ABSTRACT
The nanocomposites of poly-diallyldimethylammonium chloride (PDADMAC) and CdTe quantum dots (QDs) (i.e.QDs-PDADMAC nanocomposites) have been prepared based on electrostatic interaction and their fluorescence stability in aqueous solution has been investigated. MTT method(3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazoliumbromide method) was used to study their cytotoxicity and A549 lung cancer cell as a model cell was also used to evaluate their cellular imaging.It was shown that the fluorescence stability of QDs-PDADMAC nanocomposites was much better than that of bare QDs both in aqueous solution and cell.Meanwhile,QDs-PDADMAC nanocomposites display very low cytotoxicity in the low concentrations and better staining ability compared with QDs.QDs-PDADMAC nanocomposites will have great advantage on the cell analysis detection and imaging.
ABSTRACT
Poly(diallyldimethylammonium chloride)(PDDA) was chosen to disperse multi-walled carbon nanotubes(MWCNTs) to prepare the stable PDDA-MWCNTs aqueous dispersion. Then, the positively charged PDDA-MWCNTs composite and negatively charged choline oxidase(ChOx) were employed to fabricate multilayer films on platinum(Pt) electrodes by layer-by-layer self-assembly technique, the anti-interferential film of Nafion was dropped at the end of the last multilayer films. The results showed that MWCNTs were evenly dispersed within the PDDA films and the multilayer films of (PDDA-MWCNTs)_n could improve the catalytic current response to choline significantly with the increased number of the multilayer films. The optimum assembly number was 6. The choline biosensor fabricated showed good linear correlation from 5×10~(-6)-2.5×10~(-4) mol/L with a detection limit of 2×10~(-6) mol/L(S/N=3), and the sensitivity was 21.97 mA/mol with a response time of 6.6 s, the RSD was less than 5%(n=3). Moreover, the biosensor exhibited an excellent anti-interferential property and a good stability.