Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5403403 | Journal of Luminescence | 2007 | 7 Pages |
Abstract
The interaction of DNA bases and corresponding nucleotides with CdS nanoparticles (NPs), biofunctionalized by cysteine, has been investigated by absorption and fluorescence spectroscopy. Unique enhancement effect of adenine, in contrast to other nucleobases, on the luminescence of cysteine capped CdS (cys-CdS) NPs at both pH 7.5 and 10.5 was found, the extent of enhancement being much higher at pH 10.5. At the latter pH, the difference optical absorption spectra show development of new peak at 278Â nm with corresponding decrease in the absorption of adenine at 260Â nm, which is attributed to binding of adenine anion to the CdS surface through N7 of the purine ring. Appearance of a new band at 478Â cmâ1 and concomitant shift in the C8-N7 vibrations to 1610Â cmâ1 in the FTIR spectra of cys-CdS NPs with adenine also suggest Cd-N7 binding on the particle surface. Amongst various nucleotides, ATP exhibited maximum luminescence enhancement on CdS NPs for a given change in concentration in the micro-molar range at physiological pH. A quantitative correlation between ATP concentration and PL enhancement of CdS NPs has been established, a step which in future might assist in developing new protocols for fluorescence sensing of adenine nucleotides under certain pathological conditions.
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Authors
Anindita Chatterjee, Amiya Priyam, Subhash C. Bhattacharya, Abhijit Saha,