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Monitoring of Virulence Factors and Metabolic Activity in Aggregatibacter Actinomycetemcomitans Cells Surviving Antimicrobial Photodynamic Therapy via Nano-Chitosan Encapsulated Indocyanine Green
摘要： Aggregatibacter actinomycetemcomitans is an etiological agent frequently found in both chronic and aggressive periodontitis as well as peri-implantitis. This study assessed the effect of antimicrobial photodynamic therapy (aPDT), as an alternative treatment modality, by nano-chitosan encapsulated indocyanine green (CNPs/ICG), as a photosensitizer, on the virulence features of cell-surviving aPDT against A. actinomycetemcomitans. The cell cytotoxicity effect of CNPs/ICG was evaluated on primary human gingival fibroblast cells. A. actinomycetemcomitans ATCC 33384 photosensitized with CNPs/ICG was irradiated with diode laser at a wavelength of 810 nm for 1 min (31.2 J/cm2), and then bacterial viability measurements were done. The biofilm formation ability, metabolic activity, and antimicrobial susceptibility profiles were assessed for cell-surviving aPDT. The effect of aPDT on the expression of the fieF virulent gene, encoding the ferrous-iron efflux pump, was evaluated by the quantitative real-time PCR. CNPs/ICG-aPDT resulted in a significant reduction of cell viability (91%), biofilm formation capacity (53%), and metabolic activity (48%) of A. actinomycetemcomitans when compared to the control group (P < 0.05). Moreover, fieF gene expression was downregulated by 14.8 folds after the strains were treated with aPDT. The virulence of A. actinomycetemcomitans strain reduced in cells surviving aPDT with CNPs/ICG, indicating the potential implications of aPDT for the treatment of A. actinomycetemcomitans infections in periodontitis and peri-implantitis in vivo.
关键词： peri-implantitis,nano-chitosan,Aggregatibacter actinomycetemcomitans,antimicrobial photodynamic therapy,indocyanine green,periodontitis
更新于2025-09-23 15:21:01
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Plasmonic Colloidosomes Coupled MALDI-TOF MS for Bacterial Heteroresistance Study at Single-Cell Level
摘要： Antimicrobial resistance (AMR) is a long-term public health challenge worldwide, and it is increasingly recognized to be a heteroresistance phenomenon in an isogenic bacterial population. When the minority population of resistant bacteria with strong AMR is not handled in time, such sub-population can be enriched leading to the further development of bacterial AMR. However, conventional AMR studies based on ensemble-averaged data from large population fail to characterize the bacterial heterogeneity. In this work, we develop a method using plasmonic colloidosomes and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) to study single bacterial cell AMR. The plasmonic colloidosomes act simultaneously as bacteria containers and sample spots for MALDI-TOF MS detection. Cells of β-lactamases producing Escherichia coli (E. coli) are trapped in colloidosome containers (~200 μm in diameter) in the presence of antibiotic drug ampicillin (AMP). Benefiting from the fast reaction kinetics in microcompartments, hydrolysis product of AMP by bacteria can be detected by MALDI-TOF MS within 40 min. The colloidosomes as MALDI sample spots also benefit sensitive detection and accurate quantification of AMP and its hydrolysis product. It was found that even an isogenic population could consist of a mixture of bacteria that have different resistance degrees to antibiotics. Taken the β-lactamases producing E. coli as an example, 20% of the bacterial individuals have relatively strong activity in hydrolyzing AMP. It is expected that the colloidosome-based platform would reveal a prospective application in full characterization of single bacterial cell AMR.
关键词： MALDI-TOF MS,Antimicrobial resistance,Single-cell level,Plasmonic colloidosomes,Bacterial heteroresistance
更新于2025-09-23 15:21:01
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Structure-Activity Relationships of Photoswitchable Diarylethene-Based β-Hairpin Peptides as Membranolytic Antimicrobial and Anticancer Agents
摘要： Five series (28 structures) of photoswitchable β-hairpin peptides were synthesized, based on the cyclic scaffold of the natural antibiotic gramicidin S. Cell-type selectivity was compared for all activated (diarylethene ring-open) and deactivated (closed) forms in terms of antibacterial activity (MIC against E. coli and B. subtilis), anticancer activity (IC50 against HeLa cell line), and hemolytic cytotoxicity (HC50 against human erythrocytes). Correlations between the conformational plasticity of the peptides, their hydrophobicity and their bioactivity were also analyzed. Considerable improvements in selectivity were achieved compared to the reference compound. We found a dissociation of the anticancer activity from hemolysis. Phototherapeutic indices (PTI) – HC50(closed)/MIC(open) and HC50(closed)/IC50(open) – were introduced for the peptides as safety criteria. The highest PTI for HeLa-selective toxicity were observed among analogues containing hydroxyleucine on the hydrophobic face. For one compound, high PTIs were demonstrated across a range of different cancer cell lines, including a doxorubicin-resistant one.
关键词： photoswitchable diarylethene-based β-hairpin peptides,antimicrobial,phototherapeutic indices,gramicidin S,anticancer,hemolytic cytotoxicity
更新于2025-09-23 15:21:01
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An Insight Into the Potentiation Effect of Potassium Iodide on aPDT Efficacy
摘要： Antimicrobial photodynamic therapy (aPDT) is gaining a special importance as an effective approach against multidrug-resistant strains responsible of fatal infections. The addition of potassium iodide (KI), a non-toxic salt, is recognized to increase the aPDT efficiency of some photosensitizers (PSs) on a broad-spectrum of microorganisms. As the reported cases only refer positive aPDT potentiation results, in this work we selected a broad range of porphyrinic and non-porphyrinic PSs in order to gain a more comprehensive knowledge about this aPDT potentiation by KI. For this evaluation were selected a series of meso-tetraarylporphyrins positively charged at meso positions or at β-pyrrolic positions and the non-porphyrinic dyes Methylene blue, Rose Bengal, Toluidine Blue O, Malachite Green and Crystal Violet; the assays were performed using a bioluminescent E. coli strain as a model. The results indicate that KI has also the ability to potentiate the aPDT process mediated by some of the cationic PSs [Tri-Py(+)-Me, Tetra-Py(+)-Me, Form, RB, MB, Mono-Py(+)-Me, β-ImiPhTPP, β-ImiPyTPP, and β-BrImiPyTPP] allowing a drastic reduction of the treatment time as well as of the PS concentration. However, the efficacy of some porphyrinic and non-porphyrinic PSs [Di-Py(+)-Me opp, Di-Py(+)-Me adj, Tetra-Py, TBO, CV, and MG] was not improved by the presence of the coadjuvant. For the PSs tested in this study, the ones capable to decompose the peroxyiodide into iodine (easily detectable by spectroscopy or by the visual appearance of a blue color in the presence of amylose) were the most promising ones to be used in combination with KI. Although these studies confirmed that the generation of 1O2 is an important fact in this process, the PS structure (charge number and charge position), aggregation behavior and affinity for the cell membrane are also important features to be taken in account.
关键词： cationic porphyrins,xanthenes,potassium iodide,phenothiazines,bioluminescent E. coli,antimicrobial photodynamic therapy
更新于2025-09-23 15:21:01
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Bacteria-Targeted Supramolecular Photosensitizer Delivery Vehicles for Photodynamic Ablation Against Biofilms
摘要： Photodynamic therapy (PDT) is believed to be a potent method for biofilm treatments. However, undesired damage to normal cells may be caused due to the nonselective nature of PDT. Therefore, targeted PDT is preferred on one hand to enhance antimicrobial effects and on the other hand to reduce cytotoxicity to normal cells. For this purpose, novel bacteria-targeted photosensitizer delivery micelles are fabricated, taking advantage of α-cyclodextrin (α-CD)/polyethylene glycol (PEG) supramolecular assembly. Hydrophilic antimicrobial peptide (AMP) Magainin I is covalently bound with PEG, working as a bacterial targeting group as well as the stabilizing shell of the supramolecular micelles. Photosensitizer Chlorin e6 (Ce6) is grafted onto α-CD. The micelles exhibit excellent bacterial targeting effects. Compared to α-CD-Ce6, the supramolecular micelles possess enhanced biofilm killing ability against Gram (?) Pseudomonas aeruginosa biofilms and Gram (+) methicillin-resistant Staphylococcus aureus (MRSA) biofilms while reducing cytotoxicity to NIH/3T3 model cells.
关键词： antimicrobial peptides,biofilms,targets,cytocompatibility,photodynamic therapy
更新于2025-09-23 15:21:01
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Novel honey mediated green synthesis of Graphene@Ag Nanocomposite and its two-dimensional application in photovoltaic and anti-microbial activity
摘要： The green and facile method were successfully employed for the fabrication of Graphene/Ag nanocomposite (Gr@AgNCs) with graphite oxide (GO) as graphene precursor and AgNO3 as precursor for Ag nanoparticles. Honey was used as a reducing and stabilizing agentwhich is known to be environment-friendly in nature. The characterization of synthesized Gr@AgNCs was done using x-ray diffraction (XRD),scanning electron microscopy (SEM),Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectra (RS),Thermogravimetric analysis (TGA), and UV analysis. The results showed that Honey effectively reduced GO to graphene and silver ions to silver nanoparticles (AgNPs) which makes present synthesis more suitable for synthesizing other metals like gold (Au) on graphene sheets. This active synthesis perhaps can have wide applications in medical, technological and industrial ?eld. In addition to this, enhanced antimicrobial activity of silver nanoparticles (AgNPs) was retained in the Gr@AgNCs along with the photovoltaic activity signifyingtheir potential use as a graphene-based nanomaterial.
关键词： antimicrobial activity,honey,graphene,nano materials,graphene oxide,photovoltaic activity
更新于2025-09-23 15:19:57
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Shape-dependant photocatalytic and antimicrobial activity of ZnO nanostructures when conjugated to graphene quantum dots
摘要： To reduce the bandgap and e-/h+ pairs recombination, zinc oxide nanoflakes (ZnO-NFs) and zinc oxide nanorods (ZnO-NRs) were covalently linked to graphene oxide quantum dots (GQDs). Photocatalytic and antimicrobial activity of ZnO nanohybrids (ZnO-NFs@GQDs and ZnO-NRs@GQDs) were investigated. The formation of the distinct ZnO nanoflakes and ZnO nanorods shaped nanoparticles were evidenced by SEM. The bandgap decreased from 2.98 to 2.61 eV and 3.00 to 2.79 eV for ZnO-NFs@GQDs and ZnO-NRs@GQDs, respectively. Photoluminescence (PL) data showed a similar trend where a larger decrease was obtained for ZnO-NFs@GQDs. Photolysis ruled out adsorption mechanism for the removal of dye. Optical data and PL measurements supported photocatalytic findings that ZnO-NFs@GQDs performed better (80%) than ZnO-NRs@GQDs (18%). ZnO-NRs@GQDs however, showed greater bacterial inhibition when tested against E. coli, P. aeruginosa, B. cereus and S. aureus. The antimicrobial efficiency followed the order: ZnO-NFs < ZnO-NFs@GQDs < ZnO-NRs < ZnO-NRs@GQDs with greater efficiency being against S. aureus. Liquid photocatalysts zinc nanoparticles can thus be used to remove dyes and inhibit bacterial growth in aqueous solution.
关键词： Zinc oxide nanorods,zinc oxide nanoflakes,antimicrobial activity,photocatalysis,graphene quantum dots
更新于2025-09-23 15:19:57
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Wettability, Photoactivity, and Antimicrobial Activity of Glazed Ceramic Tiles Coated with Titania Films Containing Tungsten
摘要： Self-cleaning coatings are advanced materials for the removal of pollutants and microorganisms by combining wettability, photocatalytic degradation, and antimicrobial activity. In this work, we propose a rational design of self-cleaning films based on TiO2 synthesized by sol?gel on commercial glazed ceramic tiles for building’s indoor applications. The synthesis strategy is based on hydrolysis and condensation of Ti-isopropoxide in the presence of W(VI) precursors to tune defects and crystallinity of the resulting W?TiO2 thin film. From the microstructure and surface composition analysis for different tungsten contents and annealing temperatures, we conclude that the film is composed by sintered TiO2 particles with adsorbed polytungstates (WOx) that inhibit anatase/rutile transformation. Polytungstates on TiO2 also induce surface defects that enhance water contact angle and inactivation of Escherichia coli under visible light. The presence of W(VI) has a negligible effect toward crystal violet degradation either under visible or under UV light. These results provide evidence on the existence of at least two different types of defects: (i) intrinsic defect from a sol?gel route and (ii) induced defect by tungsten species on the surface. Understanding the correlation between composition, structure, and self-cleaning properties provides a base for an efficient design of low-cost self-cleaning ceramic tiles that can be fully manufactured in an industrial plant.
关键词： photocatalytic degradation,sol?gel,W?TiO2,TiO2,antimicrobial activity,self-cleaning coatings
更新于2025-09-23 15:19:57
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Antimicrobial biomaterials and their potential application in ophthalmology
摘要： Infections associated with the use of intraocular, periocular, or orbital implants are associated with an increase in both morbidity and in the costs of ophthalmological surgery. This is due to an increased number of visits and the need for additional treatments, at a time when some conventional therapies are losing their efficacy, or even hospitalization. To avoid such consequences, the first step should be to prevent the biomaterials that form implants from being colonized by various microorganisms, either intraoperatively or postoperatively. To this end, several lines of research have emerged that aim at equipping implants with antimicrobial properties, some of which are described in this review.
关键词： Ophthalmology,Implant-associated infections,Antimicrobial biomaterials
更新于2025-09-19 17:15:36
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Physicochemical and antimicrobial photodynamic chemotherapy (against E. Coli) by indium phthalocyanines in the presence of silver-iron bimetallic nanoparticles
摘要： In this work, Schiff base indium phthalocyanines: In-Cl tetra N,N-dimethyl-4-(methylimino) phthalocyanine (complex 1b) and In-Cl tetra-phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine (complex 2b) substituted at the peripheral positions with 4-dimethyl benzaldehyde are synthesized from tetra amino and tetra phenoxy amino phthalocyanines, respectively. These complexes were further quartenised with 1,3-propanesultone to form zwitterionic complexes 1 and 2, respectively. Silver-iron dimers (Ag-Fe3O4) and silver-iron core shell (Ag@Fe3O4) nanoparticles (NPs) were linked to the synthesised complexes. The photophysical and photochemical behaviour of the complexes and their conjugates with NPs were investigated in dimethyl sulfoxide. Complexes 2 and 2b and their conjugates were then used for photodynamic antimicrobial chemotherapy on E. coli. The zwitter ionic photosensitiser 2 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.
关键词： zwitterionic,Indium phthalocyanines,photodynamic antimicrobial chemotherapy,E-coli
更新于2025-09-19 17:15:36