DEACTIVATION OF Q-CDS PHOTOLUMINESCENCE THROUGH POLYNUCLEOTIDE SURFACE BINDING

The intrinsic interaction between cadmium hydroxide-layered Q-CdS clusters and polynucleotides has been examined via photoluminescence (PL) spectroscopy. For semiconductor clusters of 40-angstrom average diameter and a narrow luminescence maximum near 480 nm, quenching of this emission can be accomplished by the addition of polynucleotides such as deoxyribonucleic acid (DNA) from E. coli or polyadenylic acid (poly[A]). The observed PL area changes can be fit to a Perrin model, with the calculated volume of the quenching sphere for poly[A] being more than an order of magnitude for that of DNA, 4.5 X 10(4) angstrom3 versus 4.4 x 10(3) angstrom3. After exposure to polynucleotides, these CdS surfaces are shown to be reactive, as attempts to grow ZnS layers at the interface result in an overall enhancement of trap emission in the 500-700-nm region.