Amphiphilic scorpion-like macromolecules (AScMs), that self-assemble as nanocarriers, were evaluated for intracellular delivery. To qualitatively examine the intracellular fate of AScMs in human umbilical vein endothelial cells (HUVECs), representative polymers (M12P5) were labeled with a fluorescent dye, fluorescein isothiocyanate (FITC). The FITC-labeled M12P5 micelles were prepared by mixing a low concentration of FITC-labeled M12P5 polymer (10wt%) with unlabeled M12P5 polymer (90wt%). Optical sectioning by confocal laser scanning microscopy of HUVECs incubated with FITC-labeled polymer micelles revealed that the polymers were localized in subcellular components within 60 min. Transmission electron microscopy was used to highlight the rapid accumulation of a polymer-encapsulated agent in the nucleus by 60 min. This study demonstrated that the M12P5 polymers were internalized into HUVECs. Based on these data, the polymeric nanocarriers are potential candidates for intracytoplasmic and nuclear delivery of drugs, proteins and/or genes.

Amphiphilic macromolecules (AMs) have unique branched hydrophobic domains attached to linear PEG chains. AMs self-assemble in aqueous solution to form micelles that are hydrolytically stable in physiological conditions (37 degrees C, pH 7.4) over 4 weeks. Evidence of AM biodegradability was demonstrated by complete AM degradation after 6 d in the presence of lipase. Doxorubicin (DOX) was chemically conjugated to AMs via a hydrazone linker to form DOX-AM conjugates that self-assembled into micelles in aqueous solution. The conjugates were compared with DOX-loaded AM micelles (i.e., physically loaded DOX) on DOX content, micellar sizes and in vitro cytotoxicity. Physically encapsulated DOX loading was higher (12 wt.-%) than chemically bound DOX (6 wt.-%), and micellar sizes of DOX-loaded AMs (approximately 16 nm) were smaller than DOX-AMs (approximately 30 nm). In vitro DOX release from DOX-AM conjugates was faster at pH 5.0 (100%) compared to pH 7.4 (78%) after 48 h, 37 degrees C. Compared to free DOX and physically encapsulated DOX, chemically bound DOX had significantly higher cytotoxicity at 10(-7) M DOX dose against human hepatocellular carcinoma cells after 72 h. Overall, DOX-AM micelles showed promising characteristics as stable, biodegradable DOX nanocarriers.

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