Selective Electrochemical Sensing of Human Albumin By Semi-Covalent Imprinting

We devised and fabricated a conducting molecularly imprinted polymer (MIP) for human albumin (HA) determination using semi-covalent imprinting (Scheme 1).  The bis(2,2’-bithien-5-yl)methane units constituted the MIP backbone.  This MIP was deposited as a thin film on an Au disk electrode by oxidative potentiodynamic electropolymerization.  The HA template imprinting, and then its releasing from the MIP was confirmed by the XPS and PM-IRRAS measurements as well as by AFM imaging.  The DPV and EIS response to the HA presence in a test solution of the MIP film coated electrode was linear in the range of 0.8 to 20 and 4 to 80 µg/mL HA, respectively, with the limit of detection of 16.6 ng/mL and 0.8 µg/mL HA, respectively.  The semi-covalent imprinting provided a very well defined location of recognition functionalities in the MIP molecular cavities.  Those were placed only on surface of the imprinted molecular cavities and the polymer surface.  The MIP selectivity against low-molecular interferences, common for body fluids, such as blood and urea, was very high.  It showed no response to their presence at concentrations encountered in natural samples. Moreover, selectivity of the MIP film coated electrode with respect to macromolecular interferences, such as myoglobin and cytochrome c, was excellent while to lysozyme was slightly lower but still high.