In Situ Functionalization of Cellulose with Zinc Pyrithione for Antimicrobial Applications

Bacteria-responsive antimicrobial and hemostatic cellulose-based dressing for wound treatments

Microbial infection in open wounds can delay healing and lead to severe complications. This study introduces a bacterial-responsive cellulose-based fabric wound dressing (Fabric-PAC) with integrated antimicrobial and hemostatic functions. Fabric-PAC is chemically modified with polyphosphate (PolyP) and low-dose silver nanoparticles (AgNPs), and further functionalized with a phthalocyanine-based photosensitizer via supramolecular interactions on surface. Upon contact with bacteria, the photosensitizer is displaced, exposing PolyP to initiate blood coagulation and platelet-deriven tissue remodeling, promoting wound healing. Simultaneously, AgNPs are also exposed to provede sustained bacteriostasis. Moreover, the positively charged photosensitizer tightly attaches on the bacterial surface, and triggers the antimicrobial photodynamic effect upon illumination, rapidly eliminating pathogens. This study not only introduces a bacteria-responsive wound dressing with synergistic antimicrobial and hemostatic effects, but also offers a new strategy for the functionalization of cellulose-based materials.

Enhanced bactericidal performance of textiles through compound antimicrobial agents

This study aims to explore the essential functional requirements associated with controlling the proliferation of microbes in the domain of textiles used in public health areas. Herein, three antimicrobial agents, specifically iodopropylbutylcarbamate (IPBC), 1-hydroxypyridine-2-thioketone zinc (ZPT), and 2-octyl-3-isothiazolinone (OIT), were chosen for fabric finishing based on their notable effectiveness, minimal toxicity, cost-efficiency, and chemical stability. Utilizing Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) as representative bacterial strains, the Minimum Inhibitory Concentration (MIC50) of individual and combined antimicrobial agents was measured, and their antimicrobial effectiveness was rigorously evaluated. Concurrently, the antimicrobial effectiveness, whiteness, and mechanical durability of the fabric following antimicrobial treatment were thoroughly examined. The results demonstrate that some combinations of the three antimicrobial agents elicit additive effects on both S. aureus and E. coli. Notably, at an equivalent ratio of IPBC, ZPT, and OIT and a total concentration of 0.2 wt. %, the inhibition rates against both bacterial strains surpass 99%. Upon application to nylon fabric, the treated material demonstrates significant antimicrobial properties, with minimal reduction observed in the whiteness and tensile strength of the treated nylon. This study provides practicable strategies relevant to the production of textiles endowed with antimicrobial properties.

Scalable phosphorylated cellulose production with improved environmental sustainability, crosslinkability and processability using 3D bioprinting for dye remediation

In the present work, phosphorylated cellulose (PC) gel has been produced following an environmentally benign approach using agro-based chemicals with improved yield. The PC gels produced were transparent, negatively charged with high consistency, charge content (1133.33 mmol/kg), degree of substitution (DS) of 0.183 and increased yield (>87 %). The XPS and EDS analysis confirms the covalently bonded phosphate groups at weight percent of 9.42 % and 11.01 %, respectively. The life cycle assessment (LCA) shows that PC gel production via the phosphorylation route is an ecologically favourable strategy compared with traditional TEMPO oxidation, resulting in 1.67 times lower CO2 emission. The rheological studies of PC gels show shear-thinning behaviour with improved 3D printability followed by heat-induced crosslinking of phosphate groups. The mechanistic insights for the condensation of phosphate to form a phosphoric ester group during cross-linking were evaluated through 31P solid-state NMR and XPS studies. Interestingly, the 3D-printed structures showed high structural stability under both compression and tensile load in both dry and wet conditions, with high water absorption (5408.33 %) and swelling capacity of 700 %. The structures show improved methylene blue (MB) remediation capabilities with a maximum removal efficiency of 99 % for 10-200 mg/L and more than seven times reusability. This work provides a green, facile and energy-efficient strategy for fabricating PCs with easy processability through additive manufacturing techniques for producing value-added products, opening up new avenues for high-performance applications.

Male Reproductive Toxicity of Antifouling Chemicals: Insights into Oxidative Stress-Induced Infertility and Molecular Mechanisms of Zinc Pyrithione (ZPT)

Zinc pyrithione (ZPT), a widely utilized industrial chemical, is recognized for its versatile properties, including antimicrobial, antibacterial, antifungal, and antifouling activities. Despite its widespread use, recent research has shed light on its toxicity, particularly towards the male reproductive system. While investigations into ZPT's impact on male reproduction have been conducted, most of the attention has been directed towards marine organisms. Notably, ZPT has been identified as a catalyst for oxidative stress, contributing to various indicators of male infertility, such as a reduced sperm count, impaired sperm motility, diminished testosterone levels, apoptosis, and degenerative changes in the testicular tissue. Furthermore, discussions surrounding ZPT's effects on DNA and cellular structures have emerged. Despite the abundance of information regarding reproductive toxicity, the molecular mechanisms underlying ZPT's detrimental effects on the male reproductive system remain poorly understood. This review focuses specifically on ZPT, delving into its reported toxicity on male reproduction, while also addressing the broader context by discussing other antifouling chemicals, and emphasizing the need for further exploration into its molecular mechanisms.

Toxic effects and potential mechanisms of zinc pyrithione (ZPT) exposure on sperm and testicular injury in zebrafish

Zinc pyrithione (ZPT) is widely recognized for its beneficial properties as an antifouling, antibacterial, and antifungal agent. Despite its positive industrial contributions, ZPT has been proven to exhibit toxicity towards various ecosystems, particularly affecting marine life. However, there is still a dearth of comprehensive research on ZPT toxicity and its toxicological mechanism in reproductive systems of aquatic organisms. In our study, we conducted a thorough analysis and unveiled a multitude of abnormalities in zebrafish sperm and testicular tissue caused by ZPT exposure, including a dose-dependent diminishing of testosterone levels, various sperm deformities, decreased sperm concentration and motility, and ROS-induced testicular tissue DNA damage. In addition, our study suggested that ZPT-induced testicular damage is associated with heightened oxidative stress, apoptosis, and possible hyperpolarization of the mitochondrial membrane. Through RNA-seq analysis, a total of 409 DEGs associated with ZPT-induced testicular injury were identified, and the hub gene was determined using a protein-protein interaction network (PPI). The genes and pathways uncovered in this study point to potential mechanisms of ZPT exposure on sperm and testicular injury in zebrafish.

Valorization of food waste into short-chain fatty acids via enzymatic pretreatment: Effects of fermentation-pH on acid-producing processes and microbial metabolic functions

Food waste (FW) has been widely considered as an essential resource for the production of short-chain fatty acids (SCFAs), an important class of chemicals with wide applications and over 20 million tons of annual market demand, by anaerobic fermentation. Although enzymatic pre-treatment could improve the FW biodegradation efficiency, resulting in enhanced efficiency of solubilization and hydrolysis, the influence of fermentation-pH on the SCFAs production and the metabolic functions, have rarely been reported. This study demonstrated that the uncontrolled pH could efficiently lead to an increase in the SCFAs production (33011 mgCOD/L) during long-term fermentation of FW (mainly consisting of 48.8% carbohydrates, 20.6% proteins, and 17.4% lipids) after enzymatic pre-treatment compared to the control (16413 mgCOD/L). Meanwhile, the acid-producing processes (i.e., solubilization, hydrolysis, and acidification) were synchronously enhanced by the enzymatic pre-treatment and no control over fermentation-pH. Metagenomic analysis revealed that the acid-forming microorganisms (i.e., Olsenella sp. and Sporanaerobacter) were significantly accumulated, and the corresponding genetic expressions related to extracellular hydrolysis (i.e., aspB and gltB), membrane transport (i.e., metL and glnH), and intracellular material metabolism (i.e., pfkA and ackA) were evidently stimulated, thereby promoting ultimate SCFAs generation. Although the alkaline conditions could further slightly increase the SCFAs yield slightly (37100 mgCOD/L) and also stimulate the metabolic activities, it might not be suitable for large-scale practical applications due to additional costs associated with alkaline chemical additives.

Zinc pyrithione induced volatile fatty acids promotion derived from sludge anaerobic digestion: Interrelating the affected steps with microbial metabolic regulation and adaptive responses

The massive use of zinc pyrithione (ZPT, as broad-spectrum bactericides) resulted in its high levels in waste activated sludge (WAS) and affected subsequent WAS treatment. This work revealed the effects of ZPT on the volatile fatty acids (VFAs) during WAS anaerobic digestion, in which VFAs yield was enhanced by approximately 6-9 folds (from 353 mg COD/L in control to 2526-3318 mg COD/L with low level of ZPT (20-50 mg/g TSS)). The ZPT occurred in WAS enabled the acceleration of solubilization, hydrolysis and acidification processes while inhibited the methanogenesis. Also, the low ZPT contributed to the enrichment of functional hydrolytic-acidifying microorganisms (e.g., Ottowia and Acinetobacter) but caused the reduction of methanogens (e.g., Methanomassiliicoccus and Methanothrix). Meta-transcriptomic analysis demonstrated that the critical genes relevant to extracellular hydrolysis (i.e. CLPP and ZapA), membrane transport (i.e. gltI, and gltL), substrates metabolisms (i.e. fadj, and acd), and VFAs biosynthesis (i.e. porB and porD) were all upregulated by 25.1-701.3% with low level of ZPT. Specifically, the ZPT stimulus on amino acids metabolism for VFAs transformation was prominent over carbohydrates. Moreover, the functional species enabled to regulate the genes in QS and TCS systems to maintain favorable cell chemotaxis to adapt the ZPT stress. The cationic antimicrobial peptide resistance pathway was upregulated to blunt ZPT with the secretion of more lipopolysaccharide and activate proton pumps to maintain ions homeostasis to antagonize the ZPT toxicity for high microbial activities, the abundance of related genes was up-regulated by 60.5 to 524.5%. This work enlightened environmental behaviors of emerging pollutants on WAS anaerobic digestion process with interrelations of microbial metabolic regulation and adaptive responses.

A Flexible Anti-Biofilm Hygiene Coating for Water Devices

Biofilm is a microbiome complex comprising different bacterial colonies that typically adhere to device surfaces in water, which causes serious medical issues such as indwelling infections and outbreaks. Here, we developed a non-nanoparticle, flexible anti-biofilm hygiene coating consisting of lithocholic acid (LCA), zinc pyrithione (Zn), and cinnamaldehyde (Cn) (named as LCA-Zn-Cn) that largely prevents the bacteria adhesion to various water device surfaces such as stainless steel and glass through a synergistic mechanism. The existing chelated groups on LCA and Cn attract plenty of bacteria via hydrophobic interaction. Both the bactericidal reaction by grafting biocidal groups from both LCA and Cn and the bacteriostatic reaction by inhibiting cell division via zinc ions (Zn) lead to a largely improved bacteria/biofilm prevention. The antibacterial performance was assessed by using the JIS Z 2801/ISO 22196 method. The designed LCA-Zn-Cn coating displayed log₁₀ reduction of 4.23 (99.9% reduction) of E. coli and log₁₀ reduction of 3.51 (99.8% reduction) of E. faecalis on stainless steel, which are much higher than the control samples, demonstrating a promising colonization inhibition. In parallel, the polysulfone encapsulated beads also showed >99% reduction efficiency in batch and >97-98% reduction efficiency in continuous column tests using the Lake Michigan water. Due to the strong cross-linked configuration, the coating still showed >90.9% bacterial reduction after 3000 abrasion cycles and over 99.9% bacteria reduction after a high flow velocity of 1.99 m/s test, which confirmed the enhanced mechanical durability. By applying either spray or dip-coating, the designed polymer composite can be coated on a variety of irregular water devices with mass production using an auto-controlled robot arm.

Recent Trends in Protective Textiles against Biological Threats: A Focus on Biological Warfare Agents

The rising threats to worldwide security (affecting the military, first responders, and civilians) urge us to develop efficient and versatile technological solutions to protect human beings. Soldiers, medical personnel, firefighters, and law enforcement officers should be adequately protected, so that their exposure to biological warfare agents (BWAs) is minimized, and infectious microorganisms cannot be spread so easily. Current bioprotective military garments include multilayered fabrics integrating activated carbon as a sorptive agent and a separate filtrating layer for passive protection. However, secondary contaminants emerge following their accumulation within the carbon filler. The clothing becomes too heavy and warm to wear, not breathable even, preventing the wearer from working for extended hours. Hence, a strong need exists to select and/or create selectively permeable layered fibrous structures with bioactive agents that offer an efficient filtering capability and biocidal skills, ensuring lightweightness, comfort, and multifunctionality. This review aims to showcase the main possibilities and trends of bioprotective textiles, focusing on metal-organic frameworks (MOFs), inorganic nanoparticles (e.g., ZnO-based), and organic players such as chitosan (CS)-based small-scale particles and plant-derived compounds as bioactive agents. The textile itself should be further evaluated as the foundation for the barrier effect and in terms of comfort. The outputs of a thorough, standardized characterization should dictate the best elements for each approach.