Labelling of N-hydroxysuccinimide-modified rhodamine B on cellulose nanofibrils by the amidation reaction

Abstract

We have labelled cellulose nanofibrils with rhodamine B and characterized the grafting and the fluorescent properties by infrared and UV/visible spectroscopy together with fluorescence spectroscopy and confocal laser scanning microscopy. The cellulose nanofibrils were surface modified with amine groups using 4-(Boc-aminomethyl)phenyl isothiocyanate, that allows grafting of a wide number of commercially available molecules that e.g. contain carboxylic acid groups. The amine-modified cellulose nanofibrils were reacted with N-hydroxysuccinimide-modified rhodamine B ester through the amidation reaction. The labeling of the dye onto CNF results in a red-shift of the absorption and emission bands and despite some quenching of the fluorescence intensity of the surface-bound chromophore, it was possible to image the luminescent CNF at both low and high magnification using a confocal laser scanning microscope.