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Poly(L-histidine)-PEG block copolymer micelles and pH-induced destabilization
Eun Seong Lee1, Hyun Joon Shin, Kun Na
1Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 421 Wakara Way, Suite 315, Salt Lake City, UT 84108, USA.
Summary
pH-sensitive polymeric micelles were created using poly(L-histidine)-poly(ethylene glycol) diblock copolymers. These micelles destabilize at lower pH, showing potential for targeted drug delivery in acidic tumor environments.
Area of Science:
- Biomaterials Science
- Polymer Chemistry
- Nanotechnology
Background:
- Polymeric micelles offer potential for targeted drug delivery.
- pH-responsive materials are crucial for exploiting tumor microenvironment acidity.
Purpose of the Study:
- To synthesize and characterize pH-sensitive polymeric micelles using poly(L-histidine)-poly(ethylene glycol) diblock copolymers.
- To evaluate the pH-dependent stability and critical micelle concentration (CMC) of these micelles.
Main Methods:
- Synthesis of poly(L-histidine)-poly(ethylene glycol) diblock copolymers.
- Formation of polymeric micelles via diafiltration.
- Characterization using dynamic light scattering, atomic force microscopy, and fluorescence spectroscopy.
Main Results:
- Spherical micelles (approx. 114 nm) were formed with a unimodal distribution.
- The critical micelle concentration (CMC) was pH-dependent, increasing significantly below pH 7.2.
- Micelles demonstrated gradual destabilization below pH 7.4, indicated by changes in transmittance, size, and fluorescence.
Conclusions:
- The pH-dependent ionization of the polyhistidine core dictates micelle stability and CMC.
- These pH-sensitive micelles show promise for solid tumor treatment due to the acidic tumor extracellular pH.