Dual Recognition Strategy for Specific and Sensitive Detection of Bacteria Using Aptamer-Coated Magnetic Beads and Antibiotic-Capped Gold Nanoclusters

Abstract

Food poisoning and infectious diseases caused by pathogenic bacteria such as Staphylococcus aureus (SA) are serious public health concerns. A method of specific, sensitive, and rapid detection of such bacteria is essential and important. This study presents a strategy that combines aptamer and antibiotic-based dual recognition units with magnetic enrichment and fluorescent detection to achieve specific and sensitive quantification of SA in authentic specimens and in the presence of much higher concentrations of other bacteria. Aptamer-coated magnetic beads (Apt-MB) were employed for specific capture of SA. Vancomycin-stabilized fluorescent gold nanoclusters (AuNCs@Van) were prepared by a simple one-step process and used for sensitive quantification of SA in the range of 32-10(8) cfu/mL with the detection limit of 16 cfu/mL via a fluorescence intensity measurement. And using this strategy, about 70 cfu/mL of SA in complex samples (containing 3 × 10(8) cfu/mL of other different contaminated bacteria) could be successfully detected. In comparison to prior studies, the developed strategy here not only simplifies the preparation procedure of the fluorescent probes (AuNCs@Van) to a great extent but also could sensitively quantify SA in the presence of much higher concentrations of other bacteria directly with good accuracy. Moreover, the aptamer and antibiotic used in this strategy are much less expensive and widely available compared to common-used antibodies, making it cost-effective. This general aptamer- and antibiotic-based dual recognition strategy, combined with magnetic enrichment and fluorescent detection of trace bacteria, shows great potential application in monitoring bacterial food contamination and infectious diseases.

Metal Nanoparticles for Diagnosis and Therapy of Bacterial Infection

“…[64] Vancomycinmodified iron oxide nanoparticles have been widely employed to recognize and capture different bacteria owing to their strong interactions with various Gram-positive bacteria. [66] Aptamers and antibiotics were employed for specific or broadspectrum dual recognition of bacteria, giving rise to sensitive and selective quantification of S. aureus in milk and human serum samples with good recovery efficiencies. [65] Successful identification of the captured bacteria was further confirmed by different analytical methods such as transmission electron microscope (TEM), scanning electron microscope (SEM), and fluorescence.…”

“…The vancomycinmodified magnetic NPs were reported in a magnetic capture assay for multiple bacteria sensing. In addition to fluorescent Au NCs, fluorescent dyes, upconversion NPs, [66] Copyright 2016, American Chemical Society. Fluorescence methods have been widely utilized in combination with the magnetic method-based biosensors for bacterial detection.…”

Gold Nanoclusters for Bacterial Detection and Infection Therapy

“…To further improve the selectivity and sensitivity of bacterial detection, dual recognition probes based on fluorescent Au NCs have also been developed. Song and coworkers developed a dual recognition approach that integrates DNA aptamer and antibiotic-based dual recognition units, which enables sensitive and selective fluorescent detection of S. aureus in presence of ultrahigh concentrations of other bacteria strains ( Figure 4A) (Cheng et al, 2016). Aptamer-decorated magnetic beads were used for specific capture of S. aureus.…”

A novel colorimetric sensing platform for the detection ofS. aureuswith high sensitivity and specificity

“…Immunomagnetic beads based ELISA (IMBs-ELISA) is developed by combining ELISA with magnetic separation. [26][27][28] IMBs can be easily separated from the reaction mixture with a magnet and re-dispersed immediately following removal of the magnet, which allow for a nearly "in solution" reaction. 12,29 These characteristics render IMBs-ELISA more efficient and sensitive.…”