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Mycotoxins are highly toxic metabolites of some fungi that frequently contaminate water, food and feed and hence cause several human and animal diseases. In this work, a new approach to the fast and reliable determination of aflatoxin M1 (AFM1) in water and milk has been proposed with reagent free protocol of signal measurement. For this purpose, DNA aptamer selective to AFM1 was entrapped between two thin layers of polyaniline (PANI) electrodeposited on glassy carbon electrode. The incubation of the aptasensor in the AFM1 solution results in remarkable decrease of the PANI intrinsic activity monitored by direct current voltammetry or electrochemical impedance spectroscopy. Appropriate calibration curves were linear in the range from 3 to 90 ng/L with limit of detection (LOD) 1–5 ng/L depending on the measurement mode. Mechanism of signal generation involves shielding electrostatic interactions between the PANI and aptamer in the surface layer and variation of its redox activity attributed to the emeraldine form of PANI. Selectivity of the response was proved by similar experiments with aflatoxin B1 and ochratoxin A and by comparison of the results with those obtained with non‐specific aptamer in the sensing layer. Simple protocol for milk pretreatment has been proposed for reliable detection of AFM1 on the level of its threshold limited values (20 ng/L). [ABSTRACT FROM AUTHOR]

We performed a comparative study of the detection of human cellular prions (PrPC) with a quartz crystal microbalance (QCM) immunosensor using various antibodies against PrPC. The sensing layer was formed by immobilized antibodies on a surface of polyamidoamine dendrimers (PAMAM) of fourth generation (G4) with attached protein A. The sensitivity of detection depended on the kind of antibody used and the best detection limit was 0.8 nM. PrPC detection in 10 times diluted blood plasma revealed more complicated behavior of motional resistance, which is evidence on viscosity contribution. The sensor recovery was 82.2 %, suggesting certain matrix effects on prion detection. [ABSTRACT FROM AUTHOR]

A biomaterial based on multiwalled carbon nanotubes (MWCNTs) modified with His-tagged single chain D-dimer antibody trough nitrilo-triacetic-acid (NTA)/copper complex was designed for monitoring D-dimers, which were used as biomarkers of Deep Vein Thrombosis (DVT). The immunosensing evaluation of D-Dimer was followed by measuring the redox process of such complex. We demonstrate that using simple chemistry and exploiting the high surface area, electronic properties of MWCNTs and redox signal of the NTA/Cu2+ complex an efficient electrochemical immunosensor for the evaluation of wide range of D-dimer concentrations was obtained. [ABSTRACT FROM AUTHOR]