μg/mL for S. aureus. A series of formulations of tobramycin-loaded gelatine microspheres (TOB-G) were generated and the best formulation was selected by comparing the characters of the microspheres. The microsphere fabricated by 0.1 mL GTA was selected as the optimal candidate. We then used CMCS, TOB-G, and sodium alginate (SA) to prepare physically crosslinking hydrogels using CaCl₂ and investigated the mechanical properties, antibacterial activity, and biocompatibility of the hydrogels. In summary, the hydrogel dressing we produced can be used as an ideal alternative for the management of bacteria-infected wounds. Full article

Natural bone tissue is composed of calcium-deficient carbonated hydroxyapatite as the inorganic phase and collagen type I as the main organic phase. The biomimetic approach of scaffold development for bone tissue engineering application is focused on mimicking complex bone characteristics. Calcium phosphates are used in numerous studies as bioactive phases to mimic natural bone mineral. In order to mimic the organic phase, synthetic (e.g., poly(ε-caprolactone), polylactic acid, poly(lactide-co-glycolide acid)) and natural (e.g., alginate, chitosan, collagen, gelatin, silk) biodegradable polymers are used. However, as materials obtained from natural sources are accepted better by the human organism, natural polymers have attracted increasing attention. Over the last three decades, chitosan was extensively studied as a natural polymer suitable for biomimetic scaffold development for bone tissue engineering applications. Different types of chitosan-based biomaterials (e.g., molded macroporous, fiber-based, hydrogel, microspheres and 3D-printed) with specific properties for different regenerative applications were developed due to chitosan’s unique properties. This review summarizes the state-of-the-art of biomaterials for bone regeneration and relevant studies on chitosan-based materials and composites. Full article

By using the hydrothermal method, carbon microspheres (CMS) were fabricated and used for electrode modification. The characteristics of CMS were investigated using various techniques. The biocompatible sensing platform was built by immobilizing hemoglobin (Hb) on the micrometer-sized CMS-modified electrode with a layer of chitosan membrane. On the cyclic voltammogram, a couple of quasi-reversible cathodic and anodic peaks appeared, showing that direct electrochemistry of Hb with the working electrode was achieved. The catalytic reduction peak currents of the bioelectrode to trichloroacetic acid was established in the linear range of 2.0~70.0 mmol·L⁻¹ accompanied by a detection limit of 0.30 mmol·L⁻¹ (3σ). The modified electrode displayed favorable sensitivity, good reproducibility and stability, which suggests that CMS is promising for fabricating third-generation bioelectrochemical sensors. Full article

Novel magnetic Fe₃O₄/chitosan (CS) microspheres were prepared using magnetic Fe₃O₄ nanoparticles and the natural macromolecule chitosan. Then, using an easy and effective hemoglobin (Hb) immobilization method, an innovative biosensor with a Fe₃O₄/CS-Hb-Fe₃O₄/CS “sandwich” configuration was constructed. This biosensor had a fast (less than 10 s) response to H₂O₂ and excellent linear relationships were obtained in the concentration range of 5.0 × 10^-5 to 1.8 × 10^-3 M and 1.8 × 10^-3 to 6.8 × 10^-3 M with a detection limit of 4.0 × 10^-6 M (s/n = 3) under the optimum conditions. The apparent Michaelis-Menten constant K_m was 0.29 mM and it showed the excellent biological activity of the fixed Hb. Moreover, the biosensor had long-time stability and good reproducibility. The method was used to determine H₂O₂ concentration in real samples. Full article