Abstract
The use of bio-mimetic receptor systems have been considered in a quest for affinities and specificities that are on a par with natural receptors for rapid in-situ analysis based on coupled-sensor techniques. The work describes the experimental optimisation and characterisation of hydrogel-based molecularly imprinted polymers (MIPs) for a range of proteins and pathogens, including plant viruses. A variety of acrylamide-based functional monomers, along with several integrated metal complexes for signal transduction have been exploited in the fabrication of both bulk and surface imprinting of MIPs. Spectrophotochemical, electrochemical and quartz crystal microbalance (QCM) analytical techniques were utilised for quantifying imprinting effects by assessing specific and/or non-specific binding. Bulk imprinting exhibited high selectivities (rebinding efficiencies ≈ 80%) and imprinting factors of ≈ 14 (MIP/NIP ratio) across varied templates. MIP-coupled QCM sensors illustrated binding and elution of target proteins through distinct frequency and impedance transitions at 3 mg mL-1. QCM surface imprinting via electrochemically-induced polymerisation (ECIP) was less successful. Whereas electrochemical ECIP methods using glassy carbon electrodes (GCEs) illustrated good compatibility, higher sensitivities, and a limit of detection (LOD) of 16 μg mL-1 and a limit of quantification (LOQ) of 56 μg mL-1 for BHb. Pattern recognition techniques using multivariate analysis were also implemented to reduce complex data sets. Principle component analysis (PCA) and linear discriminant analysis (LDA) techniques illustrated unique binding pattern profiles depending on the sample matrix analysed, significance (ρ) ≤ 0.0005. The latter ECIP methods were also transposed onto disposable screen-printed carbon electrodes (SPCEs) based on the introduction of redox tracers (both externally and within the MIP matrix). SPCEs offer an attractive opportunity for the development of miniaturised low cost electrochemical sensors. However, several complications arose and little sensitivity was observed in terms of MIP binding. Once fully developed, the benefits of sensitivity, specificity and stability of MIPs coupled with discriminatory sensor techniques, as described here, could be crucial to the future impact of portable diagnostics for personal healthcare and use by health professionals. This technology also presents major potential benefits to environmental and food monitoring as it could provide an inexpensive, fast, and efficient diagnostic method for highly sensitive analytical procedures.