A method of detecting an anti-cancer drug in a solution including contacting a substrate with the solution and measuring a Raman signal of the anti-cancer drug in the solution. The substrate includes a layer of a nanomaterial that is at least partially coated on an outer surface of the substrate. The nanomaterial includes silver nanoparticles and a V2CTx MXene, where Tx is at least one selected from the group consisting of hydroxide (—OH), oxygen (—O), and fluorine (—F). The anti-cancer drug interacts with the nanomaterial on the outer surface of the substrate in the solution.