Rapid, simple, low-cost smartphone-based fluorescence detection of Escherichia coli

Dante Rojas-Barboza,Efren Delgado,Rolfe Sassenfeld,Jeremy Winder,Young Ho Park,Delia Valles-Rosalles,Edward Park,Geoffrey B Smith

doi:10.25165/j.ijabe.20211403.5865

Abstract

Food and waterborne diseases pose considerable public health threats even in highly industrialized parts of the world. Examples of these pathogens in food can be Escherichia coli O157: H7, Salmonella sp., and Listeria monocytogenes. Rapid, reliable detection of pathogens mitigates serious health problems and economic losses due to outbreaks and robust tests safeguard the food supply. In this study, a smartphone-based apparatus was employed to demonstrate quantitative detection of E. coli. To validate the applicability of the present smartphone-based fluorescence device, RNA was extracted from the E. coli K-12 strain and amplified using two different primers (dnaK and rpoA) via quantitative polymerase chain reaction (qPCR). Serial dilutions of RNA from 10 to 0.0001 ng/µL were prepared at the start of the PCR amplification and the PCR products were detected by CYBR Green1-based fluorescence. For a proof-of-concept test for the smartphone system, samples from these PCR products were then analyzed. The detection system employed a novel algorithm to analyze fluorescence signals and read changes in E. coli DNA concentration. The correlations between the fluorescence percentage and DNA concentrations were R=0.945 for the dnaK primer and R=0.893 for the rpoA primer, respectively. Utilizing this new fluorescent analysis technique resulted in comparable accuracy to the real-time PCR fluorescent signal detection. The key innovation of this approach was to combine efficient image processing encoded into a smartphone application with a low-cost 3-D printed device that allowed quantification of bacterial nucleic acid. Keywords: smartphone, fluorescence, E. coli, low-cost, 3D-Print DOI: 10.25165/j.ijabe.20211403.5865 Citation: Rojas-Barboza D, Park E, Sassenfeld R, Winder J, Smith G B, Valles-Rossalles D, et al. Rapid, simple, low-cost smartphone-based fluorescence detection of Escherichia coli. Int J Agric & Biol Eng, 2021; 14(3): 189–193.

Highlights

The technical specifications of smartphones have advanced over the past decades in all aspects, including global positioning system (GPS), wireless technology (Bluetooth, Wi-Fi), powerful computing capability, and complementary metal oxide semiconductor (CMOS) digital camera sensor
The key innovation of this approach was to combine efficient image processing encoded into a smartphone application with a low-cost 3-D printed device that allowed quantification of bacterial nucleic acid
Smartphone-based detection of E. coli was successfully demonstrated with the proposed smartphone-based device

Summary

Introduction

The technical specifications of smartphones have advanced over the past decades in all aspects, including global positioning system (GPS), wireless technology (Bluetooth, Wi-Fi), powerful computing capability, and complementary metal oxide semiconductor (CMOS) digital camera sensor. These functionalities enable smartphone-based biosensing systems for point-of-care testing applications, which may allow for rapid, convenient diagnostic testing of pathogens. The first smartphone-integrated visualization system that detected a single virus or bacterium was presented by Zhu et al.[2] Their smartphone-based system offered a compact, light-weight solution for specific detection of the bacterium in low-resource settings. Increased signal-to-noise ratio was demonstrated compared to traditional organic dyes by exploiting the high luminescent efficiency of quantum dots[4]

Methods

Results

Conclusion