A branched polymer as a pH responsive nanocarrier: Synthesis, characterization and targeted delivery

•We have synthesized a pH responsive four armed branched block copolymer.•The biodegradable micelle carries the DOX molecule.•The branched structure supports a very high loading (∼25%) of DOX.•The micelle shows cancer cell specific pH responsive DOX delivery.•Micelles selectively enter into the cancer cell.

A series of branched and folic acid (FA) conjugated amphiphilic block copolymers were synthesized by sequential steps of ring opening and atom transfer radical polymerizations. The chemical structure of the FA conjugated block copolymer was established by spectroscopic method. The FA conjugated copolymers give rise to nearly spherical polymeric micelles (PMs) in water (40-60 nm). The polymers are showing low range of CMC (0.63 × 10−2 to 2.01 × 10−2 mg/mL) with a negative zeta potential (−44.4 mV). The branched structure supports a very high loading (∼25%) of DOX molecules compare to the literature reported nanocarriers prepared from analogous linear block copolymers. The cell viability and cell uptake study of PMs were conducted on both normal and cancerous cell lines. The pH sensitive decrease of miceller size affords sparkling in vitro release of DOX molecule (67-88%) at physiological pH (5.0) of the cancer cells.

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