Student Ph.D. Defense - Yang Zhang

May 01 2019 09:00 AM - May 01 2019 08:00 AM

​Engineering Plasmonic Nanostructures and Their Application in Bioanalysis

Wednesday, May 1, 2019
09:00 AM - 10:00 AM
Building 2, Level 5, Room 5220


Plasmonic nanostructures, like some noble metal (gold, silver), have gained large attention to study their plasmonic properties, to reach areas like electronics, photo-catalysis, biomedicine, and sensing. Plasmonic nanomaterials are known as local surface plasmon resonance, with two important results on the properties of the nanomaterials: enhanced electromagnetic field and wavelength dependence.   The higher electromagnetic field at the surface of nanoparticles can interact with nearby molecules leading to massive increase of in the intensity of molecule signals. This phenomenon is called surface-enhanced Raman scattering (SERS) and plasmonic enhanced fluorescence (PEF), enable the plasmonic nanomaterials as a signal amplifier.  By using these plasmonic nanostructures as a signal amplifier, SERS and PEF have become ultrasensitive methods in biomedicine and biosensing. Plasmonic biosensing is real-time, fast and labels-free for detecting biologically relevant analytes. 
The objective of my doctoral dissertation focus on developing new plasmonic nanostructures for detecting biomarkers related to cancers and some other diseases based on inorganic and organic chemistry.  In this work, a newly spiky nanostructure was developed, internal standard Raman molecules were embedded into the nanostructure for quantitative SERS detection of polycyclic aromatic hydrocarbons molecules. Then the morphology and dispersity of this nanostructure were optimized to get an approximately fusiform shape, which showed a stable, reproducible and high SERS signals. This nanostructure was furtherly functionalized by double strand DNA and aptamer, showing a good performance in drug delivery and detecting circulating tumor cells. Inspired by the mechanism of SERS, a SERS and PEF dual model sensor based on plasmonic nanostructures and newly synthesized probe molecules was developed, this dual model sensor combined the advantages of SERS and PEF and exhibited a lower limit of detection in detecting γ-glutamyl transferase in living cells. This dissertation contains the fabrication of newly plasmonic nanostructures and exploring their application in bioanalysis.