Amphiphilic Scorpion-like Macromolecules (AScMs) and Amphiphilic Star-like Macromolecules (ASMs) are amphiphilic polymeric materials designed for drug delivery applications by the Uhrich group at Rutgers. AScMs are comprised of a hydrophobic part with alkyl chains pendant to a central linear sugar moiety and a poly(ethylene glycol) tail. The AScMs aggregate to form micelles at very low concentrations below 1 ÁM. ASMs are synthesized by coupling 3, 4 or more AScMs arms to a central core in a star arrangement. These molecules encapsulate hydrophobic drug molecules in their cores via their amphiphilic nature without the necessity of aggregation to form micelles. Local solvation and microviscosity of solvatochromic probe molecules are investigated by ultrafast time-resolved fluorescence spectroscopy. By selecting probe chromophores with different hydrophobicity, different regions of the AScM and ASM are characterized, in analogy to our recent work on probing A-B-A triblock copolymers (Grant, et al., Langmuir 2005, 21(5), 1745). By measuring and comparing emission spectra, excited-state lifetimes, and rotational anisotropies for three coumarins in ASM and AScM micellar solutions, polymer solvation dynamics and microviscosities relevant to drug delivery can be better understood.
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