A ratiometric fluorescent quantum dots based biosensor for organophosphorus pesticides detection by inner-filter effect

• Published in: Biosensors & bioelectronics 2015-12, Vol.74, p.277-283
• Main Authors: Yan, Xu, Li, Hongxia, Han, Xiaosong, Su, Xingguang
• Format: Article
• Language: English
• Subjects: Animals; Biosensing Techniques - methods; Biosensors; Drinking Water - analysis; Emissivity; Environmental Pollutants - analysis; Fluorescence; Fluorescent Dyes - chemistry; Gold - chemistry; Gold nanoparticle; Inhibition; Inner-filter effect; Limit of Detection; Metal Nanoparticles - chemistry; Methyl Parathion - analysis; Milk - chemistry; Organophosphorus pesticides; Oryza - chemistry; Pesticides; Pesticides - analysis; Quantum dots; Quantum Dots - chemistry; Ratiometric fluorescent quantum dots; Silicon dioxide; Spectrometry, Fluorescence - methods; Trypsin
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2015.06.020

In this work, we develop a novel and sensitive sensor for the detection of organophosphorus pesticides based on the inner-filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent quantum dots (RF-QDs). The RF-QDs has been designed by hybridizing two differently colored CdTe QDs, in which the red emissive QDs entrapped in the silica sphere acting as the reference signal, and the green emissive QDs covalently attached on the silica surface serving as the response signal.The fluorescence of RF-QDs could be quenched by AuNPs based on IFE. Protamine could effectively turn on the fluorescence due to the electrostatic attraction between protamine and AuNPs. Trypsin can easily hydrolyze protamine, leading to the quench of the fluorescence. Then, the fluorescence could be recovered again by the addition of parathion-methyl (PM) which could inhibit the activity of trypsin. By measuring the fluorescence of RF-QDs, the inhibition efficiency of PM to trypsin activity was evaluated. Under the optimized conditions, the inhibition efficiency was proportional to the logarithm of PM concentration in the range of 0.04–400ngmL−1, with a detection limit of 0.018ngmL−1. Furthermore, the simple and convenient method had been used for PM detection in environmental and agricultural samples with satisfactory results. •The RF-QDs possess a built-in correction that eliminates false signals.•The fluorescence intensity of RF-QDs could be quenched by AuNPs based on IFE.•The proposed approach for PM detection has a much lower LOD down to 0.018ngmL−1.•PM in real sample was detected with satisfactory results.