In the recent past, the application of metal and semiconductor nanoparticles (NPs) has gained attention in analytical chemistry for various advantages over other analytical tools. Most frequently nanoparticles are extensively employed as labels in optical and electrochemical assays. They also are utilized as scaffolds for assembling of small molecules and macromolecules. The conventional approach consists of synthesis and modification of nanoparticles with recognition elements followed by their application to an analytical assay. Another approach relies on the synthesis of nanoparticles in situ triggered by a recognition event. The enzymatic synthesis of NPs in situ allows to address shortcomings related with the nonspecific adsorption of pre-synthesized NPs on surfaces and improve significantly the signal to noise ratio improving significantly sensitivity of analytical assays. This review deals with conventional and unconventional applications of metal and semiconductor to analytical chemistry.