Chitosan Quaternary Ammonium Salt Research Articles

Arbitrarily shapeable and conductive hydrogel with “Magic Cube” like structure for real-time monitoring and promoting wound healing

Developing hydrogel dressings for chronic non-healing wounds in irregular-shaped or moveable sites has great practical applications. In this work, a novel polyelectrolyte composite hydrogel (HSa) was fabricated from chitosan quaternary ammonium salt (HACC) and sodium alginate (SA) through blending and acid-treated process. The positive charges of HACC and negative charges of SA self-assembled and intertwined to form a “Magic Cube”-like structure. The amino groups of HACC were protonized and the Na + of SA was replaced by proton after acid treatment, further strengthening the interactions between the two chips of “Magic Cube”. HSa hydrogel was proven to be arbitrarily shapeable with high flexibility (tensile strain is around 280%). Due to free Cl − , HSa hydrogel presented good conductivity (1.14 × 10 −3 S/cm) and positive linear relationship between its electrical resistance change and area change, which denoted its ability to monitor joint movement or subtle shrinkage. HSa hydrogel exhibited good biocompatibility and was further applied as dressing in an irregular-shaped wound model. HSa hydrogel could significantly accelerate the wound healing by elevating collagen deposition and vessel formation. Simultaneously, HSa hydrogel could monitor the wound closure in real-time. Therefore, HSa hydrogel had multifunctional potential for wound healing and monitoring, especially for irregular-shaped or movable sites. • A simple strategy for fabricating arbitrarily shapeable and conductive hydrogel. • HSa hydrogel has a “Magic Cube” like structure. • HSa hydrogel has good hemostasis effects and biocompatibility. • HSa hydrogel combines wound pro-healing and real-time monitoring functions. • HSa hydrogel could be beneficial for chronic non-healing wounds.

Anti-calcification potential of collagen based biological patch crosslinked by epoxidized polysaccharide

Biological patch is a kind of tissue substitute material derived from natural polymer materials for the repair of human soft tissue defects. The serious calcification of biological patch after implantation is one of the reasons for the decline and failure of patch. In previous studies, we synthesized a new biomaterial crosslinker epoxidized chitosan quaternary ammonium salt (EHTCC) and used it for the crosslinking of porcine acellular dermal matrix (pADM). The prepared EHTCC-pADM had good mechanical properties, biocompatibility and healing promoting properties. In order to broaden its application scenarios, the related properties of EHTCC-pADM as implant patch were further explored in this study. The results of X-ray diffraction (XRD) measurements showed that the structure of pADM did not change much before and after the crosslinking of EHTCC, which was conducive to the maintenance of the excellent biological properties of pADM. According to the enzymatic degradation resistance test in vitro, the resistance of EHTCC-pADM to type I collagenase degradation was significantly improved compared with non -crosslinked pADM. And with the increase of the amount of EHTCC, its degradation resistance was stronger. The experimental results showed that EHTCC-pADM can well support the growth of L929 fibroblasts and has good anti-calcification properties in vitro and in vivo.

Iron-based technology coupling moderate preoxidation with hybrid coagulation for highly effective removal and moderate growth inhibition of Oscillatoria in drinking water treatment plants

A novel technology coupling moderate preoxidation and hybrid coagulation was invented to solve the issues caused by Oscillatoria in drinking water treatment plants (DWTPs). In this technology K2FeO4 can reduce the electronic repulsion between Oscillatoria filaments without cells’ lysis and thereby make them tend to aggregate into flocs. After preoxidation in-situ Fe(III) reduced from Fe(VI) will form a highly efficient hybrid coagulant through addition of a low dose of chitosan quaternary ammonium salt (HTCC). This process can remove most of the algal cells and metabolites in Oscillatoria-laden water and alleviate filter blockages. After treatment, 93.0% of algal cells can be removed and the DOC, turbidity and CYN can be respectively decreased from 15.3 mg/L to 5.8 mg/L, from 5.76 NTU to 1.48 NTU, and from 22 mg/L to 4.55 mg/L. During sludge storage, the effects of the moderate oxidation of Fe(VI) and the anti-algal activity of HTCC can consistently control the proliferation of Oscillatoria and the increase of algal metabolites, thereby reducing the difficulty of sludge treatment and making the reuse of sludge water more feasible. In a nutshell, the new technology is suitable for DWTPs when Oscillatoria blooms break out in source water.

Screening of Chitosan Derivatives-Carbon Dots Based on Antibacterial Activity and Application in Anti-Staphylococcus aureus Biofilm

IntroductionPathogenic bacteria, especially the ones with highly organized, systematic aggregating bacteria biofilm, would cause great harm to human health. The development of highly efficient antibacterial and antibiofilm functional fluorescent nanomaterial would be of great significance.MethodsThis paper reports the preparation of a series of antibacterial functional carbon dots (CDs) with chitosan (CS) and its derivatives as raw materials through one-step route, and the impact of various experiment parameters upon the optical properties and the antibacterial abilities have been explored, including the structures of the raw materials, excipients, and solvents.ResultsThe CDs prepared by quaternary ammonium salt of chitosan (QCS) and ethylenediamine (EDA) exhibit multiple antibacterial effects through membrane breaking, DNA and protein destroying, and the production of singlet oxygen. The CDs showed excellent broad-spectrum inhibitory activity against a variety of bacteria (Gram-positive and negative bacteria), in particular, to the biofilm of Staphylococcus aureus with minimum inhibitory concentration at 10 µg/mL, showing great potential in killing bacteria and biofilms. The biocompatibility experiments proved that QCS-EDA-CDs are non-toxic to human normal hepatocytes and have low haemolytic effect. Furthermore, the prepared QCS-EDA-CDs have been successfully used in bacterial and biofilm imaging thanks to their excellent optical properties.ConclusionThis paper explored the preparation and application of functional CDs, which can be used as the visual probe and therapeutic agents in the treatment of infections caused by bacteria and biofilm.

A novel technology using iron in a coupled process of moderate preoxidation–hybrid coagulation to remove cyanobacteria in drinking water treatment plants

Preoxidation–coagulation is adopted by many drinking water treatment plants to enhance the removal of cyanobacteria. However, conventional technologies — such as the combination of prechlorination with Al-salt coagulation — can easily induce secondary pollution caused by cell lysis and yield unsatisfactory performance both in removal of cyanobacterial cells and metabolites and in alleviation of filter unit fouling. To solve these issues, an iron-based coupled process of moderate preoxidation–hybrid coagulation was invented. In this technology Fe(VI) can moderately oxidize algal cells, resulting in the removal of electronegative organics coating the surfaces of the cells without destroying the algae. After preoxidation, in-situ Fe(III) produced from Fe(VI) will form a highly effective hybrid coagulant by adding a low dose of chitosan quaternary ammonium salt. Combining the reduction of electrostatic repulsion between algal cells obtained from K2FeO4 preoxidation with the enhancement of charge neutralization, polymer bridging and adsorption capability obtained from hybrid coagulation, 92.6% of Microcystis aeruginosa cells were removed and the DOC and microcystin concentrations respectively decreased from 23.54 to 7.63 mg/L and from 16.2 to 0.96 mg/L. Meanwhile the membrane fouling was markedly alleviated. Hence this new technology couples moderate preoxidation and hybrid coagulation through the Fe(VI)–Fe(III) pairing, which is safer and more effective and can thus be a better alternative for cyanobacterial removal in drinking water treatment plants.

Sensitive Micro-Breathing Sensing and Highly-Effective Photothermal Antibacterial Cinnamomum camphora Bark Micro-Structural Cotton Fabric via Electrostatic Self-Assembly of MXene/HACC.

Natural fabrics are gradually becoming the ideal substrate for flexible smart wearable devices due to their excellent moisture absorption, softness, and skin-friendliness. However, the bonding fastness of the conductive layer and the corresponding durability during service have not yet been well satisfied. In this report, we successfully prepared a smart wearable multifunctional protective cotton fabric with microbreathing monitoring and rapid-photothermal antibacterial abilities of Cinnamomum camphora bark microstructure, by combining chitosan quaternary ammonium salt (HACC) with MXene nanosheets through electrostatic self-assembly. Impressively, MXene nanosheets and HACC established a strong interaction using the electrostatic attraction, endowing the fiber surface with ordered nanosheets. Meanwhile, the fabric decorated with MXene/HACC retains its original characteristics of outstanding breathability and softness, and its conductivity exhibits noticeable stability in terms of resistances to oxidation, washing, various solvents, and long-term bending cycles. On the basis of the principle of adsorption and release of water molecules in the MXene multilayer structures, the MXene/HACC fabric could accurately monitor the physiological health activities of users according to their breathing frequency and depth. Benefiting from the local surface plasmon resonance (LSPR) effect, the MXene/HACC shows encouraging photothermal conversion ability, photothermal stability under long time irradiation, washing resistance, and cycle stability. In addition, the fabric achieved an antibacterial efficiency of nearly 100% against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus within 5 min under an irradiation intensity of 400 mW/cm2. More importantly, after 10 washes, the antibacterial efficiency against the two bacteria could still reach 99.975% and 99.98%, respectively. This multifunctional protective MXene/HACC cotton fabric is expected to play a unique role in the new generation of smart wearable microbreathing sensing and against to bacterial attack, and shows a broad application prospect.

Temperature-Stress Bimodal Sensing Conductive Hydrogel-Liquid Metal by Facile Synthesis for Smart Wearable Sensor.

Conductive hydrogels have attracted great attention due to their promising applications in wearable sensors. However, developing conductive hydrogels with excellent sensor properties and multiple stimuli responsiveness for smart wearable devices is still a challenge. This paper presents a facile synthetic method of a crosslinked chitosan quaternary ammonium salt and liquid metal (CHACC-LM) composite hydrogel with temperature-stress bimodal sensing for smart wearable sensor. LM as liquid fillers toughen the hydrogel matrix (stress: 1.11MPa) and enhance the hydrogel extensibility (strain: 233%). The CHACC-LM hydrogel exhibits conductivity , excellent antibacterial properties (> 99%), an electrical self-healing property, and strain sensitivity (GF = 1.6). In addition, the CHACC-LM hydrogel can be used as wearable flexible sensors with the ability of monitoring human activities directly and the distinguished ability of discerning subtle motions (handwriting). It also shows sensitivity in the external environment such as low temperature, thermal response, and water solution. Importantly, the composite hydrogel simultaneous response to different stress and temperature stimuli. Furthermore, the CHACC-LM hydrogel can be used for gesture recognition and to control the manipulator in human-computer interaction. All these properties provide a great scope for researchers to achieve practical advances in smart wearable sensors.

Preparation of Cross-linked Chitosan Quaternary Ammonium Salt Hydrogel Films Loading Drug of Gentamicin Sulfate for Antibacterial Wound Dressing.

Hydrogels, possessing high biocompatibility and adaptability to biological tissue, show great usability in medical applications. In this research, a series of novel cross-linked chitosan quaternary ammonium salt loading with gentamicin sulfate (CTMCSG) hydrogel films with different cross-linking degrees were successfully obtained by the reaction of chitosan quaternary ammonium salt (TMCS) and epichlorohydrin. Fourier transform infrared spectroscopy (FTIR), thermal analysis, and scanning electron microscope (SEM) were used to characterize the chemical structure and surface morphology of CTMCSG hydrogel films. The physicochemical property, gentamicin sulphate release behavior, cytotoxicity, and antibacterial activity of the CTMCSG against Escherichia coli and Staphylococcus aureus were determined. Experimental results demonstrated that CTMCSG hydrogel films exhibited good water stability, thermal stability, drug release capacity, as well as antibacterial property. The inhibition zone of CTMCSG hydrogel films against Escherichia coli and Staphylococcus aureus could be up to about 30 mm. Specifically, the increases in maximum decomposition temperature, mechanical property, water content, swelling degree, and a reduction in water vapor permeability of the hydrogel films were observed as the amount of the cross-linking agent increased. The results indicated that the CTMCSG-4 hydrogel film with an interesting physicochemical property, admirable antibacterial activity, and slight cytotoxicity showed the potential value as excellent antibacterial wound dressing.

Preparation and characterization of a dual cross-linking injectable hydrogel based on sodium alginate and chitosan quaternary ammonium salt

The development of cheap and easily available injectable hydrogel is an urgent problem in the field of biomedical engineering. Herein, we used chitosan quaternary ammonium salt and sodium alginate to prepare a dual crosslinking hydrogel. The hydrogel formed in-situ crosslinking and can be injected continuously. Interestingly, the formed hydrogel possessed a homogeneous 3D network structure and exhibited reasonable mechanical properties. Moreover, the hydrogels had excellent injectability, and the compression strength of the hydrogel (Gel-0.5) was up to 27.65 kPa. Additionally, the hydrogel showed good biocompatibility that evaluated by cytotoxicity. Notably, the hydrogel was nontoxic toward NIH-3T3 cells. In summary, the hydrogel we produced can be used as an ideal biomaterial for further applications in the field of biomedical engineering.

Study on preparation and application of a multifunctional microspheric soil conditioner based on Arabic gum, gelatin, chitosan and β-cyclodextrin

All kinds of soil conditioners have been used to improve soil quality. The application of many traditional soil conditioners was limited by single performance. In this study, a novel multifunctional microspheric soil conditioner was prepared based on Arabic gum, gelatin, chitosan and β-cyclodextrin. Arabic gum and gelatin (AG-GL) microspheric carriers, which could load ferrous sulfate (FS), were synthesized via complex coagulation method. The AG-GL(FS) microspheres were covered by chitosan quaternary ammonium salt (CQAS) through single coagulation method. And β-cyclodextrin (β-CD) was used as the outermost shell to improve chemical stability of the soil conditioner by saturated solution method. Finally, the novel multifunctional microspheric soil conditioner AG-GL/CQAS/β-CD-FS was obtained and characterized by Fourier transform infrared spectroscopy, thermogravimetric analyzer, polarizing microscope, scanning electron microscope and particle size analyzer. The novel soil conditioner shows good nutrient slowly-releasing, water retention, heavy metal ions adsorption and antibacterial performances with the particle size of 14–17 μm and high thermal decomposition temperature, which has the potential application in improving soil quality.

Air superhydrophilic-superoleophobic SiO2-based coatings for recoverable oil/water separation mesh with high flux and mechanical stability

Due to the inherent differences in surface tension between water and oil, it is a challenge to fabricate air superhydrophilic-superoleophobic materials despite their promising potential in the field of oil/water separation. Herein, a facile approach is developed to fabricate air superhydrophilic-superoleophobic SiO2 coating by combination of controllable modifying SiO2 nanoparticle surface by both hydrophilic groups (i.e., –OH groups) and oleophobic groups (i.e., fluorinated groups) with constructing porous and hierarchical structures. Hydroxyl-modified SiO2 nanoparticles (NPs) are synthesized using a base-catalysed procedure in the presence of ammonia or NaOH. Chitosan quaternary ammonium salt (HACC) is introduced to bind SiO2 by forming a unique hydrogen bond between HACC and –OH, followed by adding pentadecafluorooctanoic acid (PFOA) to complex with HACC to form fluorinated groups. The SiO2 coatings are fabricated on various substrates (e.g., glass, foam and Cu mesh) by spraying procedure and characterized using SEM, FTIR, XPS, etc. The contact angles of oils (e.g., pump oil, castor oil, corn oil, hexadecane and bean oil) and water on the coatings are over 150° and close to 0°, respectively. By optimization, the representative SiO2-coated Cu mesh displayed high-efficiency of 99.2% in separating water from mixture of water/pump oil, and high penetration flux of 1.41 × 104 L·m−2 ·h−1. Besides, the coating maintains its superhydrophilic-superoleophobic properties even after 110 cycles of sandpaper abrasion or after being immersed in water for 3 h. After 20 cycles of oil/water separation, the coating retains separation efficiency up to 97.93%. This study provides a new and universal protocol to fabricate unique superwetting surfaces with effective oil/water separation performance, long-term durability and outstanding reusability.

Dual-crosslinked mussel-inspired smart hydrogels with enhanced antibacterial and angiogenic properties for chronic infected diabetic wound treatment via pH-responsive quick cargo release

The healing of chronic diabetic wounds remains a key challenge due to its susceptibility to bacterial infection, the inflammatory wound microenvironment, and difficulty in angiogenesis. Herein, a pH-responsive, mussel-inspired, double-crosslinking injectable, and adhesive smart hydrogel formula was exploited to overcome these obstacles simultaneously. The multifunctional double-crosslinking hydrogel was developed through the formation of catechol-catechol adducts and a Schiff-based reaction between amino groups (−NH2) in chitosan quaternary ammonium salt (HTCC) and aldehyde groups (–CHO) in oxidized dextran-dopamine (OD-DA). The double-crosslinking mechanism gave the hydrogels great mechanical properties. Most importantly, via the effective encapsulation of silver nanoparticles (AgNPs) and pro-angiogenic drug deferoxamine (DFO), the hydrogel was given with antibacterial and angiogenic features respectively. At the infected diabetic wound area, the double Schiff base bonds (DA and OD; HTCC and OD-DA) in the hydrogels could quickly achieve pH-response and accomplish a sustained and controlled release of drugs to accelerate wound healing. Through the combination of AgNPs and HTCC, the hydrogel exhibited antimicrobial capacities to gram-positive bacteria (S. aureus) and gram-negative bacteria (E. coli), it did not cause toxic side effects and avoided drug resistance. The DFO released at the infected diabetic wound area promoted angiogenesis by enhancing the expression of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF). We elucidated the mechanisms by which the designed hydrogels accelerated the healing of bacterial infected diabetic wounds in vitro and in vivo, and our hydrogels represented a general strategy for the healing of a wide range of tissue injuries.

The Fabrication of Cassava Silk Fibroin-Based Composite Film with Graphene Oxide and Chitosan Quaternary Ammonium Salt as a Biodegradable Membrane Material

Abstract A novel and excellent composite film was fabricated by simply casting cassava silk fibroin (CSF), chitosan quaternary ammonium salt (HACC), and graphene oxide (GO) in an aqueous solution. Scanning electron microscope images showed that when GO was dispersed in the composite films, the surface of CSF-based composite film became rough, and a wrinkled GO structure could be found. When the content of GO was 0.8%, the film displayed a higher change with respect to the breaking strength and elongation, respectively, up to 97.69 ± 3.69 and 79.11 ± 1.48 MPa, keeping good thermal properties because of the incorporation of GO and HACC. Furthermore, the novel CSF/HACC/GO composite film demonstrates a lower degradation rate, implying the improvement of the resistance to the enzyme solution. Especially in the film with 0.8 wt% GO, the residual mass arrived at 64.35 ± 1.1% of the primary mass after 21 days compared with the CSF/HACC film. This would reclaim the application of silk-based composite films in the biomaterial field.

Chitosan quaternary ammonium salt induced mitochondrial membrane permeability transition pore opening study in a spectroscopic perspective

Chitosan is non-toxic, biodegradable and biocompatible. However, it is insoluble in water, which limits its applications in biomedical areas. Hydroxypropyltrimethyl ammonium chloride chitosan (HACC), a chitosan derivative, can be dissolved in physiological condition and has been widely used in the field of biomedicine and bioengineering. The biological effect of HACC has been extensively studied. However, it is rarely investigated at the subcellular level. To study the biological effect of HACC, mitochondria, energy-producing organelles in eukaryotes, were chosen as a model. The investigation mainly focused on the changes of mitochondrial membrane property in the presence of HACC. Results showed that HACC can induce the collapse of mitochondrial transmembrane potential (∆Ψm), the increase in mitochondrial membrane swelling and the decrease of mitochondrial membrane fluidity, demonstrating that mitochondrial membrane permeability transition pore (mPTP) opening happened. Possible mechanism of mPTP opening investigation indicated that it was occurred in a typical model. In addition, HACC can induce the release of cytochrome C (Cyt c) and affect the respiratory activity of mitochondria. The study will provide a lot of important information on biosafety evaluation of HACC.

A pH and hyaluronidase dual-responsive multilayer-based drug delivery system for resisting bacterial infection

In this work, we developed an antibacterial drug-controlled release multilayer surface based on a layer-by-layer (LBL) assembly of polyacrylic acid (PAA) and chitosan quaternary ammonium salt (QCS). Gentamicin sulfate (GS) is incorporated into the multilayer and hyaluronic acid (HA) is utilized as the topmost layer as a sealing layer. During the bacterial attack, the pH of the microenvironment slightly rises, which makes the multilayer swell and promotes the release of drugs. Meanwhile, the hyaluronidase (HAase) secreted by bacteria triggers the degradation of the HA layer and further accelerates the GS release to fulfill its antibacterial activity. The surface showed high antibacterial activity against S. aureus and E. coli with pH and enzyme dual-responsive drug delivery at an accurate time. The intelligent antibacterial surface presented in this study shows promising potential in application to infection-resistance medical devices.

Synthesis and characterization of thermosensitive hydrogel based on quaternized chitosan for intranasal delivery of insulin.

Nasal administration is a form of systemic administration in which drugs are insufflated through the nasal cavity. Steroids, nicotine replacement, antimigraine drugs, and peptide drugs are examples of the available systematically active drugs as nasal sprays. For diabetic patients who need to use insulin daily, the nasal pathway can be used as an alternative to subcutaneous injection. In this regard, intranasal insulin delivery as a user-friendly and systemic administration has recently attracted more attention. In this study, a novel formulation consists of chitosan, chitosan quaternary ammonium salt (HTCC), and gelatin (Gel) was proposed and examined as a feasible carrier for intranasal insulin administration. First, the optimization of the chitosan-HTCC hydrogel combination has done. Afterward, Gel with various amounts blended with the chitosan-HTCC optimized samples. In the next step, swelling rate, gelation time, degradation, adhesion, and other mechanical, chemical, and biological properties of the hydrogels were studied. Finally, insulin in clinical formulation and dosage was blended with optimized thermosensitive hydrogel and the release procedure of insulin was studied with electrochemiluminescence technique. The optimal formulation (consisted of 2wt% chitosan, 1wt% HTCC, and 0.5wt% Gel) showed low gelation time, uniform pore structure, and the desirable swelling rate, which were resulted in the adequate encapsulation and prolonged release of insulin in 24H. The optimal samples released 65% of the total amount of insulin in the first 24H, which is favorable for this study.

Self-assembled vesicles of sodium oleate and chitosan quaternary ammonium salt in acidic or alkaline aqueous solutions

Fatty acids are anionic surfactants under their deprotonated forms, which have biodegradability and biocompatibility. The fatty acid self-assembled aggregates exhibit many potential applications. Fatty acid vesicles are the most representative because of their special hollow double-layer membrane structure. However, their application is hindered by a poor stability against variations in pH, salt, and temperature. In this work, the anionic surfactant sodium oleate (SO) and the polycationic hydroxypropyltrimethyl ammonium chloride chitosan (HACC) were mixed to form complex vesicles in a wider pH scale. The formation of vesicles was proved through TEM, fluorescence spectroscopy, and DLS; meanwhile, the intermolecular force–formed vesicles were verified through FT-IR and zeta potential analyses. The effect of electrolyte and temperature on the stability of the vesicle was also studied. The experimental results showed that with the aid of H-bonding and the electrostatic attraction separately, amphiphilic molecules were formed and they self-assembled into vesicles in both acidic and alkaline aqueous solutions.

Microcalorimetric and microscopic studies of the effect of chitosan quaternary ammonium salt on mitochondria

Chitosan quaternary ammonium salt (HACC) has been regarded as an effective biomedical carrier with good application because of its good water-solubility, high cationic potential and strong cell adhesion. Mitochondria are important organelle involved in ATP production and are the center of energy metabolism. In this work, we firstly investigated the effect of HACC on the thermogenic curve of isolated mitochondrial metabolism by microcalorimetry. The results showed that different concentration of HACC had great influence on the mitochondrial energy metabolism. Specifically, low level of HACC stimulated the metabolic activity of mitochondria and the inhibition was found with high concentration of HACC. Then, the effect of HACC on mitochondrial respiratory chain was studied, which was consistent with the results of microcalorimetry. Finally, the alteration of mitochondrial structure induced by HACC was observed and it showed that the membrane of mitochondria was dramatically damaged. These new findings can help us deeply understand the influence and action mechanism of HACC in the metabolic process and provide theoretical and practical foundation for the biosafety of HACC as a medical carrier.

Polyelectrolytes Tailored Enzyme Cascades with Enhanced Stability and Activity for One‐pot Synthesis

AbstractCascade enzymes from the same origin or different resources often differ in their pH windows of stability and activity, thus impeding one‐pot enzyme cascade reactions. Here we present a method to assemble enzyme cascades using enzyme‐polyelectrolyte as the building block, in which the polyelectrolytes not only assemble enzymatic cascades via electrostatic interactions but also create favorable microenvironments for enzymes to expand their pH windows of stability and activity. We first demonstrated the effectiveness of this method for the oxidization of p‐xylene to p‐toluic acid using chloroperoxidase (CPO) and xanthine oxidase (XO) cascade, in which CPO from Caldariomyces fumago and XO from bovine milk were covalently linked to polymethacrylic acid (PMAA) and chitosan quaternary ammonium salt, respectively. Conjugation of the enzymes with PMAA and chitosan expanded the stability and activity pH windows for CPO and XO and increased the yield of p‐toluic acid production from p‐xylene by 7.6‐fold in comparison to that obtained from their native counterparts in soluble form. We then applied this method to assemble glucose oxidase (GOx) and horseradish peroxidase (HRP) cascade. The GOx‐PMAA@HRP‐chitosan displayed a lower Km and higher apparent activity at low glucose concentration, as compared to GOx/HRP cascade in soluble form, suggesting that the assembly method boosted the outcome of the one‐pot enzyme cascade reaction.

Properties of Cotton Fabric Modified with a Chitosan Quaternary Ammonium Salt Nanoparticle

In this study, a novel fibre-reactive nanoparticle was synthesised in three steps. First a water-soluble chitosan derivative, N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (short for HTCC), was prepared by reacting chitosan with 2,3-epoxypropyltrimethylammonium chloride. Second the HTCC was further modified by reacting it with N-(hydroxymethyl)- acrylamide to prepare a fibre-reactive chitosan derivative, O-methyl acrylamide quaternary ammonium salt of chitosan (short for NMA-HTCC), which can form covalent bonds with cellulose fibre under alkaline conditions. Thirdly NMA-HTCC nanoparticles were prepared by the ionotropic gelation reaction method. The particle size and TEM researches indicated that the globular NMA-HTCC nanoparticle with a size distribution of 15 - 50 nm was successfully prepared and presented good dispersity and stability. Then the NMA-HTCC nanoparticle was used for the textile finishing of cotton fabric. The modified cotton fabric demonstrated excellent durable wrinkle-resistance and antibacterial activity against Staphylococcus aureus and Escherichia coli, even after 50 repeated launderings. Moreover the shrinkage-resistance of the modified cotton fabric was distinctly improved, and the contact angle was slightly larger, while the whiteness and mechanical properties had not changed in an obvious way.