The authors describe a dual signal amplification electrochemiluminescent (ECL) immunoassay for ultrasensitive determination of the β-adrenergic agonist salbutamol (SAL). It is based on the use of gold nanoparticles (AuNPs) and silica-coated quantum dots of the type CdSe@SiO 2 . The CdSe@SiO 2 nanoparticles (NPs) were synthesized by water-in-oil reversed-phase microemulsion. Amino-modified NPs were then prepared and used as an ECL signal probe for detection of SAL in the presence of K 2 S 2 O 8 . The gold NPs with their large specific surface carry the antigen, facilitate electron transfer and improve the electrochemical reaction efficiency of QDs and K 2 S 2 O 8 . The ECL immunosensor was fabricated by coating the AuNPs with antigen, and then SAL competed with SAL antigen for the binding sites of the antibody on the CdSe@SiO 2 NPs. Under optimized conditions, the ECL intensity is linearly related to the logarithm of the SAL concentration in the range from 0.001 to 1000 ng mL −1 , with a lower detection limit of 0.17 pg mL −1 (at an S/N ratio of 3). The assay has good operational stability, is highly sensitive and selective. It is judged to possess a wider scope in that it may be applied to many other small molecule analytes for which adequate antibodies are available.
Schematic of a dual signal amplification electrochemiluminescent immunoassay for ultrasensitive detection of the β-adrenergic agonist salbutamol based on the use of gold nanoparticles and CdSe@SiO 2 .
Liu Mingyue,Gao Zhao,Yu Yanjun,Su Rongxin,Huang Renliang,Qi Wei,He Zhimin
4-Nitrophenol (4-NP) is a priority pollutant in water and is both carcinogenic and genotoxic to humans and wildlife even at very low concentrations. Thus, we herein fabricated a novel molecularly imprinted core-shell nanohybrid as a ratiometric fluorescent sensor for the highly sensitive and selective detection of 4-NP. This sensor was functioned by the transfer of fluorescence resonance energy between photoluminescent carbon dots (CDs) and 4-NP. This sensor was synthesized by linking organosilane-functionalized CDs to silica-coated CdSe quantum dots (CdSe@SiO 2 ) via Si–O bonds. The nanohybrids were further modified by anchoring a molecularly imprinted polymer (MIP) layer on the ratiometric fluorescent sensor through a facile sol–gel polymerization method. The morphology, chemical structure, and optical properties of the resulting molecularly imprinted dual-emission fluorescent probe were characterized by transmission electron microscopy and spectroscopic analysis. The probe was then applied in the detection of 4-NP and exhibited good linearity between 0.051 and 13.7 μg/mL, in addition to a low detection limit of 0.026 μg/mL. Furthermore, the simplicity, reliability, high selectivity, and high sensitivity of the developed sensor demonstrate that the combination of MIPs and ratiometric fluorescence allows the preparation of excellent fluorescent sensors for the detection of trace or ultra-trace analytes.
Wang Jing,Peng Xiao,Li Daquan,Jiang Xiaochun,Pan Zaifa,Chen Aimin,Huang Liang,Hu Jun
A dually emitting quantum dot nanohybrid was designed for the fluorometric 2-wavelength determination of ascorbic acid (AA). The nanohybrid consists of red-emitting CdTe quantum dots (QDs) covalently linked to the surface of silica nanoparticles containing green-emitting CdSe QDs. The fluorescence of the red-emitting CdTe QDs (peaking at 616 nm) is first quenched by addition of KMnO 4 due to oxidation under formation of CdTeO 3 and TeO 2 . On addition of AA, the red fluorescence is restored due to the reduction of surface CdTeO 3 /TeO 2 to form CdTe. The green fluorescence of the green-emitting CdSe QDs (peaking at 522 nm), in contrast, remains constant and its intensity serves as a reference signal. Both kinds of QDs can be photoexcited at 380 nm. An easily distinguishable transition in fluorescence (from green to orange-red) can be observed on increasing the amount of added AA. Under optimal conditions, the ratio of the intensities of the red and the green fluorescence increases linearly in the 0.1 to 5.0 μM AA concentration range, and the detection limit is as low as 35 nM. The assay was successfully applied to the quantitation of AA in (spiked) fruit juice samples.
A new dually emitting CdSe@SiO 2 @CdTe nanohybrid was designed for ratiometric ultrasensitive fluorometric detection of ascorbic acid in fruit juice samples.
危险品化学品经营许可证（带存储）