Department: NanoEngineering
Faculty Advisor(s): Donald J. Sirbuly

Primary Student
Name: Joshua Tan Villanueva
Email: jtvillan@ucsd.edu
Phone: 858-822-4143
Grad Year: 2016

Student Collaborators
Qian Huang, q4huang@ucsd.edu

Advances in drug-delivery and nanomedicine have shifted the framework of colloidal stability research beyond ideal benchtop settings towards more realistic studies within the context of naturally occurring biochemical and micromechanical environments. Planar total internal reflection microscopy (TIRM) has traditionally been the standard technique used to investigate the complex relationship between freely diffusing particles, their dispersing medium, and macroscopic surfaces. However, to realize the changes in the current state of research it is necessary to development low-dimensional nanoscale analogues to current techniques with large potential for easy integration and multifunctional capabilities. One-dimensional (1D) optical waveguide-based devices present an ideal platform for expanding the versatility of traditional TIRM to locally probe the dynamics of colloidal solutions in complex fluid environments in situ. Our lab has demonstrated the successful implementation of SnO2 nanofibers in a simple 1D TIRM setup for use in a proof-of-concept experiment. We investigate the electrostatic interaction between the waveguide surface and gold nanoparticles freely diffusing in a model, quiescent, electrolyte solution of varying ionic strengths. By monitoring the distance-dependent scattering intensity of the particles diffusing within the evanescent field of a bare SnO2 core, we are able to generate statistical distributions of nanoparticle proximity to the waveguide surface. We then compare and analyze these distributions with respect to an electric double layer (EDL) interaction model to validate our new platform and showcase its utility for characterizing the surface properties of colloidal systems.

Industry Application Area(s)
Life Sciences/Medical Devices & Instruments

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