Preliminary Study on Light-Activated Antimicrobial Agents as Photocatalytic Method for Protection of Surfaces with Increased Risk of Infections

Abstract

Preventing and controlling the spread of multidrug-resistant (MDR) bacteria implicated in healthcare-associated infections is the greatest challenge of the health systems. In recent decades, research has shown the need for passive antibacterial protection of surfaces in order to reduce the microbial load and microbial biofilm development, frequently associated with transmission of infections. The aim of the present study is to analyze the efficiency of photocatalytic antimicrobial protection methods of surfaces using the new photocatalytic paint activated by light in the visible spectrum. The new composition is characterized by a wide range of analytical methods, such as UV-VIS spectroscopy, electron microscopy (SEM), X-ray powder diffraction (PXRD) or X-ray photoelectron spectroscopy (XPS). The photocatalytic activity in the UV-A was compared with the one in the visible light spectrum using an internal method developed on the basis of DIN 52980: 2008-10 standard and ISO 10678—2010 standard. Migration of metal ions in the composition was tested based on SR EN1186-3: 2003 standard. The new photocatalytic antimicrobial method uses a type of photocatalytic paint that is active in the visible spectral range and generates reactive oxygen species with inhibitory effect against all tested microbial strains.

Antimicrobial Properties of TiO2 Microparticles Coated with Ca- and Cu-Based Composite Layers

“…These species are removed by calcinations, and the UV-VIS spectrum of the sample, calcined in air at 800 • C, showed a significant decrease in the intensity of the visible absorption band (Figure 7, S2c sample). The obtained material with copper showed antimicrobial photocatalytic activity, as highlighted in previous publications [17].…”

“…As can be seen in the UV-Vis spectrum (Figure 7), only the sample containing Ca and Cu showed absorption in visible light. The antimicrobial photocatalytic effect of copper was highlighted for similar materials [17]. However, this study evidenced a similar antibacterial effect under dark and light conditions for all the samples.…”

“…New composite layers with Ca and Cu were obtained by coating TiO 2 surface microparticles. The aim of this study was to obtain an efficient antimicrobial agent that can eliminate the disadvantages of the current similar materials in terms of the photocatalytic effect-dependent antimicrobial activity [17,29].…”

“…The quantitative evaluation of the antimicrobial efficiency was performed based on the ISO 22196/2011 standard method [17,41] In total, 1 mL of each sample was spread on the 6-well plates, maintained for 24 h for drying, and inoculated with 500 µL of the microbial suspensions prepared in 1/500 diluted nutrient broth (distillate water/nutrient broth = 1/500), with a final density of 1.5 × 10 6 CFU/mL. The inoculated 6-well plates were divided into 3 sets.…”

“…Being an exogenous mechanism, ROS species also act on bacterial targets without interfering with the metabolic mechanisms of bacteria. Therefore, in principle, the antibacterial photocatalytic effect cannot generate a bacterial resistance response [17]. However, some studies have also showed that TiO 2 NPs exposed to UV radiation induce adverse effects on eukaryotic cells through a similar mechanism that is antimicrobial efficient: they can react with free radicals and signal molecules, and interfere with the biochemical reactions on plasmalemma, inducing human cell damage, genotoxicity, and inflammation, and exacerbating the immune response [18].…”