Ratiometric Fluorescent Quantum Dot-Based Biosensor for Chlorothalonil Detection via an Inner-Filter Effect

Abstract

A new sensitive sensor for detecting chlorothalonil (CHL) based on the inner-filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent quantum dots (RF-QDs) was developed. Here, RF-QDs were designed by two different color CdTe QDs. Based on the IFE, the AuNPs can quench the fluorescence of the RF-QDs. Because of the electrostatic attraction between protamine (PRO) and the AuNPs, the PRO can restore fluorescence effectively. Papain (PAP) can easily hydrolyze PRO and causes the quench of fluorescence quenching. The addition of CHL can inhibit PAP activity and restore the fluorescent signal. Through the characterization of the structural changes of PAP, the inhibition and mechanism of CHL on PAP activity were studied. The ability of CHL to inhibit PAP activity was evaluated by measuring the fluorescence of the RF-QDs. Under the optimal conditions, this sensing platform shows a response to CHL in the range of 0.34–2320 ng/mL and a detection limit of 0.0017 ng/mL. Based on the CHL inhibition of PAP activity, the RF-QDs showed good selectivity for CHL. The practical application of the proposed system was demonstrated by detecting CHL in food and environmental samples with satisfying results.

Rapid Surface-Enhanced Raman Spectroscopy Detection of Chlorothalonil in Standard Solution and Orange Peels with Pretreatment of Ultraviolet Irradiation

“…As indicated by Chaves et al (2008), the detection limits of chlorothalonil and its degradation products in soil and water were determined to be in the range of 1 and 0.1 µg/L for the LC and GC methods, respectively. A ratiometric fluorescent quantum dot-based biosensor previously synthesized by Sheng et al (2020) was reported to detect chlorothalonil in the range of 0.34-2320 ng/mL. Although the detection limit of chlorothalonil by using SERS method developed in this study was relatively high, maximum residue limits for pesticides in food) requirements, the maximum residue concentration of chlorothalonil in foods was established to be 0.1 ~ 5 ppm according to the Chinese national food safety standard (GB 2763(GB -2014.…”

Nanomaterial-Based Dual-Emission Ratiometric Fluorescent Sensors for Biosensing and Cell Imaging

“…These nanomaterial-based ratiometric fluorescent biosensors can be used for the precise detection of a variety of targets including pesticides, proteins, nucleic acids, and small molecules. Moreover, they have also been used for direct visualization of the target analyte with the naked eye, as well as in vitro and in vivo imaging [ 32 , 33 , 34 , 35 , 36 ]. The recent developments in the design and application of nanomaterial-based ratiometric biosensors for fluorescence sensing and cell imaging are reviewed in this section.…”

“…The established sensing platform exhibits a wider linear range (0.34–2320 ng/mL) for CHL than that of single color QDs. Furthermore, the limit of detection for CHL is achieved as low as 0.0017 ng/mL [ 36 ]. However, the hybrid nanosensors may encounter the problem of uneven local concentration, which can affect the sensitivity and accuracy.…”

“…As shown in Figure 5 B, there is only green fluorescence of FITC in normal liver L-O2 cells, while there is not only green fluorescence of FITC but also red fluorescence of TAMRA in HepG2, MCF-7, and HeLa cancer cells, indicating that this sensor can be used to distinguish cancer cells from normal cells [ 67 ]. In addition to quenching the fluorescence of dyes, AuNPs have also been used as a fluorescence quencher for QDs, and the established biosensors could be employed for the quantitative and sensitive detection of pesticides [ 36 , 68 ]. However, there are only a few reports about the construction of AuNP-based ratiometric fluorescent biosensors.…”

“…( B ) Representation of fluorescence detection of CHL through IFE of gold nanoparticles on RF-QDs. Reproduced from [ 36 ], with permission from the American Chemical Society, 2020. ( C ) Proposed mechanism of fluorescence sensing guanine by CDs-ZnCdTe QDs.…”