A Highly Sensitive Impedimetric DNA Biosensor Based on Hollow Silica Microspheres for Label-Free Determination of E. coli

A novel label-free electrochemical DNA biosensor was constructed for the determination of <i>Escherichia coli</i> bacteria in environmental water samples. The aminated DNA probe was immobilized onto hollow silica microspheres (HSMs) functionalized with 3-aminopropyltriethoxysilane and deposited onto a screen-printed electrode (SPE) carbon paste with supported gold nanoparticles (AuNPs). The biosensor was optimized for higher specificity and sensitivity. The label-free <i>E. coli</i> DNA biosensor exhibited a dynamic linear response range of 1 &#215; 10^&#8722;10 &#181;M to 1 &#215; 10^&#8722;5 &#181;M (R² = 0.982), with a limit of detection at 1.95 &#215; 10^&#8722;15 &#181;M, without a redox mediator. The sensitivity of the developed DNA biosensor was comparable to the non-complementary and single-base mismatched DNA. The DNA biosensor demonstrated a stable response up to 21 days of storage at 4 ℃ and pH 7. The DNA biosensor response was regenerable over three successive regeneration and rehybridization cycles.

Abstract licence: CC BY

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