Preparation of fluorescent nanoparticles based on broken-rice starch for live-cell imaging

Native broken-rice starch was used to create starch nanoparticles (StNPs) with particle sizes ranging from 100 nm to 800 nm. The fluorescent isothiocyanate poly-l-lysine StNPs (FITC-PLL-StNPs) were created in two steps. First, the StNPs were electrostatically modified by poly-l-lysine (PLL) molecules rich in Amino acids. Second, fluorescein isothiocyanate reacted with some amino groups on PLL molecules (FITC). Fluorescence spectrophotometry was used to determine the degree of substitution (DS) and fluorescent properties of fluorescent starches. The study found that FITC-PLL-StNP-200 has higher fluorescence stability, more phagocytic cells, and a better and clearer fluorescence detecting effect than FITC-PLL-St, FITC-PLL-StNP-100, FITC-PLL-StNP-400, and FITC-PLL-StNP-800. The biological evaluation results showed that FITC-PLL-StNP-200 did not affect the viability of HeLa cells at the lysosome labeling concentration. These findings suggest that FITC-PLL-StNP-200 has strong and stable fluorescence, indicating that FITC-PLL-StNP-200 can be used as a fluorescent probe and lysosome marker in a variety of applications, particularly in biomedicine.