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. Author manuscript; available in PMC: 2014 Oct 23.
Published in final edited form as: ACS Appl Mater Interfaces. 2013 Oct 8;5(20):10.1021/am401981g. doi: 10.1021/am401981g

Scheme 2. Schematic of ultrathin coating assembly.

Scheme 2

For electrostatic assembly, MDT functionalized PAMAM (2) is deposited directly onto the islet surface via electrostatic interactions. For covalent assembly, N3-PEG-NHS is first covalently bound to free amines on the islet surface (1), followed by covalent linkage of MDT functionalized PAMAM (2). Subsequently, hyperbranched alginate azide is covalently linked to the exposed MDT functionalized PAMAM coating (3). Interlayer covalent bonds are formed between complementary azide and MDT groups via Staudinger ligation (inset reaction scheme). Additional layers can be built via step-wise incubation of MDT functionalized PAMAM (2) and hyperbranched alginate azide (3), until desired number of layers is achieved.