Synthesis and characterization of a nano fluorescent starch

A novel nano fluorescent starch, starch-bearing 3-epoxypropoxy fluorescein (ST-EF) was developed by a simple method. First, 3-epoxypropoxy fluorescein (EF) was prepared via a nucleophilic substitution reaction between fluorescein and epichlorohydrin. Then, ST-EF was synthesized via a ring-opening reaction to attach fluorescein to native cassava starch chains. The degree of substitution (DS) of ST-EF was determined by ultraviolet-visible spectrophotometry. The 1H nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, fourier transformed infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), dynamic laser scattering (DLS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to characterize ST-EF. Fluorescent properties of ST-EF in water were studied. The results showed that the nano fluorescent starch shows strong fluorescence as fluorescein, and can be used as a fluorescent polymer in various applications, especially in biomedicine.