Microfluidics Enable Low-Cost, Label-Free Disease Diagnosis

Scientists have developed a microfluidic chip that can detect and quantify biomolecules without any fluorescent labels.

AsianScientist (Apr. 3, 2018) – A team of researchers from the National University of Singapore (NUS) have devised an inexpensive and rapid method to diagnose diseases with high accuracy. Their findings are published in Nature Communications.

Disease diagnostics involve the detection and quantification of nano-sized bio-particles such as DNA, proteins, viruses and extracellular vesicles known as exosomes. Typically, detection of biomolecules such as proteins are performed using colorimetric assays or fluorescent labelling with a secondary antibody for detection. Such techniques require complex optical detection equipment such as fluorescent microscopes or spectrophotometers.

Label-free techniques are gaining traction as viable strategies for reducing the cost and complexity of disease detection. However, such methods involve precision engineering of nano-features (in a detection chip), complex optical setups, novel nano-probes (such as graphene oxide, carbon nanotubes and gold nanorods) or additional amplification steps such as aggregation of nanoparticles to achieve sensitive detection of biomarkers.

In this study, researchers led by Professor Zhang Yong from the Department of Biomedical Engineering at the NUS Faculty of Engineering developed a tiny microfluidic chip that could effectively detect minute amounts of biomolecules without the need for complex lab equipment.

This fluorescent label-free approach relies on the lateral shifts in the position of the microbead substrate within the chip for quantifying biomolecules. When biomolecules adsorb onto the surfaces of the microbeads, changes in the surface forces and the sizes of the microbeads can be detected and measured without the need of any external equipment. By depending on lateral displacement, the presence and concentrations of biomolecules can be evaluated in real-time, and the detection is significantly faster in comparison to fluorescent label-based detection.

“This tiny biochip can sensitively detect proteins and nano-sized polymer vesicles at concentrations as low as 10 ng/mL (150 picomoles) and 3.75 μg/mL, respectively. It also has a very small footprint, weighing only 500 mg and is 6 mm3 in size. Detection can be performed using standard laboratory microscopes, making this approach highly attractive for use in point-of-care diagnostics,” Zhang explained.

The researchers noted that their method can be extended to detect many other types of nano-biomolecules, including nucleic acids and viruses. To complement this chip technology, they are also developing a portable smartphone-based accessory and microfluidic pump to make the whole detection platform portable for disease diagnostics beyond the laboratory.

“We hope to further develop this technology for commercialization,” said Zhang.

The article can be found at: Zeming et al. (2018) Fluorescent Label-free Quantitative Detection of Nano-sized Bioparticles Using a Pillar Array.


Source: National University of Singapore.
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