Ecofriendly nanoprobe for differentiation between hydrogen peroxide producing bacteria and nonproducers: Zero waste circular economy of cooking and harvesting of energy

A novel, affordable, and environmentally benign highly fluorescent carbon dots valorized from ignited peel of flame roasted eggplant (EPCDs) were introduced for the first time. The EPCDs were spontaneously and rapidly formed during eggplant roasting, for only 5 min, with high quantum yield (28.5 %). The emission of EPCDs was selectively quenched in the presence of Fe³⁺ through a mixed static quenching/ inner filter mechanism. Accordingly, a turn-off sensing platform composed of EPCDs coupled to Fe²⁺ enabled the highly sensitive detection of hydrogen peroxide (H₂O₂) through an acetate mediated Fe²⁺ oxidation. Acetate could boost sensor sensitivity by blocking Fe²⁺ back conversion to Fe³⁺ enabling the rapid detection of H₂O₂ down to concentration range from 13.12 to 87.55 nM, with very good accuracy (100 % ± 3), precision (%RSD < 3) and low detection limit (3.88 nM). The sensor was applied for H₂O₂ detection in different water samples as well as for the differentiation of H₂O₂-producing bacteria from nonproducers, for the first time, in liquid cell culture without any pretreatment step. The utilized EPCDs showed ecological superiority on Complex GAPI and AGREE metrics in addition to a 250-fold reduction in CO₂ emission compared to the greenest reported H₂O₂ sensor paving the way for circular economy practice.