Transformation of crystalline starch nanoparticles into highly luminescent carbon nanodots: Toxicity studies and their applications.

Being abundant in many tropical part of the world, Dioscorea sp. as food is limited due to its toxicity. However polysaccharides derive from these tubers could be important for other applications. Here we developed a Highly Luminescent Carbon Nanodots (C-dots) via acid hydrolysis of Gadong starch (GS). The hydrolysis rate of GS increased from 49% to 86% within 7 days while the X-ray diffraction showed the native GS particle is a C-crystalline type. The GS particles were either round or oval with diameters ranging from 50-90 nm. Further acid dehydration and surface oxidation reduced the size of GS nanoparticles to 6-25 nm. The C-dots produced a fluorescent emission at wavelength 441 nm. Toxicity tests demonstrate that zebrafish embryo were able to tolerate the C-dots for 48 h after exposure. This study has successfully demonstrated a novel approach of converting GS into excellent fluorescent C-dot.

4,4'-({[(Pyridine-2,6-di-yl)bis-(methyl-ene)]bis-(-oxy)}bis-(methyl-ene))dibenzo-nitrile.

The complete title molecule, C23H19N3O2, is generated by a twofold axis passing through the central ring. The two oxymethyl-benzo-nitrile arms are attached at the meta positions of the central pyridine ring. The dihedral angle between the pyridine ring and benzene ring of both arms is 84.55 (6)° while the benzene rings make a dihedral angle of 46.07 (7)°. In the crystal, weak C-H⋯π inter-actions link the molecules sheets parallel to the ac plane.