Carbon-based nanodots as effective electrochemical sensing tools toward the simultaneous detection of bioactive compounds in complex matrices

A comparative study about the electroanalytical performance of three types of carbon-based nanodots has been accomplished. They exhibit similar functionalities (oxygenated groups) but diverse size and core structure (morphology, crystallinity and quantum confinement): carbon nanodots (CNDs), carbon quantum dots (CQDs) and graphene quantum dots (GQDs), herein employed as potential sensing modifiers on screen printed electrode surface. All of them were top-down synthetized, as well as characterized by TEM, FTIR, Raman and fluorescence techniques. Their electrochemical properties were assessed by cyclic voltammetry using specific redox probes (outer and inner sphere systems), such as potassium hexacyanoferrate(III), hexaammineruthenium(III) chloride and dopamine, which display different electron transfer rate as a function of their electronic core structure and specific active sites. The electroanalytical capabilities of these carbogenic nanodots as suitable sensing tools toward the simultaneous detection of several bioactives like vitamins (ascorbic acid or Vit C, pyridoxine or Vit B2, riboflavin or Vit B6) and amino acids (cysteine and tyrosine), were also evaluated and discussed attending to the main interactions responsible for improvement in peak currents and potentials. Finally, GQD-based electrodes, selected as the best choice, were submitted to an exhaustive electroanalytical performance characteristics evaluation. The success of this simple drop-casting procedure was also proved by affording the simultaneous detection of three diverse bioanalytes in complex commercial matrices and with lower detection limits in comparison to other reported proposals from similar nature. [Display omitted] •Physical and electrochemical characterization of GQDs, CQDs and CNDs•Same surface oxygenated functionalities but different core structure•Edge plane ratios and defects responsible of electrocatalytic activity•GQDs as best suited to perform simultaneous electrochemical sensing•Good batch-to-batch reproducibility for their further potential manufacturing