Yen-Wen Kang

Human immunodeficiency virus drug development assisted with AlGaN/GaN high electron mobility transistors and binding-site models

Human immunodeficiency virus (HIV) Reverse Transcriptase (RT)-immobilized AlGaN/GaN high electron mobility transistors (HEMTs) and binding-site models were used to find out the dissociation constants of the HIV RT-inhibitor complex and the number of the binding sites on RT for the inhibitor, Efavirenz. One binding site on the RT for the inhibitor is predicted and the dissociation constant extracted from the binding-site model is 0.212 nM. The AlGaN/GaN HEMTs and the binding-site-models are demonstrated to be good tools to assist drug developments by elucidating the dissociation constants and the number of binding sites, which can largely reduce the cost and time for drug developments.

Viscosity-dependent drain current noise of AlGaN/GaN high electron mobility transistor in polar liquids

The drain current fluctuation of ungated AlGaN/GaN high electron mobility transistors (HEMTs) measured in different fluids at a drain-source voltage of 0.5 V was investigated. The HEMTs with metal on the gate region showed good current stability in deionized water, while a large fluctuation in drain current was observed for HEMTs without gate metal. The fluctuation in drain current for the HEMTs without gate metal was observed and calculated as standard deviation from a real-time measurement in air, deionized water, ethanol, dimethyl sulfoxide, ethylene glycol, 1,2-butanediol, and glycerol. At room temperature, the fluctuation in drain current for the HEMTs without gate metal was found to be relevant to the dipole moment and the viscosity of the liquids. A liquid with a larger viscosity showed a smaller fluctuation in drain current. The viscosity-dependent fluctuation of the drain current was ascribed to the Brownian motions of the liquid molecules, which induced a variation in the surface dipole of the gate region. This study uncovers the causes of the fluctuation in drain current of HEMTs in fluids. The results show that the AlGaN/GaN HEMTs may be used as sensors to measure the viscosity of liquids within a certain range of viscosity.

AN integrated microfluidic system using field-effect transistors for CRP detection

Cardiovascular diseases are responsible for 25-million deaths worldwide on a yearly basis. Timely diagnosis of the disease is therefore an extensive research area. Toward this end, C-reactive protein (CRP) has become a reliable biomarker for evaluating risks of cardiovascular diseases. For commercial methods of CRP detection, the diagnosis of the enzyme-linked immunosorbent assay (ELISA) protocol and the high-sensitivity CRP (hs-CRP) were relatively time-consuming and the sensitivity and the detection limit of the above methods were not satisfactory. Recently, a CRP-specific aptamer (DNA-based) with high sensitivity and specificity was used to detect CRP in a microfluidic system, which was capable of performing the detection in an automated fashion while consuming tiny volumes of reagents and samples. Alternatively, AlGaN/GaN HEMT-based field-effect transistor (FET) sensors have emerged as promising biosensors to detect small molecules, proteins and even viruses, and have demonstrated rapid and highly sensitive detection in a compact system. To date, however, the combination of the microfluidic system, CRP-specific aptamer and high sensitivity FET sensors has not yet attempted. In this study, an integrated device that combined the advantages of microfluidics, CRP-specific aptamer and FET-based sensors was developed to achieve rapid, sensitive and specific CRP detection.

Identification of ligand-receptor binding affinity using AlGaN/GaN high electron mobility transistors and binding-site models

AlGaN/GaN high electron mobility transistors (HEMTs) were immobilized with various receptors, including antibodies, duplex DNA, and HIV reverse transcriptase (RT) enzymes to detect ligands, including peptides, SARS proteins, and HIV drugs, respectively. Signals generated by the sensors were fitted into binding-site models and analyzed. The dissociation constants of the ligand-receptor pairs and the number of binding-sites on receptors were resolved. The HEMTs and the models were demonstrated to be useful for drug developments and for elucidating SARS virus replication.