Chiral Melanin-like Particle-Inspired Fluorescent Silicon Quantum Dots for Sensitively Detecting Inflammation in Cells

An abnormal concentration of ONOO – is a major contributor to inflammation and cancer. Thus, real-time detection of ONOO – concentrations is essential for the prevention of inflammation and cancer-related diseases. The fluorescence of melanin-like particles synthesized by oxidizing the tripeptide Lys-Tyr-Phe (KYF) with l -phenylalanine (L-Phe) can be specifically quenched by ONOO – . In order to decrease the photobleaching of melanin-like particles ((K/P) ox ) and retain the ability to detect ONOO – specifically, chiral SiQDs-(K/P) ox with (K/P) ox as precursor was synthesized by a one-step hydrothermal route. Compared to SiQDs-Cat, which is synthesized with catechol as the precursor, SiQDs-(K/L-P) ox and SiQDs-(K/D-P) ox have a wider emission interval (380–700 nm) with a maximum emission wavelength of 490 nm. Among them, SiQDs-(K/D-P) ox exhibits a higher quantum yield (47.66%) and SiQDs-(K/L-P) ox has a longer fluorescence lifetime (27.219 μs). Additionally, SiQDs-(K/L-P) ox shows higher biocompatibility and can be colocalized in the mitochondria of HepG2 cells with a Pearson coefficient of 0.99. Furthermore, SiQDs-(K/L-P) ox can sensitively detect endogenous ONOO – in HepG2 cells by “fluorescence off”. Therefore, the development of chiral SiQDs-(K/L-P) ox provides an important alternative for sensitively detecting inflammation in cancer cells.