Controlled synthesis of Pt nanoparticles array through electroreduction of cisplatin bound at nucleobases terminated surface and application into H2O2 sensing

Fabrication of sub-monolayer array of Pt nanoparticles (PtNPs) assembled at nucleobases terminated layers and their application into H2O2 and glucose sensing were reported. To prepare such a PtNPs assembly, 3-mercaptopropionic acid (MPA), Zr4+, nucleotide-5′-monophosphate (NTMP including guanosine, adenosine, cytidine, uridine-5′-monophosphate, and abbreviations were GMP, AMP, CMP, UMP, respectively) were adsorbed onto Au substrate sequentially to form nucleobases terminated surface and Zr4+ acted as binder to link carboxylic and phosphoric groups (NTMP/Zr4+/MPA/Au). Complexation of cisplatin, cis-Pt(NH3)2Cl2, with terminated nucleobases and following electrochemical reduction of surface-bound cisplatin gave PtNPs attached surface. Different PtNPs coverage or particle density was obtained depending on the NTMP used and decreased in the order: PtNPs/GMP/Zr4+/MPA/Au > PtNPs/AMP/Zr4+/MPA/Au > PtNPs/CMP/Zr4+/MPA/Au > PtNPs/UMP/Zr4+/MPA/Au. The surface loading of Pt was between 160 and 16 ng/cm2. The as prepared PtNPs can be used as electrocatalysts for H2O2 sensing (detection limit of H2O2 < 100 nM) and the sensitivity increased with decreasing PtNPs density. After adsorption of glucose oxidase, the modified electrode can be used as enzymatic electrode for glucose sensing and a detection limit of 38.5 μM was achieved. This study provided an example of fabricating PtNP arrays utilising surface complexation of cisplatin with nucleobases. The advantage of this method is that the NP density can be controlled through changing nucleobases or Pt complexes used to obtain suitable kinetics of the complexation reactions. Additionally, the PtNPs sub-monolayer as prepared has high sensitivity for H2O2 sensing even at a very low loading of Pt.