An Integrated Smartphone-Based Genetic Analyzer for Qualitative and Quantitative Pathogen Detection

Abstract

The use of the smartphone is an ideal platform to realize the future point-of-care (POC) diagnostic system. Herein, we propose an integrated smartphone-based genetic analyzer. It consists of a smartphone and an i ntegrated gene tic analysis unit (i-Gene), in which the power of the smartphone was utilized for heating the gene amplification reaction, and the camera function was used for imaging the colorimetric change of the reaction for quantitative and multiplex foodborne pathogens. The housing of i-Gene was fabricated by using a 3D printer, which was equipped with a macro lens, white LEDs, a disposable microfluidic chip for loop-mediated isothermal amplification (LAMP), a thin-film heater, and a power booster. The i-Gene was installed on the iPhone in alignment with a camera. The LAMP mixture for Eriochrome Black T (EBT) colorimetric detection was injected into the LAMP chip to identify Escherichia coli O157:H7, Salmonella typhimurium , and Vibrio parahaemolyticus . The proportional–integral–derivative controller-embedded film heater was powered by a 5.0 V power bank to maintain 63 °C for the LAMP reaction. When the LAMP proceeded, the color was changed from violet to blue, which was real-time monitored by the smartphone complementary metal oxide semiconductor camera. The images were transported to the desktop computer via Wi-Fi. The quantitative LAMP profiles were obtained by plotting the ratio of green/red intensity versus the reaction time. We could identify E. coli O157:H7 with a limit of detection of 10 1 copies/μL within 60 min. Our proposed smartphone-based genetic analyzer offers a portable, simple, rapid, and cost-effective POC platform for future diagnostic markets.

Portable real-time colorimetric LAMP-device for rapid quantitative detection of nucleic acids in crude samples

“…In this work, we describe a device that offers for the first time the ability to perform real-time colorimetric LAMP inside a single reaction-tube through an embedded mini-camera and extract quantitative information in a similar way to real-time fluorescent nucleic acid amplification methods but without their associated complexity and high cost. The newly developed platform is based on a contamination-free closed tube-format obviating the need for microfluidic chips, peristaltic pumps, fluorescent detectors and multiple step protocols employed elsewhere 13 , 26 , 39 , 40 , 47 , 48 , 54 . It can achieve a similar limit of detection to the real-time fluorescent PCR and LAMP protocols (< 5 copies/reaction, i.e., < 0.2 copies/μl) while it does not suffer from background non-specific signal or need for signal drift correction or precise selection of threshold values required in other more sophisticated systems 27 , 28 .…”

Portable real-time colorimetric LAMP-device for rapid quantitative detection of nucleic acids in crude samples

“…Here we describe a device that offers for the first time the ability to perform real-time colorimetric LAMP inside a single reaction-pot through an embedded minicamera and extract quantitative information in a similar way to real-time fluorescent nucleic acid amplification methods but without their associated complexity and high cost. The newly developed device is based on a contamination-free closed tube format obviating the need for microfluidic chips, peristaltic pumps, fluorescent detectors and multiple step protocols employed elsewhere 13,26,39,40,47,48,54 . It can achieve a similar limit of detection to the real-time fluorescent PCR and LAMP protocols (<5 copies/reaction, i.e., <0.2 copies/μl) while it does not suffer from background non-specific signal or need for signal drift correction or precise selection of threshold values required in other more sophisticated systems 27,28 .…”

“…Since color change can often be difficult to discern under variable conditions (lighting, target concentration, etc. ), smartphone cameras combined with algorithms or radiometric imaging have been proposed as a generic solution for more accurate and quantitative colorimetric test -results 39,[43][44][45][46][47][48] .…”

Honey bee sHSP are responsive to diverse proteostatic stresses and potentially promising biomarkers of honey bee stress

“…The ability of recent developments in 3D printing technology to facilitate advances in POCT are particularly exciting 65 . For example, Nguyen et al designed and fabricated a single accessory that can perform the heating required for the LAMP reaction and assist in the imaging using a smartphone 66 .…”