基于超疏水高黏附结构的痕量农药分子现场检测SERS基底研究

多种农药,包括孔雀石绿(MG)作为禁用兽药,存在食用致癌的风险.由于MG低廉的价格和极好的药效,在渔业养殖中一直被不法商贩非法使用,使得鱼类生鲜中时有MG残留检出.针对MG分子痕量残留的检测,目前一般是抽取少量养殖水样,再利用高效液相色谱柱、液相色谱-光谱等方法来评估其是否超标.这类传统的检测方法一般需要依赖价格昂贵的...

A SERS Substrate for On-Site Detection of Trace Pesticide Molecules Based on Parahydrophobic Nanostructures

As banned veterinary drugs, many pesticides, including malachite green (MG), pose a risk of carcinogenesis. Due to its low price and strong antiseptic qualities, MG has been used illegally in fisheries. As a result, MG residues are usually detected in fresh fish. To evaluate MG residues, currently, approaches include high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS) and other methods are used, and the detections are performed using a small volume of aquaculture water. However, such traditional detections rely on large and expensive equipment, which are cumbersome, and their processes are complicated, time-consuming and expensive. Consequently, these traditional methods cannot meet the needs of on-site detection of pesticides in markets, which are with features of large circulation, fast speed and low price. In recent years, with the emergence of surface-enhanced Raman scattering (SERS) and portable Raman spectrometers, a rapid on-site detection method for trace pesticide molecules becomes possible. Herein, the SERS technology uses surface plasmon of metallic nanostructures to sense molecules located nearby, thus obtaining information of molecular species and concentrations. In order to achieve an extremely low limit of detection(LOD), generally, the coffee ring effect or other means are used on SERS substrates to enrich molecules into a certain region sufficiently. When a droplet contact the substrate for a hydrophilic substrate, the liquid spreads on the surface, leading to a long perimeter of its coffee ring and a decrease in molecular distribution concentration. While when a superhydrophobic substrate is used for molecule enrichment, due to its small surface adhesion, droplets are unable to be fixed and would roll on the surface, thus shall significantly increase the difficulty of operation. Taking detection of trace residues of MG molecule as an example, due to the noisy environment caused by people in the market, collisions occur from time to time, and due to the lack of professional experiment platforms in the market, it is not desirable to use a superhydrophobic SERS substrate to detect pesticide molecules under this condition. A SERS substrate based on parahydrophobic nanostructures is proposed for rapid on-site trace detection of MG molecules in this work. Compared with previous superhydrophobic substrates, parahydrophobic substrates presented herein is able to firmly grasp droplets to be measured, which perfectly solves the problem that in on-site detections, droplets roll on conventional supehydrophobic substrates. In addition, compared with the hydrophilic substrates, due to a large contact angle of the parahydrophobic substrate, the area of the coffee ring can be reduced by 5.73 times, thus enriching concentration of the molecules can be largely increased, which as a result, can ultimately reduce LOD by at least two orders of magnitude. In short, the parahydrophobic SERS substrate proposed in this work is expected to be applied in rapid on-site detections of trace pesticide molecules.