Molecular imprinting for sensor recognition elements

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Stanley, S.M., 2001. Molecular imprinting for sensor recognition elements. PhD, Nottingham Trent University.

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Abstract

Molecular recognition is a highly efficient and essential feature of biological systems in nature and as such has found increasing application in biosensors. Natural recognition systems, whilst highly selective, are of limited use because of poor chemical and thermal stability, limited assay range and lifespan. The use of artificial recognition materials has been examined in order to address these shortfalls.

The development and application of molecularly imprinted polymers (MIPs) as artificially generated recognition materials is described. MIPs are highly cross-linked polymers, inherently stable and capable of selectivities approaching their natural counterparts. This thesis describes, in the first instance, the design, development and application of a range of MIP recognition materials as recognition elements applied to quartz crystal microbalances (MIP-QCM).

Initially non-covalent imprinting is employed to produce a recognition element for an important source of ozone producing VOCs, namely the monoterpene L-menthol. The MIP film is cast directly onto the surface of a quartz crystal microbalance (QCM) and enantioselective rebinding of the analyte over its analogues is observed as a frequency shift quantified by piezoelectric microgravimetry. The lower limit of detection to L-menthol was 200 ppb with the device giving a linear response between 0 and 1.0 ppm. This is the first report of an enantioselective MIP utilizing a single monomer-functional moiety interaction.

Non-covalent imprinting has been further examined to produce an MIP-QCM capable of the enantioselective rebinding of the aminoacid L-serine. It is envisaged that such a device could be employed in the identification of chirally active amino acids of importance to the pharmaceutical industry. The lower limit of detection to L-serine was 2 ppb with a linear response range of 0-0.4 ppm. The enantioselectivities of the L-menthol and L-serine sensors are compared and conclusions drawn regarding the importance of functional groups within the recognition site and on the analyte.

The use of covalent imprinting in the production of an artificial receptor for topical abuse steroid. The development of a screening device for nandrolone is reported. Rebinding of the analyte over its analogues is observed as a frequency shift quantified by piezoelectric microgravimetry. The limit of detection of the resultant device to nandrolone is 6 ppb with a linear response range of 0-1.0 ppm.

An alternate approach to recognition element design has been developed to produce a chemically coated piezoelectric sensor for the determination of PAHs in the liquid phase. An organic monolayer attached to the surface of a gold electrode of a quartz crystal microbalance (QCM) has been produced. Selective binding of anthracene via π,π-interaction has been observed as a frequency-shift subsequently quantified by piezoelectric microgravimetry with the QCM transducer. The lower limit of detection of the target analyte was 2 ppb with a linear response range of 0 - 50 ppb. The sensor was able to distinguish between different PAHs despite π,π-interaction being the sole communication between recognition element and analyte. It is envisaged that these techniques could be employed to create recognition elements for different PAHs.

Item Type:

Thesis

Creators:

Stanley, S.M.

Date:

2001

ISBN:

9781369314625

Identifiers: