Eggshell nano-CaCO3 decorated PANi/rGO composite for sensitive determination of ascorbic acid, dopamine, and uric acid in human blood serum and urine

A novel and green method of extraction of nano-sized CaCO3 from white chicken eggshells, its characterization and application for electrochemical sensing of ascorbic acid, dopamine, and uric acid has been described. XRD analysis showed that the average size of the nano-CaCO3 particles extracted was 32.3 +/- 14.7 nm (alpha, 12) and match with the calcite phase. The best peak separation for the three analytes found when its composite with PANi and rGO was in 1:1:1 ratio. The nano-CaCO3 based sensor was able to detect all the three analytes in raw blood sample, showed excellent selectivity and LODs 10.81 mu M, 0.01 mu M and 0.04 mu M respectively for ascorbic acid, dopamine and uric acid. The capability of the extraction process to control the size of CaCO3 in a perfect nanometer range and the significant role played by nano-CaCO3 in resolving the oxidation peaks of the three typical analytes expected to impact significantly the future sensor research through substitution of the costly and hazardous nanomaterials.