Chen-Hsun Weng

Screening of Aptamers on Microfluidic Systems for Clinical Applications

The use of microfluidic systems for screening of aptamers and their biomedical applications are reviewed in this paper. Aptamers with different nucleic acid sequences have been extensively studied and the results demonstrated a strong binding affinity to target molecules such that they can be used as promising candidate biomarkers for diagnosis and therapeutics. Recently, the aptamer screening protocol has been conducted with microfluidic-based devices. Furthermore, aptamer affinity screening by a microfluidic-based method has demonstrated remarkable advantages over competing traditional methods. In this paper, we first reviewed microfluidic systems which demonstrated efficient and rapid screening of a specific aptamer. Then, the clinical applications of screened aptamers, also performed by microfluidic systems, are further reviewed. These automated microfluidic systems can provide advantages over their conventional counterparts including more compactness, faster analysis, less sample/reagent consumption and automation. An aptamer-based compact microfluidic system for diagnosis may even lead to a point-of-care device. The use of microfluidic systems for aptamer screening and diagnosis is expected to continue growing in the near future and may make a substantial impact on biomedical applications.

Cancer Cell-Specific Oligopeptides Selected by an Integrated Microfluidic System from a Phage Display Library for Ovarian Cancer Diagnosis

Ovarian cancer is one of the leading causes of female mortality worldwide. Unfortunately, there are currently few high-specificity candidate oligopeptide targeting agents that can be used for early diagnosis of this cancer. It has been suggested that cancer-specific oligopeptides could be screened from a phage display library. However, conventional methods are tedious, labor-intensive, and time consuming. Therefore, a novel, integrated microfluidic system was developed to automate the entire screening process for ovarian cancer cell-specific oligopeptides. An oligopeptide screened with microfluidic chip-based technique was demonstrated to have high affinity to ovarian cancer cells and demonstrated relatively low binding to other cancer cells, indicating a high specificity. Furthermore, the developed method consumed relatively low volumes of samples and reagents; only 70 μL of reactant was used within the whole experimental process. Each panning process was also significantly shortened to only 7.5 hours. Therefore, the screened oligopeptide could be used to isolate ovarian cancer cells in a rapid manner, thus greatly expediting the diagnosis and its application as oligopeptide targeting agent for theranostics of this cancer.

Synthesis of gold nanoparticles using microfluidic reaction systems

A new microfluidic reaction system capable of mixing, transportation and reaction is developed for synthesis of nanoparticles. It allows for rapid, cost-effective, and environmentally friendly approach to accelerate the synthesis of the gold nanoparticles. The developed system integrated a micromixer, micropumps, microvalves, microheaters, and micro temperature sensors to form a microfluidic reactor. Successful synthesis of gold nanoparticles with varying sizes has been demonstrated within a shorter period of time. The development of the microfluidic reaction system could be promising for synthesis of functional nanoparticles for biomedical applications.

A suction-type, pneumatic microfluidic device for rapid DNA extraction

This current study presents a new miniature, integrated system capable of rapid extraction of genomic DNA (gDNA) from saliva samples. Three major components of the DNA extraction chip, including six symmetrical, normally-closed microvalves, a sample transport/mixing unit and a waste unit are integrated in this device. The microfluidic DNA extraction chip was made of CNC machining and PDMS casting processes to integrate a liquid channel layer, an air chamber layer and a glass layer on a single chip. Liquid samples can be transported and mixed by the suction-type sample transport/mixing unit by using micropumps, micromixers and normally-closed microvalves. Experimental results showed the pumping rate can be as high as 400 µL/min at an applied pressure of −70 KPa for an air chamber with a depth of 1.5 mm. A mixing efficiency as high as 96.5% can be achieved within 3 sec. Experimental data also showed that gDNA with an average concentration of 45 ± 3 ng/µL and an optical intensity (OD) value (260/280) of 1.5 ± 0.2 from ten measurements can be successfully achieved within 25 minutes. Consequently, the proposed miniature system can provide a powerful platform for automatic, rapid DNA extraction.