We report the development of a simple surface chemistry strategy for the construction of sensitive aptasensors on a polypyrrole (PPy)-polyethylene glycol (PEG) platform in order to provide enhanced anti-fouling properties. We report the covalent modification of a PPy film formed on a gold electrode by PEG molecules, without prior chemical functionalization of the pyrrole monomer. This process was mediated by electro-oxidation of amine groups present on the one of the PEG's end chains. Poly-histidine modified aptamers were immobilized to this surface via a Nα,Nα-Bis(carboxymethyl)-L-lysine ANTA/Cu 2+ redox complex covalently attached to the PPy-PEG adduct. The fabricated aptasensor was then utilized for the detection of αmethylacyl-CoA racemase (AMACR; P504S), an emerging biomarker for prostate cancer. Protein/aptamer interactions were monitored through variation of the copper redox signal, using the square wave voltammetry (SWV) technique. We demonstrate that the PPy-PEG-ANTA/Cu 2+ hybrid material is characterized by enhanced anti-fouling properties and sensitivity. The aptasensor was able to detect AMACR down to 5 fM both in buffer and spiked human plasma with a limit of detection (LOD) of 0.15 fM and 1.4 fM, respectively. The developed aptasensor can be generalized for use with any type of aptamer-based sensor. Recently, several research groups have tried to develop biosensors for AMACR detection. 8 In 2014, Yang et al. 9 first reported an anti-AMACR DNA aptamer (AMC51) with a dissociation constant of 44 nM and demonstrated a fluorescent enzyme-linked aptamer assay (ELAA) for AMACR detection, which featured a low detection limit of 0.44 nM. A DNA aptamer is a ligand binding single stranded DNA that binds to its target with high affinity and specificity by undergoing conformational changes. 10 Compared to antibodies, aptamers have several advantages including ease of synthesis and modification, chemical stability, small size, and low immunogenicity. These features make aptamers promising alternatives to antibodies for biosensor research. 3,11 In this work, we present the development of an electrochemical AMACR aptasensor based on electro-patterned polyethylene glycol (PEG) on polypyrrole (PPy) film. PEG as a polymer has been widely used to develop biosensors, due to its anti-fouling properties. 12 However, it becomes difficult to employ PEG in an electrochemical platform due to its electri

A new SELEX scheme is proposed for the selection of aptamers targeting a specific epitope of a native protein. Anti-sialic acid receptor (SAR) aptamers that inhibit H1 hemagglutination at a low picomole dose are selected accordingly.

The controlled coverage of immobilized biomolecules is introduced, illustrating a concept for designing biomaterial surfaces such that the extent of manipulation employed to elicit biological responses is controlled according to density changes in the underlying chemical motifs and the density of immobilized biomolecules.

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