Molecularly imprinted polymer for the extraction and detection of insulin

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Since the development of solid phase microextraction (SPME), several alternatives for the fiber coating have been proposed to open the applicability of this microextraction technique to as much families of compounds as possible. Moreover, looking for higher selectivity is also a transversal research line in this methodology. Molecularly imprinted polymers (MIPs) can be used for this purpose although they are still scarcely used as coatings in SPME. MIP micro-solid phase extraction (MIMSPE) is a renovated version of MIP-SPME. The main difference between both techniques is the extent to which the analyte is extracted, being exhaustive for the formed which can be considered as a total recovery extraction method.

One of the latest articles published in Journal of Chromatography A combines MIMSPE with a multiwalled carbon nanotubes-MIP composite sensor. The main goal of this proposal is to achieve a high sensitivity thanks to the double preconcentration carried out in the extraction and detection steps which allows the determination of insulin at the ultra-trace levels. The selectivity is assured owing to the molecular recognition performed by the MIP.
Figure. Use of MIPs as extracting material and as a part of the sensing element in insulin determination
The selective SPME coating was immobilized in the silica fiber following two different procedures (viz, surface-attached and sol-gel) which are deeply described in the article. The performance og both coatings is exhaustively described in the manuscript through excellent figures, tables and micrographs. As a results, the authors concluded that the surface-attached mode was superior in terms of sensitivity, precision and stability. As far as cross-reactivity is concerned, non-specific adsorption of analytes and interferents were eliminated by subjecting the fibres to a 4-5 waters-washing cycles.

A final application of the method to human serum samples is described in the article with an interesting discussion of the influence of the sample dilution on the sensor response.. No doubt the proposal is of the highest relevance for the rapid and reliable diagnosis of insulin resistance disease.

Reference
(1) An insulin monitoring device based on hyphenation between molecularly imprinted micro-solid phase extraction and complementary molecularly imprinted polymer-sensor.Link to the article

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