Ultra-pH-sensitive polypeptide micelles with large fluorescence off/on ratio in near infrared range. Issue 6 (9th January 2017)

• Record Type: Journal Article
• Authors: Fu, Liyi; Yuan, Pan; Ruan, Zheng; Liu, Le; Li, Tuanwei; Yan, Lifeng
• Is Part Of: Polymer chemistry. Volume 8:Issue 6(2017)
• Page Start: 1028
• Page End: 1038
• Publication Date: 2017-01-09
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/c6py01818a
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : Ionizable tertiary amines functional polypeptide based micelles conjugated with NIR dye Cy5.5 and quencher have been synthesized, and a strong fluorescence switch-on in the NIR region under weak acidic conditions can be found, which is ultra-pH-sensitive. Abstract : An amphiphilic copolymer of poly(oligo(ethylene glycol) methacrylate) (POEGMA) and poly(benzyl-l -aspartic acid) (PBLA) has been prepared by means of reversible addition–fragmentation chain transfer (RAFT) polymerization, ring-opening polymerization, and click reaction. After the PBLA segment was aminolyzed by the primary amine, N, N -diisopropylethylenediamine (DIEDA) and N, N -dibutylethylenediamine (DBEDA) with different ratios, amphiphilic block copolymers with various ionizable tertiary amines have been prepared, which can form stable micelles in neutral pH by self-assembly and disassembly under weak acidic conditions. After conjugation of Cy5.5/quencher to the copolymer, the as-formed micelles exhibit low fluorescence due to the Fluorescence Resonance Energy Transfer (FRET) between Cy5.5 and the quencher. However, an ultra-pH-sensitive fluorescence can be switched-on when it was in weak acidic conditions. The as-prepared nanoparticles have potential application in highly sensitive detection of the pH of tissues and cells, and can also work as a theranostic for cancer with drug delivery and imaging ability.