Preparation of Gold Nanorods Modified by G-Quadruplex DNA and Its Application to Fluorospectrophotometric Determination of Pb(Ⅱ)

Gold nanorods modified by G-quadruplex was used for the fluorescence determination of Pb(Ⅱ). Pb(Ⅱ) can drive the formation of G-quadruplex DNA which can chelate with the fluorescent probes zinc protoporphyrin because Pb(Ⅱ) can stabilize the G-quadruplex DNA structure with high efficiency. The gold nanorods not only are a DNA carrier, but also enhance the fluorescence intensity of ZnPPIX-G4. Based on the fact, a new Pb(Ⅱ) sensitive fluorescent sensor was constructed. The G-quadruplex DNA-gold nanorods were characterized by transmission electron microscopy, fluorescence spectroscopy and UV absorption spectroscopy. The linearity range of the Pb(Ⅱ) found were within 100 nmol·L-1 and 150-1 000 nmol·L-1, with detection limit (3S/N) of 0.1 nmol·L-1. The sensor was used to analyze tap water samples, giving results in agreement with that obtained by ICP-AES.