This study details the synthesis, structural characterization, and functional evaluation of poly-L-lysine (PLL)-modified carbon dots (CDs) designed for high-performance fluorescence sensing of bacterial endotoxin (LPS). The CDs were synthesized through a microwave-assisted pyrolysis process using citric acid and urea as precursors, yielding nanomaterials with strong green emission and a high quantum yield of 8.42%. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and proton nuclear magnetic resonance (¹H NMR) confirmed the successful surface functionalization of the CDs with PLL via amide bond formation.Fibrinogen β Antibody Biological Activity The presence of characteristic peaks from both PLL and CDs in the spectra, along with the disappearance of carboxyl stretching vibrations and emergence of amide bands, verified covalent conjugation.BHLHE41 Antibody Autophagy Transmission electron microscopy (TEM) revealed spherical nanoparticles with an average size of 3.2 nm, while dynamic light scattering (DLS) indicated a slightly larger hydrodynamic diameter of 5.PMID:34605552 6 nm, consistent with surface coating. The XPS data showed the presence of C, N, and O elements with binding energies corresponding to C–C, C–N/C–O, CO, and amide functionalities. The PLL-CDs exhibited enhanced thermal stability compared to pristine CDs, attributed to the polymer layer. UV-vis absorption and photoluminescence (PL) analyses demonstrated excitation-independent emission at 520 nm under 410 nm excitation, with a reduced quantum yield of 3.53% after PLL modification—likely due to quenching by the polymer matrix. However, this remained sufficient for sensitive detection. The probe maintained stable fluorescence across a broad pH range (2–8) and was resistant to high ionic strength (up to 1 M NaCl), indicating robustness in complex biological environments. These results collectively confirm the successful fabrication of well-defined PLL-CDs with favorable physicochemical properties suitable for biosensing applications.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
