Energy-Transfer Phenomena in Thermoresponsive and pH- Switchable Fluorescent Diblock Copolymer Vesicles

Authors:
Open Access
Publisher website
Google Scholar
Abstract
We describe the development of a polymeric vesicle that not only selectively fluoresce at low pH, a condition prevailing in cancer cells, but also can potentially monitor thermoresponsive release of a drug even if the drug is non-fluorescent. The developed fluorescence resonance energy transfer (FRET)-based thermoresponsive vesicular nanocarriers comprised of a new poly(PEGMA)-b-poly(NIPA-r-R6GMED) block copolymer, which undergoes pH switchable superior turn ‘on-off’ fluorescence characteristics. The block copolymer was synthesized using RAFT technique, and its solution properties and self-assembly behavior were investigated by turbidity measurement, fluorescence spectroscopy, 1H NMR, dynamic light scattering and transmission electron microscopy. The block copolymer self-assembled to form nanostructured vesicles above critical aggregation temperature in physiologically relevant condition. Steady-state and time-resolved fluorescence spectroscopy were utilized to study FRET process between encapsulated hydrophobic guest C-153 (donor) and polymer-bound R6GMED units (acceptor) in the thermo-responsive vesicles. FRET rate and efficiency was found to vary due to pH-dependent changes in quantum yield of the acceptor molecules. The occurrence of a highly efficient FRET in this polymeric vesicular nanocarrier in acidic pH, a condition similar to cytoplasm and cell nucleus in leukemic tissues, as well as the ability to encapsulate hydrophilic and hydrophobic molecules and their temperature controlled release make it potentially useful as imaging guided real-time monitoring drug delivery vehicles.
Funding Information
  • University Grants Commission
  • Anusandhan National Research Foundation (EMR/2016/007040)

This publication has 46 references indexed in Scilit: