Student: Yunfei Zhao
Advisor: Meng Lu
Title: Photoacoustic- and photothermal-based detection of gold nanoparticles and biomarkers
Abstract: Biomarker detection is of great importance in the field of medical research and diagnostics. The early detection of certain biomarkers related to some diseases can be used as a tool for early diagnosis of such diseases such as cancer, cryptococcal infection, and some other diseases which don’t have an obvious symptom at their early stage. To increase the sensitivity of such detection and enable earlier diagnosis, we have developed several photoacoustic (PA)- and photothermal (PT)-based detection techniques. One is a lab-based photoacoustic immunoassay, derived from standard enzyme-linked immunosorbent assay format. This technique uses gold nanoparticles (AuNPs) instead of enzyme as the label and utilizes the plasmonic resonance of the AuNPs to boost the PA signal. Another technique is a paper-based PA lateral flow assay (LFA). Since LFA uses conjugated AuNPs as a colorimetric reporter, it is very convenient to be directly used in PA detection. Further enhancement of the PA and PT signals include the use of photonic crystal (PC) substrates. These substrates, which, under the right excitation wavelength and incident angle, can support guided-mode resonance and enhance the near field two orders of magnitude higher than the incident light field. Two PC-enhanced techniques were developed, one is PC-enhanced PA detection and the other is PC-enhanced PT lens. All the aforementioned technique has increased the sensitivity of the assays by 10x to 100x times, as compared to traditional colorimetric or fluorescence-based methods. Future work includes multiplexing of analyte to increase the throughput and the use of new types of nanoparticles to increase the plasmonic resonance even further.