@article {49311, title = {Photo and pH dual stimuli-responsive block copolymer micelles with defined incorporation of o-nitrobenzyl units in poly(ε-caprolactone) ε-caprolactone) block for controlled release}, journal = {European Polymer Journal}, volume = {220}, year = {2024}, month = {NOV}, pages = {113501}, type = {Article}, abstract = {

A series of dual stimuli-responsive block copolymers with varying content of photocleavable o-nitrobenzyl (ONB) ester group pendent in the hydrophobic poly(epsilon-caprolactone) block and pH-cleavable acetal linkage at the junction with hydrophilic poly(ethylene glycol) block is synthesized. The hydrophobic block is a random copolymer synthesized by ring-opening copolymerization of epsilon-caprolactone and ONB-substituted epsilon-caprolactone containing varying compositions of the two monomers. Kinetics of polymerization shows that ONBfunctionalized monomer has lower reactivity than that of the unsubstituted monomer. The series of block copolymers shows self-assembly into well-defined spherical micelles of average size of 150-200 nm in aqueous solution. Photocleavage of ONB groups is studied by NMR and UV-vis spectroscopy, and its extent is determined. The two stimuli viz. . UV light and pH are used individually as well as simultaneously to study the controlled release of the encapsulated drug Camptothecin and the synergistic effect of the two stimuli is demonstrated. The effect of varying content of ONB groups is observed on drug release profile. MTT assay showed non-cytotoxic nature of the polymer. Cell uptake and photoinduced release of doxorubicin (DOX) from the micelles in MDAMB-231 cells is demonstrated.

}, keywords = {drug delivery, micelles, O-nitrobenzyl, pH-responsive, Photoresponsive, Poly(epsilon-caprolactone)}, issn = {0014-3057}, doi = {10.1016/j.eurpolymj.2024.113501}, author = {Avhad, V. Shankarrao and Choudhari, Shakeb N. and Ambade, V. Ashootosh} } @article {49026, title = {Visible light and pH-responsive star copolymer and doxorubicin-polymer conjugate micelles for combination drug delivery and bioimaging}, journal = {Journal of macromolecular science part A- pure and applied chemistry}, volume = {61}, year = {2024}, month = {FEB }, pages = {105-116}, type = {Article}, abstract = {

Amphiphilic 3-arm star copolymer containing visible light-cleavable BODIPY group and pH-responsive imine bonds at the junction of hydrophilic poly(ethylene glycol) (PEG) and two poly(epsilon-caprolactone) (PCL) arms was synthesized by the combination of ring-opening polymerization (ROP) and click chemistry. The formation and stimuli-responsive disruption of micelles were analyzed using dynamic light scattering and transmission electron microscopy. Dual stimuli-responsive release of anticancer drugs Doxorubicin (Dox) and Camptothecin (CPT) from the micelles was studied. Micellar assemblies containing Dox conjugated to PEG-BODIPY through imine bonds were prepared and controlled release of Dox in response to visible light and pH was shown. CPT and Dox-loaded star copolymer micelles as well as CPT loaded Dox-conjugated micelles were used in cellular uptake studies on MDA-MB 231 cells, and the synergistic effect of the two stimuli on the release of the two drugs was demonstrated inside the cells. Micellar assemblies also showed excellent bioimaging properties in the cellular uptake studies. [GRAPHICS]

}, keywords = {BODIPY, drug conjugate, micelles, pH-responsive, visible light-responsive}, issn = {1060-1325}, doi = {10.1080/10601325.2024.2302857}, author = {Basutkar, Nitin B. and Surapaneni, Sai Geetika and Alam, Md. Shafi and Ambade, Ashootosh V.} } @article {49794, title = {Redox- and pH-responsive block copolymer nanocarriers with dual drug conjugation through dynamic covalent and hydrogen bonds}, journal = {Journal of Applied Polymer Science}, volume = {143}, year = {2026}, month = {MAR}, pages = {e70205}, type = {Article}, abstract = {

Loading of multiple drugs in a nanocarrier with high entrapment efficiency is important for combination therapy in cancer treatment. Here, a block copolymer comprising hydrophobic poly(epsilon-caprolactone) block with a defined number of pendent propargyl groups, polyethylene glycol monomethyl ether as a hydrophilic block, and a redox-responsive disulfide group at the block junction is synthesized using click chemistry and ring-opening polymerization (ROP). Benzaldehyde and thymine groups are introduced in the side chains for selective attachment of anti-cancer drugs, doxorubicin (DOX) and methotrexate (MTX), via the formation of pH-responsive imine linkage and hydrogen bonds, respectively. The drug-conjugated block copolymers are assembled into spherical micelles of \< 200 nm, and the preferential release of DOX and MTX in response to acidic pH and redox conditions is shown. At pH 5, DOX release was 59.5\%, and MTX release was 40\% compared to 13\% and 12\% at pH 7.4, whereas at pH 5 with 10 mM GSH, a DOX release of 81.5\% was observed after 48 h. Cellular uptake of drug-conjugated micelles and their apoptosis compared to free DOX in the MDA-MB-231 breast cancer cells is demonstrated. Caveolae-mediated endocytosis was found to be the major pathway used by drug-loaded nanocarriers.

}, keywords = {biodegradable, copolymers, DOX-conjugate, drug delivery systems, methotrexate, micelles, pH-responsive, redox-responsive}, issn = {0021-8995}, doi = {10.1002/app.70205}, author = {Avhad, Shankarrao V. and Surapaneni, Sai Geetika and Purohit, Poorvi M. and Ambade, Ashootosh V.} }