Facile Conversion of Toxic Cigarette Butts to NS-CodopedCarbon Dots and Their Application in Fluorescent Film Security InkBioimaging Sensing and Logic Gate Operation

摘要

The present work is emphasized on converting toxic cigarette butts (CBs) into highly fluorescent N,S-codoped carbon dots by a facile hydrothermal approach and exploring their multiple applications. The as-produced carbon dots (CBCDs) exhibited bright and stable fluorescence with a quantum yield of 26% and used as a label-free probe for “on–off–on” sequential detection of Fe³⁺ and ascorbic acid (AA). The fluorescence of CBCDs can be significantly quenched by Fe³⁺ ions through static quenching and restored upon the subsequent addition of AA due to the reduction of Fe³⁺ to Fe²⁺ by AA. This nanoprobe presented great selectivity and excellent sensitivity to Fe³⁺ and AA with a detection limit of 0.13 and 0.2 μM, respectively. Furthermore, the nanoprobe was extended to biosystem (intracellular detection) and successfully applied for the detection of Fe³⁺ in real water (tap, bore, and pond) and AA in biological samples (human urine and serum). In addition, we have constructed an IMPLICATION logic gate based on these unique sensing characteristics. The “visible–invisible” and “UV–visible”property explored their use as invisible ink for security applications.Furthermore, highly photostable fluorescent polymer films were preparedby incorporating CBCDs in poly(vinyl alcohol). It is anticipated thatthe strong and stable fluorescence emission nature of these filmsmight find direct or indirect applications in various optical/optoelectronicdevices, ranging from fluorescent displays to light-emitting diodes.