Abstract
A novel label-free electrochemical DNA biosensor was constructed for the determination of Escherichia coli 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 E. coli DNA biosensor exhibited a dynamic linear response range of 1 × 10−10 µM to 1 × 10−5 µM (R2 = 0.982), with a limit of detection at 1.95 × 10−15 µM, 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.
Highlights
Escherichia Coli (E. coli) O157:H7 is an important foodborne and waterborne pathogen that can lead to cramps, bloody diarrhea, kidney failure, and other diseases in humans
The small size of the DNA is suitable for immobilization of the inner and outer shells of hollow silica microspheres (HSMs) [21]
Infrared spectroscopy was used to characterize the features of HSMs before and after the calcination process (Figure 2b)
Summary
Escherichia Coli (E. coli) O157:H7 is an important foodborne and waterborne pathogen that can lead to cramps, bloody diarrhea, kidney failure, and other diseases in humans. This E. coli O157:H7 strain generates a strong and sturdy toxin that lead to severe illness [1]. In 1982, E. coli O157:H7 was first identified in contaminated hamburgers, causing disease [1]. In 1999, people became sick after drinking contaminated water in Washington county in. New York and after swimming in contaminated water in Clark country, Washington. In 2014, traces of E. coli were found in water in Batu Ferringhi, Malaysia [2]. E. coli traces have been found in Malaysia’s flooded north-east [3]
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