Miniature optical sensors that specifically identify low concentrations of biological and environmental substances are in high demand. Currently, there is no optical sensor that provides identification of the aforementioned species without amplification techniques and at naturally occurring concentrations. Recently, it has been demonstrated that triangular silver nanoparticles have remarkable optical properties and that their enhanced sensitivity to small changes in their local environment can be used to develop a new class of optical sensors using localized surface plasmon resonance (LSPR) spectroscopy and optimized surface chemistry. The examination of both model and non-model biological assays will be presented. It will be demonstrated that the LSPR nanosensor rivals the sensitivity and selectivity of and provides a low-cost alternative to commercially available sensors.