THE TOXIC EFFECT OF CELL MEMBRANE OF E. COLI CAUSED BY CdTe/MPA QUANTUM DOTS

The biological effects of CdTe/MPA quantum dots (QDs) were studied on the membrane of the Escherichia coli (E. coli) cells. The free radicals produced by QDs lead to the rupture of lipopolysacchride (LPS) patches on cell surface. Ca super(2+) and Mg super(2+) also released to the solution with the broken LPS patches. An increase in the fluorescence polarization of 1,6-Diphenyl-1,3,5-hexatriene(DPH) was observed, indicating a significant decrease in membrane fluidity of E. coli. The alteration of functional group on the E. coli surface determined by attenuated total reflection fourier transform infrared (ATR-FTIR) has confirmed the ion analysis and fluorescence polarization results. By microcalorimetry, the thermal curves showed the growth of E.coli was inhibited significantly in the presence of QDs under UV light. This phenomenon could also be caused by the free radical produced by QDs, which would inhibit the synthesis of bio-molecules in cells.