Abstract
Highly-active, surface-modified anatase TiO2 nanoparticles were successfully synthesized and characterized. The morphological and optical properties of the obtained (metallo)porphyrin@qTiO2 materials were evaluated using absorption and fluorescence spectroscopy, scanning electron microscopy (SEM) imaging, and dynamic light scattering (DLS). These hybrid nanoparticles efficiently generated reactive oxygen species (ROS) under blue-light irradiation (420 ± 20 nm) and possessed a unimodal size distribution of 20–70 nm in diameter. The antimicrobial performance of the synthetized agents was examined against Gram-negative and Gram-positive bacteria. After a short-term incubation of microorganisms with nanomaterials (at 1 g/L) and irradiation with blue-light at a dose of 10 J/cm2, 2–3 logs of Escherichia coli, and 3–4 logs of Staphylococcus aureus were inactivated. A further decrease in bacteria viability was observed after potentiation photodynamic inactivation (PDI), either by H2O2 or KI, resulting in complete microorganism eradication even when using low material concentration (from 0.1 g/L). SEM analysis of bacteria morphology after each mode of PDI suggested different mechanisms of cellular disruption depending on the type of generated oxygen and/or iodide species. These data suggest that TiO2-based materials modified with sulfonated porphyrins are efficient photocatalysts that could be successfully used in biomedical strategies, most notably, photodynamic inactivation of microorganisms.
Highlights
Application of inorganic semiconductors as heterogeneous photocatalysts, and in particular the role of TiO2 in environmental and biomedical sciences and technologies, has already been extensively investigated
Semiconductor-based photocatalysts are routinely used in the degradation of dyes present in waste-water for the following reasons: (i) they are inexpensive and can be obtained in a large-scale preparation; (ii) they are non-toxic; (iii) they exhibit tunable properties that can be modified by the size of the particles, doping, and/or sensitization; (iv) they facilitate electron transfer processes; and (v) they are capable of extending their use without substantial loss in the photocatalytic activity [10]
Catalysts 2019, 9, 821 photocatalysts are known for their photo-antimicrobial properties, being able to inactivate a broad spectrum of pathogenic microorganisms such as bacteria, fungi, and/or viruses [11]
Summary
Application of inorganic semiconductors as heterogeneous photocatalysts, and in particular the role of TiO2 in environmental and biomedical sciences and technologies, has already been extensively investigated. The most efficient methods in this respect are advanced oxidation processes (AOPs) including environmental [1,2,3,4] and biomedical photocatalysis [5,6,7,8,9]. Semiconductor-based photocatalysts are routinely used in the degradation of dyes present in waste-water for the following reasons: (i) they are inexpensive and can be obtained in a large-scale preparation; (ii) they are non-toxic; (iii) they exhibit tunable properties that can be modified by the size of the particles, doping, and/or sensitization; (iv) they facilitate electron transfer processes; and (v) they are capable of extending their use without substantial loss in the photocatalytic activity [10]. The application of semiconductor nanoparticles as antimicrobial agents seems to be one of the most promising approaches because of the increased antibiotic resistance and lack of effective treatment modality [10].
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