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A Novel Biocompatible Titaniuma??Gadolinium Quantum Dot as a Bacterial Detecting Agent with High Antibacterial Activity
摘要： In this study, the titanium–gadolinium quantum dots (TGQDs) were novel, first of its type to be synthesized, and fully characterized to date. Multiple physical characterization includes scanning electron microscopy (SEM), scanning electrochemical microscope (SCEM), x-ray fluorescence, spectrophotometry, and dynamic light scattering were carried out. The obtained results confirmed appropriate size and shape distributions in addition to processing optical features with high quantum yield. The synthesized TGQD was used as a fluorescent dye for bacterial detection and imaging by fluorescent microscopy and spectrophotometry, where TGQD stained only bacterial cells, but not human cells. The significant antibacterial activities of the TGQDs were found against a highly pathogenic bacterium (Staphylococcus aureus) and its antibiotic resistant strains (vancomycin and methicillin resistant Staphylococcus aureus) using growth curve analysis and determination of minimum inhibitory concentration (MIC) analysis. Live/dead cell imaging assay using phase-contrast microscope was performed for further confirmation of the antibacterial activity. Cell wall disruption and release of cell content was observed to be the prime mode of action with the reduction of cellular oxygen demand (OD).
关键词： titanium–gadolinium quantum dots,bacterial resistance,antibacterial activity,bacterial detection,SECM
更新于2025-09-23 15:19:57
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Silver and copper oxide nanoparticles-decorated graphene oxide via pulsed laser ablation technique: Preparation, characterization, and photoactivated antibacterial activity
摘要： Graphene oxide, silver and copper oxide nanoparticles display photoactivated antibacterial behavior owing to their ability to generate charge carriers via light exposure. In this work, silver nanoparticles (AgNPs) and copper oxide nanoparticles (CuONPs) were embedded through graphene oxide (GO) using laser ablation technique. The microstructural behavior of the synthesized compositions has been investigated via XRD and TEM. The optical properties were studied by (UV–Vis), while the antibacterial properties were investigated in addition to the cell viability towards normal cell line (HFB4) in vitro. The antibacterial activity of GO was enhanced significantly with addition nanoparticles; by meaning, the inhibition zone enlarged from 5.4 mm with pure GO to be around 11.2 mm against E. coli with contribution of CuONPs. This trend of enhancement suggests that GO could be a great platform for different kinds of photo-activated antibacterial to be recommended for versatile biomedical applications.
关键词： CuO,Ag,Pulsed laser ablation,Graphene oxide,Antibacterial activity,Bacterial resistance
更新于2025-09-23 15:19:57
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Photoinactivation of planktonic and biofilm forms of Escherichia coli through the action of cationic zinc(II)phthalocyanines
摘要： Novel water soluble Zn(II)phthalocyanines (ZnPc) peripherally substituted with 4-dimethylaminopyridine (DMAP) units (ZnPc 1-2) and the corresponding quaternized derivatives (ZnPc 1a-2a) were synthesized and their photodynamic inactivation (PDI) efficiency against a Gram-negative bacterium, a recombinant bioluminescent Escherichia coli strain either in planktonic and biofilm form was investigated. The analysis of the photophysical properties revealed that the increase in the number of DMAP units on ZnPc shifted the absorption and emission band in aqueous media to red. The presence of multi-positive charges on ZnPc derivatives prevented aggregation and enhances the solubility in aqueous medium. The quaternized derivatives ZnPc 1a and 2a displayed good stability and promising efficacy to generate singlet oxygen (1O2). The affinity of the amphiphilic ZnPc 1-2 and quaternized ZnPc 1a-2a to planktonic bacterial cells corresponded to an average uptake of ~106 PS molecules.CFU-1. The PDI assays conducted with planktonic cells and biofilms of E. coli show that irradiation with red or white light (150 mW.cm-2) in the presence of 20 μM of ZnPc derivatives caused an effective inactivation. ZnPc 1a and ZnPc 2a exhibited the highest inactivation efficiency, particularly of the planktonic form, causing 5 log (99.99%) reductions in bioluminescence. The inactivation factor for biofilms was 99% (2 log). ZnPc 1a and ZnPc 2a can be regarded as promising photosensitizers for the photodynamic inactivation of Gram-negative bacteria.
关键词： Reactive Oxygen Species,Cationic Phthalocyanines,E. coli,Bacterial Resistance,Biofilm,Antimicrobial Photoinactivation
更新于2025-09-19 17:15:36
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Photoinduced Antibacterial Activity of the Essential Oils from Eugenia brasiliensis Lam and Piper mosenii C. DC. by Blue Led Light
摘要： The objective of this work was to evaluate the phytochemical composition and the antibacterial and antibiotic-modulating activities of the essential oils of Eugenia brasiliensis Lam (OEEb) and Piper mosenii C. DC (OEPm) singly or in association with blue LED (Light-emitting diode) light. The antibacterial and antibiotic-modulatory activities of the essential oils on the activity of aminoglycosides were evaluated to determine the minimum inhibitory concentration (MIC, μg/mL) in the presence or absence of exposure to blue LED light. The chemical analysis showed α-pinene and bicyclogermacrene as major constituents of OEPm, whereas α-muurolol was the main compound of OEEb. Both OEEb and OEPm showed MIC ≥ 512 μg/mL against the strains under study. However, the association of these oils with the blue LED light enhanced the action of the aminoglycosides amikacin and gentamicin. In conclusion, the association of aminoglycosides with the blue LED light and essential oils was effective against resistant bacteria.
关键词： blue light,Piper mosenii,bacterial resistance,Eugenia brasiliensis,Staphylococcus aureus,Escherichia coli
更新于2025-09-11 14:15:04