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Flexible organic light-emitting diodes for antimicrobial photodynamic therapy
摘要： Bacterial infection and the growth of antibiotic resistance is a serious problem that leads to patient suffering, death and increased costs of healthcare. To address this problem, we propose using flexible organic light-emitting diodes (OLEDs) as light sources for photodynamic therapy (PDT) to kill bacteria. PDT involves the use of light and a photosensitizer to generate reactive oxygen species that kill neighbouring cells. We have developed flexible top-emitting OLEDs with the ability to tune the emission peak from 669 to 737 nm to match the photosensitizer, together with high irradiance, low driving voltage, long operational lifetime and adequate shelf-life. These features enable OLEDs to be the ideal candidate for ambulatory PDT light sources. A detailed study of OLED–PDT for killing Staphylococcus aureus was performed. The results show that our OLEDs in combination with the photosensitizer methylene blue, can kill more than 99% of bacteria. This indicates a huge potential for using OLEDs to treat bacterial infections.
关键词： Photodynamic therapy,Flexible organic light-emitting diodes,Staphylococcus aureus,Antimicrobial,Methylene blue
更新于2025-09-12 10:27:22
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Rapid pathogen identification and antimicrobial susceptibility testing in in vitro endophthalmitis with matrix assisted laser desorption-ionization Time-of-Flight Mass Spectrometry and VITEK 2 without prior culture
摘要： Prompt clinical diagnosis and initiation of treatment are critical in the management of infectious endophthalmitis. Current methods used to identify causative agents of infectious endophthalmitis are mostly inefficient, owing to suboptimal sensitivity, length, and cost. Matrix Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) can be used to rapidly identity pathogens without a need for culture. Similarly, automated antimicrobial susceptibility test systems (AST, VITEK 2) provide accurate antimicrobial susceptibility profiles. In this proof-of-concept study, we apply these technologies for the direct identification and characterization of pathogens in vitreous samples, without culture, as an in vitro model of infectious endophthalmitis.
关键词： endophthalmitis,pathogen identification,MALDI-TOF MS,antimicrobial susceptibility testing,VITEK 2
更新于2025-09-12 10:27:22
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A Study of the Effect of Anisotropic Gold Nanoparticles on Plasmonic Coupling with a Photosensitizer for Antimicrobial Film.
摘要： Development of antimicrobial surfaces for sterilization is much needed to avoid the spreading of drug resistant bacteria. Light can activate antimicrobial surfaces by an interaction between nanoparticles and a photosensitizer dye, to produce a steady and efficient killing of bacteria. The film studied in this work contains gold nanorods (AuNRs) of 32 nm length and 16 nm diameter and gold nanostars (AuNSs) of 50 nm of diameter, in combination with crystal violet dye (CV). The surface plasmon resonance (SPR) of the nanoparticles used in the film was mathematically simulated and characterized to understand difference SPR between the particles. Their effects on plasmonic coupling with the dye, thus the production of reactive oxygen species (ROS) and consequently the activity of the film against bacteria were studied. The films showed great antimicrobial activity against gram negative bacteria (E. coli) in 4 h of light exposure, when modified with AuNSs, it could kill E. coli in 5 orders of magnitudes (5-log) and the one modified with AuNRs could kill with 4 order of magnitudes (4-log). While maintaining partial activity against gram positive bacteria (S. aureus), i.e. being able to kill in 2.5 orders of magnitudes by the film containing AuNSs and 3 orders of magnitudes by those containing AuNRs. The differential response of gram (-) and gram (+) bacteria to the ROS generated by the films, would allow more targeted approach for specific bacterial species, for example, surfaces of bedpans or common contact surfaces (handles, handrails etc.) that are contaminated principally by gram (-) or gram (+) bacteria, respectively.
关键词： anisotropy,light-activated,non-contact sterilization,antimicrobial surface,simulations,Plasmonic coupling
更新于2025-09-12 10:27:22
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Investigating the efficiency of α-Bismuth zinc oxide heterostructure composite/UV-LED in methylene blue dye removal and evaluation of its antimicrobial activity.
摘要： Heterostructured α-Bismuth zinc oxide (α-Bi2O3-ZnO) photocatalyst was fabricated by a facile and cost-effective, ultrasound assisted chemical precipitation method followed by hydrothermal growth technique. As synthesized α-Bi2O3-ZnO photocatalyst showed enhanced photocatalytic performance for the MB dye degradation in contrast to pure ZnO and α-Bi2O3. Light emitting diodes (UV-LED) were used in the experimental setup, which has several advantages over conventional lamps like wavelength selectivity, high efficacy, less power consumption, long lifespan, no disposal problem, no warming-up time, compactness, easy and economic installation. XRD study confirmed the presence of both the lattice phases i.e. monoclinic and hexagonal wurtzite phase corresponding to α-Bi2O3 and ZnO in the α-Bi2O3-ZnO composite photocatalyst. FESEM images showed that α-Bi2O3-ZnO photocatalyst is composed of dumbbell like structures of ZnO with breadth ranging 4-5 μm and length ranging from 10 to 11 μm respectively. It was observed that α-Bi2O3 nanoparticles were attached on the ZnO surface and were in contact with each other. Low recombination rate of photo-induced electron-hole pairs, due to the migration of electrons and holes between the photocatalyst could be responsible for the 100 % photocatalytic efficiency of α-Bi2O3-ZnO composite. In addition, photocatalyst was also observed to show the excellent antimicrobial activity with 1.5 cm zone of inhibition for 1 mg/L dose, against the human pathogenic bacteria (S. aureus).
关键词： Heterostructure,antimicrobial activity,Methylene blue,Photocatalyst,α-Bi2O3-ZnO,UV-LED,α-Bi2O3
更新于2025-09-11 14:15:04
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Feasibility of transgingival laser irradiation for antimicrobial photodynamic therapy
摘要： Aim: Diode lasers are commonly used for antimicrobial photodynamic therapy (aPDT). This study aimed to assess the feasibility of transgingival laser irradiation during aPDT and evaluate whether the photosensitizer can be activated. Materials and Methods: Four diode laser settings were assessed for transgingival irradiation: 120 mW, 80 mW, 60 mW, and 40 mW. Fifteen soft-tissue pieces from a pig’s lower jaw were prepared. The specimens’ thickness was measured and transgingival laser irradiation was performed. A digital power meter measured laser power on the other side of the tissue. The power outcome after staining of the nonbuccal aspect of the tissue with photosensitizer dye was assessed similarly. Results: Transgingival laser irradiation (average soft-tissue thickness: 0.84 ± 0.06 mm) resulted in di?erent power transmission depending on the power settings and photosensitizer. The lowest values were observed with the 40 mW setting and photosensitizer (median 3.3 mW, max. 5.0 mW, min. 2.3 mW, interquartile range 1.2), and the highest at 120 mW without photosensitizer (median 41.3 mW, max. 42.7 mW, min. 38.0 mW; interquartile range 1.5). Conclusions: This study indicates that transgingival irradiation may be suitable for aPDT, since power transmission through the gingival tissue was observed in all specimens. However, the decrease in laser power caused by both the soft tissue and the photosensitizer has to be taken into account.
关键词： Transgingival irradiation,Low-level laser therapy,Periodontitis,Diode laser,Antimicrobial photodynamic therapy
更新于2025-09-11 14:15:04
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One-pot synthesis of nanostructured CdS, CuS, and SnS by pulsed laser ablation in liquid environment and their antimicrobial activity
摘要： We describe here a generic method for producing high-quality metal sulfide nanoparticles of a controllable and narrow size distribution in the nano-metric range. Metal sulfide nanostructures (CdS, CuS, and SnS) are synthesized by using nanosecond pulsed laser ablation in a liquid solution containing sulfur precursor in just one step (one-pot versatile synthesis method). The optical properties have been studied using UV–Visible spectroscopy showing the main characteristic transition peaks of metal sulfides. Transmission electron microscope (TEM) shows a uniform Smaller-sized and nearly spherical nanocrystals exhibited a cross lattice pattern. The structure study by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) reveal the purity and the spherical crystalline structure of all the prepared nano metal sulfides. After that, the antibacterial activity has been examined against four types of bacteria and unicellular fungi by using agar plate diffusion methods followed by studying the required time for killing. The tested microorganisms strain is showing that CuS nanoparticles have the highest antimicrobial activity.
关键词： Metal sulfides,PLAL,Antimicrobial,Laser ablation,Nanostructure
更新于2025-09-11 14:15:04
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Plasmonic Colloidosome-Based Multifunctional Platform for Bacterial Identification and Antimicrobial Resistance Detection
摘要： Antimicrobial resistance (AMR) is an urgent threat to public health. Rapid bacterial identification and AMR tests are important to promote personalized treatment of patients and to limit the spread of AMR. Herein, we explore the utility of plasmonic colloidosomes in bacterial analysis based on mass spectrometry (MS) and Raman scattering. It is found that colloidosomes can provide a rigid micron-size platform for bacterial culture and analysis. Coupled with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS, this platform enables bacterial identification at the species level with cell counts as low as 50, > 100 times more sensitive than the standard method of MALDI-TOF MS based bacterial identification. Coupled with Raman scattering, it can distinguish single bacterial cells at the strain level and recognize AMR at the single-cell level. These reveal the broad potential of the platform for flexible and versatile bacterial detection and typing.
关键词： Plasmonic colloidosomes,MALDI-TOF MS,Raman scattering,antimicrobial resistance detection,bacterial identification
更新于2025-09-11 14:15:04
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Green synthesized CeO <sub/>2</sub> quantum dots: a study of its antimicrobial potential
摘要： Cerium oxide (CeO2) nanoparticles (NPs) of size ～4 nm were successfully synthesized by green synthesis method using cerium nitrate as precursor and aloe-vera leaf extract as reducing and stabilizing agent. The switching between Ce3+ and Ce4+ state by reaction with H2O2 inferred the biomedical applications of CeO2 NPs. This switching enhances due to the presence oxygen vacancies and that was con?rmed by photoluminescence spectrum. The SEM images showed spherical morphology of cubic ?uorite structured CeO2 NPs which avoids the harming of cell. In the present study, CeO2 NPs show signi?cant inhibition effect on gram negative bacteria, E. coli and P. aeruginosa which are responsible for food poisoning. Thus study analyze the synthesized CeO2 NPs as promising candidates for removal of biological pollutants and thus have great potential in the environmental remediation.
关键词： antimicrobial activity,green synthesis,quantum dots
更新于2025-09-11 14:15:04
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Action of antimicrobial photodynamic therapy with red leds in microorganisms related to halitose
摘要： Introduction: Halitosis is the term used to describe any unpleasant odor relative to expired air regardless of its source. The prevalence of halitosis in the population is approximately 30%, of which 80 to 90% of the cases originate in the oral cavity resulting from proteolytic degradation by gram negative anaerobic bacteria. Antimicrobial photodynamic therapy (aPDT) has been widely used with very satisfactory results in the health sciences. It involves the use of a non-toxic dye, called photosensitizer (FS), and a light source of a speci?c wavelength in the presence of the environmental oxygen. This interaction is capable of creating toxic species that generate cell death. The objective of this controlled clinical study is to verify the effect of aPDT in the treatment of halitosis by evaluating the formation of volatile sulphur compounds with gas chromatography and microbiological analysis before and after treatment. Materials and Methods: Young adults in the age group between 18 and 25 years with diagnosis of halitosis will be included in this research. The selected subjects will be divided into 3 groups: G1: aPDT; G2: scraper, and G3: aPDT and scraper. All subjects will be submitted to microbiological analysis and evaluation with Oral ChromaTM before, immediately after treatment, 7, 14, and 30 days after treatment. For the evaluation of the association of the categorical variables the Chi-square test and Fisher’s Exact Test will be used. To compare the means the student t test and analysis of variance (ANOVA) will be used and to analyse the correlation between the continuous variables the correlation test by Pearson will be applied. In the analyses of the experimental differences in each group the Wilcoxon test will be used. For all analyses a level of signi?cance of 95% (P < .05) will be considered. Discussion: Halitosis treatment is a topic that still needs attention. The results of this trial could support decision-making by clinicians regarding aPDT using aPDT for treating halitosis.
关键词： qPCR,halitosis,antimicrobial photodynamic therapy
更新于2025-09-11 14:15:04
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Antimicrobial Biophotonic Treatment of Ampicillin-Resistant Pseudomonas aeruginosa with Hypericin and Ampicillin Cotreatment Followed by Orange Light
摘要： Bacterial antibiotic resistance is an alarming global issue that requires alternative antimicrobial methods to which there is no resistance. Antimicrobial photodynamic therapy (APDT) is a well-known method to combat this problem for many pathogens, especially Gram-positive bacteria and fungi. Hypericin and orange light APDT efficiently kill Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and the yeast Candida albicans. Although Gram-positive bacteria and many fungi are readily killed with APDT, Gram-negative bacteria are difficult to kill due to their different cell wall structures. Pseudomonas aeruginosa is one of the most important opportunistic, life-threatening Gram-negative pathogens. However, it cannot be killed successfully by hypericin and orange light APDT. P. aeruginosa is ampicillin resistant, but we hypothesized that ampicillin could still damage the cell wall, which can promote photosensitizer uptake into Gram-negative cells. Using hypericin and ampicillin cotreatment followed by orange light, a significant reduction (3.4 log) in P. aeruginosa PAO1 was achieved. P. aeruginosa PAO1 inactivation and gut permeability improvement by APDT were successfully shown in a Caenorhabditis elegans model.
关键词： hypericin,antimicrobial photodynamic therapy (APDT),Pseudomonas aeruginosa,ampicillin,Caenorhabditis elegans,orange light
更新于2025-09-11 14:15:04