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From Aggregates to Porous Three-Dimensional Scaffolds through a Mechanochemical Approach to Design Photosensitive Chitosan Derivatives
摘要： The crustacean processing industry produces large quantities of waste by-products (up to 70%). Such wastes could be used as raw materials for producing chitosan, a polysaccharide with a unique set of biochemical properties. However, the preparation methods and the long-term stability of chitosan-based products limit their application in biomedicine. In this study, different scale structures, such as aggregates, photo-crosslinked films, and 3D scaffolds based on mechanochemically-modified chitosan derivatives, were successfully formed. Dynamic light scattering revealed that aggregation of chitosan derivatives becomes more pronounced with an increase in the number of hydrophobic substituents. Although the results of the mechanical testing revealed that the plasticity of photo-crosslinked films was 5–8% higher than that for the initial chitosan films, their tensile strength remained unchanged. Different types of polymer scaffolds, such as flexible and porous ones, were developed by laser stereolithography. In vivo studies of the formed structures showed no dystrophic and necrobiotic changes, which proves their biocompatibility. Moreover, the wavelet analysis was used to show that the areas of chitosan film degradation were periodic. Comparing the results of the wavelet analysis and X-ray diffraction data, we have concluded that degradation occurs within less ordered amorphous regions in the polymer bulk.
关键词： laser stereolithography,mechanochemical synthesis,long-term stability,tissue reaction,chitosan,scaffold
更新于2025-09-23 15:22:29
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Sequential Photodynamic Therapy with Phthalocyanine Encapsulated Chitosan-Tripolyphosphate Nanoparticles and Flucytosine Treatment against Candida tropicalis
摘要： Antibiotic resistance has become a crisis. Candida tropicalis (C. tropicalis) is one of the most highly virulent and drug-resistant pathogens. An alternative antimicrobial therapy to eradicate C. tropicalis effectively, without the risk of developing drug-resistance, is needed. Photodynamic therapy (PDT) is an alternative therapy that does not carry the risk of undesired drug resistance. To target the pathogens and to enhance the cellular penetration of the applied photosensitizer, we fabricated cationic chitosan/tripolyphosphate nanoparticles to encapsulate phthalocyanine. Our strategy promotes the uptake of phthalocyanine four-fold. This enhanced PDT can effectively inhibit planktonic C. tropicalis, such that only ~20% of C. tropicalis in the test survived; but it has a limited ability to inhibit adherent C. tropicalis. Further tests with adherent C. tropicalis indicated that sequential treatment with PDT and flucytosine significantly eliminates pseudohyphae and yeast-like C. tropicalis cells. The cell viability is only ~10% after this sequential treatment. This study provides evidence of an effective therapy against drug resistant C. tropicalis, and this strategy can be potentially applied to other pathogens.
关键词： photodynamic therapy,chitosan,Candida tropicalis,phthalocyanine,flucytosine
更新于2025-09-23 15:22:29
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Chitosan-based hydrogels prepared by UV polymerization for wound dressing
摘要： Chitosan-based hydrogels were prepared by grafting with poly(acrylic acid) (PAA) and poly(hydroxyethyl methacrylate) (pHEMA) through ultraviolet polymerization to further improve its hydrophilic nature and enhance its mechanical properties. The epidermal growth factor (EGF) was incorporated inside the hydrogels to stimulate the wound healing. The physical characterization of chitosan-PAA-pHEMA hydrogel indicates that it is highly hydrophilic with adequate properties for wound dressing purpose. The biological characterization shows that chitosan-based hydrogel retains its thrombogenic and antibacterial properties. The in vivo wound healing experiment demonstrates that the hydrogel-incorporated EGF has better wound healing rate than other dressings.
关键词： hydrogel,Chitosan,2-hydroxyethyl methacrylate,epidermal growth factor,wound dressing,acrylic acid
更新于2025-09-23 15:22:29
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Surface-functionalized silver nanowires on chitosan biopolymers for highly robust and stretchable transparent conducting films
摘要： We develop highly robust and stretchable conductive transparent electrodes based on silver nanowires (AgNWs) deposited on functionalized chitosan biopolymer substrates. 11-aminoundecanoic acid is introduced as a surface modifier for enhancing the chemical bond. The chemically functionalized AgNW films achieve a low sheet resistance of 12.2 ohm/sq with a high transmittance of 88.9%. In addition, stretchable alternating current-driven electroluminescent devices and stretchable transparent heaters have been fabricated with AgNW/chitosan thin-films which can be cut, stretched, bent, and twisted without performance degradation. With this approach, stretchable electronics prepared on bio-compatible substrates can be easily applied to curved surfaces or human skins.
关键词： wearable electronics,chitosan,silver nanowires,Transparent electrodes,stretchable electronics
更新于2025-09-23 15:22:29
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Facile Synthesis and Characterization of CoS2–SiO2/Chitosan: The Photocatalysis in Real Samples, and Antimicrobial Evaluation
摘要： In the present work, The SiO2, and CoS2–SiO2 nanomaterials and incorporated on chitosan was developed as photocatalyst for photocatalytic degradation of toxic compound such as ethidium bromide as a hazard mutagenic pollutant. The SiO2, and CoS2–SiO2 nanomaterials were prepared using the sol–gel/sonochemical method. Therefore, the nano photocatalyst were characterized by various analytical devices such as scanning electron microscopy (SEM), X-ray diffraction and photoelectron (XRD and XPS) analysis, energy dispersive X-ray spectrometer (EDS), UV–Vis absorption spectroscopy and dynamic light scattering, in order to attain the structural properties. The average crystallite size values of SiO2, CoS2–SiO2, and CoS2–SiO2/Chitosan nanocomposites are 0.63, 40.28, and 69.75 nm, respectively. The band-gap values was obtained 8.9–2.7 eV for SiO2, CoS2–SiO2, and CoS2–SiO2/Chitosan nanocomposites, respectively. The photocatalytic performances of the three prepared nano-photocatalyst were examined by UV-light with help the photo-degradation of ethidium bromide. The CoS2–SiO2/Chitosan nanocomposites photocatalyst shows the high amount of photocatalytic degradation (96.00%) in comparison to SiO2, and CoS2–SiO2 nanomaterials. The results demonstrated that the all prepared nano-photocatalyst under UV irradiation was in pH 5 at 40 min. The antifungal and antibacterial of the SiO2, CoS2–SiO2, and CoS2–SiO2/Chitosan were examined. The CoS2–SiO2/Chitosan (high 11.00 mm inhibition zone) has appropriate antimicrobial activity compared with pure SiO2.
关键词： Antibacterial,Chitosan,CoS2,SiO2,Photocatalytic activity
更新于2025-09-23 15:22:29
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Ochratoxin A detection in coffee by competitive inhibition assay using chitosan-based surface plasmon resonance compact system
摘要： This study demonstrates the evaluation of ochratoxin A (OTA) in coffee on compact surface plasmon resonance (SPR) biosensors based on crosslinked chitosan and carboxymethyl chitosan nanomatrix substrates. Ochratoxin A is a toxic secondary metabolite widely produced by Aspergillus and Penicillium fungi and requires regular quantification and detection in food samples. The gold coated SPR chips were synthesized with chitosan and carboxymethyl chitosan through spin coating technique. The SPR nanomatrix chips were used for the immobilization of ochratoxin A-bovine serum albumin (OTA-BSA) conjugate to develop a competitive inhibition immunoassay. The monoclonal ochratoxin A antibodies (mAb-OTA) were used as biological receptors for the detection of OTA in buffer and coffee samples. The limit of detection (LOD) in coffee for chitosan (CS) and carboxymethyl chitosan (CMC) substrates was 5.7 ng/mL and 3.8 ng/mL, respectively. Compact surface plasmon resonance (SPR) system based on chitosan-based (CS-AU) nanomatrix substrates provides a platform for the detection of ochratoxin A with high sensitivity, accuracy, ease-of-use and cost-effectiveness. This compact SPR system can be used at farm and industrial levels for the detection of OTA in food matrices.
关键词： Carboxymethyl chitosan,SPR immunoassay,Coffee,Ochratoxin A,Chitosan
更新于2025-09-23 15:21:21
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Highly sensitive and selective estimation of aspartame by chitosan nanoparticles–graphene nanocomposite tailored EQCM-MIP sensor
摘要： Here, a molecularly imprinted electrochemical quartz crystal microbalance (MIP-EQCM) sensor for aspartame is developed by grafting the aspartame-imprinted polymeric matrix of chitosan on gold-coated quartz crystal electrode. Chitosan nanoparticles being biocompatible, biodegradable and also having large surface area provide a better platform by forming a well-dispersed composite suspension with graphene. Additionally graphene facilitates direct electron transfer to electrode surface for electrochemical study because of having enhanced electrical conductivity. This EQCM-MIP sensor was characterized by atomic force microscopy, contact angle measurements, cyclic voltammetry and differential pulse voltammetry (DPV). The obtained MIP showed high affinity to aspartame. A reliable method for analysis of aspartame in real and commercial samples was achieved by coupling EQCM-MIP with DPV. Linear relationship with R2 = 0.9749 (EQCM) and R2 = 0.9760 (DPV) on binding of aspartame at various concentrations was observed. Detection limit of 0.45 μg mL?1 (EQCM) and 0.07 μg mL?1 (DPV) of the fabricated sensor shows that high sensitivity and high selectivity among various structural analogues of aspartame were also achieved. The improved detection limit is promising for determination of trace amount of aspartame. This demonstrates good memory capacity of this EQCM sensor. High recovery percentage and applicability of EQCM-MIP sensor in real matrices and commercial samples offers good potential for various applications.
关键词： Electrodeposition,Aspartame,Quartz crystal microbalance,Graphene,Chitosan nanoparticles,Molecular imprinting
更新于2025-09-23 15:21:21
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Monitoring of Virulence Factors and Metabolic Activity in Aggregatibacter Actinomycetemcomitans Cells Surviving Antimicrobial Photodynamic Therapy via Nano-Chitosan Encapsulated Indocyanine Green
摘要： Aggregatibacter actinomycetemcomitans is an etiological agent frequently found in both chronic and aggressive periodontitis as well as peri-implantitis. This study assessed the effect of antimicrobial photodynamic therapy (aPDT), as an alternative treatment modality, by nano-chitosan encapsulated indocyanine green (CNPs/ICG), as a photosensitizer, on the virulence features of cell-surviving aPDT against A. actinomycetemcomitans. The cell cytotoxicity effect of CNPs/ICG was evaluated on primary human gingival fibroblast cells. A. actinomycetemcomitans ATCC 33384 photosensitized with CNPs/ICG was irradiated with diode laser at a wavelength of 810 nm for 1 min (31.2 J/cm2), and then bacterial viability measurements were done. The biofilm formation ability, metabolic activity, and antimicrobial susceptibility profiles were assessed for cell-surviving aPDT. The effect of aPDT on the expression of the fieF virulent gene, encoding the ferrous-iron efflux pump, was evaluated by the quantitative real-time PCR. CNPs/ICG-aPDT resulted in a significant reduction of cell viability (91%), biofilm formation capacity (53%), and metabolic activity (48%) of A. actinomycetemcomitans when compared to the control group (P < 0.05). Moreover, fieF gene expression was downregulated by 14.8 folds after the strains were treated with aPDT. The virulence of A. actinomycetemcomitans strain reduced in cells surviving aPDT with CNPs/ICG, indicating the potential implications of aPDT for the treatment of A. actinomycetemcomitans infections in periodontitis and peri-implantitis in vivo.
关键词： peri-implantitis,nano-chitosan,Aggregatibacter actinomycetemcomitans,antimicrobial photodynamic therapy,indocyanine green,periodontitis
更新于2025-09-23 15:21:01
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NIR-Based Simultaneous Measurement of Amine Loading and Degree of Neutralization during Flotation Reagent Preparation for Potash Processing
摘要： A continuous spectroscopy-based monitoring approach of the amine reagent preparation prior to flotation processing was investigated. The process involved the neutralization of a long carbon chain amine, C16-C20, with hydrochloric acid. Current methods of monitoring the degree of neutralization, controlling the HCl addition, and monitoring the amine content were based on pH measurements, with out-of-line sample lab-validation carried out using titration-based methods. Industry feedback indicated this method was prone to error and had resulted in challenges in process control. This work demonstrates a novel method of measuring both amine content and degree of neutralization using a mini-fluidic reactor and FT-NIR system equipped with a flow-through heated transmission cell. Analysis of the spectral response for wavenumbers in the range of 4,258-4,400 cm-1 yielded amine content and degree of neutralization measurements accurately to within ± 0.065 wt%, and ± 6.0% margin of errors, respectively. This led to monitoring intensification to increase KCl recoveries in flotation processing.
关键词： Millet husk,Zinc ions,Sorption materials,Wastewater,Chitosan
更新于2025-09-23 15:21:01
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Novel ?2-1,3-D-glucan porous microcapsule enveloped folate-functionalized liposomes as a Trojan horse for facilitated oral tumor-targeted co-delivery of chemotherapeutic drugs and quantum dot
摘要： In this study, a new type of β-1,3-D-glucan porous microcapsule (GPM)-enveloped and folate conjugated chitosan-functional liposome (FCL), FCL@GPM, was developed for the potential oral co-delivery of chemotherapeutic drugs and quantum dots (QDs) with facilitated drug absorption and antitumor efficacy. In this dual-particulate system, multiple FCLs serve as the cores for effective loading, folate-mediated tumor-targeting, facilitated intracellular accumulation, and pH-responsive controlled release of chemotherapeutic agents, while a GPM acts as the shell for affording macrophage-mediated tumor selectivity. Gefitinib (GEF) was selected as a chemotherapeutic agent, while acid degradable ZnO QDs were selected due to its dual role both as an anticancer agent for synergistic chemotherapy and as a fluorescent probe for potential cancer cellular imaging. The GEF and ZnO QDs co-loaded FCL@GPMs (GEF/ZnO-FCL@GPMs) have a prolonged release manner with limited release before uptake by intestinal cells. Furthermore, the Peyer’s patches uptake, macrophages uptake, cytotoxicity, and biodistribution of FCL@GPMs were tested. In addition, GEF and ZnO QDs co-loaded FCLs (GEF/ZnO-FCLs) not only have a tumor acidity responsive release property, but also induce a superior cytotoxicity on cancer cells as compared to GEF. Moreover, a 1.75-fold increase in the bioavailability of GEF delivered from GEF/ZnO-FCL@GPMs as compared to its trademarked drug (Iressa?). As a result, GEF/ZnO-FCL@GPMs exerted a superior antitumor efficacy (1.47-fold) as compared to its trademarked drug in mice. Considered together, the developed FCL@GPMs, combining the unique physicochemical and biological benefits of FCLs and GPMs, possess a great potential as an efficient delivery system for the co-delivery of chemotherapeutic agents and quantum dots.
关键词： chemotherapeutic drugs,pH-responsive controlled release,tumor-targeting,oral co-delivery,macrophage-mediated tumor selectivity,β-1,3-D-glucan porous microcapsule,folate conjugated chitosan-functional liposome,quantum dots
更新于2025-09-23 15:19:57