Facile reflux synthesis of polyethyleneimine‐capped fluorescent carbon dots for sequential bioassays toward Cu²⁺/H₂S and its application for a logic system

Abstract

In this work, we present a novel facile strategy for green synthesis of polyethyleneimine (PEI)-capped carbon dots (PEI-CDs), in which citric acid and PEI were chosen as reactants and highly fluorescent PEI-CDs could be readily obtained via a simple one-pot refluxing under 120 • C within 2 H. Fluorescence studies indicate that the as-prepared PEI-CDs exhibit strong fluorescence emission at 446 nm with excitation at 365 nm. Upon the sequential addition of Cu 2+ and H 2 S, PEI-CDs result in an interesting "ON−OFF−ON" three-state emission responses, promising a bifunctional sensory platform. Moreover, the Cu 2+ /H 2 S-facilated reversible fluorescence changes of PEI-CDs have demonstrated the design of an INHIBIT logic system based on Boolean logic.

Carbon Dots-Based Logic Gates

“…Cr 6+ sensing and antibacterial activity AND Single [67] N-doped CDs Hg 2+ and glutathione detection, cell imaging IMP Single [49] Polyethyleneimine-capped fluorescent CDs Cu 2+ and H 2 S detection INHIBIT Single [43] CDs-gold nanoparticle Detection of pesticides INHIBIT-OR Combination [25] Nitrogen-doped CDs Cu 2+ and GSH detection AND Single [39] Nitrogen-doped CDs chlorpromazine hydrochloride detection AND Single [70] Pristine CDs Fe 3+ anf Fsensing AND Single [40] Holium doped CDs dual imaging XOR+INH-OR Integrative [58] 6. Future Perspectives…”

“…There are several reports that have constructed AND logic operation through the detection of different metal ions, such as Cr 6+ [37], Hg 2+ [38], Cu 2+ [39], and Fe 3+ [40]. Apart from AND, other logic operations such as the INHIBIT function were also fabricated through sensing of various metal ions through different amino acid derivatized CDs [41], histidine [42], Cu 2+ , H 2 S [43], arginine, and acetaminophen [44]. Other researchers developed IMPLICATION logic operations using the sensing ability of CDs for Hg (II) and cysteine [45], AA [46], Fe 3+ [47], Hg 2+ , and biothiols [48], Hg(II), and glutathione [49].…”

“…The reversible system with the activated condition can revert to its original state with the introduction of a reactivator. CDs-based reversible logic gates work on the principle of quenching the FI signal, which further recovers by a recovery agent [43]. This type of logic gate is a potential candidate for low-power computing [60].…”

“…In another study, Zhang et al capped CDs with polyethyleneimine and used them bioassay of Cu 2+ and S 2 . The INHIBIT Boolean logic is influenced by the FI quenching and recovery process in presence of analytes [43]. For the limited tunability of the CDs spectrum, it is essential to improve the homogeneity of local electronic structure by controlling the size of sp2 domains, the surface functional group through surface passivation.…”

“…In another study, Zhang et al capped CDs with polyethyleneimine and used them bioassay of Cu 2+ and S 2 . The INHIBIT Boolean logic is influenced by the FI quenching and recovery process in presence of analytes [43].…”