One-Pot Synthesis of Carbon Nanodots in an Organic Medium with Aggregation-Induced Emission Enhancement (AIEE): A Rationale for “Enzyme-Free” Detection of Cholesterol

Abstract

Addressing the limitations associated with the detection of cholesterol, we present a one-pot synthesis of a carbon nanodot (CD) in an organic medium (CDorg) from a novel bile acid hydrazone-based organogel. Interestingly, CDorg possesses the aggregation-induced emission enhancement (AIEE) phenomenon, which rationally aids in the “enzyme-free” detection of cholesterol through a fluorescence turn-on mechanism. On dilution of the THF/water mixture of CDorg with its poor solvent (water), a 9.8-fold enhancement in its photoluminescence (PL) emission is witnessed. Such an enhancement in PL emission is credited to the occurrence of molecular restrictions due to the formation of nanoaggregates of CDorg, thereby initiating a radiative pathway for exciton decay. Excitingly on adding cholesterol to CDorg, we observed a similar enhancement in its PL emission without the use of any cholesterol oxidase (ChOx) enzyme. The limit of detection and limit of quantification of cholesterol is found to be as low as 1.09 and 3.64 μM, respectively. Hence, this contribution highlights the enzyme-free fluorescence turn-on detection of cholesterol by a novel CD rationally designed to extend its applicability in an organic medium, where it is still considered a major restraint.