查找使用阿拉丁产品的科研文献

Enhanced enzymatic hydrolysis of chitosan via MOF-mediated activation of chitosanase

Wanting Li,Yangkun Cao,Kunpeng Gao,Lili Yin,Kang Lian,Hong Jiang,Yang Hu,Xiangzhao Mao

Chitosanases are attractive biocatalysts for producing bioactive chito-oligosaccharides (COS), but their applications are limited by insufficient catalytic efficiency, poor stability, and challenging recovery. Although many chitosanases can be activated by metal ions, the direct addition of free ions into reaction systems suffers from low efficiency and separation challenges. This study presented a MOF-based strategy to create a Cu-enriched coordination microenvironment, enabling simultaneous immobilization and activation of marine polysaccharide hydrolases. Taking chitosanase OUC-CsnCA as a model, the immobilization on Cu-trimesic acid (Cu-BTC) doubled its activity (413.5 ± 34.7 U/mg) and increased k cat from 361.8 ± 8.0 to 704.4 ± 16.1 min −1 , along with improved thermostability and pH tolerance. MALDI-TOF-MS and HPLC confirmed deeper substrate depolymerization upon immobilization. Kinetic and spectroscopic analyses revealed that Cu 2+ -binding modulated enzyme conformation and promoted enzyme–substrate interactions. Molecular dynamics simulations further indicated that Cu 2+ coordination was associated with adjustments in catalytic cleft geometry (D102–E84) and reinforcement of hydrogen-bond interactions within the substrate-binding pocket. Enhanced activities were further observed for immobilized ι-carrageenase and α-agarase, demonstrating the potential applicability of this strategy to other metal-responsive marine polysaccharide hydrolases.

A multifunctional quaternary chitosan/sericin composite sponge for antibiosis and hemostasis

Kangping Lu,Xiaomen Zheng,Huaxin Zhou,Dini Huo,Yanxiao Han,Xida Qian,Hongbin Xie,Lin Shi,Gang Du,Zhipeng Li,Bin Jin

Effective management of traumatic and infected wounds remains challenging because hemorrhage, bacterial contamination, and impaired early repair often occur simultaneously. This study designed a multifunctional composite sponge via physical cross-linking between quaternary chitosan (QCS) and silk sericin (SER), further loaded with dicresulene diammonium (Di). The QCS/SER/Di sponge was systematically evaluated for its physicochemical properties, biocompatibility and functional performance. The sponge formulations exhibited hemolysis ratios below 5%, while significantly enhancing fibroblast migration and proliferation. Furthermore, the QCS/SER/Di sponge reduced viable Staphylococcus aureus and Escherichia coli by more than 99% within 12 h and caused marked disruption of bacterial membrane integrity. During in vitro hemostasis tests, it induced complete whole-blood clotting within 2 min, compared with more than 8 min in the untreated control. In the rat tail-amputation model, the sponge reduced blood loss from 1656 ± 315.2 mg in untreated animals to approximately 204 mg, with comparable hemostatic benefits observed in the liver injury hemorrhage model. When applied to infected wounds, the sponges significantly reduced the bacterial load and were associated with greater wound-area reduction, re-epithelialization and collagen deposition, increased vascular structures, and changes in selected inflammation- and repair-associated markers during the 14-day observation period. This study presents a multifunctional composite sponge platform for complex wound management which integrates rapid hemostasis and strong antibacterial activity.

Development and optimisation of esculin-loaded chitosan microspheres for intravitreal injection

Ning He,Danqing Wu,Rui Luo,Ziqin Cao,Shuang Shan,Qingsong Fei,Jiabao Wu,Shaoyun Bai

This study was to prepare the esculin-loaded chitosan microspheres for intravitreal injection and explore the feasibility of the treatment of macular degeneration. The microspheres were fabricated using an emulsification crosslinking technique. The drug loading, encapsulation efficiency, and mean particle diameter of the optimised esculin-loaded chitosan microspheres were 8.03 ± 1.30%, 93.03 ± 2.16%, and 4.81 ± 1.60 μm, respectively. The thermal stability evaluation at 25 °C demonstrated consistent particle diameter maintenance, with microspheres retaining sizes of 4.73 ± 1.75 μm and 4.89 ± 1.55 μm after 15 and 30 days’ storage periods, respectively. The in vitro release profile demonstrated 80% cumulative drug release from the microspheres over a 72 h period. Subsequent pharmacokinetic analysis revealed significantly enhanced parameters in the vitreous humour following intravitreal administration, with the half-life (t1/2) reaching 879.88 ± 44.00 min and the area under curve (AUC) attaining 150.18 ± 2.28 × 103 mg·min/mL. Intravitreal injection of esculin-loaded chitosan microspheres offers a promising drug delivery system for the treatment of macular degeneration.

Conical Chitosan Conduits Combined With Methylcobalamin for Sciatic Nerve Transposition Repair

Qicheng Li,Fengshi Zhang,Shiyan Liu,Yusong Yuan,Yuhui Kou

Background:The repair technology of peripheral nerve injuries has made great progress, but the simultaneous repair and promotion of nerve regeneration in multiple distal nerves remains a challenging task. The current cylindrical nerve conduits are unsuitable for nerve transposition repair. This study aims to assess the effect of conical chitosan conduits (different inner diameters at both ends) on nerve transposition repair, in conjunction with methylcobalamin (MeCbl).Methods:In this study, a conical chitosan conduit was used to bridge a 2 mm defect between the proximal common peroneal nerve and distal tibial nerve and common peroneal nerve in rats. Additionally, we administered MeCbl at various concentrations to evaluate post-surgical adjuvant treatment effect. At 16 weeks post-surgery, gait analysis, electrophysiology testing, transmission electron microscopy (TEM) observation, toluidine blue staining, immunofluorescence staining, muscle wet weight determination and Masson’s trichrome staining were performed to assess nerve regeneration and reinnervation of gastrocnemius.Results:Gross observations did not reveal the formation of neuromas after bridging the distal nerves in each group. In terms of motor function (**p < 0.01), compound muscle action potential (CMAP) amplitude and latency (**p < 0.01), the quantity of regenerated nerve fibers, muscle fiber morphology and other parameters (**p < 0.01), 200 μg/kg MeCbl administration as a supplementary treatment had a significant positive impact compared to the chitosan conduit+normal saline (Chi/NS) group.Conclusions:Our findings demonstrated that conical chitosan conduits combined with MeCbl can effectively promote nerve transposition repair following multiple distal nerve injuries.

Structurally colored chitosan membrane with dual-response for food spoilage detection

Jilong Lu,Meizhen Xie,Lipin Chen,Yong-Huan Yun

Colorimetric indicators of real-time food spoilage detection are typically fabricated using chromogenic agents or nanoparticles; however, their potential migration into food raises considerable safety concerns. Although structurally colored functional biomaterials, which do not pose such risks, represent promising alternatives, their application in food spoilage detection remains largely unexplored. In this study, a structurally colored chitosan membrane (CSM) was obtained from shrimp shells, and its responsiveness to acids and aldehydes was investigated. Fresh coconut water was used to evaluate the performance of CSM as a colorimetric spoilage indicator. Results indicate that CSM is a mesoporous material with a Bouligand structure and a deacetylation degree of 83.93 %. The specific surface area, average pore volume, and average pore size of CSM were 0.44 m 2 /g, 0.001 cm 3 /g, and 9.67 nm, respectively. CSM exhibited chromatic responsiveness to acids at a low pH of 3 due to the protonation of –NH 2 groups, as well as to aldehydes via the formation of imine bond (C=N). Acid and aldehyde exposure altered the crystalline polymorphism of chitosan in CSM. After 18 h of storage at room temperature, the membrane successfully detected spoilage in fresh coconut water through visible color changes, which can be attributed to the synergistic effects of organic acids and aldehydes accumulated during spoilage. These findings demonstrate the effectiveness of CSMs in detecting food spoilage. To our knowledge, this study is the first to demonstrate the potential application of structurally colored CSMs for detecting food spoilage, offering a novel approach for developing food spoilage indicators.

Azobenzene-modified chitosan composites harnessing high-efficiency photosensitive shape memory behaviors

Ziyun Li,Shuai Yang,Menghua Hou,Sitong Wang,Jiaying Liu,Zhichao He,Zijian Song,Yingchun Li

Chitosan-based shape memory polymers (SMPs) represent a promising class of smart materials for biomedical and packaging applications, yet their development is often limited by the reliance on solutions and thermal stimuli. To enable remote and precise control, this study focuses on developing photosensitive SMPs by conferring light responsiveness to chitosan. Azobenzene-modified chitosan (CSM) was synthesized via a three-step process involving maleic anhydride modification of chitosan followed by free radical grafting with 4-acryloyloxyazobenzene. Composite films (CSMCFs) were then prepared by blending the CSM with poly(vinyl alcohol) (PVA) at varying mass ratios. The chemical structures of the intermediates and the final composite were confirmed by 1 H NMR and FTIR spectroscopy. The incorporation of azobenzene groups was verified by UV–vis spectroscopy, and the thermal properties were assessed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The photosensitive shape memory behavior was quantitatively evaluated by measuring the shape fixation rate (R f ) and shape recovery rate (R r ) under 365 nm UV light irradiation. The optimal composites (CSMCF-3), with a CSM/PVA ratio of 3/7 and 0.5 % azobenzene derivative, exhibited a high shape fixation rate of 97.2 % and an exceptional shape recovery rate of 93.3 % within 300 s. These results demonstrate the high potential of these composite films for applications in smart packaging and biomedical devices where remote, light-triggered actuation is desired.

Synthesis, Characterization, and the Antioxidant Activity of Double Quaternized Chitosan Derivatives

Lijie Wei,Qing Li,Wenqiang Tan,Fang Dong,Fang Luan,Zhanyong Guo

With the specialty of improving the water solubility of chitosan, quaternary ammonium salts have broadened the application of this polysaccharide in food, medicine and pesticides. To identify the effect of quaternary ammonium salts’ quantity, single quaternized chitosanN-phenmethyl-N,N-dimethyl chitosan (PDCS), double quaternized chitosanN-(1-pyridylmethyl-2-ylmethyl)-N,N-dimethyl chitosan (MP2MDCS),N-(1-pyridylmethyl-3-ylmethyl)-N,N-dimethyl chitosan (MP3MDCS), andN-(1-pyridylmethyl-4-ylmethyl)-N,N-dimethyl chitosan (MP4MDCS) were designed and synthesized successfully through chemical modification of chitosan. Besides, three kinds of antioxidant activities, including hydroxyl radicals, superoxide radicals, and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radicals were tested in vitro. As shown in this paper, the scavenging ability was ranking in order of MP3MDC > MP4MDCS > MP2MDCS > PDCS > chitosan at 1.6 mg/mL in all assays. All double quaternary ammonium salts were better than chitosan or the single quaternary ammonium salt. In addition, MP3MDCS could scavenge hydroxyl radicals totally at 1.6 mg/mL. MP2MDCS and MP4MDCS with more than 90% scavenging indices both had great scavenging ability on hydroxyl radicals or DPPH radicals. Furthermore, these data demonstrated that the increasing number of the positive charge would improve the antioxidant property of chitosan derivatives, and theN-pyridinium position would influence the scavenging radical ability.

Determination sulfamethoxazole based chemiluminescence and chitosan/graphene oxide-molecularly imprinted polymers

Qiu Huamin,Fan Lulu,Xiangjun Li,Leilei Li,Sun Min,Luo Chuannan

A novel flow injection chemiluminescence (FI-CL) sensor for the determination of sulfamethoxazole (SMZ) was established which using chitosan/graphene oxide-molecularly imprinted polymers (CG-MIP) as recognition element. The SMZ-CG-MIP was synthesized in acetone as solvent and chitosan/graphene oxide for support, using acrylamide as functional monomer, ethylene glycol dimethacrylate as cross-linker and 2,2-azobisisobutyronitrile as initiator. The CG-MIP showed satisfactory recognition capacity for the SMZ. Then the synthesized CG-MIP was employed as recognition by packing into a lab-made tube connected in FI-CL analyzer to establish a novel CL sensor respectively. The CL intensity responded linearly to the concentration of SMZ in the range 1.0   ×   10 −7   mol/L to 2.3   ×   10 −3   mol/L with a detection limit of 2.9   ×   10 −8   mol/L (3 σ ), which is lower. The relative standard deviation for the determination of 4.0   ×   10 −4   mol/L of SMZ was 1.92% ( n   =   11). The sensor is reusable and has a great improvement in sensitivity and selectivity for CL analysis which applied to the determination of SMZ in drug samples.

Multi-Bit Biomemristic Behavior for Neutral Polysaccharide Dextran Blended with Chitosan

Lei Li

Natural biomaterials applicable for biomemristors have drawn prominent attention and are of benefit to sustainability, biodegradability, biocompatibility, and metabolism. In this work, multi-bit biomemristors based on the neutral polysaccharide dextran were built using the spin-casting method, which was also employed to explore the effect of dextran on the ternary biomemristic behaviors of dextran–chitosan nanocomposites. The doping of 50 wt% dextran onto the bio-nanocomposite optimized the ratio of biomemristance in high-, intermediate-, and low-resistance states (105:104:1). The interaction between dextran and chitosan (hydrogen-bond network) was verified by Fourier transform infrared (FTIR) and Raman spectroscopy analysis; through this interaction, protons derived from the self-dissociation of water may migrate under the electric field, and so proton conduction may be the reason for the ternary biomemristic behaviors. Observations from X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) analysis displayed that the 50 wt% dextran/50 wt% chitosan nanocomposite had the greatest amorphous ratio as well as the highest decomposition and peak transition temperatures in comparison with the other three dextran–chitosan nanocomposites. This work lays the foundation for neutral biomaterials applied to green ultra-high-density data-storage systems.

Magnetic Actuation Analysis of Chitosan Hydrogel Robots for Emergency Medical Applications

Jingxi Wang,Baoyu Liu,Kun Li,Jin Ma,Ping Li

Porous carbon derived from Congo Red-adsorbed Chitosan for supercapacitor electrodes

Gao Yang,Gao Shan,Zhang Yunhua,Lyu Shaoyi,Wang Feijun

Reuse of dye-containing wastewater for valuable products offers significant potential. Chitosan, a natural high-molecular-weight porous material, served as an effective carrier for dye molecules. This study uses chitosan to adsorb Congo Red, preparing hierarchical porous carbon materials, which are then applied in supercapacitors. The findings reveal that chitosan achieves an impressive adsorption capacity of 1450 mg g −1 for Congo Red. When the chitosan–Congo Red composite material-based carbon is used as the electrode material, it shows an outstanding specific capacitance of 318 F g −1 at a current density of 1 A g −1 . Furthermore, due to its high content of heteroatoms such as N, O, and S, the double-layer supercapacitor fabricated with this electrode material demonstrates a specific capacitance of 149.49 F g −1 at 1 A g −1 , with an energy density of 8.77 Wh kg −1 at a power density of 335.35 W kg −1 . These results highlight the considerable potential of this material after adsorption of dye-containing wastewater for applications in the energy storage field.

High-strength chitosan-sericin cryogel with synergistically reinforced networks for hemostasis

Ya-Qing Zhou,Xudong Deng,Zi-Xu Zhao,Xue-Ting Wang,Xiao-Qian Jin,Jun-Bin Xiong,Liang-Liang Chen,Wei-Hong Guo,Ren-Bin Zhou,Da-Chuan Yin

Developing chitosan-based hemostatic cryogels with simultaneously excellent mechanical properties and good biocompatibilities is still a challenge yet crucial for hemostasis of deep tissue bleeding. Typical approaches to enhancing the mechanical properties sacrifice biocompatibility of chitosan cryogels, thereby increasing the potential application risk. In this study, we develop a chitosan-sericin-ε-polylysine (CS-Ser-EPL) cryogel with synergistically reinforced networks achieved by physical and chemical crosslinking to address the limitations. The chitosan-sericin (CS-Ser) cryogel exhibits enhanced mechanical properties, improved thermal stability, erythrocyte aggregation capability, biocompatibilities and superior hemostatic performance. The addition of ε-polylysine further improves composite cryogel antibacterial activity, accelerating the wound healing process. In tests using a liver penetrating injury model, CS-Ser-EPL outperformed commercial gelatin sponges in hemostasis. Additionally, it exhibits faster wound healing in full-thickness skin defects exposed to S. aureus due to its antibacterial and angiogenic properties. Overall, the CS-Ser-EPL cryogel, with its enhanced mechanical and antibacterial properties, shows great promise for deep tissue hemostasis and wound healing.