A colorimetric sensor for detecting an analyte of interest that includes a metal layer disposed upon a substrate, a plurality of nanostructures, and a corresponding plurality of metal deposits spaced apart from the metal layer. The metal layer defines a plurality of holes, each nanostructure includes a first portion disposed within a respective hole, and each metal deposit is disposed upon a second portion of a respective nanostructure. The sensor also includes a molecularly imprinted polymer layer that may cover the metal layer, the nanostructures, and/or the metal deposits. The molecularly imprinted polymer layer defines a cavity shaped to receive the analyte of interest, and the sensor is configured such that, when an analyte contacts the molecularly imprinted polymer layer and becomes disposed within the cavity, an optical property of at least a portion of the sensor changes thereby to cause a detectable color change in and/or from the sensor.