Ultrafast and Sensitive Screening of Pathogens by Functionalized Janus Microbeads‐Enabled Rotational Diffusometry in Combination with Isothermal Amplification

Abstract

Polymerase chain reaction (PCR) is widely considered the gold standard in molecular diagnostics because of its high accuracy. However, conventional PCR is very time‐consuming (turnaround time 4–6 h), labor‐intensive, and high‐tech instruments dependent. Therefore, developing an ultrafast and sensitive nucleic amplification‐based detection method is still in high demand. Herein, a rapid screening of Escherichia coli using an advanced and sensitive biosensing method known as rotational diffusometry in combination with loop‐mediated isothermal amplification (LAMP) is reported. Given that the solution viscosity is increased with nucleic acid amplification, the viscosity change can be measured by the functionalized Janus microbeads‐enabled rotational diffusometry. The rotational diffusivity derived from capturing images of microbeads is expressed in terms of blinking signals. Under such conditions, this method can achieve a limit of detection of 42.8 fg μL−1 in 10 min for E. coli with sample volume as low as 2 μL. Additionally, detection of E. coli whole cells extracted from artificially contaminated milk, juice, and water is performed by the developed method and validated with real‐time PCR. Through this biosensing technique, a rapid, reliable, and low sample volume screening tool can be established, improving the shortcomings of the current time‐consuming and labor‐intensive methods.

Keywords

• DNA
• Escherichia coli
• functionalized Janus microbeads
• loop-mediated isothermal amplification
• nucleic acid
• pathogen screening