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The effect of iodide and temperature on enhancing antibacterial properties of nanoparticles with an encapsulated photosensitizer
摘要： Aqueous dispersions of sulfonated polystyrene nanoparticles (average diameter: 30 ± 14 nm) with encapsulated 5,10,15,20-tetraphenylporphyrin (TPP) are promising candidates for antibacterial treatments due to the photogeneration of cytotoxic singlet oxygen species O2(1Δg) under physiological conditions using visible light. The antibacterial effect on gram-negative Escherichia coli was significantly enhanced after the addition of nontoxic potassium iodide (0.001–0.01 M) because photogenerated O2(1Δg) oxidized iodide to I2/I3-, which is another antibacterial species. The improved antibacterial properties were predicted using luminescence measurements of O2(1Δg), transient absorption of TPP triplets and singlet oxygen-sensitized delayed fluorescence (SODF). In contrast to a solution of free photosensitizers, the aqueous dispersion of photoactive nanoparticles did not exhibit any quenching of the excited states after the addition of iodide or any tendency toward aggregation and/or photo-aggregation. We also observed a decrease in the lifetime of O2(1Δg) and a significant increase in SODF intensity at higher temperatures, due to the increased oxygen diffusion coefficient in nanoparticles and aqueous surroundings. This effect corresponds with the significantly stronger antibacterial effect of nanoparticles at physiological temperature (37 °C) in comparison with that at room temperature (25 °C).
关键词： Nanoparticles,Antibacterial,Potassium iodide,Singlet oxygen-sensitized delayed fluorescence,Singlet oxygen
更新于2025-09-23 15:22:29
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Reduced Graphene Oxide Functionalized with Gold Nanostar Nanocomposites for Synergistically Killing Bacteria through Intrinsic Antimicrobial Activity and Photothermal Ablation
摘要： The exploration of multifunctional photothermal agent is important for antibacterial photothermal lysis, which has emerged as an effective approach to address the problem of pathogenic bacteria infection irrespective of the drug resistant effect. In the present work, a 2D reduced graphene oxide supported Au nanostar nanocomposite (rGO/AuNS) was prepared by the seed mediated growth method for synergistically killing multidrug resistant bacteria. Owing to the prickly and sharp-edge nanostructure, the rGO/AuNS displayed superior antibacterial activity probably due to the damaging of the cell walls or membranes. The cell viability of MRSA was as low as 32% when the MRSA were incubated with rGO/AuNS for 180 min in the absence of light. The 2D structure of the rGO/AuNS facilitated the strong binding affinity towards bacteria. Upon the 808 nm NIR laser irradiation, significant enhancement in bactericidal efficiency (complete death) was obtained due to the localized hyperthermal effect of rGO/AuNS. Moreover, the RGO/AuNS displayed promising biocompatibility. It indicates that the rGO/AuNS can be an alternative and effective dual functional photothermal agent for synergistically killing the multidrug resistant bacteria.
关键词： Reduced Graphene Oxide,Multidrug-resistant bacteria,Antibacterial photothermal lysis,Gold nanostars,Prickly nanostructure
更新于2025-09-23 15:22:29
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Co <sub/>3</sub> (PO <sub/>4</sub> ) <sub/>2</sub> /Ag <sub/>3</sub> PO <sub/>4</sub> with Enhanced Simulated Sunlight Photocatalytic Activity toward Ofloxacin Degradation and Mechanism Insight
摘要： BACKGROUND: Ofloxacin is a frequently detected fluoroquinolone antibiotic in wastewater treatment plants effluents, sea waters and surface waters. Photocatalytic technology is considered to the most promising treatment technology for the removal of ofloxacin. However, it is a big challenge to exploit the novel sunlight driven photocatalyst and reveal the mechanism of the ofloxacin degradation. RESULTS: Co3(PO4)2/Ag3PO4 composites were prepared using a facile hydrothermal synthesis method. The structural, morphological, optical properties of the composites were well characterized. Both the degradation efficiency and cyclical stability of the Co3(PO4)2/Ag3PO4 composites increased significantly under simulated sunlight irradiation, when ofloxacin (OFX) or methyl orange (MO) was used as the target molecule, as compared to single-phase Ag3PO4 and Co3(PO4)2. The reduction of antimicrobial activity for 8%Co3(PO4)2/Ag3PO4 reached to 88.8% after 5 min sunlight irradiation. CONCLUSIONS: Co3(PO4)2 played a critical role in suppressing carrier recombination and provided a large number of photogenerated holes and ?O2- to oxide OFX or MO. The OFX degradation mechanism included piperazinyl dealkylation, decarboxylation, defluorination. The reduction of antimicrobial activity for degradation byproducts was obvious after simulated sunlight irradiation over Co3(PO4)2/Ag3PO4. Therefore, Co3(PO4)2/Ag3PO4 is an attractive candidate for the removal of OFX.
关键词： Antibacterial activity,Mechanism,Ofloxacin,Co3(PO4)2/Ag3PO4,Simulated sunlight
更新于2025-09-23 15:22:29
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Facile Synthesis and Characterization of CoS2–SiO2/Chitosan: The Photocatalysis in Real Samples, and Antimicrobial Evaluation
摘要： In the present work, The SiO2, and CoS2–SiO2 nanomaterials and incorporated on chitosan was developed as photocatalyst for photocatalytic degradation of toxic compound such as ethidium bromide as a hazard mutagenic pollutant. The SiO2, and CoS2–SiO2 nanomaterials were prepared using the sol–gel/sonochemical method. Therefore, the nano photocatalyst were characterized by various analytical devices such as scanning electron microscopy (SEM), X-ray diffraction and photoelectron (XRD and XPS) analysis, energy dispersive X-ray spectrometer (EDS), UV–Vis absorption spectroscopy and dynamic light scattering, in order to attain the structural properties. The average crystallite size values of SiO2, CoS2–SiO2, and CoS2–SiO2/Chitosan nanocomposites are 0.63, 40.28, and 69.75 nm, respectively. The band-gap values was obtained 8.9–2.7 eV for SiO2, CoS2–SiO2, and CoS2–SiO2/Chitosan nanocomposites, respectively. The photocatalytic performances of the three prepared nano-photocatalyst were examined by UV-light with help the photo-degradation of ethidium bromide. The CoS2–SiO2/Chitosan nanocomposites photocatalyst shows the high amount of photocatalytic degradation (96.00%) in comparison to SiO2, and CoS2–SiO2 nanomaterials. The results demonstrated that the all prepared nano-photocatalyst under UV irradiation was in pH 5 at 40 min. The antifungal and antibacterial of the SiO2, CoS2–SiO2, and CoS2–SiO2/Chitosan were examined. The CoS2–SiO2/Chitosan (high 11.00 mm inhibition zone) has appropriate antimicrobial activity compared with pure SiO2.
关键词： Antibacterial,Chitosan,CoS2,SiO2,Photocatalytic activity
更新于2025-09-23 15:22:29
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Morphological expedient flower like nanostructures WO3–TiO2 nanocomposite material and its multi applications
摘要： The prepare WO3 -TiO2 nanocomposite material has been successfully achieved precipitation route and sonication technique. The experimental results expose that 400 °C of WO3–TiO2 nanocomposite material exhibited the higher photoatalytic activity for the degradation of azo dye Acid block 1(AB 1) under UV-Light. This nanocomposite material was characterized by High-resolution scanning electron microscopy (HR-SEM) with elementary dispersive X-ray (EDX), High-resolution transmission electron microscopy (HR-TEM), XRD analysis, photoluminescence spectroscopy (PL), UV–Vis DRS and BET. The HR-SEM images reveal that most nanoflower are linked together by an edge-to-flat-surface combination. EDX studies that Ti, O and W are in higher mediation. The HR-TEM images indicate nanorod structure. As a reaction of this nanoparticle was found to be stable and reusable. This nanoparticle was antibacterial activity and electrochemical activity showed highest activity by WO3–TiO2 compared that of TiO2 nanocomposite material was reported.
关键词： UV-Light,HR-TEM,Antibacterial activity,Nanoflower,Photocatalytic activity,Electrochemical activity
更新于2025-09-23 15:21:21
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High-throughput laser generation of Si-nanoparticle based surface coatings for antibacterial applications
摘要： High-productivity regime of nanosecond IR-laser ablative generation of silicon colloidal solutions in water for anti-bacterial applications was found in terms of GW/cm2-level laser intensity and scanning velocity by measuring multi-shot ablative mass loss and extinction coefficients of the colloids as sub-linear and third-power intensity functions, respectively. This advantageous regime implies sub-linear mass loss versus laser intensity at the simultaneous third-power yield of nanoparticles, resulting from the subcritical-density, opaque ablative plasma regulating the sample ablation rate and the related plasma-mediated dissociation (dispergation) of the ablation products. In contrast, at higher intensities, there is a drastic increase in mass loss with the corresponding increased yield of (sub) micrometer-sized particles owing to intense plasma-driven expulsion of micro-scale melt droplets and the corresponding saturation of the extinction coefficient of the colloidal solutions because of their dynamic local “self-limiting” effect during the high-rate ablation. The optimal low-intensity regime for Si nanoparticle production demonstrates the monotonous correlated increase of mass loss and extinction coefficient in terms of increasing laser scanning velocity, indicating the diminished cumulative effects. Surface coatings prepared from the generated Si nanoparticles exhibit minor surface oxidation, as acquired as their elemental composition via energy-dispersive X-ray spectroscopy, making their contact angle for water droplets (≈51°) close to that of bare Si wafer (≈58°) with its nanometer-thick native oxide layer. Owing to good wetting, the nanoparticle-based surface coatings show strong antibacterial response regarding Gram-negative Pseudomonas auereginosa bacteria even despite their minor oxidative passivation.
关键词： Silicon nanoparticles,Colloids,Surface oxidation,Extinction coefficient,Wetting,Antibacterial tests,Gram-negative bacteria Pseudomonas auereginosa,Sub-critical ablative plasma,Nanosecond laser ablation,Mass loss
更新于2025-09-23 15:21:21
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Visible Light Driven Mesoporous Mn and S Co-doped TiO2 Nano material: characterization and Applications in Photocatalytic Degradation of Indigocarmine dye and Antibacterial Activity
摘要： The present study explored the Photocatalytic & antibacterial activity of Mesoporous Mn and S co-doped TiO2 nano material synthesized by sol-gel method. As prepared samples were characterized by X-ray diffraction (XRD), X-ray photo electron spectroscopy(XPS), Scanning electron microscopy (SEM), Energy dispersive X-ray Spectroscopy(EDX), Fourier transform infrared spectroscopy(FT-IR), UV-Visible Diffused Reflectance Spectroscopy(UV-Vis-DRS),Transmission electron Microscopy(TEM), Brunauer-Emmett-Teller (BET) and Photoluminescence (PL).The Characterization results revealed that all the co-doped and undoped samples shows anatase phase. The Frequency shift of Ti-O-Ti in the catalyst samples was observed in FT-IR due to substitutional doping of Mn and S by replacing Ti and O, Further the catalyst shows smooth spherically shaped small particle size (7.6 nm) with high surface area (155.87 m2/g) and having less band gap energy (2.58 eV). The most reactive ?OH are produced during the progress of reaction was determined by using Photo luminescence (PL) technique. The photocatalytic efficiency and antibacterial activity was evaluated by degradation of Indigo carmine(IC), Bacillus coagulans and klebsiella pneumonia respectively. The complete degradation of IC was achieved at optimum reaction parameters such as 0.150g of the catalyst dosage, solution pH=4 and initial dye concentration 20ppm with the catalyst of 1.0Wt% of Mn-0.25Wt% of S co-doped Titania with in 90 min. The zone of inhibition bacterial growth was observed (24mm and 23mm) compared to control value (Chloramphenicol) 25mm and 24mm.
关键词： antibacterial activity,Mn-S,TiO2,Indigo carmine,Photocatalytic activity,Sol-gel method
更新于2025-09-23 15:21:21
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Schiff base rare earth metal complexes: Studies on functional, optical and thermal properties and assessment of antibacterial activity
摘要： We used the condensation chemistry with anthracene 9 carbaldehyde and 3,4 diaminopyridine to form Schiff base (SB) ligand, N2,N3 bis (anthracen 9 ylmethylene) pyridine 3,4 diamine incorporating Er, Pr and Yb rare earth metals to form a series of SB complexes. Surface, structure, thermal, and optical properties of the resulting complexes were investigated using a variety of tools. The characteristic luminescence properties were observed after rare earth metal inclusions in SB. Antibacterial studies were performed against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa in terms of zone of inhibition for SB complexes. The SB-Pr complexes showed better immune behavior against all the pathogens than the other SB metal complexes.
关键词： Schiff base,Antibacterial,Rare earth metal,Fluorescence,Fourier transform infrared
更新于2025-09-23 15:21:21
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Aloe-Emodin/Carbon Nanoparticles Hybrid Gels with Light-Induced and Long-Term Antibacterial Activity
摘要： Development of effective antimicrobial wound dressings has drawn wide attention in the wound care market. Here, we synthesized a natural antibiotic (aloe-emodin, AE) and carbon nanoparticles co-embedded polymer hybrid hydrogel as a novel wound dressing in the fight against skin infections potently. We systematically evaluated the properties of the obtained hydrogels, including physic-chemical characteristics, photothermal conversion efficiency, reactive oxygen species (ROS) generation, AE-released profile, antibacterial activity and wound-healing capability. The hybrid gels can initially deduct the number of bacteria rapidly in a short time through the near-infrared-light (NIR)-triggered photothermal/ROS route, and continuously kill the remaining live cells by released-AE from gels after turning off NIR source with the long-term antibacterial effect. These two antibacterial manners that complement each other lead to the excellent antibacterial performances towards various bacterial strains including multidrug-resistant bacteria. Moreover, in vivo Staphylcoccus aureus-infected animal experiments indicate that the hybrid gels upon NIR irradiation have a striking ability towards wound infection. These studies demonstrate that the AE and carbon nanoparticles co-embedded hybrid polymer hydrogels with NIR exposure may have applications in the wound combined care for bacterial infections.
关键词： NIR irradiation,aloe-emodin,wound dressing,ROS,carbon nanoparticles,antibacterial hydrogel
更新于2025-09-23 15:21:21
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Synergistic interactions of cadmium-free quantum dots embedded in a photosensitised polymer surface: efficient killing of multidrug-resistant strains at low ambient light levels
摘要： Cadmium-free quantum dots (QD) were combined with crystal violet photosensitising dye and incorporated into medical grade polyurethane via a non-covalent dipping process known as ‘swell-encapsulation-shrink’. The antibacterial efficacy of the prepared quantum dot-crystal violet polyurethane substrates (QD + CV PU) was investigated under low power visible light illumination at similar intensities (500 lux) to those present in clinical settings. The antibacterial performance of QD + CV PU was superior to the constituent polymer substrates, eliminating ~99.9% of an environmental P. aeruginosa strain, a clinical P. aeruginosa strain from a cystic fibrosis patient and a clinical E. coli strain. The nature of the reactive oxygen species (ROS) involved in antibacterial activity of the QD + CV PU surface was investigated using ROS inhibitors and time-resolved optical spectroscopy. The photo-physical interaction of the green-emitting QDs with CV lead to a combination of Type I and II electron transfer and energy transfer processes, with the highly potent ROS singlet oxygen playing a dominant role. This study is the first to demonstrate highly efficient synergistic killing of clinical and environmental strains of intrinsically resistant and multi-drug resistant Gram-negative bacteria using light-activated surfaces containing biocompatible cadmium-free QDs and crystal violet dye at ambient light levels.
关键词： photodynamic therapy,antibacterial,reactive oxygen species,surfaces,quantum dots
更新于2025-09-23 15:21:01