Low-dimensional Nanomaterials for Chemical and Biological Sensing
Keng-Ku Liu
Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan
kkliu@mx.nthu.edu.tw
Abstract
In this talk, I will talk about the low-dimensional nanomaterials including gold nanostructures, hollow plasmonic nanostructures, and graphene for chemical and biosensing. Hollow and porous metal nanostructures are a novel class of plasmonic nanostructures that exhibit extraordinary optical and catalytic properties compared to their solid counterparts, due to a higher surface to volume ratio and the facile tunability of the LSPR wavelength over a broad range from visible to parts of near infrared. We demonstrate that hollow and porous plasmonic nanostructures exhibit a significantly higher refractive index sensitivity compared to other solid nanostructures of similar size, leading to LSPR sensors with higher sensitivity and lower limit-of-detection compared to biosensors based on solid counterparts. For the first time, we demonstrate that the large refractive index sensitivity and small electromagnetic decay length of gold nanocages (AuNCs) make them excellent candidates for label-free plasmonic biosensing. Compared to gold nanorods, molecularly imprinted AuNCs could easily detect kidney injury biomarker (neutrophil gelatinase-associated lipocalin, NGAL) from synthetic urine with more than an order of magnitude lower.
Porous core-shell plasmonic nanostructures host electromagnetic hotspots between the core and the shell, offering significantly higher SERS enhancement as compared to other solid nanostructures of similar size. Through a systematic study, we unveil the influence of size, shape, and orientation of the porous core-shell plasmonic nanostructures on the optical properties and SERS enhancement. Furthermore, the SERS-active substrate based on gold nanoparticles-decorated chemical vapor deposition (CVD)-growth graphene for the multiplexing detection of DNA will also be discussed. The combination of plasmonic nanomaterials and graphene dramatically enhanced the Raman signals of the DNA-labeled dye. Moreover, a simple and universal method based on flexible elastomeric film with adsorbed plasmonic nanostructures will be introduced for the large and uniform fluorescence enhancement. The novel fluorescence-based immunoassays improve the sensitivity of existing analytical methods for the biomarker detection and disease diagnosis in an easy to handle and cost-effective manner.
Short Bio
Keng-Ku Liu received the B.S and M.S. degrees in the department of engineering and system sciences from National Tsing Hua University, Taiwan, and the Ph.D. degree in materials sciences and engineering from Washington University in St. Louis, MO, USA in 2017. He is currently an assistant professor with the department of biomedical engineering and environmental sciences at the National Tsing Hua University, Taiwan. His research interests include the biosensors, low-dimensional nanomaterials, plasmonics, nanomedicine, electronic and optoelectronic devices.