Abstract
Microfluidic devices enable the precise operation of liquid samples in small volumes. This motivates why microfluidic devices have been applied to point-of-care (PoC) liquid biopsy. Among PoC liquid biopsy studies, some report diagnostic reagents being freeze-dried in such microfluidic devices. This type of PoC microfluidic device has distinct advantages, such as simplicity of the procedures, compared with other PoC devices using liquid-type diagnostic reagents. Despite the attractive characteristic, only diagnostic reagents based on the cloned enzyme donor immunoassay (CEDIA) have been freeze-dried in the microfluidic device. However, development of the PoC device based on the CEDIA method is time-consuming and labor-intensive. Here, we employed a molecule-responsive protein synthesis system as the diagnostic reagent to be freeze-dried in the microfluidic device. Such molecule-responsive protein synthesis has been well investigated in the field of molecular biology. Therefore, using the accumulated information, PoC devices can be efficiently developed. Thus, we developed a microfluidic device with an integrated freeze-dried molecule-responsive protein synthesis system. Using the developed device, we detected two types of bio-functional molecules (i.e., bacterial quorum sensing molecules and mercury ions) by injecting 1 µL of sample solution containing these molecules. We showed that the developed device is applicable for small-volume biosensing.
Highlights
Microfluidic devices make it possible to analyze sample solutions even in small volumes
This result shows that the freeze-dried cell-free protein synthesis (CFPS) system and the freeze-dried DNAs remain functional for gene expression after rehydration
This study aimed to develop a biosensing device that can be used via simple operation with a small volume of samples
Summary
Microfluidic devices make it possible to analyze sample solutions even in small volumes. The sample volume required to analyze with microfluidic devices is smaller than that of a general plate reader (~5 μL) This advantage is useful to reduce invasiveness in liquid biopsy using blood, urine, saliva, and tears. PoC device has been developed [5] (i.e., a microfluidic device equipped with freeze-dried diagnostic reagents) Such device has a distinct advantage compared with other PoC devices using liquid-based diagnostic reagents: Simple operational procedure, users do not need to mix and/or apply diagnostic reagents when using the PoC device, and simple loading of the sample solution to the PoC device enables liquid biopsy. PoC devices with freeze-dried diagnostic reagents have these attractive characteristics, only the antigen-antibody diagnostic reagents based on the cloned enzyme donor immunoassay method have been freeze-dried so far.
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