Nano particles facilitate a wide range of new functions and purposes in both science and society. The novel, size dependent properties of nanomaterials are central to these applications. For instance, the size dependent optical properties of coinage nanoparticles are known as the localized surface plasmon resonance (LSPR). These optical properties facilitate a phenomenon known as surface enhanced Roman scattering (SERS) and enhances molecular detection in biomedical forensic applications. Herein, gold nanoparticles are used for quick detection of the drug mimic, 2-naphthalenethiol. The nanoparticle concentration is maintained at 4 nanomolar while the 2-naphthalenethiol concentration varied from 1 to 8 micromolar. When the drug mimic is added to the nanoparticle containing solution, the optical properties of the nanostructures vary as a function of time and 2-naphthalenethiol concentration. These detectable signals arise because of nanoparticle-induced instability (i.e. aggregation). Systematic trends in nanoparticle aggregation are observed. As a result, this method could be used to develop an inexpensive and rapid sensor for biomedical and/or forensic sample analysis.