New core-shell hyperbranched chitosan-based nanoparticles as optical sensor for ammonia detection.

In this paper, preparation of new core-shell amino-terminated hyperbranched chitosan nanoparticles (HBCs-NH2) NPs is described. The synthesized nanoparticles were characterized using ninhydrin assay, FTIR, TGA, and FESEM. The newly prepared (HBCs-NH2) NPs were then used as a platform for facile and controlled synthesis of silver nanoparticles (AgNPs) which was confirmed using FTIR, UV-vis spectrometry, X-ray diffraction, SEM and HRTEM. Formation of the AgNPs was also noted upon changing the color of (HBCs-NH2) NPs suspension from colorless into yellow as well as through the appearance of surface plasmon resonance (SPR) peak at 400 nm. HRTEM showed a uniform and spherical morphology of the resulting HBCs-NH2 NPs with average size 400 nm, and the AgNPs were formed mainly on their surface with average size of 20-50 nm. The newly developed (HBCs-NH2) NPs-AgNPs showed a great potential as optical sensor for efficient detection of the ammonia concentration in solutions based on the change in the SPR.