Electrochemical sensor based on N,P–doped carbon quantum dots derived from the banana flower bract (Musa acuminata) biomass extract for selective and picomolar detection of dopamine

A facile route was proposed in preparing phosphorus and nitrogen dual carbon quantum dots (N,P-CQD) from banana flower bract extract by hydrothermal synthesis for selective and reliable detection of catecholamines such as dopamine (DA). By morphologically characterizing the synthesized CQD using Transmission Electron Microscopy (TEM), it is discovered that its average particle size is 3.8 nm. While the doping of the heteroatoms upsurges the electrical conductivity of the CQD, the presence of the functional sites like acid (–COOH), (–NH₂) and phosphate (-PO₄^3-) groups selectively attract the cations via., an ion-exchange mechanism leaving behind the anions, due to the electrostatic repulsion. The synthesized N,P-CQD/PIGE electrode-based electrochemical sensors demonstrated high selectivity and sensitivity for DA with a relatively low limit of detection (LOD) (∼500 pM) and a wide linear range, extending from 6.0 μM to 0.1 mM. The N,P-CQD's detection selectivity is further validated by utilizing a combination with a somewhat larger concentration of uric (UA) and ascorbic (AA) acids and only a modest amount of DA. Additionally, the N,P-CQD/PIGE electrode successfully detects DA with a LOD as low as 630 pM and a larger linear range of 2.5 M to 0.16 mM in real-time samples of dopamine injection.