Enzyme-free fluorescence determination of uric acid by combining CdTe quantum dots with metal-organic framework for signal amplification.

Abstract

Thecomposite of CdTe quantum dots (QDs) with ZIF-8 was elaborately designed and synthesized as an enzyme-free fluorescent probe for the sensitive determination of uric acid (UA), based on the fluorescence detection property of CdTe QDs and the signal amplification function of ZIF-8. The structure and feature of the composite were characterized with transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, and fluorescence spectrometry. With adding UA to the composite, the emission of CdTe QDs reduced due to the inner filter anddynamic quenching effects of UA, and the adsorption ability of ZIF-8 toward UA promoted the response signal of CdTe QDs. On this basis, UA was quantified by the composite in the concentration range 0.05 to 10μM with excitation/emission wavelength at 287/615nm, and the detection limit of the composite toward UA was 32nM. The reproducibility of the composite for determining UA was further evaluated, and the relative standard deviations were below 10.2%. The composite also exhibited the merits of enzyme-free analysis such as low testing cost, short analysis time (1min), and loose pH condition (application in whole physiological pH range, 5.0 - 8.0). The composite was applied to thedetermination of UA in human urine with recoveries of spiked samplesin the range 99 to 113%.