| dc.description.abstract | Ultra-low concentration nucleic acid detection has been widely applied in the diagnosis and treatment of diseases to improve patient treatment strategies and outcomes. Real-time polymerase chain reaction (PCR) and next-generation gene sequencing are the most common methods for nucleic acid detection, while their high cost and relatively lengthy processing times present challenges. Some studies have started to adopt silicon nanowire field-effect transistor (SiNW FET) devices due to their high sensitivity, real-time detection, small size, and ease of operation. Therefore, the SiNW FET devices are promising platforms for nucleic acid detection, including the potential use as Point-of-Care Testing (POCT) equipment.
Despite the advantages of real-time sample detection offered by FETs, the reaction time for nucleic acid diffusion to the detection surface remains a critical consideration. In previous studies using SiNW FETs for nucleic acid detection, the diffusion and reaction of the target oligonucleotide were primarily influenced by fluid flow convection and Brownian diffusion without the additional influence of an external force field, such as an electric field. As the target molecule gradually moves towards the probe surface for binding, the time required for diffusion becomes a limiting factor, especially when nucleic acid concentrations in the sample are low. Therefore, speeding up nucleic acid detection lies in accelerating the diffusion reaction rate of the primary rate-limiting step during the hybridization of target nucleic acids with probes.
This study used polycrystalline silicon nanowire field effect transistors (poly-SiNW FET) as biosensors, with oligonucleotides as probes to recognize complementary target DNA. A negative voltage was applied to the liquid gate used for detection to create an electric field that drives nucleic acids to the surface. This attempt to shorten the diffusion from nucleic acids to the probe surface. The research involved adjusting the gate voltages, injection flow rates, and probe immobilization times to find suitable electric field parameters for accelerating FETs in nucleic acid detection.
X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) confirm the successful immobilization of probes on the chip. By combining FET with adjusted gate voltage and injection flow rate, it was found that at a low injection flow rate and a -1 V electric field, the target DNA can stably diffuse, reducing the equilibrium time from approximately 60 minutes to 20 minutes. Further changes in probe immobilization time enhance surface immobilization, and applying an electric field via FET increases the collision probability between target DNA and probes. The signal differences significantly improve, maintaining superior performance at different detection concentrations, and the reaction time still achieves the detection endpoint 10 minutes earlier than without applying voltage.
This study first explores the results of applying an external electric field to accelerate detection time in field-effect transistors. The successful outcomes highlight the potential of an external electric field in accelerating the detection of low-concentration nucleic acids in nanowire field-effect transistors. | en_US |