Receptor Mediated Glycotargeting

Amino-OPE glycosides and blue light: a powerful synergy in photodynamic therapy

Herein we report the synthesis and biological properties of sugar-conjugated oligophenylene ethynylene (OPE) dyes, used as novel photosensitizers (PSs) for photodynamic treatment (PDT) under blue light. The OPE-bearing glycosides at both ends are successfully prepared by a Pd-catalyzed Sonogashira cross-coupling reaction. The live-cell imaging studies have shown that these OPE glycosides (including glucose, mannose and maltose derivatives) efficiently penetrate the cytoplasm of cultured HeLa cancer cells. No dark toxicity was observed, but upon irradiating the cells under blue light an extraordinary photodynamic effect was observed at low concentrations (10^-6-10^-8 M). The localization studies indicate that OPE-glucose 1 and OPE-mannose 2 have Golgi patterns, whereas OPE-maltose 3 could be in lysosomes. The PDT and morphological studies in HeLa cells treated with sublethal doses of PS 1-3 revealed that cell death occurs by necrosis.

Mannan-coated gelatin nanoparticles for sustained and targeted delivery of didanosine: in vitro and in vivo evaluation

Macrophages of the reticuloendothelial system and brain act as major reservoir for HIV because of their long term survival after HIV infection and ability to spread virus particles to bystander CD4 positive lymphocyte cells. The objective of the present study was to investigate mannan-coated nanoparticles for macrophage targeting of didanosine. Different didanosine loaded nanoparticles were prepared using the double desolvation technique and were characterized in vitro, ex vivo and in vivo. Results of the ex vivo cellular uptake study indicated 5-fold higher uptake of didanosine from the mannan-coated nanoparticles formulation (62.5 +/- 5.4%) by the macrophages in comparison with didanosine solution in phosphate buffer saline (PBS, pH 7.4) (12.1 +/- 2.3%). The better cellular uptake from the nanoparticles formulation was further confirmed by fluorescence microscopy using hydrophilic 6-carboxyfluorescein as a marker. Results of the quantitative biodistribution study showed 1.7, 12.6 and 12.4 times higher localization of didanosine in the spleen, lymph nodes and brain, respectively, after administration of mannan-coated nanoparticles compared to that after injection of didanosine solution in PBS (pH 7.4). Results of the present study showed that the mannan-coated nanoparticles targeted didanosine to the macrophage by mannosyl receptor mediated endocytosis.

Glycotargeting to improve cellular delivery efficiency of nucleic acids

Nucleic acids bearing glycans of various structures have been under vigorous investigation in the past decade. The carbohydrate moieties of such complexes can serve as recognition sites for carbohydrate-binding proteins-lectins-and initiate receptor-mediated endocytosis. Therefore, carbohydrates can enhance cell targeting and internalization of nucleic acids that are associated with them and thus improve the bioavailability of nucleic acids as therapeutic agents. This review summarizes nucleic acid glycosylation in nature and approaches for the preparation of both non-covalently associated and covalently-linked carbohydrate-nucleic acid complexes.