Development of molecularly imprinted polymer nanoarrays of N-acryloyl-2-mercaptobenzamide on a silver electrode for ultratrace sensing of uracil and 5-fluorouracil†
The present work describes a new, simple and easy method for the generation of novel molecularly imprinted polymer-based nanoarrays with uracil and 5-fluorouracil as template(s) on the surface of a silver electrode. The procedure involved electrochemical etching of silver-wire to develop nanopores on its tip. In these nanopores, a prepolymer mixture with template(s) was filled-in via spin coating and subjected to free radical thermal polymerization. The bulk polymer and polymer film characteristics were investigated using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The prepolymerization complex stoichiometry involved one template molecule and two molecules of the N-acryloyl-2-mercaptobenzamide functional monomer. The molecular structure of this complex was thermodynamically optimized via density functional theory at the MP2/6-31+G(d,p) level. The nanoarrays, vertically tethered imprinted polymer brushes with embedded carbon nanotubes, helped enhancing the surface area of the electrode. This drastically facilitated unhindered vertical diffusion with selective binding of uracil and 5-fluorouracil and their sensitive analysis using differential pulse anodic stripping voltammetry, with detection limits as low as 0.50 and 0.33 ng mL−1 (S/N = 3), respectively. The proposed nanoscale electro-chemical sensor was also validated with the complex matrices of blood plasma and pharmaceutics which assured reliable results, without any matrix effect, cross-reactivity, and false-positives. The large therapeutic range of the test analyte (uracil 1.49–278.76 ng mL−1, 5-fluorouracil 1.33–401.15 ng mL−1), demonstrating a perfect linearity (R2 = 0.98) with the improved voltammetric response, merits special significance for the primitive diagnosis of several chronic diseases, in clinical settings, without any sample pretreatment.