RUI: Development of Novel Plasmonic Nanotransducers for Solution-based Molecular Imprinted Sensing

With the support of the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry, Dr. Ying Bao of Western Washington University is studying the development and implementation of a new class of nanoparticle-based sensors, which detect tiny amounts of biological molecules in solution. Metal nanoparticles that can be made to have waves of electrons on their surfaces by shining light on the particles are called plasmonic nanoparticles.

The energy at which the electron waves are formed is dependent on the density of materials close to the surface of the plasmonic nanoparticles. Small changes in the type and density of the nearby materials cause a large change in the energy of the electron waves, that can be measured by the energy of the light absorbed by the metal nanoparticle. Such plasmonic nanoparticles will be made to detect very small numbers of protein molecules in solution by creating locations on the nanoparticles that bind to the proteins in a selective way and by placing these binding sites at locations on the nanoparticles that give the biggest change in the energy of the light that is absorbed.

The selective nature of these "nanotransducers" is being achieved by making a molecular mold or imprint of proteins in a glass-like material. This molecular imprinting process creates physically robust and low-cost sensors capable of selectively binding to target molecules. This project will combine the benefits of individual plasmonic nanotransducers with molecular imprinting and open new avenues in nanosensor development.

The fundamental principles that will be discovered in this research can be applied by researchers when developing the next generation of new plasmonic nanosensors, with applications in areas such as clinical diagnosis, food safety, and environmental monitoring. The project will provide opportunities for students in the Chemistry Department at Western Washington University to engage in nanomaterial-related research and gain experience in materials, environmental, and analytical chemistry.

Furthermore, through both a course-based undergraduate research experience (CURE) and summer research positions, students at a local community college will gain nanoscience research experience.

To develop and implement a new class of anisotropic plasmonic nanotransducers permitting solution-based molecular imprinted sensing, this project is focused on three main objectives: 1) Synthesis and fundamental study of novel plasmonic nanotransducers. 2) Performing molecular imprinting of plasmonic nanotransducers in solution. 3) Evaluating sensing properties of imprinted nanosensors in solution. Methods for site-specific deposition of silica on plasmonic nanorods, as well as methods for controlling growth of nanoscale "tentacle" features will be used and further modified to produce this novel class of anisotropic plasmonic nanotransducer.

The development of such nanotransducers could address key shortcomings of existing plasmonic nanomaterials for molecular imprint-based sensing, most prominently their low stability in solution and limited effective surface area. Applying molecular imprinting and sensing in solution also has the possibility to address important restrictions in substrate-based (planar) systems, including limited numbers of imprinted molecular recognition sites, attrition in the number of sensors connected to the substrate, reduced refractive index sensitivity due to immobilization of the nanoparticles, and restricted flexibility on adjusting the number and types of nanosensors in the sensing system.

The proposed fundamental studies have the potential to provide useful information for the improved design of nano-transducers and imprinted plasmonic nanosensors.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.