Encapsulation and cellular internalization of cyanine dye using amphiphilic dendronized polymers
S. Kumar, K. Achazi, C. Böttcher, K. Licha, R. Haag, and S. K. Sharma – 2015
An amphiphilic molecular transporter has been developed by immobilized Candida antarctica lipase catalyzed copolymerization of PEG diethyl ester and azidotriglycerol via its primary hydroxyl groups. The co-polymer was further grafted by the C12 alkyl chain and polyglycerol dendron moieties via the azide group of the polymer backbone by following ‘Click’ chemistry approach. The secondary hydroxyl groups on the backbone provide an additional site for acylation and fine-tune the physico-chemical properties. The aggregation behavior and transport potential of the resulting amphiphilic polymers were studied by surface tension (pendant drop method), DLS, cryo-TEM, UV and fluorescence measurements. The particle size of the micelles was found to have an average diameter of 8–12 nm. The encapsulation potential of these polymeric systems using cyanine 3, a highly fluorescent dye, used frequently for cellular imaging, has been studied. The transport capacity was observed to be in the range 7.58–19.15 mmol/mol of polymer. The cytotoxic study of the polymeric materials carried by using adenocarcinoma human alveolar basal epithelial cell lines (A549) and doxorubicin as a control drug revealed that a fine balance between hydrophilic (polyglycerol moiety) and the hydrophobic (alkyl chain) forces is critical to maintain minimal cytotoxicity. The cellular uptake of Cy3 encapsulated polymers were also studied by means of confocal laser scanning fluorescence microscopy (CFM) and fluorescence activated cell sorting (FACS) measurements. Among all the polymers, [G2.0] grafted dendronized polymer 5c exhibit prominent transport potential.