Carbon dots (CDs) have emerged as a promising class of zero-dimensional nanomaterials due to their unique optical properties, biocompatibility, and tunable surface chemistry. In recent years, they have attracted significant attention in the development of fluorescent nanosensors for biomedical and environmental applications. However, the rational design of CDs with specific functional groups that enable selective recognition remains a critical challenge. This study presents a simple yet effective strategy to synthesize highly fluorescent carbon dots functionalized with carbon-carbon double bonds (C=C) through a hydrothermal method using itaconic acid and branched polyethylenimine (PEI) as precursors. The resulting CDs exhibit strong blue emission at 465 nm under excitation at 350 nm, with excellent photostability and water dispersibility.ITGA1 Antibody custom synthesis The presence of C=C bonds on the CD surface was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), and fluorescence quenching experiments. These unsaturated bonds serve as reactive sites for electrophilic addition reactions, enabling the use of bromine as a molecular bridge. Upon exposure to bromine aqueous solution, the fluorescence of the CDs is efficiently quenched via addition across the C=C bond, forming a stable dibromide product.NEU1 Antibody Purity This quenching effect is concentration-dependent and linearly correlates with bromine levels within the range of 0–20 μM. To exploit this mechanism for analyte detection, a novel assay was developed for phenylephrine (PHE), a sympathomimetic drug used clinically for increasing blood pressure. PHE reacts selectively with bromine via a substitution reaction, consuming the bromine reagent. When PHE is present prior to bromine addition, less bromine remains available to quench the CD fluorescence. Thus, the degree of fluorescence recovery is directly proportional to the PHE concentration. A calibration curve based on the relative fluorescence intensity showed excellent linearity (R² = 0.998) over the range of 0.1–0.5 mg/mL. The method demonstrated high sensitivity, selectivity, and reproducibility, even in the presence of common interferents such as Na⁺, K⁺, Cl⁻, SO₄²⁻, and PO₄³⁻ ions.PMID:34625364 Real sample analysis using spiked eye drop formulations confirmed the accuracy and reliability of the method, with recoveries ranging from 96% to 104%. Compared to traditional titration methods, this approach eliminates the need for large amounts of hazardous bromine, avoids complex instrumentation, and allows for rapid visual assessment under UV light. Overall, this work introduces a versatile and environmentally friendly platform for the detection of bioactive molecules using C=C-functionalized carbon dots and bromine-mediated signal transduction, paving the way for future developments in CD-based chemosensing systems.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
