Molecularly imprinted polymer of bis(2,2′-bithienyl)methanes for selective determination of adrenaline

New chemical sensors for adrenaline Adr were fabricated. For that, a thin film of a molecularly imprinted polymer (MIP) was templated with protonated adrenaline HAdr. Differential pulse voltammetry (DPV), capacitive impedometry (CI), or piezoelectric microgravimetry (PM) was integrated within each chemosensor for analytical signal transduction. First, molecular structure of prepolymerization complex of HAdr with bis(2,2′-bithienyl)methane substituted with the benzo-(18-crown-6) 2 and 4-carboxyphenyl 3 was thermodynamically optimized at the B3LYP/6-31g(d) level. Then, a HAdr-templated MIP film was deposited on the Pt disk electrode and on the Au film electrode of a 10-MHz quartz crystal resonator (QCR) by potentiodynamic electropolymerization from solution of HAdr, 2, 3, and the cross-linking tris([2,2′-bithiophen]-5-yl)methane 4 monomer at the HAdr:2:3:4 = 1:1:1:2 mole ratio. For determination of Adr, the DPV peak current for the K4[Fe(CN)6] redox probe under batch conditions and the resonant frequency and capacity of the electrical double layer under FIA conditions were measured. The lower limits of detection (LOD) were 2 nM, 0.5 μM, and 1.5 μM for the DPV, PM, and CI chemosensor, respectively, indicating suitability of the DPV chemosensor for Adr determination in biological systems (~ 50 nM). The chemosensors were appreciably selective to Adr in the presence of common interferents.