Chemotherapy is one of the major systemic treatments for cancer, in which the drug release kinetics is a key factor for drug delivery. In the present work, a versatile fluorescence-based real-time monitoring system for intracellular drug release has been developed. First, two kinds of star-conjugated copolymers with different connections (e.g., pH-responsive acylhydrazone and stable ether) between a hyperbranched conjugated polymer (HCP) core and many linear poly(ethylene glycol) (PEG) arms were synthesized. Owing to the amphiphilic three-dimensional architecture, the star-conjugated copolymers could self-assemble into multimicelle aggregates from unimolecular micelles with excellent emission performance in the aqueous medium. When doxorubicin (DOX) as a model drug was encapsulated into copolymer micelles, the emission of star-conjugated copolymer and DOX was quenched. In vitro biological studies revealed that fluorescent intensities of both star-conjugated copolymer and DOX were activated when the drug was released from copolymeric micelles, resulting in the enhanced cellular proliferation inhibition against cancer cells. Importantly, pH-responsive feature of the star-conjugated copolymer with acylhydrazone linkage exhibited accelerated DOX release at a mildly acidic environment, because of the fast breakage of acylhydrazone in endosome or lysosome of tumor cells. Such fluorescent star-conjugated copolymers may open up new perspectives to real-time study of drug release kinetics of polymeric drug delivery systems for cancer therapy.

To elucidate the effect of polymeric branched architecture on the protein resistant properties, the protein adsorption behaviour of polymers with different branched architectures on a gold surface was investigated. A series of poly((S-(4-vinyl) benzyl S′-propyltrithiocarbonate)-co-(poly(ethylene glycol) methacrylate))s (poly(VBPT-co-PEGMA)s) with different branched architecture were prepared by reversible addition-fragmentation chain transfer (RAFT) copolymerization, and then grafted onto a gold surface via thiols obtained from aminolysis reaction. With the increase of polymeric branched architecture, the thiol content of poly(VBPT-co-PEGMA)s increased, resulting in the formation of a highly uniform film with high stability and multifunctionality on the gold substrate. On the other hand, incubation of the poly(VBPT-co-PEGMA)-coated surface with bovine serum albumin (BSA) and immunoglobulin (IgG) showed that the protein resistant properties of the polymer-coated surface were enhanced with the decrease of branched architecture. After surface coating with branched poly(VBPT-co-PEGMA) onto a gold surface, the adhesion and proliferation of Hela cells were inhibited efficiently. By only adjusting the branched architecture of polymers on a substrate, the high protein resistance and multifunctionality can be integrated together, realizing the optimization of nonfouling properties of polymer-coated surface.

To elucidate the effect of polymeric branched architecture on the protein resistant properties, the protein adsorption behaviour of polymers with different branched architectures on a gold surface was investigated. A series of poly((S-(4-vinyl) benzyl S′-propyltrithiocarbonate)-co-(poly(ethylene glycol) methacrylate))s (poly(VBPT-co-PEGMA)s) with different branched architecture were prepared by reversible addition-fragmentation chain transfer (RAFT) copolymerization, and then grafted onto a gold surface via thiols obtained from aminolysis reaction. With the increase of polymeric branched architecture, the thiol content of poly(VBPT-co-PEGMA)s increased, resulting in the formation of a highly uniform film with high stability and multifunctionality on the gold substrate. On the other hand, incubation of the poly(VBPT-co-PEGMA)-coated surface with bovine serum albumin (BSA) and immunoglobulin (IgG) showed that the protein resistant properties of the polymer-coated surface were enhanced with the decrease of branched architecture. After surface coating with branched poly(VBPT-co-PEGMA) onto a gold surface, the adhesion and proliferation of Hela cells were inhibited efficiently. By only adjusting the branched architecture of polymers on a substrate, the high protein resistance and multifunctionality can be integrated together, realizing the optimization of nonfouling properties of polymer-coated surface.