Ultrasmall platinum nanoparticles synthesized in reline deep eutectic solvent explored towards the voltammetric sensing of riboflavin in beverages and biological fluids

We report a solvothermal synthesis of ultrasmall platinum nanoparticles (USPtNPs) with an average size of 0.204 ( ± 0.008) nm using reline deep eutectic solvent (DES) as a stabilizing medium at a temperature of 80 ºC. SEM and EDS were used to morphologically characterize the USPtNPs. These revealed approximately spherical shapes with emission lines characteristic of platinum. DES was characterized by FT-IR and NMR, which indicated its formation through hydrogen bonds between the precursors. DSC was also used to characterize the precursors and the formed DES. Furthermore, an electrochemical sensor for determining riboflavin (RB) in commercial energy drinks and biological fluids was developed using the USPtNPs together with multiwalled carbon nanotubes (MWCNT). The USPtNPs-DES/MWCNT/GCE film was characterized by SEM, which demonstrated the characteristic tubular morphology of MWCNT. The RB voltammetric response was studied, and a significant enhanced on the current response was observed, especially due to the USPtNPs. This sensor displayed a linear response for RB in the range of 0.02–1.2µmol L−1, with a limit of detection of 1.8 nmol L−1. Besides detectability at nanomolar range, excellent performance was verified for repeatability and anti-interference features. The sensor based on extraordinary USPtNPs synthesized in DES in a simpler and environmentally friendly way was successfully applied to determine RB in different matrices. •First synthesis of USPtNPs using deep eutectic solvent as stabilizing medium.•USPtNPs with an average size of 0.208 nm obtained in a solvothermal synthesis.•First sensor based on USPtNPs and MWCNTs to detect RB in biological and food samples.