Stiffness Alterations of Single Cells Induced by UV in the Presence of NanoTiO₂

Abstract

Nanocrystalline titanium dioxide (nanoTiO2) has been reported to generate reactive oxygen species (ROS) under UV illumination. In our studies, changes in mechanical properties of human skin fibroblasts, exposed to the oxidative stress induced in the presence of nanoTiO2 and UV light, were studied using atomic force microscopy (AFM). The exposure of cells to the action of ROS was performed at low TiO2 concentration (4 microg/mL) and under illumination with low-intensity UVA (8 and 20 mW/cm2) or UVC (0.1 mW/ cm2). AFM measurements of the cell stiffness were carried out immediately after exposure of cells to the oxidative stress. The data suggest that under illumination with low-intensity UVA nanoTiO2 generates ROS, which, in turn, damage cellular and subcellular structures. This process was detected by AFM as a marked drop in the cellular stiffness of ca. 30-75%, which occurred rapidly, in the time frame of 1 min. The photo-oxidative stress inducing the decrease of cell stiffness was cancelled in the presence of a well-established antioxidant, beta-carotene. The results highlight the sensitivity of AFM to detect early changes in mechanical properties of cells exposed to oxidative stress.

Photoinduced Damage to Cellular DNA: Direct and Photosensitized Reactions†

“…• OH in the UVA activation of nanocrystalline TiO 2 was provided by atomic force microscopy (AFM) measurements showing a marked decrease in the stiffness of phototreated human skin fibroblasts (201).…”

Mechanical properties of Callitriche cophocarpa leaves under Cr(VI)/Cr(III) influence

“…The elastic properties of leaves were measured using a commercially available device (PSIA XE120, Park Systems, Korea) equipped with the ''liquid cell'' setup (Vileno et al 2007). Standard silicon cantilevers in the conical shape of a probing tip were used in all experiments (NSC36, Park Systems).…”

“…This process can undergo through the surface of leaves, which leads us to the hypothesis that Cr uptake can alter the mechanical properties of leaves. In the present study, in order to verify this hypothesis, we have used atomic force microscopy (AFM) (Vileno et al 2007) to determine the mechanical properties of C. cophocarpa leaves exposed to 100 lM concentration of Cr(III) and Cr(VI). We have shown an important correlation between Cr(VI), Cr(III) and Ca content in relation to the stiffness of the leaf.…”

Photocatalytic Reaction of Gas-Phase Naphthalene on Paint- and Sunscreen-Coated Surfaces

“…In this capacity, human skin serves as a substrate on which photocatalytic reactions can take place. Several studies have already demonstrated the potential dangers to human skin in contact with reactive 2 ISRN Chemical Engineering oxygen species (ROS) produced by photo-excited nanoparticles [4,[13][14][15][16][17][18][19][20]. To date, few researchers have examined the photocatalytic degradation of volatile or semi-volatile species on sunscreen surfaces.…”