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pH‐Responsive Fluorescence Enhancement in Graphene Oxide–Naphthalimide Nanoconjugates: A Fluorescence Turn‐On Sensor for Acetylcholine
Author(s) -
Mangalath Sreejith,
Abraham Silja,
Joseph Joshy
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201702198
Subject(s) - carbodiimide , graphene , fluorescence , chemistry , covalent bond , chromophore , photoinduced electron transfer , photochemistry , acetylcholinesterase , quenching (fluorescence) , combinatorial chemistry , aqueous solution , electron transfer , nanotechnology , materials science , organic chemistry , enzyme , physics , quantum mechanics
A pH‐sensitive, fluorescence “turn‐on” sensor based on a graphene oxide–naphthalimide (GO–NI) nanoconjugate for the detection of acetylcholine (ACh) by monitoring the enzymatic activity of acetylcholinesterase (AChE) in aqueous solution is reported. These nanoconjugates were synthesized by covalently anchoring picolyl‐substituted NI derivatives on the GO/reduced GO surface through a 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide/ N ‐hydroxysuccinimide coupling strategy, and the morphological and photophysical properties were studied in detail. Synergistic effects of π–π interactions between GO and the NI chromophore, and efficient photoinduced electron‐ and energy‐transfer processes, were responsible for the strong quenching of fluorescence of these nanoconjugates, which were perturbed under acidic pH conditions, leading to significant enhancement of fluorescence emission. This nanoconjugate was successfully employed for the efficient sensing of pH changes caused by the enzymatic activity of AChE, thereby demonstrating its utility as a fluorescence turn‐on sensor for ACh in the neurophysiological range.