A Route to Superior Performance of a Nanoplasmonic Biosensor: Consideration of Both Photonic and Mass Transport Aspects

Journal article, 2018

Optical biosensors based on plasmonic nanostructures present a promising alternative to conventional biosensing methods and provide unmatched possibilities for miniaturization and high-throughput analysis. Previous works on the topic, however, have been overwhelmingly directed toward elucidating the optical performance of such sensors, with little emphasis on the topic of mass transport. To date, there exists no examination, experimental nor theoretical, of the bioanalytical performance of such sensors (in terms of detection limits) that simultaneously addresses both optical and mass transport aspects in a quantitative manner. In this work we present a universal model that describes the smallest concentration that can be detected by a nanoplasmonic biosensor. Accounting for both optical and mass transport aspects, this model establishes a relationship between bioanalytical performance and the biosensor's design parameters. We employ the model to optimize the performance of a nanoplasmonic DNA biosensor consisting of randomly distributed gold nanorods on a glass substrate. Through both experimental and theoretical results, we show that the proper design of a nanostructured sensing substrate is one that m aximizes mass transport efficiency while preserving the quality of the optical readout. All results are compared with those obtained using a conventional SPR biosensor. We show that an optimized nanoplasmonic substrate allows for the detection of DNA at concentrations of an order of magnitude lower with respect to an SPR biosensor.