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A novel electrochemical sensing platform based on Fe3O4-antibody conjugate was developed for the rapid and sensitive determination of Salmonella typhimurium antigen in model suspensions. The conjugates Fe3O4-antibody were synthesized via carbodiimide cross-linking and characterized by infrared spectroscopy and cyclic voltammetry. The electrochemical properties of Fe3O4 magnetic nanoparticles in water were investigated; the possible mechanism of direct electrochemical reduction was proposed and justified as an analytical signal. The design of an electrochemical sensing platform with magnetically controlled flows has been proposed. Under the most appropriate conditions, the developed portable device was provided the linear response as I (µA) = (7.20 ± 0.35) × (–lg CAg) − (23.77 ± 1.95) in the concentration range 1 × 10−7–1 × 10−4 mg/mL. The detection limit was 390 ng/mL and was comparable to other works. [ABSTRACT FROM AUTHOR]

Analytical chemistry is now developing mainly in two areas: automation and the creation of complexes that allow, on the one hand, for simultaneously analyzing a large number of samples without the participation of an operator, and on the other, the development of portable miniature devices for personalized medicine and the monitoring of a human habitat. The sensor devices, the great majority of which are biosensors and chemical sensors, perform the role of the latter. That last line is considered in the proposed review. Attention is paid to transducers, receptors, techniques of immobilization of the receptor layer on the transducer surface, processes of signal generation and detection, and methods for increasing sensitivity and accuracy. The features of sensors based on synthetic receptors and additional components (aptamers, molecular imprinted polymers, biomimetics) are discussed. Examples of bio- and chemical sensors' application are given. Miniaturization paths, new power supply means, and wearable and printed sensors are described. Progress in this area opens a revolutionary era in the development of methods of on-site and in-situ monitoring, that is, paving the way from the "test-tube to the smartphone"., Competing Interests: The authors declare no conflict of interest.