Molecularly imprinted polymers-coated gold nanoclusters for fluorescent detection of bisphenol A

A flexible fluorescent sensing strategy for the recognition and detection of bisphenol A (BPA) has been proposed based on molecularly imprinted polymers (MIPs)-coated gold nanoclusters (AuNCs), by taking advantages of the high selectivity of MIPs and the strong fluorescence property of AuNCs. SiO2@AuNCs were initially prepared by making use of the powerful amido bonds between carboxyl-terminated AuNCs and amino-functionalized SiO2 nanoparticles. Then MIPs-coated AuNCs were formed by anchoring MIP layer on the surface of SiO2@AuNCs via a solgel process. In the presence of imprinting template BPA, a Meisenheimer complex could be formed between BPA and the primary amino groups on the surface of the AuNCs, and the photoluminescent energy of AuNCs would be transferred to the complex, and thereby result in the fluorescence quenching of AuNCs. The fluorescence-quenching fractions of the sensor presented a satisfactory linearity with BPA concentrations over the range of 013.1 mu M and the detection limit could reach 0.10 mu M. Distinguished selectivity was also exhibited to BPA over other possibly competing molecules. Moreover, the sensor was successfully applied to determine BPA in seawater, and the average recoveries of BPA at three spiking levels ranged from 91.3 to 96.2% with relative standard deviations below 4.8%. This AuNCs-MIPs based sensor provided great potentials for recognition and determination of phenolic environmental estrogens in complicated samples. (C) 2015 Elsevier B.V. All rights reserved.A flexible fluorescent sensing strategy for the recognition and detection of bisphenol A (BPA) has been proposed based on molecularly imprinted polymers (MIPs)-coated gold nanoclusters (AuNCs), by taking advantages of the high selectivity of MIPs and the strong fluorescence property of AuNCs. SiO2@AuNCs were initially prepared by making use of the powerful amido bonds between carboxyl-terminated AuNCs and amino-functionalized SiO2 nanoparticles. Then MIPs-coated AuNCs were formed by anchoring MIP layer on the surface of SiO2@AuNCs via a solgel process. In the presence of imprinting template BPA, a Meisenheimer complex could be formed between BPA and the primary amino groups on the surface of the AuNCs, and the photoluminescent energy of AuNCs would be transferred to the complex, and thereby result in the fluorescence quenching of AuNCs. The fluorescence-quenching fractions of the sensor presented a satisfactory linearity with BPA concentrations over the range of 013.1 mu M and the detection limit could reach 0.10 mu M. Distinguished selectivity was also exhibited to BPA over other possibly competing molecules. Moreover, the sensor was successfully applied to determine BPA in seawater, and the average recoveries of BPA at three spiking levels ranged from 91.3 to 96.2% with relative standard deviations below 4.8%. This AuNCs-MIPs based sensor provided great potentials for recognition and determination of phenolic environmental estrogens in complicated samples. (C) 2015 Elsevier B.V. All rights reserved

Surface-enhanced Raman scattering on a zigzag microfluidic chip: towards high-sensitivity detection of As(III)ions

In this study, a microfluidic platform was combined with surface-enhanced Raman scattering (SERS) to implement the rapid quantitative detection of As(III) ions in a continuous flow. Silver nanoparticles (AgNPs) were used as the SERS enhancement substrate, and glutathione (GSH) with 4-mercaptopyridine (4-MPY) was conjugated on the surface of the AgNPs. When As(III) ions encountered GSH/4-MPY functionalized AgNPs, the original monodispersed probes would aggregate because As(III) ions had a strong affinity to the GSH. As a result, Raman signals of 4-MPY adsorbed on the surface of the AgNPs were improved and the As(III) ions could be detected. Due to the advantages of microfluidics technology combined with SERS detection, the highly sensitive and reproducible analysis of As(III) ions was realized in several minutes. The proposed method allowed the quantitative analysis of As(III) ions with a linear range (3 to 200 ppb), and the limit of detection (LOD) of the As(III) ions was determined to be 0.67 ppb. The real water sample was also analyzed to confirm the practicability of the method and the consumption of several microliters of the sample was found to be environmentally friendly. This method also showed great potential in applying SERS combined with a lab-on-a-chip technique in the area of environmental monitoring with a high sensitivity and in an environmentally friendly way.In this study, a microfluidic platform was combined with surface-enhanced Raman scattering (SERS) to implement the rapid quantitative detection of As(III) ions in a continuous flow. Silver nanoparticles (AgNPs) were used as the SERS enhancement substrate, and glutathione (GSH) with 4-mercaptopyridine (4-MPY) was conjugated on the surface of the AgNPs. When As(III) ions encountered GSH/4-MPY functionalized AgNPs, the original monodispersed probes would aggregate because As(III) ions had a strong affinity to the GSH. As a result, Raman signals of 4-MPY adsorbed on the surface of the AgNPs were improved and the As(III) ions could be detected. Due to the advantages of microfluidics technology combined with SERS detection, the highly sensitive and reproducible analysis of As(III) ions was realized in several minutes. The proposed method allowed the quantitative analysis of As(III) ions with a linear range (3 to 200 ppb), and the limit of detection (LOD) of the As(III) ions was determined to be 0.67 ppb. The real water sample was also analyzed to confirm the practicability of the method and the consumption of several microliters of the sample was found to be environmentally friendly. This method also showed great potential in applying SERS combined with a lab-on-a-chip technique in the area of environmental monitoring with a high sensitivity and in an environmentally friendly way

Water-compatible temperature and magnetic dual-responsive molecularly imprinted polymers for recognition and extraction of bisphenol A

Versatile molecularly imprinted polymers (MIPs) have been widely applied to various sample matrices, however, molecular recognition in aqueous media is still difficult. Stimuli-responsive MIPs have received increasing attentions due to their unique feature that the molecular recognition is regulated. by specific external stimuli. Herein, water-compatible temperature and magnetic dual-responsive MIPs (WC-TMMIPs) with hydrophilic brushes were prepared via reversible addition-fragmentation chain transfer precipitation polymerization for reversible and selective recognition and extraction of bisphenol A (BPA). Transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT-IR) and vibrating sample magnetometry (VSM) as characterization methods were used to examine the successful synthesis of polymers, and the resultant WC-TMMIPs showed excellent thermosensitivity and simple rapid magnetic separation. Controlled adsorption and release of BPA by temperature regulation were investigated systematically, and the maximum adsorption and removal efficiency toward BPA in aqueous solutions were attained at 35 degrees C and 45 degrees C, respectively, as well as a good recoverability was exhibited with the precision less than 5% through five adsorption-desorption cycles. Phenolic structural analogs were tested and good recognition specificity for BPA was displayed. Accordingly, the WC-TMMIPs were employed as adsorbents for magnetic solid-phase extraction (MSPE) and packed SPE of BPA from seawater samples. Using the two modes followed by HPLC-UV determination, excellent linearity was attained in the range of 0.1-14.5 mu M and 1.3-125 nM, with low detection limits of 0.02 mu M and 0.18 nM, respectively. Satisfactory recoveries for spiked seawater samples were achieved ranging from 86.3-103.5% and 96.2-104.3% with RSD within 2.12-4.33%. The intelligent WC-TMMIPs combining water-compatibility, molecular recognition, magnetic separation, and temperature regulation proved potentially applicable for selective identification, controlled adsorption/release and high-efficiency enrichment/removal of trace targets in complicated aqueous media. (C) 2016 Elsevier B.V. All rights reserved