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ROS mediated antibacterial activity of photoilluminated riboflavin: A photodynamic mechanism against nosocomial infections
摘要： Nosocomial infections are a major threat to modern therapeutics. The major causative agent of these infections is multidrug-resistant gram-negative bacteria, which impart high morbidity and mortality rate. This has led to an urge for the development of new antibiotics. Antimicrobial photodynamic therapy is a promising strategy to which till date no resistant strain has been reported. Since the efficacy of photodynamic therapy largely depends on the selection and administration of an appropriate photosensitizer, therefore, the realization of clinically active photosensitizers is an immediate need. Here, by using E. coli as a study model we have demonstrated the antimicrobial photodynamic potential of riboflavin. Intracellular ROS formation by DCFH-DA assay, lipid peroxidation, protein carbonylation, LDH activity was measured in treated bacterial samples. Enzymatic (SOD, CAT, GSH) antioxidants and non-enzymatic (GSH) was further evaluated. Bacterial death was confirmed by colony forming assay, optical microscopy and scanning electron microscopy. The treated bacterial cells exhibited abundant ROS generation and marked increment in the level of oxidative stress markers as well as significant reduction in LDH activity. Marked reduction in colony forming units was also observed. Optical microscopic and SEM images further confirmed the bacterial death. Thus, we can say that photoilluminated riboflavin renders the redox status of bacterial cells into a compromised state leading to significant membrane damage ultimately causing bacterial death. This study aims to add one more therapeutic dimension to photoilluminated riboflavin as it can be effectively employed in targeting bacterial biofilms occurring on hospital wares causing several serious medical conditions.
关键词： ROS,Antibacterial,Riboflavin,Photodynamic therapy,Nosocomial infection
更新于2025-09-23 15:23:52
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Red Fluorescent Chlamydia trachomatis Applied to Live Cell Imaging and Screening for Antibacterial Agents
摘要： In this study, we describe the application of a transformed Chlamydia trachomatis strain constitutively expressing the red fluorescent protein mCherry, to allow real-time monitoring of the infection cycle and screening for agents that block replication of C. trachomatis. The red fluorescent C. trachomatis strain was detected autonomously without antibody staining and was equally susceptible to doxycycline as the wild type strain. A high-throughput screening assay was developed using the transformed strain and automated fluorescence microscopy. The assay was used in a pilot screen of a 349 compound library containing natural products from Australian flora and fauna. Compounds with anti-chlamydial activity were tested for dose response and toxicity to host cells and two non-toxic compounds had 50% effective concentration (EC50) values in the low micromolar range. Natural products are valuable sources for drug discovery and the identified Chlamydia growth inhibition may be starting points for future drug development. Live cell imaging was used to visualize growth of the red fluorescent C. trachomatis strain over time. The screening assay reduced workload and reagents compared to an assay requiring immunostaining and could further be used to monitor the development of Chlamydia inclusions and anti-chlamydial effect in real time.
关键词： mCherry,antibacterial,Chlamydia trachomatis,Australian natural products,high content screening,fluorescence-based screening,anti-chlamydial
更新于2025-09-23 15:23:52
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Studies on structural and optical properties of pure and transition metals (Ni, Fe and co-doped Ni–Fe) doped tin oxide (SnO2) nanoparticles for anti-microbial activity
摘要： In this present work, pure and transition metal ions (Ni, Fe and co-doped Ni–Fe) doped SnO2 nanoparticles (NPs) were synthesized using a simple chemical co-precipitation method. Transition metal ions (Ni, Fe and co-doped Ni–Fe) were doped in order to study the influence of structural and optical properties. The synthesized samples were analyzed by using powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, UV–Visible spectroscopy, FT-IR, and photoluminescence spectroscopic techniques. SnO2 crystallites were found to exhibit tetragonal rutile structure with space group P42/mnm (136) with average particle size in the range of 20–30 nm. Also confirmed that all the doped metal ions were incorporated to SnO2. The UV–Vis-NIR spectroscopy revealed a significant red shift in the absorbing band edge due to increase in the amount of Ni, Fe and co-doped Ni–Fe contents. The SEM image shows the morphology of pure and doped (Fe, Ni and Fe–Ni co-doped) SnO2 NPs with large spherical shapes. In FT-IR spectra, the strong peaks are attributed to the antisymmetric stretching mode of O-Sn-O. The PL spectrum exhibits a strong blue emission peak. The antimicrobial studies were investigated against standard bacterial strains and enhanced anti-bacterial activity in doped and co-doped samples was observed, which can be attributed to the ROS and the particles were in the nanoscale regime.
关键词： Antibacterial activity,Photoluminescence,Co-precipitation,Nanoparticle,Co-dopant
更新于2025-09-23 15:23:52
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Carboxylic acid-functionalized TiO <sub/>2</sub> nanoparticle-loaded PMMA/PEEK copolymer matrix as a dental resin for 3D complete denture manufacturing by stereolitographic technique
摘要： The main goal of the present investigation was to the synthesis of bioactive TiO2 nanoparticle-incorporated poly(methylmethacrylate)/polyetheretherketone nanocomposite for enhanced antibacterial and biocompatibility characteristics with suitable properties for manufacturing 3D printed stereolitographic dental prosthesis. The carboxylic acid-functionalized TiO2 nanoparticles have been dispersed into the copolymer matrixes through emulsion polymerization method, and the structural and morphological properties were investigated by using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy, and energy dispersive X-ray (EDX) analytical techniques. The FTIR spectrum of synthesized nanocomposites that shows high intense peaks at 2,970–2,850 cm?1 is related to the symmetric and asymmetric stretching C-H vibration of methyl and methylene groups of the polymer matrix. The microscopic results of nanocomposite exhibited that functionalized nanoparticles were effectively and uniformly dispersed into the polymer matrix in the absence of particle agglomerations, and it has been given excellent killing efficiency of 99% under dark conditions against bacterial pathogens Escherichia coli and Staphylococcus aureus and also exhibited favorable cell compatibility with dental pulp cells. This facile synthesized nanocomposite was efficaciously employed for denture manufacturing with stereolitographic technique.
关键词： Stereolitographic method,TiO2 nanoparticles,Antibacterial,Dental,Copolymer
更新于2025-09-23 15:23:52
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Photocatalytic and antibacterial activities of <i>Paeonia emodi</i> mediated silver oxide nanoparticles
摘要： Green synthesis of nanomaterials and its verity of applications have linked chemistry, biotechnology and environmental chemistry. Green process get more attention due to its easy handling and inertness to ecosystem. The selection of green synthesis and silver oxide nanoparticles (Ag2O NPs) are purely based on its nontoxic behavior and promising activates. Eco-friendly process was applied for the synthesis of silver oxide nanoparticles (Ag2O NPs) using Paeonia emodi (P. emodi) fresh leaves extract as reducing agent. The average crystallite size was found to be 38.29 nm, calculated from the FWHM of the diffraction bands of X-rays diffractometer (XRD). The morphological study was made by performing transmission electron microscopy (TEM) and scanning electron microscope (SEM) and the particles size estimated from the micrographs of both techniques are 38.29 and 86.4 nm respectively. The energy dispersive X-ray (EDX) was used to study the purity and percent composition of the Ag2O NPs. The band gap energy (4.02 eV) and surface functional groups was studied by diffuse reflectance spectroscopy (DRS) and fourier transform infrared spectroscopy (FTIR) respectively. The 97.78% methylene blue (MB) was degraded in the presence of Ag2O NPs and UV-Visible light source in 180 min. The antibacterial activity of the Ag2O NPs were tested against Gram-positive (Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus)) and Gram-negative (Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) bacteria. It was found that the Ag2O NPs have strong growth inhibiting activity against Gram-negative bacteria than Gram-positive bacteria.
关键词： Photocatalytic degradation,Methylene blue,Eco-friendly,Antibacterial Activity,Silver oxide,Leaves extract
更新于2025-09-23 15:23:52
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Preparation and Characterization of Polymer Composite Materials Based on PLA/TiO2 for Antibacterial Packaging
摘要： Polymer composite materials based on polylactic acid (PLA) filled with titanium dioxide (TiO2) nanoparticles were prepared. The aim of this work was to investigate the antibacterial action of TiO2 against a strain of E. coli (DH5α) to obtain information on their potential uses in food and agro-alimentary industry. PLA/TiO2 systems were prepared by a two-step process: Solvent casting followed by a hot-pressing step. Characterization was done as a function of particle size (21 nm and <100 nm) and particle content (0%, 1%, 5%, 10%, and 20%, wt %). Structural characterization carried out by X-ray diffraction (XRD) and Fourier Transformed Infrared spectroscopy (FTIR) did not reveal significant changes in polymer structure due to the presence of TiO2 nanoparticles. Thermal characterization indicated that thermal transitions, measured by differential scanning calorimetry (DSC), did not vary, irrespective of size or content, whereas thermogravimetric analysis (TGA) revealed a slight increase in the temperature of degradation with particle content. Bacterial growth and biofilm formation on the surface of the composites against DH5α Escherichia coli was studied. Results suggested that the presence of TiO2 nanoparticles decreases the amount of extracellular polymeric substance (EPS) and limits bacterial growth. The inhibition distances estimated with the Kirby-Bauer were doubled when 1% TiO2 nanoparticles were introduced in PLA, though no significant differences were obtained for higher contents in TiO2 NPs.
关键词： antibacterial packaging,polylactic acid (PLA),polymer nanocomposites,TiO2 nanoparticles
更新于2025-09-23 15:22:29
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Dual metal oxide loaded cotton/polyester fabric with photo, bio and magnetic properties
摘要： This research aimed at sonochemical synthesis and deposition of Fe3O4/ZnO nanocomposites on cotton/polyester fabric using the ultrasonic bath at 80°C. For this purpose, in situ sonosynthesis of magnetite nanoparticles on the fabric surface was carried out and followed by the generation of crystalline ZnO nanoparticles through the sonochemical approach, eliminating the need for high temperature after-treatment of the fabrics. This effect was achieved thanks to the shock waves formed by the cavitation bubbles also called microcalcination, resulting in the formation and adsorption of crystalline nanomaterials on the fabric surface. Magnetic properties with saturation magnetization of 1.5 emu/g, self-cleaning activities toward methylene blue discoloration, and excellent antibacterial and antifungal properties along with low cell toxicity were among the obtained properties. The current study is the first research indicating the potential of the sonochemical method to produce non-toxic cotton/polyester fabric with various properties including magnetic, photocatalytic, and antibacterial activities.
关键词： antibacterial,Fe3O4/ZnO nanocomposites,magnetic,self-cleaning,sonochemistry
更新于2025-09-23 15:22:29
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Poly(dopamine) and Ag nanoparticle-loaded TiO <sub/>2</sub> nanotubes with optimized antibacterial and ROS-scavenging bioactivities
摘要： Aim: To create polydopamine (PDA) and Ag nanoparticle-loaded TiO2 nanotubes coating on titanium (Ti) alloy. Materials & methods: TiO2-PDA-Ag coating was fabricated on Ti implants by electrochemical anodization. The in vitro and in vivo bactericidal and antibiofilm activities were tested. Intracellular reactive oxygen species (ROS) and antioxidative capability were measured, and cell proliferation, adhesion and cell morphology were characterized. Results: TiO2-PDA-Ag coating showed satisfactory bactericidal and antibiofilm activities in vitro and in vivo, improved Ag release pattern, evident ROS scavenging properties and enhanced cell adhesion and proliferation. Conclusion: Our study successfully fabricated a PDA and Ag nanoparticle-loaded TiO2 nanotubes coating on Ti alloy. The improved Ag release kinetics and ROS-scavenging properties achieve an optimal balance between antibacterial ability and biocompatibility.
关键词： antibacterial,nanotubular structures,enhanced adhesion,ROS scavenging,poly(dopamine)
更新于2025-09-23 15:22:29
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Mini submersible pump assisted sonochemical reactors: Large-scale synthesis of zinc oxide nanoparticles and nanoleaves for antibacterial and anti-counterfeiting applications
摘要： Low cost, environmentally friendly and industrial-scale approaches for the synthesis of anti-counterfeiting and antibacterial materials are a challenging task. The current research reports novel and inexpensive approaches for the synthesis of zinc oxide nanostructures (ZnO-NSs) using Mini Submersible Pump (MSP) assisted sonochemical reactors. Zinc oxide nanoleaves (ZnO-NLs) were synthesized using MSP assisted sonochemical mixing reactor at gram-scale (4 g). Zinc oxide nanoparticles (ZnO-NPs) were synthesized using MSP assisted sonochemical flow loop reactor at gram-scale (11.5 g). Synthesized ZnO-NSs were characterized by UV-visible spectroscopy, fluorescence spectroscopy, XRD, FTIR, TGA, BET, FEG-SEM, and FEG-TEM. Bare ZnO-NPs and ZnO-NPs coated cotton fabric showed high antibacterial activity against diseases causing Gram-positive bacteria Staphylococcus aureus. Based on the UV fluorescence property of the ZnO-NLs, invisible security ink was developed for anti-counterfeiting applications. The invisible security ink was tested as a rubber stamp and fountain pen inks which were found to be stable on the various kinds of microporous papers. As compared to our previously reported method, disperser assisted sonochemical approach for ZnO-NLs synthesis; the current approach reduces the cost of equipment used from ~1700 to 4 USD. Both reactors are designed simply (less complicated), based on an environmentally friendly approach, highly scalable, increases the effectiveness of the sonochemical technique and suitable for industrial applications.
关键词： antibacterial,anti-counterfeiting,sonochemical reactors,Mini submersible pump,zinc oxide nanoparticles and nanoleaves
更新于2025-09-23 15:22:29
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Controlling Silver Ion Release from Ag-Based Nanocoatings by Plasma Surface Engineering
摘要： Environmental surfaces have been widely recognized as an important source of hospital-associated transmissions. A number of silver-based antibacterial coatings have been reported in the literature. However, the success of any antibacterial strategy depends on the ability to control the kinetics of the silver ions released from the coating. The novel strategy proposed in this work is based on plasma surface engineering for a controlled-release of silver ions. Plasma-based nanocoatings, plasma oxidation processes and surface patterning of silver coatings were designed and optimized. Surface analyses such as XPS and AFM, as well as silver ion release over 168 h, was evaluated by MIP-AES. Results showed that surface plasma engineering successfully allow tuning the silver release and bioactivity in Ag-containing antibacterial coatings.
关键词： diamond-like carbon,plasma oxidation,silver release,antibacterial activity
更新于2025-09-23 15:22:29