Integrated nanoplasmonic biosensors: from innovative materials to multimode sensing

Gold nanostructures are a highly attractive class of materials with unique electrochemical and optical sensing properties. Recent developments have greatly improved the sensitivity of optical sensors based on metal nanostructured arrays. We introduce the localized surface plasmon resonance (LSPR) sensors and describe how its exquisite sensitivity to size, shape and environment can be harnessed to detect molecular binding events. We then describe recent progress in three areas representing the most significant challenges: integration of LSPR with complementary electrochemical techniques, long term live-cell biosensing and practical development of sensors and instrumentation for routine use and high-throughput detection. As an example we will demonstrate a novel refractive index and charge sensitive device integrated with nanoplasmonic islands to develop nano-metal-insulator-semiconductor (nMIS) junctions. The developed sensor facilitates simultaneous detection of charge and mass changes on the nanoislands due to biomolecule binding. A brief insight on microcontact printing to functionalize proteins on nanoplasmonic sensors will also be discussed. The developed nanosensors can readily be adopted for multiplexed and high throughput label-free immunoassay systems, further driving innovations in biomedical and healthcare research.