Abstract
This study reports the design and evaluation of a new synthetic receptor sensor based on the amalgamation of biomolecular recognition elements and molecular imprinting to overcome some of the challenges faced by conventional protein imprinting. A thiolated DNA aptamer with established affinity for prostate specific antigen (PSA) was complexed with PSA prior to being immobilised on the surface of a gold electrode. Controlled electropolymerisation of dopamine around the complex served to both entrap the complex, holding the aptamer in, or near to, it's binding conformation, and to localise the PSA binding sites at the sensor surface. Following removal of PSA, it was proposed that the molecularly imprinted polymer (MIP) cavity would act synergistically with the embedded aptamer to form a hybrid receptor (apta-MIP), displaying recognition properties superior to that of aptamer alone. Electrochemical impedance spectroscopy (EIS) was used to evaluate subsequent rebinding of PSA to the apta-MIP surface. The apta-MIP sensor showed high sensitivity with a linear response from 100pg/ml to 100ng/ml of PSA and a limit of detection of 1pg/ml, which was three-fold higher than aptamer alone sensor for PSA. Furthermore, the sensor demonstrated low cross-reactivity with a homologous protein (human Kallikrein 2) and low response to human serum albumin (HSA), suggesting possible resilience to the non-specific binding of serum proteins.
Highlights
These authors contributed to the manuscript.with regards to commercially relevant applications of molecular recognition
This study aims to develop a hybrid-molecularly imprinted polymer (MIP) receptor for use in an electrochemical sensor targeting the quantitative analysis of prostate specific antigen (PSA)
Following immobilisation of the aptamer–PSA complex a reduction in current, and a shift in peak voltage, were observed (Fig. 1e, red line). This is attributed to the formation of a resistive aptamer–PSA self-assembled monolayer (SAM) on the gold surface
Summary
These authors contributed to the manuscript.with regards to commercially relevant applications of molecular recognition. The hybrid-MIP strategy was first proposed for the detection of lipopolysaccharide (LPS) using the cyclic peptide polymyxin (Bowen, 2011) and has been reported for concanavalin A detection using mannose (Dechtrirat et al, 2014). Another type of bioreceptor that has been employed in hybridMIP approaches is the DNA aptamer (Bai and Spivak, 2014; Poma et al, 2015).
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