Synthesis and characterization of GNR-FND nanohybrids. (a) Covalent conjugation of PLA with carboxylated FNDs through carboxyl-to-amine crosslinking by carbodiimide chemistry for physical adsorption of bare GNRs. (b) TEM image of PLA-coated FNDs decorated with 10-nm × 41-nm GNRs. (c) Comparison between the absorption spectra of 10-nm × 41-nm GNRs and the emission spectrum of 100-nm FNDs in water. Two vertical black bars indicate the sites of laser excitation at 532 and 808 nm.