Towards the development of molecularly imprinted polymer based screen-printed sensors for metabolites of PAHs

Abstract

This paper describes the fabrication of a sensor for 1-hydroxypyrene (1-OHP) based on a screen-printed carbon electrode (SPCE) modified with a molecularly imprinted polymer (MIP); 1-OHP was chosen as a model metabolite of polyaromatic hydrocarbons (PAHs). It was shown that 1-OHP could be readily oxidised at a plain SPCE and the electrochemical mechanism was found to involve an ECE (electron transfer-chemical reaction-electron transfer) process. The MIP for 1-OHP was prepared using only divinylbenzene (DVB) and styrene as monomers and the binding was only based on hydrophobic interactions. Batch binding studies revealed that optimum uptake of 1-OHP by the MIP occurred from solutions containing 35% water in methanol. Selectivity of the binding sites in the MIP was examined by performing uptake studies in the same solution containing either phenol or 1-naphthol; the specific binding of 1-OHP was twenty times greater than the former and five times greater than the latter. Preliminary calibration studies were performed with the MIP-SPCE using a two-step approach; accumulation was carried out in 35% water in methanol followed by measurement in 50% methanol-0.025 mol dm(-3) phosphate buffer pH 12. This two-step non-competitive affinity assay gave encouraging results and indicated potential for use in pollution studies.

Voltammetric Determination of Urinary 1‐Hydroxypyrene Using Molecularly Imprinted Polymer‐Modified Screen‐Printed Carbon Electrodes

“…In contrast to these reports we have previously described the direct determination of 1-OHP by CV in a noncompetitive assay using a MIP-modified SPCE [16]. The binding of 1-OHP to the MIP was based on hydrophobic interactions and/or p À p bonding of the aromatic groups of the pyrene derivative with those of the polymer.…”

“…In our previous work [16] the recognition of 1-OHP by the DVB-co-Styrene MIP was only based on hydrophobic interactions and/or p À p bonding. Although good selectivity was achieved, the MIP-SPCE suffered from a low but notable, non-specific binding of the analyte to the carbon ink.…”

“…(Vinylbenzyl)trimethylammonium chloride (mixture of 3-and 4-isomers) was purchased from Aldrich Chemical Co. Ltd. Azo-bis-isobutyronitrile (AIBN) was from Fluka and recrystallized from methanol. 1-Hydroxypyrene was synthesized according to the method described by Sehgal and Kumar [17]; the procedure for which is described in more detail elsewhere [16]. Divinylbenzene (DVB tech 80%) and ethyleneglycol dimethacrylate (EGDM) (both Aldrich Chemical Co. Ltd.) were extracted with NaOH solution to remove inhibitors, dried over MgSO 4 and filtered through activated neutral Al 2 O 3 prior to polymerization.…”

“…SPCEs were modified as described previously [16]. Briefly, this was achieved by spreading a proportion of the MIP or NIP previously mixed with C10903D14 ink over an area of the SPCE defined by a mask of 3 mm diameter.…”

“…In the first section the preparation of MIPs for 1-OHP using a different imprinting strategy to that previously reported [16] will be discussed. Secondly, the use of the more sensitive techniques of DPV and square-wave voltammetry (SWV) will be described for the measurement step, and finally the possibility of using the proposed sensor for the determination of 1-OHP levels in spiked human urine samples will be investigated.…”