Design and performance of novel molecularly imprinted biomimetic adsorbent for preconcentration of prostate cancer biomarker coupled to electrochemical determination by using multi-walled carbon nanotubes/Nafion®/Ni(OH)2-modified screen-printed electrode

Abstract

The present paper describes the development of a new electroanalytical method for prostate cancer biomarker (sarcosine) by coupling molecularly imprinted solid-phase extraction (MISPE) with electrochemical determination at a MWCNT/Nafion®/Ni(OH)2-modified screen-printed electrode using a flow injection analysis (FIA) system. The synthesized MIP prepared by using dual functional monomers 2-acrylamido-2-methyl-1-propanesulfonic acid and 4-vinylpyridine was characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) and nitrogen adsorption/desorption measurements. The optimized pH for adsorption of sarcosine was 5.0 and the elution was completed with MeOH:HAc (90:10, v/v), whilst the electrochemical determination was performed in FIA system using a sample volume of 121.0 μL, 0.05 mol L−1 NaOH carrier solution, a flow rate of 2.0 mL min−1 and applied potential of 0.7 V vs Ag/AgCl. The proposed method provided enrichment factor of 50.6-fold, linear analytical curve from 3.2 to 25.0 μmol L−1 (R2 = 0.995), and limit of detection of 0.96 μmol L−1. The precision was evaluated in terms of intra (n = 6) and interday (n = 2) for concentrations of 10.0, 15.0, and 20.0 μmol L−1, giving rise to low percentages of relative standard deviations (RSD %), ranging from 2.2 to 4.3%. A highly improved response for sarcosine using MIP when compared to NIP (non-imprinted polymer) was obtained. The method also exhibited higher selectivity toward sarcosine compared to glycine, alanine, proline, and urea. Analysis of synthetic urine samples yielded recoveries in the range of 95.0–108.0%, thereby indicating the absence of matrix effect and the feasibility of the method for sarcosine determination.