Development of a piezoelectric immunosensor for the measurement of paclitaxel

Construction of a piezoelectric immunosensor for ultra-sensitive and highly selective detection of ribavirin in animal-derived foods

In this work, a suppressive piezoelectric immunosensor based on the ultra-sensitive quartz crystal microbalance and highly specific immunosorbent assay was constructed for the detection of ribavirin for the first time. The carboxyl group was modified on the surface of the gold electrode by electropolymerization, and then the carboxyl group was combined with the amino-modified antigen, and then the corresponding antibody was able to bind to it according to the principle of immune recognition, which interlocked to cause the frequency change of the piezoelectric sensor. The preparation conditions of the sensor and the antibody concentration were optimized, and the performance of the sensor was evaluated. Under the optimal conditions, a wide linear range of 1-750 μg L^-1, a low detection limit (IC₁₅) of 2.64 μg L^-1, and a good sensitivity (IC₅₀) of 31.49 μg L^-1 were obtained. The sensor was used for the detection of ribavirin in chicken and milk samples, and the recovery rate ranged from 88.01 to 94.42%, which shows satisfactory consistency with the detection results of high performance liquid chromatography. It was suggested that the proposed piezoelectric immunosensor has good sensitivity and selectivity for ribavirin, and can be applied to the detection of actual food samples.

Quartz-Crystal Microbalance (QCM) for Public Health: An Overview of Its Applications

Nanobiotechnologies, from the convergence of nanotechnology and molecular biology and postgenomics medicine, play a major role in the field of public health. This overview summarizes the potentiality of piezoelectric sensors, and in particular, of quartz-crystal microbalance (QCM), a physical nanogram-sensitive device. QCM enables the rapid, real time, on-site detection of pathogens with an enormous burden in public health, such as influenza and other respiratory viruses, hepatitis B virus (HBV), and drug-resistant bacteria, among others. Further, it allows to detect food allergens, food-borne pathogens, such as Escherichia coli and Salmonella typhimurium, and food chemical contaminants, as well as water-borne microorganisms and environmental contaminants. Moreover, QCM holds promises in early cancer detection and screening of new antiblastic drugs. Applications for monitoring biohazards, for assuring homeland security, and preventing bioterrorism are also discussed.

The fabrication of a piezoelectric immunosensor based on DNA-antibody conjugate layer

In this article, we report a method of antibody immobilization carried out by hybridizing DNA-antibody conjugates on a mixed self-assembled monolayer composed of DNA thiols and mercaptopropionic acid via sequence-specific hybridization. The proposed method was applied to fabricate an immunosensor for detecting human immunoglobulin G (IgG). Under the optimized experimental conditions, a wide linear range from 50.0 to 500 μg/ml was reached with a detection limit of 30.13 μg/ml. The developed immunosensor possesses advantages such as simple fabrication, wide linear range, easy regeneration, and excellent reproducibility.

Self-assembly and recrystallization of bacterial S-layer proteins of Bacillus sphaericus and Bacillus thuringiensis on silicone, mica and quartz crystal supports

The Oriented architecture of macromolecules plays a critical role in many aspects of Nanobiotechnology such as in the development of biosensors. To this regard, S-layers which constitute the outermost cell envelope component of many prokaryotic organisms, represent unique self assembled systems with the capability to rearrange into monomolecular and oriented arrays. These properties can be exploited to promote their crystallization on surfaces (e.g. silicone) which is pivotal for the subsequent immobilization of macromolecules and development of new biosensors. In this work the crystallization of bacterial S-layers obtained from Bacillus thuringiensis and Bacillus sphaericus CCM2177 on silicone, mica and quartz crystal surfaces were investigated. The SDS page results of S-layers isolated from the above mentioned bacteria put in evidence that their molecular weight (MW) was around 120 KDa and, as reported in the literature, slightly higher for those extracted by Bacillus thuringiensis. In addition, results showed that S-layers isolated from Bacillus thuringiensis form large crystalline domains on mica after 5 min whereas those extracted from Bacillus sphaericus CCM 2177 form a compact monolayer on silicone after 2 h. Results in this work put in evidence the possibility to use these substrates for the fabrication of sensitive biosensors.