Positively-charged microcrystalline cellulose microparticles: Rapid killing effect on bacteria, trapping behavior and excellent elimination efficiency of biofilm matrix from water environment

Sandwich-structured continuous ZIF-8/Ti3C2 MXene/ZIF-8 for efficient sterilization: Enhanced photocatalytic activity, photothermal effect, and environmental safety

The development of effective water purification systems is crucial for controlling and remediating environmental pollution, especially in terms of sterilization. Herein, we demonstrate elaborately designed composite nanosheets with a sandwich structure, composed of two-dimensional (2D) Ti3C2 MXene nanosheet core and conformal ZIF-8 ultrathin outer layers, and their potential applications in photocatalytic sterilization. The study results indicate that the conformal ZIF-8-MXene nanosheet exhibits an expanded light absorption range (826 nm), improved photothermal conversion efficiency (6.2 °C s-1), and photocurrent response, thus boosting photocatalytic sterilization efficiency (6.63 log10 CFU mL-1) against Escherichia coli under simulated sunlight within 90 min. Interestingly, 2D ZIF-8 layers exhibit positive zeta potential (19 mV), good hydrophilicity (40.6°), and local photogenerated-hole accumulation, possessing efficient bacteria-trapping efficiency. Membrane filters fabricated from optimized composite nanosheets exhibit an outstanding bacteria-trapping and sterilization efficiency (almost 100 %) against Escherichia coli under simulated sunlight within 30 min of the flow photocatalytic experiments. This work not only presents a rational structural design of the conformal and ultrathin anchoring of ZIF-8 onto a 2D conductive material for bacteria-trapping and sterilization, but also opens new opportunities for using metal-organic frameworks in photocatalytic disinfection of drinking water.

Microbial inactivation of pressure spray combined with high-voltage electrospray and its application in honey raspberry juice

Pressure spray combined with high-voltage electrospray (PS-ES) has garnered considerable interest as a novel, non-thermal approach for microbial inactivation and preservation of liquid food. This study compared PS-ES with heat treatment (HT) to understand its inactivation mechanism against E. coli and S. aureus in a simulated system. Microbial activity, cell permeability, membrane integrity, membrane potential, and cell membrane structure were assessed. Furthermore, the impact of PS-ES treatment on microbial activity and flavor in honey raspberry juice, was examined. The changes in microbial growth and color during storage were also discussed. The experimental findings revealed that PS-ES treatment effectively reduced the number of E. coli and S. aureus by 1.99 and 1.83 log colony-forming units (CFU/mL). Additionally, it disrupted the integrity of bacterial cell membranes increasing their permeability, which led to the release of cellular proteins and nucleic acids. PS-ES treatment lowered the membrane potential and altered the structure of bacterial proteins. Application of PS-ES in honey raspberry juice reduced bacterial counts from 4.48 log CFU/mL to 1.99 log CFU/mL, with less flavor deterioration compared to HT treatment. After 30 days of storage at 4 °C and room temperature, PS-ES effectively controlled the growth of microorganisms in raspberry juice and maintained the color of the juice.

Chitosan modified magnetic nanocomposite for biofilm destruction and precise photothermal/photodynamic therapy

Getting rid of the biofilms is a major challenge when treating skin and soft tissue infections (SSTI), an inflammatory illness brought on by bacteria. Traditional magnetic materials have a limited dispersibility and a biofilm permeable property, making it challenging to remove biofilms and causing infection to linger. To solve these problems, we developed a kind of magnetic composite nanoplatform coated with indocyanine green carbon dots and modified with chitosan modification (Fe-ICGCDs@CS). Fe-ICGCDs@CS has high dispersibility and improves the conductivity of biofilms under magnetic action. Fe-ICGCDs@CS can adsorb bacteria via the positive charge and achieve precise photothermal sterilization and photodynamic therapy (PDT). Moreover, by catalyzing hydrogen peroxide (2 mM), Fe-ICGCDs@CS can produce oxygen to relieve the anoxic state in the deep layer of biofilms and activate dormant bacteria to make them sensitive to external stimuli. All in all, unlike the common "just kill" sterilization model, Fe-ICGCDs@CS can accurately kill bacteria and be recovered by an external magnetic field at the end of treatment, thus reducing the potential biological toxicity of nanomaterials. Therefore, the proposed Fe-ICGCDs@CS provides a new antibacterial method with low biotoxicity for clinical application in the treatment of biofilm infections.

Phage Lytic Protein CHAPSH3b Encapsulated in Niosomes and Gelatine Films

Antimicrobial resistance (AMR) has emerged as a global health challenge, sparking worldwide interest in exploring the antimicrobial potential of natural compounds as an alternative to conventional antibiotics. In recent years, one area of focus has been the utilization of bacteriophages and their derivative proteins. Specifically, phage lytic proteins, or endolysins, are specialized enzymes that induce bacterial cell lysis and can be efficiently produced and purified following overexpression in bacteria. Nonetheless, a significant limitation of these proteins is their vulnerability to certain environmental conditions, which may impair their effectiveness. Encapsulating endolysins in vesicles could mitigate this issue by providing added protection to the proteins, enabling controlled release, and enhancing their stability, particularly at temperatures around 4 °C. In this work, the chimeric lytic protein CHAPSH3b was encapsulated within non-ionic surfactant-based vesicles (niosomes) created using the thin film hydrating method (TFH). These protein-loaded niosomes were then characterized, revealing sizes in the range of 30-80 nm, zeta potentials between 30 and 50 mV, and an encapsulation efficiency (EE) of 50-60%. Additionally, with the objective of exploring their potential application in the food industry, these endolysin-loaded niosomes were incorporated into gelatine films. This was carried out to evaluate their stability and antimicrobial efficacy against Staphylococcus aureus.

Effect of high-voltage electrospray on the inactivation, induced damage and growth of microorganisms and flavour components of honey raspberry wine

Electrospray (ES) is a new non-thermal processing technology for pasteurising liquid foods. This study aimed to investigate the effects of ES on the cell structure and function of Saccharomyces cerevisiae, Escherichia coli and Staphylococcus aureus and then compare the effects of ES and heat treatment (HT) on microbial inactivation and flavour composition in honey raspberry wine. First, we found that the inactivation effect of ES treatment on the three microorganisms was significantly influenced by the voltage intensity. The degree of damage to the cellular structures and functions of the three microorganisms increased with increasing voltage. Second, the environment in which the microorganisms were present significantly influenced the ES pasteurisation effect. Pasteurisation by ES was better when the three microorganisms were in honey raspberry wine than in saline. Finally, the total number of colonies in honey raspberry wine was reduced from 4.50 to 2.03 log colony forming units/mL after ES treatment, and the wine had good stability during storage (84 days at 4 °C). In the honey raspberry wine, the contents of the main flavour substances (ketones and esters) did not change significantly after ES treatment, but HT decreased the content of esters and ketones by 13.5 % and 75.4 %, respectively.

Improvement of Antibacterial and Antifouling Properties of a Cellulose Acetate Membrane by Surface Grafting Quaternary Ammonium Salt

Through etherification reaction, epoxy propyl dimethyl dodecyl ammonium chloride (EPDMDAC) was grafted onto the surface of a cellulose acetate (CA) membrane to prepare a stable nonleaching antibacterial antifouling membrane (QCA-X). The results showed that with the extension of grafting reaction time, the quaternary ammonium salt groups on the membrane surface increased and the hydrophilicity was enhanced. Compared with those of the CA membrane, the filtration capacity and antifouling performance of the QCA-X membrane are improved. When the grafting time is 4 h, the water permeability and flux recovery rate of the QCA-4 membrane are increased by 139 and 21.5%, respectively. The QCA-X membrane showed excellent antibacterial performance, and the sterilization rate against S. aureus and E. coli was more than 99.99%. After four repeated antibacterial cycles, the bactericidal rates against S. aureus and E. coli were maintained at about 99.69 ± 0.02 and 99.98 ± 0.02%, respectively, with good antibacterial persistence. Moreover, the QCA-X membrane can effectively inhibit bacterial adhesion. Mild and simple EPDMDAC grafting modifications improve the antibacterial, antifouling, and antibioadhesion properties of the CA membrane, showing its application potential in long-term water treatment, especially in biofouling water treatment.

Polyhexamethylene guanidine hydrochloride modified sodium alginate nonwoven with potent antibacterial and hemostatic properties for infected full-thickness wound healing

The development of multifunctional wound dressings has always been considered as a promising strategy to promote blood coagulation, inhibit bacterial infection, and accelerate wound healing. Herein, an antibacterial and hemostatic dressing (SA-PHMG) was developed based on sodium alginate (SA) nonwoven and polyhexamethylene guanidine hydrochloride (PHMG) through a completely green industrial route, including dipping, padding, and drying. According to studies, SA-PHMG dressings exhibited excellent liquid absorption capacity and water vapor permeability. Moreover, bactericidal assays have demonstrated that SA-PHMG dressings have ideal antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and mixed bacteria, maintaining potent antibacterial activity even after 10 cycles of antibacterial trials or 50 times of washing or soaping. The in vitro evaluation of the hemostatic effect indicated that the SA-PHMG could significantly promote blood clotting by activating platelets, and in vitro and in vivo hemolysis, cytotoxicity and skin irritation studies demonstrated the ideal biocompatibility of the dressings. In addition, better wound closure and tissue regeneration were recorded using SA-PHMG nonwoven as the dressing based on an infected full-thickness wound model. In conclusion, this antibacterial, hemostatic, biocompatible, and environmentally friendly SA-PHMG nonwoven exhibit the potential for infected wound healing.

Modification strategies of membranes with enhanced Anti-biofouling properties for wastewater Treatment: A review

This review addresses composite membranes used for wastewater treatment, focusing heavily on the anti-biofouling properties of such membranes. Biofouling caused by the development of a thick biofilm on the membrane surface is a major issue that reduces water permeance and reduces its lifetime. Biofilm formation and adhesion are mitigated by modifying membranes with two-dimensional or zero-dimensional carbon-based nanomaterials or their modified substituents. In particular, nanomaterials based on graphene, including graphene oxide and carbon quantum dots, are mainly used as nanofillers in the membrane. Functionalization of the nanofillers with various organic ligands or compositing the nanofiller with other materials, such as silver nanoparticles, enhances the bactericidal ability of composite membranes. Moreover, such membrane modifications reduce biofilm adhesion while increasing water permeance and salt/dye rejection. This review discusses the recent literature on developing graphene oxide-based and carbon quantum dot-based composite membranes for biofouling-resistant wastewater treatment.