Light-responsive polymeric micelles have emerged as site-specific and time-controlled systems for advanced drug delivery. Spiropyran (SP), a well-known photochromic molecule, was used to initiate the ring-opening multibranching polymerization of glycidol to afford a series of hyperbranched polyglycerols (SP-hb-PG). The micelle assembly and disassembly were induced by an external light source owing to the reversible photoisomerization of hydrophobic SP to hydrophilic merocyanine (MC). Transmission electron microscopy, atomic force microscopy, UV/vis spectroscopy, and dynamic light scattering demonstrated the successful assembly and disassembly of SP-hb-PG micelles. In addition, the critical micelle concentration (CMC) was determined through the fluorescence analysis of pyrene to confirm the amphiphilicity of respective SP-hb-PGn (n = 15, 29, and 36) micelles, with CMC values ranging from 13 to 20 mg/L, which is correlated to the length of the polar polyglycerol backbone. Moreover, the superior biocompatibility of the prepared SP-hb-PG was evaluated using WI-38 cells and HeLa cells, suggesting the prospective applicability of the micelles in smart drug delivery systems.

An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation.

Poly(ethylene glycol) (PEG) has attracted significant interest because of its superior antifouling properties, water solubility, and biocompatibility. However, the translation of its antifouling properties onto target surfaces has been challenging because of its limited functionality. Herein, the superior antifouling properties of PEG-based block copolyethers functionalized with catechol, a mussel-inspired, versatile moiety for coating surfaces, were evaluated within a framework of polyethers exclusively. A series of catechol-functionalized polyethers with diverse molecular weights and catechol contents were synthesized via anionic ringopening polymerization in a controlled manner. The versatile adsorption and antifouling effects of block copolyethers were evaluated using a quartz crystal microbalance with dissipation. Furthermore, the crucial role of the topology (loop vs brush) in the antifouling properties was analyzed via a surface force apparatus and direct atomistic molecular dynamics simulations. This study demonstrates that the catechol-functionalized triblock copolymer shows excellent antifouling properties, exhibiting its great potential in various biomedical applications.

Marine mussels use catechol-rich interfacial mussel foot proteins (mfps) as primers that attach to mineral surfaces via hydrogen, metal coordination, electrostatic, ionic, or hydrophobic bonds, creating a secondary surface that promotes bonding to the bulk mfps. Inspired by this biological adhesive primer, it is shown that a ≈1 nm thick catecholic single-molecule priming layer increases the adhesion strength of crosslinked polymethacrylate resin on mineral surfaces by up to an order of magnitude when compared with conventional primers such as noncatecholic silane- and phosphate-based grafts. Molecular dynamics simulations confirm that catechol groups anchor to a variety of mineral surfaces and shed light on the binding mode of each molecule. Here, a ≈50% toughness enhancement is achieved in a stiff load-bearing polymer network, demonstrating the utility of mussel-inspired bonding for processing a wide range of polymeric interfaces, including structural, load-bearing materials.

Polymers that are biocompatible and degrade in response to stimuli are highly desirable as smart drug-delivery carriers. We report the first novel redox-degradable hyperbranched polyglycerols. A glycerol monomer containing a disulfide bond, i.e., 2-((2-(oxiran-2-ylmethoxy)ethyl)disulfanyl)ethan-1-ol (SSG), was designed and polymerized through anionic ring-opening multibranching polymerization to yield a series of redox-degradable hyperbranched polyglycerols (PSSGs) with controlled molecular weights (2000− 11 000 g/mol) and relatively low molecular weight distributions (M w /M n < 1.15). In addition, copolymerization with a nondegradable glycerol (G) monomer provided P(G-co-SSG) copolymers, which contained an adjustable fraction of degradable moieties within their polyglycerol backbones. The polymerization was characterized using 1 H and 13 C NMR spectroscopy, GPC, and MALDI-ToF mass spectrometry. The copolymerization process was also evaluated using quantitative in situ 13 C NMR kinetic measurements in bulk, which revealed that the reaction kinetics of G were faster than those of the SSG monomer, leading to a gradient during the copolymerization process. Furthermore, we explored the redox-responsive degradation of the polymers upon treatment with a reducing agent, which resulted in selective degradation of the polymers in small segments. In vitro cytotoxicity studies, such as MTT and CCK-8 assays, revealed the superior biocompatibility of these new polymers even at high concentrations of 500 μg/ mL. We anticipate that these novel redox-degradable and highly biocompatible polyglycerols will find applications in a variety of emerging biomedical fields.