Binding of Human Serum Proteins to Titanium Dioxide Particles In Vitro

Abstract

Binding of Human Serum Proteins toTitanium Dioxide Particles In Vitro: Mazen S.K. Zaqout, et al. Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan-Objectives: To determine the capacity of human serum proteins to bind to titanium dioxide (TiO 2 ) particles of different polymorphs and sizes. Methods: TiO 2 particles were mixed with diluted human serum, purified human serum albumin (HSA) or purified human serum gamma-globulin (HGG) solutions. After incubation at 37°C for 1 h, the particles were sedimented by centrifugation, and proteins in the supernatant, as well as those bound to the particles, were analyzed. Results: The total protein concentration in the supernatant was lowered by TiO 2 , whereas the albumin/globulin ratio was elevated by the particles. Incubation with TiO 2 also lowered the immunoglobulin, pre-albumin, beta2-microglobulin, ceruloplasmin and retinol-binding protein levels, but not ferritin levels, in the supernatant. After sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE), proteins in the supernatant, especially HGG, were observed to decrease, while those released from the particles (after adding 1% SDS and heating) increased, depending on the dose of TiO 2 . Purified HGG and HSA were also bound to TiO 2 , although the former appeared to have a higher affinity. All the proteins tested showed the highest binding potency to the amorphous particles (<50 nm) and the lowest to the rutile particles (<5,000 nm), while binding to anatase particles was intermediate. The affinity to the larger anatase was higher than that to smaller anatase particles in most cases. Conclusions: Human serum proteins, including the two major components, HSA and HGG, are bound by TiO 2 particles. The polymorph of the particles seems to be important for determining the binding capacity of the particles and it may affect distribution of the particles in the body. (J Occup Health 2011; 53: 75-83)

The effect of blood protein adsorption on cellular uptake of anatase TiO2 nanoparticles

“…The adsorption of proteins onto TiO 2 NPs has been a subject of several studies. [18][19][20][21][22][23][24] In these studies, the connection between protein adsorption and cellular uptake was not investigated. Previously, we have evaluated the effect of physicochemical characteristics of a panel of TiO 2 NPs on uptake by fibroblasts.…”

Nonactivated titanium-dioxide nanoparticles promote the growth ofChlamydia trachomatisand decrease the antimicrobial activity of silver nanoparticles

“…While the primary entry of TiO 2 nanoparticles (NPs) is the gastrointestinal tract, there are data indicating that the TiO 2 NPs can bind to abundant serum proteins/protein fractions (Zaqout et al . ) and distribute to various organs, further away from the site of the administration. Indeed, Wang et al .…”

“…Apart from the larger particles, approximately 5-15% of E171 and E171 containing foods contain below 100-nm diameter nano-sized TiO 2 particles (Peters et al 2014). While the primary entry of TiO 2 nanoparticles (NPs) is the gastrointestinal tract, there are data indicating that the TiO 2 NPs can bind to abundant serum proteins/protein fractions (Zaqout et al 2011) and distribute to various organs, further away from the site of the administration. Indeed, Wang et al (2007) showed that the orally administered TiO 2 NPs could be detected in the liver, spleen, kidneys and lung tissues.…”

Binding of titanium dioxide nanoparticles to lactate dehydrogenase

“…We have observed that with A549 cells (human pulmonary epithelial type II cells) exposed to TiO 2 NPs for 24 h, LDH activity in the cell culture medium dropped markedly at higher TiO 2 concentrations, even though there was a TiO 2 dose-dependent decrease in cell viability as determined by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay (unpublished data). Based on our recent data showing that TiO 2 particles bind to several serum proteins [7], we hypothesized that TiO 2 NPs could bind to the LDH protein, which might account for the observed effect of TiO 2 NPs on measured LDH activity, particularly if centrifugation is a step in the assay protocol. To provide insight into this possibility, purified LDH preparations were mixed with TiO 2 NPs, followed by centrifugation to separate the supernatant from the precipitated TiO 2 NPs, and the activity and amount of LDH protein in the supernatant was determined.…”