Novel SiQDs-(K/L-P)ox: Enhanced Fluorescence, Biocompatibility, and ONOO- Detection for Biomedical Applications

Silicon quantum dots (SiQDs) have garnered attention from scientists due to their low cytotoxicity and water solubility. However, the current SiQDs have limited use in biomedical applications due to their short emission wavelengths and low quantum yield (QY). To address this issue, a novel SiQDs, called SiQDs-(K/P)ox, which was inspired by chiral melanin-like ((K/P)ox), was prepared. The effect of chiral phenylalanine (Phe) on fluorescence properties was explored in the synthesis of (K/L-D-P)ox and SiQDs-(K/L-D-P)ox.

Compared to previous SiQDs, SiQDs-(K/L-D-P)ox have a wider emission interval (380 nm – 700 nm) with a maximum emission wavelength of 490 nm. 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 have higher biocompatibility and can be colocalized in the mitochondria of HepG2 cells with a Pearson coefficient of (0.99).

Furthermore, the fluorescence (K/L-P)ox, which is synthesized by tripeptide, can be oxidized by ONOO-, and SiQDs-(K/L-P)ox is also sensitive to the detection of ONOO- by 'fluorescence off', exhibiting higher fluorescence intensity and anti-interference than (K/L-P)ox. Therefore, SiQDs-(K/L-P)ox provides an important means for detecting inflammation and liver cancer in cells.

In conclusion, SiQDs-(K/L-P)ox is a promising material for biomedical applications due to its improved fluorescence properties, biocompatibility, and sensitivity to the detection of ONOO-. Its ability to detect inflammation and liver cancer in cells makes it a valuable tool in biomedical research.