This paper is an overview of the recent developments in immunosensors, which have attracted considerable attention. Immunosensors can play an important role in the improvement of public health by providing applications for which rapid detection, high sensitivity, and specificity are important, in areas such as clinical chemistry, food quality, and environmental monitoring. This review focuses on the current research in immunoassay methods based on electrochemical detection for the analysis of environmental samples or medical diagnostic methods with emphasis on recent advances, challenges and trends. Technological aspects in the development of immunosensors such as kinetics of biomolecular interaction, techniques of immobilization, simplification of assay procedures, immunointeration and catalytic studies and system miniaturization are presented

A mechanistic model was proposed by Gordillo for the representation of lipase production by Candida rugosa, with the bioreactor in batch and fed-batch operation. However, the model was not able to represent the lipolytic activity. The objective of the present study is to propose an efficient hybrid neural-phenomenological model (HNM) for this process. The experimental data used corresponded to fed-batch operation with constant substrate feed rate at 2.8 × 10 −7 ; 5.6 × 10 −7 and 9.7 × 10 −7 kg s −1 . Artificial neural networks (ANNs) were trained to represent the aqueous and intracellular lipase activity and were further associated with a reduced version of the mechanistic model of the proposed HNM. When compared to the experimental data, the HNM exhibited higher accuracy. The HNM can be employed in process monitoring using only on-line measurements of CO 2 and substrate feed rate to infer enzyme activities and also substrate and biomass concentrations.

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The optimal conditions for salicylic acid biodegradation by Pseudomonas fluorescens HK44 were determined in this study with the intention to create a microbial sensor. Kinetic experiments permitted a definition of 60 and 30min the time needed to achieve the maximum degradation of salicylic acid presented in a medium with and without yeast extract, respectively. The degradation in medium without yeast extract and the quantification by spectrophotometry 230 nm were selected to be used in further tests. The use of preactivated cells or on the exponential growth phase showed better salicylic acid degradation percentages when compared to nonactivated cells or on the stationary growth state. Finally, the best cellular concentration used on the salicylic acid degradation was 0,1 g.L -1. Strain HK44 shows to be capable of degrade salicylic acid presented in simple aqueous systems, making this strain a promising tool for the application on a luminescent microbial sensor.

An immunosensor for detecting the antibody anti-apyrase of Schistosoma mansoni based on rigid composite materials, containing graphite powder and epoxy resins, developed in this work, is described. A surface modification strategy for the use of oxidized graphite in the detection of antibody-antigen interaction was developed. This modification strategy is based on silanization of conductive composite. First, the graphite powder-epoxy resin was treated with concentrated hydrogen peroxide to improve surface hydroxyl groups and to form a hydrophilic layer. Second, 3- aminopropyltriethoxysilane was subsequently used to functionalize the treated surface to form amino groups, which were further activated with glutaraldehyde to introduce a layer of aldehyde groups. Contact angle microscopy and scanning electron microscopy were used as a qualitative analysis of the deposition of silane on the surface of the sensor. The effectiveness of the modification strategy was validated by amperometric immunoassays of S. mansoni. Amperometric signals related to concentrations of this immobilized protein were observed, and the effects of pH and incubation times were analyzed. This surface modification strategy provides a platform on which proteins can be directly immobilized for immunosensor and protein array applications.