Determination of Lead(II) by a Nitrocellulose Membrane Fluorescent Biosensor Based on G-Quadruplex Conformational Changes

Abstract

A simple, label-free fluorescence method was developed for the sensitive determination of lead(II) using a nitrocellulose membrane biosensor. The surface of the nitrocellulose membrane was modified by glutaraldehyde to conjugate streptavidin, followed by the immobilization of a DNA probe via a biotin modifier. The biotinylated DNA probe can fold into a G-quadruplex structure in the presence of potassium ion that selectively binds to N-methyl mesoporphyrin IX and yields a strong fluorescence signal. The presence of lead(II) can induce a conformational change of the G-quadruplex to a more compact structure, which results in the release of potassium ion and N-methyl mesoporphyrin IX with a concomitant reduction of the fluorescence signal. The biosensor displayed a detection limit as low as 10 nM with excellent selectivity for lead(II) over other metal ions. The developed biosensor was employed for the determination of lead(II) in spiked river water.

Keywords:

• Biosensor
• G-quadruplex
• Lead
• Lead(II)
• N-methyl mesoporphyrin IX
• Nitrocellulose membrane

Notes

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lanl.