Mannosylated fluorescent cellulose-based glycopolymers for stable uniform nanoparticles

In living organisms, carbohydrate-protein interactions play key roles in physiological and pathological processes, which are amplified by the “glycol-cluster effect.” In this work, we synthesized novel fluorescent cellulose derivatives bearing mannose moieties via thiol-ene click reactions by sequentially conjugating hydrophilic mannose-oxyethoxylpropane-thiol (Mann-SH) and fluorescent coumarin-oxyhexyl-thiol (Coum-SH) and rhodamine B-ethyl-thiol (RhB-SH) to cellulose undecenoate with terminal double bonds. The amphiphilic fluorescent cellulose derivatives were converted into nanoparticles (NPs) by dropping into low ionic strength solutions (<0.085 M). Obtained NPs have average sizes between 240 and 554 nm depending on the solution concentrations, exhibiting uniform size distributions (PDI values <0.12). These uniform NPs exhibited excellent dispersion stability even at elevated temperatures. The mannose moieties were accessible to 1,4-benzenediboronic acid (BDBA) in NaOH aqueous solutions. Under irradiation with UV light of 320–400 nm, the fluorescence of NPs increased by the formation of open-ring rhodamine spiroamide, which could be a promising candidate for biomedical application.