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Accurate detection of protein biomarkers in complex media remains a challenge due to severe nonspecific adsorption and biofouling, and sensing interfaces that combine the high sensitivity and antifouling ability are highly desirable. Herein, an antifouling sensing interface capable of sensitively assaying immunoglobulin E (IgE) in biological samples was constructed. The sensing interface was fabricated through the self-assembly of a zwitterionic peptide and the IgE aptamer onto a macroporous Au substrate, which was electrochemically fabricated with the aid of multilayer polystyrene nanospheres self-assembled on glassy carbon electrode. Due to the huge surface area arising from porous morphology and high specificity of aptamer, the developed electrochemical biosensor exhibits ultrahigh sensitivity and selectivity towards IgE, with the linear range of 0.1-10 pg mL, and a very low limit of detection down to 42 fg mL. Interestingly, owing to the presence of the zwitterionic peptide, the biosensing interface can satisfyingly reduce the nonspecific adsorption and fouling effect. Consequently, the biosensor was successfully applied to detect IgE in complex biological samples, indicating great promise of this peptide-based sensing interface for antifouling assays. Graphical abstract ᅟ.

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A novel biosensor was developed by entrapping cytochrome c (Cyt c) in thin films of the room temperature ionic liquid (RTIL) containing nanocomposites of poly(diallyldimethylammonium chloride)-graphene nanosheets-gold nanoparticles (PDDA-Gp-AuNPs) at a 11-mercaptoundecanoic acid-6-mercapto-1-hexanol modified gold electrode. The synthesized PDDA-Gp-AuNPs hybrid nanocomposites were characterized by UV-vis spectroscopy, Raman spectroscopy, scanning electron microscopy and atomic force microscopy. The PDDA-Gp-AuNPs nanocomposites could increase the effective surface of the electrode, enhance the fixed amount of Cyt c on the electrode surface, promote the electron transfer and facilitate the catalytic activity of Cyt c. The RTIL could provide a biocompatible microenvironment to keep Cyt c biological activities, act as an effective mediator to immobilize a large number of Cyt c on the electrode and have good conductivity to improve electron transfer. Therefore, the resultant electrode exhibited good electrochemical performance and electrocatalytic activity. It could be used for electrochemical detection of H 2 O 2 with rapid response, high sensitivity, wide linear range and low detection limit, as well as good stability, repeatability and selectivity. The sensor might be promising for practical application.

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Four types of carbon fiber microelctrodes modified with polyaniline (PAn) and platinum particles (Pt) were fabricated to determine H 2 O 2 at þ 0.60 V (vs. SCE). The sensitivity, stability and selectivity of different electrodes were compared. The electrode modified with a sandwich film of PAn-Pt-PAn offered the best result. The linear range was 4.0 × 10 ¹7 -2.4 × 10 ¹4 M with a detection limit of 1.0 × 10 ¹7 M. The relative standard deviation (RSD) for 10 mM H 2 O 2 was 1.9 % (n ¼7). The electrode was used to determine the H 2 O 2 in the rainwater.

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