title: In situ forming reduction-sensitive degradable nanogels for facile loading and triggered intracellular release of proteins.
abstract: In situ forming reduction-sensitive degradable nanogels were designed and developed based on poly(ethylene glycol)-b-poly(2-(hydroxyethyl) methacrylate-co-acryloyl carbonate) (PEG-P(HEMA-co-AC)) block copolymers for efficient loading as well as triggered intracellular release of proteins. PEG-P(HEMA-co-AC) copolymers were prepared with controlled Mn of 9.1, 9.5, and 9.9 kg/mol and varying numbers of AC units per molecule of 7, 9 and 11, respectively (denoted as copolymer 1, 2, and 3) by reversible addition-fragmentation chain transfer copolymerization. These copolymers were freely soluble in phosphate buffer but formed disulfide-cross-linked nanogels with defined sizes ranging from 72.5 to 124.1 nm in the presence of cystamine via ring-opening reaction with cyclic carbonate groups. The sizes of nanogels decreased with increasing AC units as a result of increased cross-linking density. Dynamic light scattering studies showed that these nanogels though stable at physiological conditions were rapidly dissociated in response to 10 mM dithiothreitol (DTT). Interestingly, FITC-labeled cytochrome C (FITC-CC) could be readily loaded into nanogels with remarkable loading efficiencies (up to 98.2%) and loading contents (up to 48.2 wt.%). The in vitro release studies showed that release of FITC-CC was minimal under physiological conditions but significantly enhanced under reductive conditions in the presence of 10 mM DTT with about 96.8% of FITC-CC released in 22 h from nanogel 1. In contrast, protein release from 1,4-butanediamine cross-linked nanogels (reduction-insensitive control) remained low under otherwise the same conditions. MTT assays showed that these nanogels were nontoxic to HeLa cells up to a tested concentration of 2 mg/mL. Confocal microscopy results showed that nanogel 1 delivered and released FITC-CC into the perinuclei region of HeLa cells following 8 h incubation. CC-loaded reductively degradable nanogels demonstrated apparently better apoptotic activity than free CC as well as reduction-insensitive controls. These in situ forming, surfactant and oil-free, and reduction-sensitive degradable nanogels are highly promising for targeted protein therapy.
authors.affiliation: Biomedical Polymers Laboratory, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Meng
authors.initials: M
authors.lastname: Zheng
authors.forename: Fenghua
authors.initials: F
authors.lastname: Meng
authors.forename: Ru
authors.initials: R
authors.lastname: Cheng
authors.forename: Chao
authors.initials: C
authors.lastname: Deng
authors.forename: Jan
authors.initials: J
authors.lastname: Feijen
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Zhong
mesh_terms: D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D004229:Dithiothreitol / Q000737:chemistry*; D004337:Drug Carriers / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D058990:Molecular Targeted Therapy / Q000379:methods*; D000080385:Nanogels; D010084:Oxidation-Reduction; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry*; D011094:Polyethyleneimine / Q000138:chemical synthesis* / Q000737:chemistry*; D058105:Polymerization; D011108:Polymers / Q000737:chemistry; D011700:Putrescine / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D008689:Methacrylates; D000080385:Nanogels; D011108:Polymers; C413692:polyethylene glycol polyethyleneimine nanogel; D011092:Polyethylene Glycols; C005044:hydroxyethyl methacrylate; D011094:Polyethyleneimine; D045304:Cytochromes c; D004229:Dithiothreitol; D011700:Putrescine