Use In Antimicrobial Applications Research Articles

Self‐Degradable Photoactive Micromotors for Inactivation of Resistant Bacteria

AbstractPathogenic bacteria pose a significant threat to human health, and their removal from food and water supplies is crucial in preventing the spread of waterborne and foodborne diseases. Recently, silver‐based photocatalytic micromotors have emerged as promising candidates for inactivating pathogenic microbes due to their high antibacterial activity. In this study, the synthesis of photoactive Ag3PO4 micromotors with a well‐defined tetrapod‐like structure (TAMs) is presented using a simple precipitation method. These TAMs autonomously move and release Ag ions/nanoparticles (NPs) through a photodegradation process when exposed to light, which enhances their antimicrobial activity against Gram‐negative (Escherichia coli) and Gram‐positive (Staphylococcus aureus) bacterial strains. Interestingly, different motion modes are observed under different manipulated light wavelengths and fuels. Furthermore, the self‐degradation of TAMs is accelerated in the presence of negatively charged bacteria, which results in higher removal rates of both bacteria, E. Coli and S. aureus. The findings introduce a new concept of self‐degradable micromotors based on photocatalytic components, which hold great potential for their use in antimicrobial applications. This work offers significant implications for materials chemistry, especially in designing and developing the next generation of light‐driven antimicrobial agents.

Synthesis and Characterization of Functionalized Starch by Grafting Pyridine for Use in Antimicrobial Applications

AbstractThe urgent need for new, efficient solutions to antibiotic resistance is a serious worldwide healthcare concern. Recently, new classes of antimicrobials known as antimicrobial polymers have played a significant role in tackling multidrug‐resistant bacteria. To achieve this purpose, antimicrobial biodegradable materials made from affordable renewable resources, including polysaccharides, are extensively applied. Here, this study presents a simple one‐pot method for generating powerful antimicrobial polymer using soluble starch and an easily accessible chemical pyridine. The quaternary pyridine‐grafted starch (St‐QP) is prepared and characterized using structural and thermal techniques. To assess the antimicrobial capabilities of the St‐QP for textile application, antimicrobial activities of the St‐QP, antimicrobial activity of the St‐QP‐coated fabric, cytotoxicity, durability of the St‐QP coated fabric, surface morphology of St‐QP coated fabric and antimicrobial activity after washing cycles are also examined. According to the findings, St‐QP and its modified materials have shown good antimicrobial activity against three bacteria, Staphylococcus aureus, Escherichia coli, and Mycobacterium smegmatis, and the fungus Candida albicans. The St‐QP displays low toxicity to human fibroblasts, and after being coated on fabrics, it shows good durability and antimicrobial activity. The St‐QP coated fabric material shows 80% inhibition for all four microorganisms even after 25 washing cycles.

Photocatalytic and Antibacterial Activities of a Nickel(II)-Bipyridine Complex-Modified Graphene Oxide Nanocomposite: Synthesis and Characterization

In this study, we aimed to synthesize and characterize a nickel(II) complex-modified graphene oxide (Ni-GO) nanocomposite with enhanced photocatalytic and antimicrobial properties. The nanocomposite was prepared through a modified Hummer’s method, followed by an adsorption technique using the precursor complex [Ni(bipy)3]Cl2·5H2O, which was preferentially adsorbed onto the graphene oxide (GO) surface. The surface interaction between the nickel complex ions and GO was characterized using various analytical techniques, including FTIR, XRD, SEM-EDX, DRS, and XPS analyses. Photoluminescence analysis demonstrated the fluorescence property of the prepared composite. The DRS spectra indicated that the adsorption of composite particles extended to the visible region, making it excitable by visible light. The photocatalytic activity of the Ni-GO nanocomposite was tested by studying the degradation of an organic model pollutant, Rhodamine B dye, under real sunlight irradiation. The introduction of the Ni(II) complex onto the GO surface matrix intensified the photocatalytic property, making it more efficient under direct sunlight exposure. Comparisons with pristine graphite and GO revealed that Ni-GO exhibited enhanced photocatalytic potential. Additionally, we have evaluated the antimicrobial property of the Ni(II) complex-modified GO against Klebsiella pneumoniae. The results demonstrated that both the Ni(II) precursor complex and Ni-GO nanocomposite possessed an excellent antimicrobial efficacy, suggesting their potential use in antimicrobial applications. The synthesis and characterization of the Ni(II) complex-modified GO nanocomposite presented in this study showed promising results for both ameliorative photocatalytic and antimicrobial activities. These findings indicated the potential utility of Ni-GO as an efficient photocatalyst and antimicrobial agent, surpassing the performance of pristine graphite and GO. This research opens up new avenues for the development of advanced nanocomposites with diverse applications in environmental remediation and biomedical fields.

Synthesis and Assessment of Antimicrobial Composites of Ag Nanoparticles or AgNO3 and Egg Shell Membranes.

Engineering research has been expanded by the advent of material fusion, which has led to the development of composites that are more reliable and cost-effective. This investigation aims to utilise this concept to promote a circular economy by maximizing the adsorption of silver nanoparticles and silver nitrate onto recycled chicken eggshell membranes, resulting in optimized antimicrobial silver/eggshell membrane composites. The pH, time, concentration, and adsorption temperatures were optimized. It was confirmed that these composites were excellent candidates for use in antimicrobial applications. The silver nanoparticles were produced through chemical synthesis using sodium borohydride as a reducing agent and through adsorption/surface reduction of silver nitrate on eggshell membranes. The composites were thoroughly characterized by various techniques, including spectrophotometry, atomic absorption spectrometry, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, as well as agar well diffusion and MTT assay. The results indicate that silver/eggshell membrane composites with excellent antimicrobial properties were produced using both silver nanoparticles and silver nitrate at a pH of 6, 25 °C, and after 48 h of agitation. These materials exhibited remarkable antimicrobial activity against Pseudomonas aeruginosa and Bacillus subtilis, resulting in 27.77% and 15.34% cell death, respectively.

Novel Microwave Synthesis of Copper Oxide Nanoparticles and Appraisal of the Antibacterial Application

The exceptional characteristics of bio-synthesized copper oxide nanoparticles (CuO NPs), including high surface-to-volume ratio and high-profit strength, are of tremendous interest. CuO NPs have cytotoxic, catalytic, antibacterial, and antioxidant properties. Fruit peel extract has been recommended as a valuable alternative method due to the advantages of economic prospects, environment-friendliness, improved biocompatibility, and high biological activities, such as antioxidant and antimicrobial activities, as many physical and chemical methods have been applied to synthesize metal oxide NPs. In the presence of apple peel extract and microwave (MW) irradiation, CuO NPs are produced from the precursor CuCl2. 2H2O. With the help of TEM analysis, and BET surface area, the average sizes of the obtained NPs are found to be 25-40 nm. For use in antimicrobial applications, CuO NPs are appropriate. Disk diffusion tests were used to study the bactericidal impact in relation to the diameter of the inhibition zone, and an intriguing antibacterial activity was confirmed on both the Gram-positive bacterial pathogen Staphylococcus aureus and Gram-negative bacterial pathogen Escherichia coli. Moreover, CuO NPs did not have any toxic effect on seed germination. Thus, this study provides an environmentally friendly material and provides a variety of advantages for biomedical applications and environmental applications.

Green synthesis of Ag-doped ZnO using Nelumbo nucifera flower extract for antibacterial activity

A straightforward, environmentally friendly approach for creating Ag-doped ZnO was developed using Nelumbo nucifera flower extract as a reducing agent. Antibacterial activity is measured alongside structural, morphological, and basic optical characterization of produced nanoparticles using Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and a UV–visible spectrophotometer. FESEM validates the sponge-like composition of the nanostructures. Utilizing the well diffusion technique, the antibacterial activity is assessed for different human pathogenic microorganisms (Pseudomonas aeruginosa and Staphylococcus aureus). Nanostructures showed maximum inhibition zone against gram negative than gram positive Staphylococcus aureus than gram negative Pseudomonas aeruginosa. The current study provided a plausible approach to designing nanostructures with useful features for use in antimicrobial applications.

Influence of bacterial culture medium on peptidoglycan binding of cell wall lytic enzymes

The bacteriolysin lysostaphin (Lst) and endolysin PlyPH are potent modular lytic enzymes with activity against clinically-relevant Gram-positive Staphylococcus aureus and Bacillus cereus, respectively. Both enzymes possess an N-terminal catalytic domain and C-terminal binding domain, with the latter conferring significant enzyme specificity. Lst and PlyPH show reduced activity in the presence of bacterial growth-supporting conditions, such as complex media. Here, we hypothesize that Lst and PlyPH bind poorly to their targets in growth media, which may influence their use in antimicrobial applications in the food industry, as therapeutics, and for control of microbial communities. To this end, binding of isolated Lst and PlyPH binding domains to target bacteria was quantified in the presence of three increasingly complex media – phosphate buffered saline (PBS), defined growth medium (AAM) and undefined complex medium (TSB) by surface plasmon resonance (SPR) and flow cytometry. Evaluation of binding kinetics by SPR demonstrated that PlyPH binding was particularly sensitive to medium composition, with 8-fold lower association and 3.4-fold lower dissociation rate constants to B. cereus in TSB compared to PBS. Flow cytometry studies indicated a decrease in the binding-dependent fluorescent populations of S. aureus and B. cereus, for lysostaphin binding domain and PlyPH binding domain, respectively, in TSB compared to PBS. Enzyme binding behavior was consistent with the enzymes’ catalytic activity in the three media, thereby suggesting that compromised enzyme binding could be responsible for poor activity in more complex growth media.

Zinc(ii) centered biologically active novel N,N,O donor tridentate water-soluble hydrazide-based O-carboxymethyl chitosan Schiff base metal complexes: synthesis and characterisation

In this study, novel eco-friendly and water-soluble chitosan Schiff base derivatives have been designed for potential use in antimicrobial applications.

Stimuli-Responsive Release of Antimicrobials Using Hybrid Inorganic Nanoparticle-Associated Drug-Delivery Systems.

Recently, the combination of metallic nanoparticles (NPs) of Au, Ag, Fe2 O3 , and Fe3 O4 with traditional soft matter drug-delivery systems has emerged as a promising strategy to achieve site-specific and controlled release of antimicrobial agents. By harnessing the plasmonic and magnetic properties of inorganic NPs, the disruption of antibiotic-loaded liposomes, polymersomes, and hydrogels can be remotely triggered by mechanisms such as photo- and magneto-thermal effects, microbubble cavitation, magnetic positioning, and pH-changes, hence offering significant advantages in improving antibacterial efficacy, reducing side effects, and in overcoming antimicrobial resistance. This review highlights the latest development of stimuli-responsive antibiotic delivery systems incorporating inorganic NPs. The methods employed for preparation of hybrid inorganic NP-associated drug-delivery systems and the effects this has upon the system are discussed. Finally, a detailed exposition of the NP-mediated triggering mechanisms is provided and pertinent examples of their use in antimicrobial applications are presented.

Antimicrobial electrospun ultrafine fibers from zein containing eucalyptus essential oil/cyclodextrin inclusion complex

The aim of this study was to produce ultrafine fibers from zein incorporated with a complex of eucalyptus essential oil (EEO) and β-cyclodextrin (β-CD) with antimicrobial properties by electrospinning technique. The EEO was characterized by chemical composition and antimicrobial tests against three Gram positive and four Gram negative bacteria. The inclusion complex (IC) was prepared with β-CD and EEO by co-precipitation technique and added at different concentrations in zein polymer solution using aqueous ethanol as solvent. The morphology, thermal properties, functional groups, and antimicrobial activity against L. monocytogenes and S. aureus of the ultrafine fibers were evaluated. The composite membranes containing 24% IC exhibited a greater reduction of growth as compared to the fibers without addition of IC. For L. monocytogenes the growth reduction was 28.5% and for S. aureus it was 24.3%. The electrospun IC-β-CD/EEO composite membranes are promising for use in antimicrobial applications, such as food packaging.

A study on the preparation of poly(vinyl alcohol) nanofibers containing silver nanoparticles

In this study, two practical methods for the facile and controlled preparation of poly(vinyl alcohol) (PVA) nanofibers containing Ag nanoparticles were investigated for use in antimicrobial applications. In the first method, PVA nanofibers containing Ag nanoparticles were successfully electrospun from PVA/silver nitrate (AgNO 3) aqueous solutions after first refluxing them. The Ag nanoparticles in the PVA/AgNO 3 aqueous solutions were generated by refluxing them. Interestingly, it was found that the Ag nanoparticles were also spontaneously generated during the electrospinning process. In the second method, Ag nanoparticles were generated by annealing the PVA nanofibers electrospun from PVA/AgNO 3 aqueous solutions. Residual Ag + ions and the Ag nanoparticles generated during the electrospinning process in the PVA nanofibers were diffused and aggregated into larger Ag nanoparticles during the annealing process. All of the Ag nanoparticles were sphere shaped and evenly distributed in the PVA nanofibers prepared by the two methods.