PH/redox/photo responsive polymeric micelle via boronate ester and disulfide bonds with spiropyran-based photochromic polymer for cell imaging and anticancer drug delivery

This paper reports the development of multi-functionalized stimuli responsive polymeric micelle as a carrier to transport a hydrophobic drug, Taxol, with photo-responsive fluorescence polymer as an imaging agent. The formed micelle is responsive to acidic and higher redox environments due to the pH-responsive boronate ester and DTT-responsive disulfide bonds for triggered drug release, respectively. The polymeric micelle [PC-SPMA] was constructed using facile cross-linked polymerization [Plu-Ch] between phenylboronic acid-conjugated Pluronic (Plu-SS-BA) and lactose-modified chitosan (chitlac, Ch), and the spiropyran/boronic acid-conjugated poly(dimethylamino ethyl methacrylate-co-methacrylic acid) (S-PMA) was conjugated into Plu-Ch, which was confirmed by ¹H NMR, UV-vis and fluorescence spectroscopy and the size of the polymeric micelles were measured by dynamic light scattering (DLS). Drug-loaded micelles showed an ability to release the drug in response to mildly acidic and higher-DTT conditions. The prepared micelles show strong fluorescence due to the merocyanine (MC) form of spiropyran, which displayed the successful entrance of the micelles by confocal laser scanning microscopy (CLSM). This facile strategy can be a useful platform to stimulate the detection and delivery of anticancer drugs in cancer cells through imaging, and as a carrier of hydrophobic drugs based on intracellular environment.