Towards Simple and Low-cost On-site Diagnosis with New Microfluidic Biosensors
Scientists combine a variety of techniques to make microfluidic biosensing simpler, practical, and more sensitive
Biochips are highly reliable for on-site diagnostic applications. However, their closed-form configuration often requires off-chip sample preparation. Now, scientists from Korea and Taiwan have developed a novel, “open-well” approach to lab-on-chip biosensing that is simple, low-cost, and enables biomarker detection without laborious preparation steps and complex equipment, opening doors to better and more accessible on-site diagnosis.
The study and diagnosis of diseases often requires measuring minute concentrations of “biomarkers” (biological molecules that signal the presence of a disease) in fluid samples. While many well-established protocols now exist for this purpose, they all share certain disadvantages. Conventional methods require large-scale laboratory equipment and are too expensive for point-of-care testing. Moreover, the preparation of the samples for analysis is often tedious.
One option is lab-on-chip (LoC) designs, in which microfluidic components are used to engineer more practical, all-in-one approaches for analyzing samples. Unfortunately, they too require laborious off-chip preparation steps and suffer from an inferior limit of detection (LOD) — the lowest biomarker concentration measurable — compared to the conventional techniques. Additionally, their closed-form configuration makes them less versatile.
In a new study, a team of researchers, led by Dr. Jae-Sung Kwon from Incheon National University, Korea, took things to the next level with an innovative “open-well” configuration biosensor that achieved a record-breaking LOD without needing any complex preparation procedure or expensive equipment. Their study was made available online on 21 July, 2021 and was published in Volume 193 of the journal in Biosensors and Bioelectronics.
The team used magnetic particles as “anchors” that allowed a mixture of specially selected antibodies to bind and capture the biomarker in the fluid, enabling easy separation. A second group of fluorescent antibodies then “sandwiched” the captured biomarker, allowing the team to quantify the concentration of the biomarker using fluorescence microscopy. A magnetic stirrer held the magnetic particles in place, enabling the entire process to be conducted directly in the open well configuration of the microfluidic system.
The team next used an approach called “optoelectrokinetics,” in which a laser light and an alternating electric field controlled the movement of particles, to concentrate the loaded magnetic particles over a very small area above one of two coplanar electrodes and imaged it with the fluorescence microscope. This grouping of particles, in turn, greatly increased the LOD of the system. Dr. Kwon states: “As observed in our experiments with tumor necrosis factor alpha (TNF-α), a common biomarker found in many diseases, the optoelectrokinetic technique greatly enhanced the measured signal within just one minute and lowered the LOD to 2.9 pg/mL.”
Furthermore, the researchers measured the TNF-α concentration in human tear samples using the new technique against a standard technique. The results matched, validating their strategy. “Our study provides insights for future facile clinical diagnosis techniques,” highlights Dr. Kwon, “By simply modifying the surface linkers (or antibodies) on the magnetic particles, our approach can be further extended to detect other trace biomarkers.”
Hopefully, as biosensing and LoC systems evolve and flourish, the early diagnosis of diseases will become easier, allowing for timely medical treatment.
Reference
Authors: Wei-Long Chen (1), Mansha Jayan (1), Jae-Sung Kwon (2), and Han-Sheng Chuang (1,3,4)
Title of original paper: Facile open-well immunofluorescence enhancement with coplanar-electrodes-enabled optoelectrokinetics and magnetic particles
Journal: Biosensors and Bioelectronics
DOI: https://doi.org/10.1016/j.bios.2021.113527
Affiliations:
1. Department of Biomedical Engineering, National Cheng Kung University
2. Department of Mechanical Engineering, Incheon National University
3. Core Facility Center, National Cheng Kung University
4. Medical Device Innovation Center, National Cheng Kung University
About Incheon National University
Incheon National University (INU) is a comprehensive, student-focused university. It was founded in 1979 and given university status in 1988. One of the largest universities in South Korea, it houses nearly 14,000 students and 500 faculty members. In 2010, INU merged with Incheon City College to expand capacity and open more curricula. With its commitment to academic excellence and an unrelenting devotion to innovative research, INU offers its students real-world internship experiences. INU not only focuses on studying and learning but also strives to provide a supportive environment for students to follow their passion, grow, and, as their slogan says, be INspired.
Website: http://www.inu.ac.kr/mbshome/mbs/inuengl/index.html
About the author
Dr. Jae-Sung Kwon is an Assistant Professor at the Department of Mechanical Engineering, Incheon National University since 2016. He obtained M.S. and B.S. degrees from the Department of Mechanical Engineering and the Department of Nuclear Engineering, Hanyang University, Seoul, in 2006 and 2001, respectively, and received his Ph.D. degree from the School of Mechanical Engineering, Purdue University-West Lafayette, USA in 2013. He is currently a director of the Multi-scale Flow Control laboratory. His research interests include bio-microfluidics, MEMS/NEMS technology, optical diagnostics, and nuclear thermal-hydraulics. He has published 34 papers with over 300 citations to his credit.
