Development of a new molecularly imprinted polymer method for determination of gentamicin sulfate in drug sample

A molecularly imprinted polymer (MIP) for the determination of gentamicin sulfate (GNS) was present for the first time. molecular imprinting technology has become a well-established analytical equipment, which has been widely applied for the preparation of polymeric materials that have the ability to specifically bind species [1, 2]. Molecular imprinting involves positioning functional monomers around the target molecules (template) by covalent interaction or non-covalent interaction, followed by polymerization [3]. After removing the template, molecularly imprinted polymers (MIPs) were obtained. MIPs possess surface cavities complementary to the template. The imprinting effect was verified by comparing electrochemical response of MIP and none imprinted polymer (NIP) tested by cyclic voltammetry between -0.6 and 0.8 V in redox peak currents of hexacyanoferrate. As shown in Fig.1. A couple of typical redox peaks of [Fe(CN)6]3- appeared at bare GCE (curve a). (curves b and c), when the NIP and MIP was deposited on the surface of the electrode, the peak current was not observed. This may be due to the fact that the synthesized polymer film caused to create a protective layer on the surface of the electrode. The K3[Fe(CN6)] could not pass through the layer of polymer to arrive at the surface of the electrode for electrochemical processes. When the template removal process was done on both NIP and MIP electrode, no notable changes were observed in NIP electrode behavior (curve d), but in the MIP, the redox current of K3[Fe(CN6)] observed (curve e). This well illustrates the fact that removal of the template and the formation of recognition sites or binding cavity made electron transmission possible and K3[Fe(CN6)] could pass through the cavity in MIP and reach the surface of the electrode more easily for electrochemical process. When the electrodes were loaded by the template again, but in the case of NIP, there was no change in the behavior of the electrode in a K3[Fe(CN6)] solution (curve f). But the MIP, the peaks of K3[Fe(CN6)] disappear again (curve g). It can be ascribed that after loading with template, the cavity in MIP film occupied by template and the process of the probe to the surface of the electrode was stopped. It is also noted that compared with the bare GCE (curve a), an obvious current increased appeared when using the MIP/GCE after the template removal (curve e) in the presence of [Fe(CN)6]3- . This may result from the high conductivity of the film coated on GCE. Some parameters affecting sensor response were optimized and then a calibration curve plotted. A dynamic linear range of 5 to110 µM was obtained. The detection limit was 0.9 µM (S/N=3). This imprinted electrochemical sensor was used successfully for PHE determination in real samples.