Study On Piezoelectric Sensor For The Rapid Detection Of Diethylstilbestrol In Milk

Endocrine disrupting chemicals(EDCs) are kinds of natural or synthetic compounds that can change the endocrine function in the human body through imitating and interfering endogenous hormones. A variety of cancers are related with the damages of endocrine system resulting from EDCs. Most of EDCs enter human body through the food chain and greatly threaten human health. Therefore, it is necessary to establish a simple, rapidly and efficiently method for the detection of EDCs.ObjectivesBased on the principle of antigen-antibody reaction, diethylstilbestrol(DES)which is one kind of the typical EDCs was chosen as the research object to establish a highly sensitive and specified method employing piezoelectric sensor for detecting EDCs rapidly.Methods1. Based on the platform of QCM, a sensitive membrane which can recognize DES specifically was prepared on the surface of gold electrode through the molecular self-assembly technique. The anti-DES antibodies were coupled with the AuNPs to increase their masses so that the signals of QCM which was related to the changes of mass could be amplified. DES was detected through competitive immunoassay and the standard curve was got at the same time. The detection limit was calculated based on the standard curve. The specificity was evaluated through detecting DES and its analogues with the same concentrations.2. Then, five gold electrodes were plated on a single langasite crystal in order to prepare an arrayed langasite crystal microbalance. Sensitive membrane which can recognize DES specifically was prepared on the surface of gold electrode through the molecular self-assembly technique. The reliability of the arrayed sensor was studied through control experiments; the efficiency of high-through detection of the arrayed sensor was evaluated through detecting different concentrations of anti-DESantibodies.Results1. The characterization results of AuNPs: Most of AuNPs were roundness with diameters of 40 nm. The results of Fourier transform infrared spectrum and X-ray photoelectron spectroscopy indicated that amino was modified on the surface of AuNPs successfully and the content of amino was 5.4 nmol/mg.2. The results of condition optimization: 15 nmol/L AuNPs and 7μg/mL antibody were chosen as the best ratio for their coupling. 2.2 mg/mL antigen and 14 μg/mL AuNPs-Ab were used to conduct the subsequent experiments.3. The results of detection for QCM: This QCM immunosensor had good specificity; the detection range was 0.16 ng/m L ~ 500 ng/mL and the detection limit of this method was 0.13 ng/mL. The milk samples exhibited a recovery rate of98.00% ~ 104.80% which showed good consistency with the national standard method.4. The results of detection for LCM: For the control experiment, there were obvious differences between control group and experiment group. On the different electrodes of the same crystal, the frequency shifts caused by the same concentrations of anti-DES antibody were similar; with the increasing of concentrations of anti-DES antibody, the frequency shifts were rising.ConclusionsUnder the optimal conditions, the QCM immunosensor can detect DES within30 min. Compared with traditional large-scale equipment, this method is simpler and more quickly for the detection of target molecules. Besides, the method is wider in the detection range and lower in the detection limit. What’s more, the arrayed LCM sensor is fabricated successfully and it can detect DES with arrayed method.