Fabrication and evaluation of a label-free piezoelectric immunosensor for sensitive and selective detection of amantadine in foods of animal origin.

A label-free piezoelectric immunosensor was fabricated and applied to the detection of the antiviral drug amantadine (AM) in foods of animal origin. Experimental parameters associated with the fabrication and measurement process were optimized and are discussed here in detail. The proposed piezoelectric sensor is based on an immunosuppression format and uses a portable quartz crystal microbalance (QCM) chip. It was found to provide a good response to AM, with a sensitivity and limit of detection (LOD) of 33.9 and 1.3 ng mL-1, respectively, as well as low cross-reactivity (CR, < 0.01%) with AM analogues. The immunosensor was further applied to quantify AM at three levels in spiked samples of typical foods of animal origin, and yielded recoveries of 83.2-93.4% and standard deviations (SDs, n = 3) of 2.4-4.5%, which are comparable to the results (recoveries: 82.6-94.3%; SDs: 1.7-4.2%) obtained using a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. Furthermore, the piezoelectric immunosensing chip can be regenerated multiple (at least 20) times with low signal attenuation (about 10%). A sample analysis can be completed within 50 min (sample pretreatment: about 40 min, QCM measurement: 5 min). These results demonstrate that the developed piezoelectric immunosensor provides a sensitive, accurate, portable, and low-cost analytical strategy for the antiviral drug AM in foods of animal origin, and this label-free detection method could also be applied to analyze other targets in the field of food safety. Graphical abstract.

An electrodeposited molecularly imprinted quartz crystal microbalance sensor sensitized with AuNPs and rGO material for highly selective and sensitive detection of amantadine.

In the present work, a new amantadine (AM) imprinted quartz crystal microbalance (QCM) sensor sensitized by Au nanoparticles (AuNPs) and reduced graphene oxide (rGO) material was fabricated by electrodeposition in the presence of o-aminothiophenol (o-AT) by cyclic voltammetry scanning. AuNPs and graphene, with the advantages of great chemical stability, electrical conductivity, and large surface area, show exceptionally high sensitivity. The results of different modifications of the QCM sensor fabrication process were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. Under the optimal experimental conditions, the frequency shift of the MIP-QCM sensor showed a linear relationship with the concentration of the AM template in the range of 1.0 × 10-5 to 1.0 × 10-3 mmol L-1 with a limit of detection (LOD) of 5.40 × 10-6 mmol L-1. The imprinting factor for AM reached 7.1, the selectivity coefficient for the analogues rimantadine (RT), adamantine (AMT) and 1-chloroadamantane (CMT) were 7.3, 5.6, and 6.1, respectively. Here, a highly sensitive, selective and stable QCM sensor prepared via the imprinting approach is reported for the first time for detection of AM from animal-derived food samples.

Nanomaterials for Electrochemical Immunosensing.

Electrochemical immunosensors resulting from a combination of the traditional immunoassay approach with modern biosensors and electrochemical analysis constitute a current research hotspot. They exhibit both the high selectivity characteristics of immunoassays and the high sensitivity of electrochemical analysis, along with other merits such as small volume, convenience, low cost, simple preparation, and real-time on-line detection, and have been widely used in the fields of environmental monitoring, medical clinical trials and food analysis. Notably, the rapid development of nanotechnology and the wide application of nanomaterials have provided new opportunities for the development of high-performance electrochemical immunosensors. Various nanomaterials with different properties can effectively solve issues such as the immobilization of biological recognition molecules, enrichment and concentration of trace analytes, and signal detection and amplification to further enhance the stability and sensitivity of the electrochemical immunoassay procedure. This review introduces the working principles and development of electrochemical immunosensors based on different signals, along with new achievements and progress related to electrochemical immunosensors in various fields. The importance of various types of nanomaterials for improving the performance of electrochemical immunosensor is also reviewed to provide a theoretical basis and guidance for the further development and application of nanomaterials in electrochemical immunosensors.

A double responsive smart upconversion fluorescence sensing material for glycoprotein.

A novel strategy was developed to prepare double responsive smart upconversion fluorescence material for highly specific enrichment and sensing of glycoprotein. The novel double responsive smart sensing material was synthesized by choosing Horse radish peroxidase (HRP) as modal protein, the grapheme oxide (GO) as support material, upconversion nanoparticles (UCNPs) as fluorescence signal reporter, N-isopropyl acrylamide (NIPAAM) and 4-vinylphenylboronic acid (VPBA) as functional monomers. The structure and component of smart sensing material was investigated by transmission electron microscopy (TEM), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared (FTIR), respectively. These results illustrated the smart sensing material was prepared successfully. The recognition characterizations of smart sensing material were evaluated, and results showed that the fluorescence intensity of smart sensing material was reduced gradually, as the concentration of protein increased, and the smart sensing material showed selective recognition for HRP among other proteins. Furthermore, the recognition ability of the smart sensing material for glycoprotein was regulated by controlling the pH value and temperature. Therefore, this strategy opens up new way to construct smart material for detection of glycoprotein.