Chiang Mai Journal of Science

On the basis of previous findings that nanoparticles (NPs) have profound effects on the environment and living cells, we applied a biophysical approach, spot tracking technique, to study NP effects on Escherichia coli with regard to MinD protein dynamics. We used TiO2 NPs that were concentrated in the range of 5-35 mg/L. Investigations on size distribution showed that NP cluster formation was concentration-dependent. Above 25 mg/L, NPs were found to aggregate, forming large clusters of more than 100 nm in average diameter. In addition, no interference in MinD oscillation periods was found. Below 25 mg/L, we observed less particle aggregation, measuring a mean cluster size below 100 nm. In contrast to the higher concentrated and larger NP clusters, the lower concentrated NPs had a significant effect on the protein period and protein intensity. These results indicate that only the specific sized of the suspension particles had an effect on protein dynamic system. To the best of our knowledge, this is the first report on the NP effects observed on the Min protein oscillation system. Importantly, this study may increase the awareness of the effect of NPs on living cells, particularly in an aqueous environment.