Enzyme-based fluorometric biosensor-based on coffee waste-derived carbon dots modified with APBA and NADP+ cofactor for selective dual detection of γ-aminobutyric acid in in vitro and in vivo models.

An enzyme-based fluorescent sensor was developed by adapting carbon dots derived from coffee waste to detect inhibitory neurotransmitters such as γ-aminobutyric acid (GABA). In this study, CDs were synthesized from biomass-derived coffee waste by the facile hydrothermal reaction (i.e., C-CDs). A C-CDs-based enzyme-based sensor was then developed using 3-aminophenyl boronic acid (APBA) and nicotinamide adenine dinucleotide phosphate (NADP+) cofactors (i.e., C-CANs). As a result of the addition of the GABase enzyme, the resulting blue-fluorescent C-CANs were effective in detecting GABA. This sensor is capable of sensing GABA in the range of 0–20 μM with a detection limit of 95.09 nM. A distinguished fluorescence quenching was observed in human neuroblastoma (SH-SY5Y) cells where probe (C-CANs-GABase) was able to detect GABA intracellularly. Zebrafish larvae were used to study the sensing potentials of the developed probe against GABA at different concentrations (10 and 20 μM). A validation study was conducted on real samples such as human serum, which showed high recovery values between 97 and 105.6%. [Display omitted] [ABSTRACT FROM AUTHOR]