Abstract

Nanoplasmonic Biosensors: a Search for the Optimum Balance Between Optical Performance and Analyte Transport

Nicholas Scott Lynn, Research Scientist, The Institute of Photonics and Electronics of the Czech Academy of Sciences (IPE)

There has recently been an extensive amount of work in the field of nanoplasmonics, where plasmonic phenomena occurring on a variety of nanostructrues present an alternative approach to surface plasmon resonance (SPR) biosensing. Many of these nanostructures are composed of arrays of surface-bound metal nanoparticles (NPs), for example, sparse arrays of NPs that support localized surface plasmons (LSPs), or dense arrays of NPs that support a guided mode. To a large extent, previous work on this topic has focused on optimization of a nanostructure in terms of its sensitivity to refractive index (RI) changes. In contrast, there has been little discussion regarding how changes to a NP array affect the rate of convective and diffusive analyte transport. This latter topic is important in the design of a nanostructure for sensing purposes: changes to a nanostructure that result in an increase in RI sensitivity might induce a detractive change in the rate of analyte capture, resulting in a sensor with a reduced performance. This presentation will focus on the balance between optical performance and analyte transport regarding immunoaffinity biosensors based on arrays of NPs. Using both theoretical, numerical, and experimental results, we will discuss how the parameters related to the nanostructure (e.g. NP shape and size, packing density) affect both the RI sensitivity as well as the rate of analyte transport. We will discuss under what conditions lead to optimized biosensing performance, when to expect reaction- or diffusion-limitations, and what designs should be avoided.