Nanoparticles, methods of preparation thereof, and methods of detecting a target molecule using embodiments of the nanoparticle, are disclosed. One embodiment of an exemplary nanoparticle, among others, includes a surface-enhanced Raman spectroscopic active composite nanostructure. The surface-enhanced Raman spectroscopic active composite nanostructure includes a core, at least one reporter molecule, and an encapsulating material. The reporter molecule is bonded to the core. The reporter molecule is selected from: an isothiocyanate dye, a multi-sulfur organic dye, a multi-heterosulfur organic dye, a benzotriazole dye, and combinations thereof. The encapsulating material is disposed over the core and the reporter molecule. After encapsulation with the encapsulating material, the reporter molecule has a measurable surface-enhanced Raman spectroscopic signature.