Fabrication of high-performance cell-imprinted polymers based on AuNPs/MXene composites via metal-free visible light-induced ATRP.

Cell-imprinted polymers (CIPs) for yeasts were fabricated via metal-free visible-light-induced atom transfer radical polymerization (MVL ATRP) on the surface of a glassy carbon electrode (GCE) which had been modified with gold nanoparticles (AuNPs)/MXene (Ti3C2Tx) composites. Here, the AuNPs/Ti3C2Tx composites form a macroporous structure, which could improve the electron transfer rate of the materials and facilitate the leaving or rebinding of cells. Methacrylic acid (MAA) and N,N'-methylene bis-acrylamide (MBA) were selected as the functional monomer and cross-linker of CIPs, because they could form efficient hydrogen bonding with mannan from yeast cell walls. The obtained electrode (CIPs/AuNPs/Ti3C2Tx/GCE) was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Further experiments indicated that the CIPs/AuNPs/Ti3C2Tx/GCE electrode could be utilized as an electrochemical biosensor to determine yeast cells by differential pulse voltammetry (DPV). The linear response range was 1.0 × 102 to 1.0 × 109 cells per mL and the detection limit was 20 cells per mL (S/N = 3). The CIPs/AuNPs/Ti3C2Tx/GCE electrode also showed good selectivity, repeatability, reproducibility, and regeneration. Finally, the proposed sensor was used to detect yeast cells in commercial samples of Saccharomyces boulardii sachets by a standard addition method. The obtained recovery was from 96.9 to 104.8% showing its potential applications in clinical and diagnostic research.

Fabrication and properties of temperature-responsive imprinted sensors based on fluorescently labeled yeast cells via MVL ATRP.

Temperature-responsive yeast cell-imprinted sensors (CIPs/AuNPs/Ti3C2Tx/AuNPs/Au) were prepared based on fluorescein isothiocyanate labeled yeast cells (FITC-yeast) via metal-free visible-light-induced atom transfer radical polymerization (MVL ATRP). Here, N-isopropyl acrylamide (NIPAM) was used as a temperature-responsive functional monomer, α-methacrylic acid (MAA) was chosen as an auxiliary functional monomer, N,N'-methylene bisacrylamide (MBA) was used as a cross-linker, and FITC-yeast was selected as both a template and photocatalyst. Under the optimal conditions, the detection range of the yeast cell-imprinted sensor toward yeast cells was 1.0 × 102 to 1.0 × 109 cells per mL, and the detection limit was 11 cells per mL (S/N = 3), with a linear equation of ΔI (µA) = 8.44 log[C (cells per mL)] + 7.62 (R2 = 0.993). The sensor showed good selective recognition in the presence of interfering substances such as autolyzed yeast cells (AY), dead yeast cells (DY), human mammary epithelial cells (MCF-10A), human breast cancer cells (MCF-7) and Escherichia coli (EC). The sensor also had good consistency and reproducibility. Finally, spiked recovery experiments were performed to investigate the recognition of yeast cells in the actual sample using the yeast cell-imprinted sensor. The spiked recoveries were all in the range of 98.5-108.0%, and the RSD values were all less than 4%, indicating that the sensor had good application prospects.