Liposomes are frequently used as carriers of drugs and imaging agents. Although several successful targeting strategies are reported, the liposomes suffer from a lack of stability and slow release of the encapsulated contents at the targeted site. Polymersomes are bilayer structures formed from amphiphilic polymers in aqueous media. These vesicles are considerably more stable compared to liposomes; however, they also demonstrate a slow release for the encapsulated contents, limiting their efficacy as a drug-delivery tool. As a potential solution, we have successfully prepared echogenic, redox-sensitive, targeted polymersomes. Ultrasound-scattering and imaging experiments confirmed the echogenicity of the vesicles. These polymersomes showed excellent release profiles when incubated with cytosolic concentrations of reducing agents, releasing more than 80% of the contents within 20 minutes. However, in serum levels of reducing agents, minimal release was observed. When a folate lipid was incorporated in the bilayer, the polymersomes showed an enhanced uptake with folate-receptor overexpressing breast- and pancreatic-cancer cells. A combination of the two anticancer drugs, gemcitabine and doxorubicin, was successfully encapsulated in the polymersomes. These targeted, dual-drug encapsulating polymersomes significantly decreased the viability of breast- and pancreatic-cancer cells in the monolayer as well as in spheroid cultures. Our results are expected to encourage further research about the use of ultrasound-reflective polymersomes as multimodal drug carriers with targeting and triggered release properties  .

Stimuli-responsive polymersomes for cytosolic drug delivery to cancer cells

248th National Meeting (2014)

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