Efficient Antibacterial Activity Research Articles

Enhancing Strawberry Freshness: Multifunction Sustainable Films Utilizing Two Types of Modified Carbon Nanotubes for Photothermal Food Packaging.

Currently, antimicrobial films with stable and efficient antibacterial activities are receiving considerable attention in the food packaging industry. Herein, a chemically/physically linked konjac glucomannan-sodium alginate (KGM-SA)@carbon nanotubes (CNTs)/Fe3+ composite film with outstanding resistance to ultraviolet radiation, oxidation, and bacteria, as well as excellent photothermal effects and mechanical properties, was successfully prepared using a solvent flow method. Tannic acid-modified carboxyl-functionalized CNTs (TCCNTs), l-cysteine-modified carboxyl-functionalized CNTs (LCCNTs), and Fe3+ were incorporated into the prepared film. The film structure of KGM-SA@CNTs/Fe3+ was characterized using various methods, confirming the formation of a dual-cross-linked network through metal-coordination bonds and hydrogen bonding. This unique structure endowed the film with excellent water vapor permeability (3.58 g mm/m2 day kPa), water resistance (water contact angle = 93.66°), and thermal stability. Further, the film exhibited outstanding photothermal conversion efficiency and stability under near-infrared irradiation (300 mW/cm2) as well as excellent bactericidal properties against Staphylococcus aureus and Escherichia coli, achieving a bacterial inhibition rate of >99%. In a strawberry preservation experiment, the KGM-SA@CNTs/Fe3+ composite film exhibited remarkable preservation effects, extending the shelf life of strawberries by 4-6 d. Thus, this photothermal antibacterial film offers a new approach for the application of CNTs in food packaging.

Cu2O/H2Ti3O7/Cellulose biohybrid film with efficient photocatalytic and antibacterial activities in solar-driven environmental decontamination

Increasing efforts have been devoted to cellulose-based multifunctional biomaterials for environmental applications. In this study, solvothermal method combined with impregnation reduction process of Cu2+ has been developed to create versatile Cu2O/H2Ti3O7/CP (cellulose paper) biocomposite films that demonstrates efficacy in treating wastewater from organic compounds, disinfecting it from microbes and also purifying the air from volatile organic compounds (VOCs). H2Ti3O7 nanosheets decorated with Cu2O nanoparticles exhibit an excellent visible-light responsibility. Furthermore, the Cu2O/H2Ti3O7/CP biocomposite film demonstrated enhanced efficacy in removing aniline in the liquid phase and 1-propanol in the gaseous phase compared to the H2Ti3O7/CP. This enhanced photocatalytic activity is primarily due to the synergistic effect between Cu2O and H2Ti3O7, which suppresses the recombination of charge carriers and improves their mobility. Reuse tests confirm the stability of the prepared hybrid photocatalyst. Moreover, the biocomposite exhibits good antimicrobial properties, which contributed to the effective inactivation of Escherichia coli. This proves its versatility as a photocatalyst for a broad range of biological and environmental applications.

Antimicrobial peptide-based pH-responsive Polyvinyl alcohol hydrogel artificial vascular grafts with excellent antimicrobial and hematologic compatibility

Thrombosis and infection are the primary challenges limiting the clinical application of small-diameter artificial blood vessels. Numerous studies have focused on improving the hemocompatibility of artificial vascular materials, addressing properties such as anticoagulant activity, antithrombogenicity, low hemolysis rates, and reduced platelet adhesion. However, there has been comparatively less attention given to the antibacterial properties of these materials. This study utilizes polyester braided tubes and PVA/PAAm hydrogel materials, combined with surface modification techniques, to develop a pH-responsive antibacterial hydrogel artificial blood vessel graft. The hydrogel surface was grafted with a polymer brush hierarchical structure, and antimicrobial peptide MLT was immobilized to confer antibacterial properties. Additionally, 2,3-dimethylmaleic anhydride (DMMA) was covalently attached as a shielding group to achieve an environment-responsive strategy. The research demonstrates that this artificial blood vessel graft exhibits structural stability, excellent mechanical properties, and good cellular and hemocompatibility. Furthermore, it exhibits pH-responsive capabilities, triggering efficient antibacterial activity in low pH environments. The modified antibacterial hydrogel artificial blood vessel material shows low hemolysis rates, excellent anticoagulant properties, and reduced platelet adhesion. Therefore, the strategy of combining MLT with DMMA may effectively enhance the hemocompatibility and responsive antibacterial performance of artificial blood vessel materials.

Construction of acidic microenvironment by Cu-TCPP nanozyme composited deprotonatable polymeric nanofibers for efficient antibacterial activity

The issue of bacterial resistance caused by conventional antibiotics has emerged as a major challenge in clinical treatment. Nanozymes, based on catalysis and devoid of bacterial resistance, provide a novel approach to eradicating bacteria. However, the practical potential of these nanozymes is limited by their low and readily pH-affected catalytic activity. Herein, the enzyme activity was optimized starting from the synthesis of nanozyme and the selection of carboxylate-containing polymers for the matrix. Specifically, various copper-tetrakis (4-carboxyphenyl) porphyrin (Cu-TCPP) were initially synthesized employing three copper sources, and among them, Cu-TCPP derived from Cu2O with higher catalytic activity was preferred. Subsequently, Cu-TCPP composite fibrous membranes were further obtained by electrospinning from their blend solutions with different polymers with distinct deprotonation capabilities. Thus, an acidic microenvironment conducive to the exertion of enzyme activity was constructed. The fabricated composite nanofibrous membrane could dissociate hydrogen ions to construct a localized acidic microenvironment even under weakly alkaline conditions, thereby enhancing the enzyme activity and improving the antibacterial effect. Further in vivo experiments demonstrated its favorable antibacterial ability and accelerated wound healing effect. The enhancement strategy of enzyme activity in this study brings inspiration for the design of nanozyme composited wound dressings and holds significant potential for clinical antibacterial applications

The zinc transporter Slc30a1 (ZnT1) in macrophages plays a protective role against attenuated Salmonella.

The zinc transporter Slc30a1 plays an essential role in maintaining cellular zinc homeostasis. Despite this, its functional role in macrophages remains largely unknown. Here, we examine the function of Slc30a1 in host defense using mice models infected with an attenuated stain of Salmonella enterica Typhimurium and primary macrophages infected with the attenuated Salmonella. Bulk transcriptome sequencing in primary macrophages identifies Slc30a1 as a candidate in response to Salmonella infection. Whole-mount immunofluorescence and confocal microscopy imaging of primary macrophage and spleen from Salmonella-infected Slc30a1flag-EGFP mice demonstrate Slc30a1 expression is increased in infected macrophages with localization at the plasma membrane and in the cytosol. Lyz2-Cre-driven Slc30a1 conditional knockout mice (Slc30a1fl/fl;Lyz2-Cre) exhibit increased susceptibility to Salmonella infection compared to control littermates. We demonstrate that Slc30a1-deficient macrophages are defective in intracellular killing, which correlated with reduced activation of nuclear factor kappa B and reduction in nitric oxide (NO) production. Notably, the model exhibits intracellular zinc accumulation, demonstrating that Slc30a1 is required for zinc export. We thus conclude that zinc export enables the efficient NO-mediated antibacterial activity of macrophages to control invading Salmonella.

Green synthesis of silver nanoparticles using Lepidium sativum seed mucilage as a bioreductant/capping agent for efficient antibacterial and photocatalytic activities

Contamination of aquatic resources with organic dyes and pathogenic bacteria ranks among the most serious threats to human survival and the environment. The current work investigated L. sativum seed mucilage as a reducing and capping agent for Ag NPs. From UV–vis spectroscopy, the characteristic surface plasmon resonance peak and the band gap energy of as-fabricated NPs were 440 nm and 2.07 eV, respectively. SEM revealed irregular-shaped NPs with an average diameter of 73.85 nm and EDX disclosed Ag along with C, O, and Si from mucilage’s biomolecules. The antibacterial and antibiofilm results showed higher inhibitory effects against the Gram-positive (B. cereus) than the Gram-negative (E. coli, and E. aerogenes) bacteria. The biosynthesized NPs were impressive in degrading methylene blue (MB, 89.45 %) and methyl orange (MO, 84.78 %) under optimized conditions viz., dye solution (20 ppm), photocatalyst dose (5 mg), light intensity (UV index of 10 +), and irradiation time (120 min). The kinetic data strongly supported the pseudo-first order model with maximum adsorption capacities of 787.40 and 724.64 mg/g for MB and MO, respectively as determined through the Langmuir isotherm model. The photocatalyst exhibited sufficient stability even after six repeated cycles, highlighting its suitability for industrial and commercial applications.

Intelligent Hydrogel with Physiologically Dependent Capacities of Photothermal Conversion and Nanocatalytic Medicine to Integratively Inhibit Bacteria and Inflammation for On-Demand Treatment of Infected Wound.

Although chemodynamic therapy (CDT) and photothermal therapy (PTT) based on a variety of nanoparticles have been developed to achieve effective anti-bacterial therapy, the limited therapeutic efficiency of CDT alone, as well as the undifferentiated damage of PTT to both bacteria and surrounding healthy tissue are still challenges for their clinical application of infected wounds treatments. In addition, during the CDT and PTT-mediated antimicrobial processes, the endogenous macrophages would be easily converted to pro-inflammatory macrophages (M1 phenotype) under local ROS and hyperthermia to promote inflammation, resulting in unexpected suppression of tissue regeneration and possible wound deterioration. To address these problems, a biodegradable sodium alginate/hyaluronic acid hydrogel loaded with functional CeO2-Au nano-alloy (AO@ACP) is fabricated to not only achieve precise and efficient antibacterial activity through infection-environment dependent photothermal-chemodynamic therapy but also rapidly eliminate the excess reactive oxygens (ROS) in the M1 type macrophage at the infected area to induce their polarization to M2 type for significant inhibition of inflammation and remarkable enhancement of tissue regeneration, hopefully developing an effective strategy to treat infected wound.

Micro-nano bubbles in action: AC/TiO2 hybrid photocatalysts for efficient organic pollutant degradation and antibacterial activity

Developing highly active and sustainable photocatalysts is crucial for environmental remediation. This work focuses on the enhanced photocatalytic degradation efficiency of synthetic dyes using TiO2-coated AC hybrid photocatalysts under MNB aeration. The TiO2-coated AC hybrid photocatalyst (HP) was synthesized via a sol-gel method and characterized using XRD, FTIR, SEM, EDS, HR-TEM, and DRS. The study investigated the photocatalytic degradation of three dyes indigo carmine (IC), reactive black 5 (RB5), and methylene blue (MB) in wastewater, with initial dye concentrations ranging from 10 to 100 μM. Under UVA irradiation, the hybrid photocatalyst with MNB aeration (HP + UVA + MNB) achieved the highest degradation efficiencies of 69.09%, 60.06%, and 55.19% for IC, MB, and RB5, respectively. Further analysis showed that the chromophores and complex structures of these dyes were broken into intermediate products. The Langmuir-Hinshelwood kinetic model was used to describe the reaction mechanisms. The HP + UVA + MNB system demonstrated superior photocatalytic degradation activity, making it suitable for operational and environmental applications in dye wastewater treatment. Additionally, the antibacterial properties of AC and HP were tested at 100 μg/mL, showing effectiveness against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli.

A Facile and Safe Route to Fabricate Boscalid‐Loaded ZIF‐8 Nanoparticles With Efficient Antibacterial Activity and Long‐Sustained Release

ABSTRACTSynthesis of ZIF‐8 mainly uses zinc nitrate hexahydrate (Zn(NO3)2.6H2O) as the zinc source. Zn (NO3)2.6H2O is flammable, explosive, and highly corrosive, posing a threat to human health. It also requires a molar ratio of 2‐methylimidazole to zinc source greater than 20, resulting in increased costs. In this work, a pH‐sensitive controlled‐release nano‐capsule of fungicide, ZIF‐8@Boscalid, was established using green zinc sources (zinc sulfate and zinc acetate) and was prepared based on metal–organic framework (ZIF‐8) for higher antifungal effect and low bio‐toxicity. The loading ratio is as high as 34%. In addition, the release of fungicide Boscalid showed pH‐sensitive response due to the weak acidic group in the ZIF structure, in which the rate of release was more rapid under acid condition (< 5). Cumulative release rates of the ZIF‐8(A)@Boscalid system and ZIF‐8(S)@Boscalid system were 76.15% and 86.22%, respectively. Meanwhile, the antifungal effect of ZIF‐8@Boscalid was 1.5 times more of that commercially available product on CI‐8 at the concentration of 300 mg/L, and the antibacterial activity values of the ZIF‐8(A)@Boscalid system and ZIF‐8(S)@Boscalid system against CJ‐8 were 84.54% and 78.65%, respectively. Furthermore, the obtained ZIF‐8@Boscalid system using the method described in this article exhibited certain UV resistance. Thus, this work not only proves that ZIF‐8@Boscalid could be used as nanoparticles platform for smart control over CJ‐8 but also has great potential effective utilization of Boscalid and achieving sustained release.

Highly efficient and broad-spectrum antibacterial carbon dots combat antibiotic resistance

Bacterial infections have become a major global public health issue, particularly with the emergence of multidrug-resistant strains. Therefore, developing non-antibiotic antimicrobial agents is crucial for treating drug-resistant bacterial infections. Building on previous research into natural products as novel antibacterial agents, this study synthesized curcumin-derived carbon dots using curcumin and ethylenediamine as raw materials through a hydrothermal method. The resulting carbon dots not only improved the water solubility and stability of curcumin but also exhibited highly efficient broad-spectrum antibacterial activity. Detailed investigations into the antibacterial performance and mechanisms of the carbon dots were conducted through experiments such as minimum inhibitory concentration (MIC) determination, live/dead bacterial staining, morphological studies, nucleic acid concentration detection, and reactive oxygen species (ROS) detection. The results indicated that the carbon dots significantly damaged the structural integrity of bacteria and generated large amounts of ROS. They exhibited remarkable antibacterial effects against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, and effectively inhibited drug-resistant MRSA. Their antibacterial efficacy was notably superior to that of broad-spectrum antibiotics such as chloramphenicol and Sulfadiazine. This study highlights the potential application of curcumin-derived carbon dots in combating bacterial infections and provides valuable insights for developing novel antibacterial agents derived from natural products.

Near-Infrared Carbon Dots With Antibacterial and Osteogenic Activities for Sonodynamic Therapy of Infected Bone Defects.

Repairing infected bone defects is hindered by the presence of stubborn bacterial infections and inadequate osteogenic activity. The incorporation of harmful antibiotics not only fosters the emergence of multidrug-resistant bacteria, but also diminishes the osteogenic properties of scaffold materials. In addition, it is essential to continuously monitor the degradation kinetics of scaffold materials at bone defect sites, yet the majority of bone repair materials lack imaging capability. To address these issues, this study reports for the first time the development of a single nanomaterial with triple functionality: efficient sonodynamic antibacterial activity, accelerated bone defect repair capability, and NIR imaging ability for visualized therapy of infected bone defects. Through rationally regulating the surface functional groups, the obtained multifunctional NIR carbon dots (NIR-CD) exhibit p-n junction-enhanced sonodynamic activity, narrow bandgap-facilitated NIR imaging capability, and negative charge-augmented osteogenic activity. The validation of NIR-CDs antibacterial and osteogenic activities in vivo is conducted by constructing 3D injectable hydrogels encapsulated by NIR-CDs (NIR-CD/GelMA). The implantation of multifunctional NIR-CD/GelMA hydrogel scaffolds in a model of MRSA-infected craniotomy defects results in almost complete restoration of the infected bone defects after 60 days. These findings will provide traceable, renewable, repairable and antibacterial candidate biomaterials for bone tissue engineering.

Organosilica with tunable pore structure and antibacterial activity for intelligent humidity control

The spontaneous sorption and release of moisture by sorbents is proposed to be an energy-saving strategy for air humidity control. However, rational design of sorbents with humidity control ability and wide applicability still faces challenges. This study demonstrates quaternary ammonium-functionalized organosilica capable of controlling humidity intelligently and tuning humidity range as required. The prepared organosilica exhibited step-shaped water sorption isotherm due to its highly ordered pore structure, which was capable of precisely maintaining humidity within a narrow range. Importantly, the step position could be broadly tuned by easily changing the pore size during synthesis. Series organosilica with different pore sizes could realize humidity maintenance in 20%-40%, 40%-60% and 55%-80%, respectively, making it suitable for diverse humidity control applications. Grand Canonical Monte Carlo simulations elucidated the underlying mechanism of different water sorption behaviors in different pore structures. Quaternary ammonium groups act as the initial nucleation sites for water vapor, followed by distinct water condensation mechanisms in micropores (pore filling) and mesopores (capillary condensation), respectively. Moreover, organosilica exhibits efficient antibacterial activity and self-cleaning capability due to the function of quaternary ammonium groups. The organosilica with tunable pore structure and antibacterial activity provides a new model for intelligent and low-energy humidity control.

Biomimetic Ag-modified core-shell nanofibrous membrane with enhanced solar absorption and water replenishment for efficient clean water production and antibacterial activity

Microorganism contamination of evaporators can deteriorate their performance during solar-driven water evaporation. Herein, we developed a biomimetic core-shell nanofibrous membrane with enhanced solar absorption, water replenishment, and antimicrobial properties via modification of silver nanoparticles (Ag-NPs). By mimicking the core-shell structure of natural pine needles, (1) the core of polyvinylidene fluoride hexafluoropropylene (PVDF-HFP) nanofiber, like the xylem of pine needles, can act as a support skeleton for dimensional stability; and (2) the shell of Ag-NPs-modified copper oxide (CuO) crystals (Ag@CuO), like the mesophyll of pine needles (photosynthesis for pine growth), can perform the photothermal and antimicrobial properties. The Ag@CuO nanofibrous membrane achieved increased solar absorption from 92.44 % to 95.88 % and decreased water contact angle from 36.1° to 0° after the incorporation of Ag-NPs. Furthermore, the Ag@CuO nanofibrous membrane exhibited stable evaporation rates of 1.31 kg⋅m−2⋅h−1 for 3.5 wt% saline water and 1.27 kg⋅m−2⋅h−1 for actual dye wastewater. Moreover, the nanofibrous membrane possessed excellent flexibility and robust adhesion of Ag-NPs due to the strong interfacial bonding induced by polydopamine. In addition, inhibition rates above 99.97 % against Staphylococcus aureus and Escherichia coli demonstrated the outstanding antimicrobial properties of the Ag@CuO membrane. In conclusion, the high evaporation performance, excellent flexibility, and outstanding antimicrobial properties enable the Ag@CuO nanofibrous membrane to be a good option for sustainable clean water production by treating evaporation media containing microorganisms.

Se-functionalized ZIF-8 nanoparticles: synthesis, characterization and disruption of biofilms and quorum sensing in Serratia marcescens

The majority of research on nanomaterials has been concentrated on metal nanoparticles since they are easily made and manipulated. Nanomaterials have shown a wide range of applications in biology. Nevertheless, their bioactivity declines due to their extreme susceptibility to and novel Se@ZIF-8 by chemical method. The sizes and morphologies of Se (0) and Se@ZIFchemical and physical stimuli. The goal of encapsulating these nanomaterials in a matrix is gradually being pursued, which boosts their affordability, stability, and usability. Metal-organic frameworks, often known as MOFs, have the potential to be the best platforms for encapsulating metal nanoparticles due to their well-defined frameworks, persistent porosity, and flexibility in modification. In this investigation, we report the synthesis and optimization of polyvinylpyrrolidone-stabilized Se(0) nanoparticles -8 were affected by the ratios of Se/Zn2+and [hmim]/Zn2+used. The optimized Se@ZIF-8 nanoparticles exhibited a particle size and zeta potential of 319 nm and -34 mv respectively. Transmission electron microscopy displayed spherical morphology for Se(0) nanoparticles, whereas the surface morphology of novel Se@ZIF-8 nanoparticles was drastically changed to hexagonal shaped structures with smooth surface morphologies in scanning electron microscopy (SEM). The DTA, TG/DTG, XRD analysis confirmed the presence of novel Se incorporated ZIF-8 nanoparticulate framework. The synthesized novel Se@ZIF-8 nanoparticles showed efficient antibacterial activity as evidenced by low MIC values. Interestingly, these Se@ZIF-8 NPs not only inhibited biofilm formation inS. marcescens,but also effectively eradicated mature biofilms by degrading the eDNA of the EPS layer. It was validated by confocal laser scanning microscopy and SEM analysis. It was observed that Se@ZIF-8 targeted the Quroum Sensing pathway and reduced its associated virulence factors production. This work opens up a different approach of Se@ZIF-8 nanoparticles as novel antibiotics to treat biofilm-associated infections caused byS. marcescensand offer a solution for antimicrobial resistance.

Aluminum doped CuS nanocrystals for efficient antibacterial activity via photothermal and photodynamic pathways

The overuse of antibiotics has led to the emergence of drug-resistant bacteria, presenting a significant risk to public health and human well-being. A novel antibacterial material with safe and effective antibacterial properties is a viable strategy to address these issues. In this work, Al ions doped CuS particles (CuS@Al) with a flower-like nanostructure were synthesized through a simple hydrothermal method, exhibiting good photothermal and photodynamic antibacterial properties. The morphological, microstructural and crystallinity of CuS@Al were evaluated by SEM, EDS, TEM, FTIR, XRD and XPS analyses. The introduction of Al ions significantly enhanced the photothermal effects of CuS@Al, and the temperature increased from 50.7 ℃ (CuS) to 58.1 ℃ (CuS-6) under irradiation (808 nm, 2.0 W·cm−2, 10 min). The resulting CuS@Al exhibited a good photothermal conversion efficiency, effective release of reactive oxygen species (ROS), and remarkable photothermal antibacterial activity. Both E. coli and S. aureus were completely inactivated by CuS@Al (0.5 mg/mL) under photodynamic conditions. The synthesis of CuS@Al provides a strategy for creating highly effective antibacterial materials in particulate form.

NH2-MXene/OXG nanocomposite hydrogel with efficient photothermal antibacterial activity for potentially removing biofilms

The adhesion of bacteria to the surface leads to formation of biofilms causing numerous infection problems in implanting medical devices or interventional therapy. Traditional treatment for such problems is generally to administrate patients with antibiotics or antifungal agent. Alternatively, devices are taken out of the body to mechanically destroy the biofilm and re-used by surgery. In this study, a straightforward method was developed to remove biofilms using a MXene-based photothermal hydrogel. The hydrogel consists of dynamic crosslinking network formed by Schiff-base reaction between aldehyde-containing xyloglucan (OXG) and amine-containing MXene (NH2-MXene), which showed efficient killing of both gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) bacteria upon near-infrared (NIR) laser irradiation. The NH2-MXene/OXG nanocomposite hydrogel showed a high photothermal antibacterial efficiency and stable photothermal conversion, demonstrated by efficient removal of biofilms ex vivo.

Octopus‐Inspired Adaptive Molecular Motion for Synergistic Photothermal and Nitric Oxide Antibacterial Therapy in Diabetic Wound Repair

AbstractBacterial infections, especially those from drug‐resistant strains, pose a significant threat to healing diabetic skin injuries, with current treatments being intricated and often unsatisfactory. Inspired by octopuses, a biomimetic material using α‐cyclodextrin (α‐CD) and polyethylene glycol (PEG) assembled with graphene oxide end‐capped polyrotaxanes (GO‐PR) is developed, where α‐CD mimics the flexible tentacles of an octopus. Further, α‐CD is cationically modified with polyethyleneimine (PEI) to resemble octopus suction cups, creating GO‐PRP, which effectively captures and adheres to bacteria. Importantly, to emulate an octopus's ink defense, GO‐PRP is used as a carrier for nitric oxide (NO), resulting in GO‐PRP/NONOate. Utilizing the photothermal conversion of GO, near‐infrared light exposure triggers rapid heating and NO release, providing efficient antibacterial activity and biofilm dispersion, significantly reducing inflammation in diabetic skin injuries in type I rats. During wound healing, sustained NO release promotes vascular endothelial growth factor production and blood vessel regeneration, enhancing collagen formation and shortening the healing time for diabetic skin infections. Thus, octopus‐inspired GO‐PRP/NONOate emerges as a novel biomaterial for treating drug‐resistant bacterial infections in diabetic wounds in the biomedical field.

Electrospun Photodynamic Antibacterial Konjac Glucomannan/Polyvinylpyrrolidone Nanofibers Incorporated with Lignin-Zinc Oxide Nanoparticles and Curcumin for Food Packaging.

Due to the growing concerns surrounding microbial contamination and food safety, there has been a surge of interest in fabricating novel food packaging with highly efficient antibacterial activity. Herein, we describe novel photodynamic antibacterial konjac glucomannan (KGM)/polyvinylpyrrolidone (PVP) nanofibers incorporated with lignin-zinc oxide composite nanoparticles (L-ZnONPs) and curcumin (Cur) via electrospinning technology. The resulting KGM/PVP/Cur/L-ZnONPs nanofibers exhibited favorable hydrophobic properties (water contact angle: 118.1°), thermal stability, and flexibility (elongation at break: 241.9%). Notably, the inclusion of L-ZnONPs and Cur endowed the nanofibers with remarkable antioxidant (ABTS radical scavenging activity: 98.1%) and photodynamic antimicrobial properties, demonstrating enhanced inhibitory effect against both Staphylococcus aureus (inhibition: 12.4 mm) and Escherichia coli (12.1 mm). As a proof-of-concept study, we evaluated the feasibility of applying nanofibers to fresh strawberries, and the findings demonstrated that our nanofibers could delay strawberry spoilage and inhibit microbial growth. This photodynamic antimicrobial approach holds promise for design of highly efficient antibacterial food packaging, thereby contributing to enhanced food safety and quality assurance.

Design amino acids Schiff base ligands and their Cu(II) and Zn(II) complexes as potent anticancer agent on human lung carcinoma, efficient CT-DNA binder, antibacterial and mesomorphic properties

A new mesogenic amino acid Schiff base ligands of the type Potassium (E)-4-((4-(hexadecyloxy)-2-hydroxybenzylidene)amino)butanoate (HL1) and Potassium (E)-6-((4-(hexadecyloxy)-2-hydroxybenzylidene)amino)hexanoate (HL2) and their copper(II) and zinc(II) complexes have been successfully synthesized and characterized by various elemental analyses, UV–visible, FT-IR, 1HNMR , 13CNMR , ESI-MS and thermogravimetric analysis (TGA). Both the ligands were found to exhibit mesophase with multiple textures as revealed from the polarizing optical microscope (POM) and differential scanning calorimetry (DSC). The metal complexes were found to exhibit efficient CT-DNA interaction and antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli). The complexes were assessed for their in-vitro anticancer efficacy against A549 cell line and findings indicate notable cytotoxicity effect which is comparable to that of standard drug, cisplatin. The Density Functional Theory (DFT) study of the compounds was carried out by using LanL2DZ and 6–31 G (d, p) basis set with meta-hybrid Truhlar's functional M06–2X in order to obtain the optimized geometry.

GC-MS based identification of anti-microbial bioactive compounds, isolated from Bacillus halotolerans of marine sediment

Marine environments are known for their complex habitats due to the spread of industrial pollutants, and microorganisms that endure adverse conditions are evolving as extremophiles. The present study is designed to explore the antimicrobial activity of microbes present in marine ecosystems that secrete bioactive compounds. The bacterial strains VT-2, VT-4, and VT-5 isolated from the marine sediment exerted an inhibitory effect against the human pathogenic microorganisms Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa). Among the three strains, VT-5 exhibited efficient antibiotic potential. Based on biochemical characterisation, the VT-5 strain is gram-positive, rod-shaped, and demonstrates resilience to stress, salt, and drought. The 16 s r-RNA analysis confirmed Bacillus halotolerans, having a similarity of 99.75%. Bioactive compounds released by the VT-5 strain had efficient antibacterial activity, which was also observed in FESEM micrographs as deformation of cellular structure in pathogens. The chromatographic extraction of VT-5 was identified to have antibacterial bioactive compounds, and that was further determined by using FTIR and GC/MS. The peaks observed in the FTIR spectrum with different functional groups showed similarity to the structures of these isolated bioactive compounds. GC/MS analysis also revealed the presence of nine vital bioactive compounds, most of which have been reported to exhibit antimicrobial activity. Our study further strengthens that VT-5 (Bacillus halotolerans) is resistant to MDR (Pseudomonas aeruginosa) and MRSA (Staphylococcus aureus) pathogenic strains. Furthermore, this study explores marine-associated microbes as a promising avenue for new antimicrobial drugs, revealing possibilities for marine organism-derived compounds.