Redox imbalance and oxidative stress-related biomarkers are raising increasing consensus in the scientific community for their significant role in a wide range of human disorders. In this framework, the total antioxidant capacity (TAC), namely, the overall pattern of both enzymatic and nonenzymatic antioxidant compounds within the body, represents an important bioanalytical parameter. To date, however, antioxidant assays require costly instrumentations, laboratory setups, and reagents, and they are invasive. Yet, their accuracy typically suffers from strong sensitivity to interfering matrices and inability to detect the complete pattern of physiological antioxidant molecules, due to the use of reaction schemes and probes/substrates that are not sensitive to the diverse range of relevant target species. Here, we exploit the enzyme-mimetic properties of platinum nanoparticles combined with hydroxyl radical probes produced at the particle surface to develop an effective detection scheme that is sensitive to both single electron transfer (SET) and hydrogen atom transfer (HAT) reactions, thus covering all the physiologically relevant antioxidant species. Importantly, the nanozyme-enabled method allows fast (5 min), accurate, and noninvasive evaluation of the body TAC through saliva via simple naked-eye or smartphone-based inspection.

Among prevalent food allergies, cow milk allergy (CMA) is most common and may persist throughout the life. The allergic individuals are exposed to a constant threat due to milk proteins’ presence in uncounted food products like yogurt, cheese, and bakery items. The problem can be more severe due to cross-reactivity of the milk allergens in the food products due to homologous milk proteins of diverse species. This problem can be overcome by proper and reliable food labeling in order to ensure the life quality of allergic persons. Therefore, highly sensitive and accurate analytical techniques should be developed to detect the food allergens. Here, significant research advances in biosensors (specifically immunosensors and aptasensors) are reviewed for detection of the milk allergens. Different allergic proteins of cow milk are described here along with the analytical standard methods for their detection. Additionally, the commercial status of biosensors is also discussed in comparison to conventional techniques like enzyme-linked immunosorbent assay (ELISA). The development of novel biosensing mechanisms/kits for milk allergens detection is imperative from the perspective of enforcement of labeling regulations and directives keeping in view the sensitive individuals.

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In this study, we report the development of a sensitive label‐free impedimetric sensor based on molecularly imprinted polymer (MIP) as biomimetic receptor coupled with screen‐printed electrodes (SPEs) for the detection of vascular endothelial growth factor (VEGF). Firstly, electropolymerization of o‐phenylenediamine (o‐PD) in the presence of VEGF molecule by cyclic voltammetry was performed onto graphite screen‐printed electrodes. The solvent extraction of the target was then carried out. The MIP based sensor was characterized by electrochemical techniques and scanning electron microscopy (SEM). Using optimized experimental conditions, the single‐use MIP‐based sensor showed a good analytical performance for VEGF detection from 20 to 200 pg mL−1 with limit of detection of 0.08 pg mL−1. Finally, the developed MIP‐based sensor in human serum samples was also tested.

In this work, we present a new electrochemical disposable platform based on poly(aniline‐co‐anthranilic acid) (PANI/PAA) composite polymer coupled with an aptamer for sensitive detection of β‐lactoglobulin. Firstly, PANI/PAA film was electrodeposited on the graphite screen‐printed electrode surface by cyclic voltammetry. The co‐polymer modified electrode was then employed as platform for the covalent immobilization of an amino‐modified aptamer. Various β‐lactoglobulin solutions, with a fixed amount of biotinylated oligonucleotide complementary sequence, were dropped onto the aptasensor surface. A streptavidin‐alkaline phosphatase conjugate was then employed to trace the affinity reaction. After the addition of 1‐naphthyl‐phosphate enzymatic substrate, 1‐naphthol electroactive product was detected by differential pulse voltammetry. A decrease in the signal was obtained when the target concentration was increased, in according to a signal‐off approach. After optimization of key experimental parameters, a dose‐response curve was obtained between 0.01–1.0 μg mL−1 β‐lactoglobulin concentration range. The limit of detection of 0.053 μg L−1 was obtained. Milk samples spiked with β‐lactoglobulin were analyzed.

Arsenic, one of the most abundant mineral and also one to the most toxic compounds. Due to its high toxicity sensitive analytical methods are highly important, taking into account that the admitted level is in the range of µg L−1. A novel and easy to use platform for As(III) detection from water samples is proposed, based on gold and platinum bi metallic nanoparticles and a conductive polymer (polyaniline). The electrochemical detection was achieved after optimization of cathodic pre-concentration and stripping parameters by square wave anodic stripping voltammetry at modified screen-printed carbon-based electrochemical cells, proving its applicability for disposable and cost-effective in situ analysis of arsenic.

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