As a novel class of dynamic and non-covalent polymers, supramolecular polymers not only display specific structural and physicochemical properties, but also have the ability to undergo reversible changes of structure, shape, and function in response to diverse external stimuli, making them promising candidates for widespread applications ranging from academic research to industrial fields. By an elegant combination of dynamic/reversible structures with exceptional functions, functional supramolecular polymers are attracting increasing attention in various fields. In particular, functional supramolecular polymers offer several unique advantages, including inherent degradable polymer backbones, smart responsiveness to various biological stimuli, and the ease for the incorporation of multiple biofunctionalities (e.g., targeting and bioactivity), thereby showing great potential for a wide range of applications in the biomedical field. In this Review, the trends and representative achievements in the design and synthesis of supramolecular polymers with specific functions are summarized, as well as their wide-ranging biomedical applications such as drug delivery, gene transfection, protein delivery, bio­imaging and diagnosis, tissue engineering, and biomimetic chemistry. These achievements further inspire persistent efforts in an emerging interdisciplin­ary research area of supramolecular chemistry, polymer science, material science, biomedical engineering, and nanotechnology.

Overabundance of hydrogen peroxide originating from environmental stress and/or genetic mutation can lead to pathological conditions. Thus, the highly sensitive detection of H₂O₂ is important. Herein, supramolecular fluorescent nanoparticles self-assembled from fluorescein isothiocyanate modified β-cyclodextrin (FITC-β-CD)/rhodamine B modified ferrocene (Fc-RB) amphiphile were prepared through host–guest interaction between FITC-β-CD host and Fc-RB guest for H₂O₂ detection in cancer cells. The self-assembled nanoparticles based on a combination of multiple non-covalent interactions in aqueous medium showed high sensitivity to H₂O₂ while maintaining stability under physiological condition. Owing to the fluorescence resonance energy transfer (FRET) effect, addition of H₂O₂ led to obvious fluorescence change of nanoparticles from red (RB) to green (FITC) in fluorescent experiments. In vitro study showed the fluorescent nanoparticles could be efficiently internalized by cancer cells and then disrupted by endogenous H₂O₂, accompanying with FRET from “on” to “off”. These supramolecular fluorescent nanoparticles constructed via multiple non-covalent interactions are expected to have potential applications in diagnosis and imaging of diseases caused by oxidative stresses.

Stimuli-responsive hyperbranched polymers have attracted great attention in recent years because of their wide applications in biomedicine. Through proton-transfer polymerization of triethanolamine and 1,2,7,8-diepoxyoctane with the help of potassium hydride, a series of novel backbone thermo and pH dual-responsive hyperbranched poly(amine-ether)s were prepared successfully in one-pot. The degrees of branching of the resulting polymers were at 0.40–0.49. Turbidity measurements revealed that hyperbranched poly(amine-ether)s exhibited thermo and pH dual-responsive properties in water. Importantly, these responsivities could be readily adjusted by changing the polymer composition as well as the polymer concentration in aqueous solution. Moreover, in vitro evaluation demonstrated that hyperbranched poly(amine-ether)s showed low cytotoxicity and efficient cell internalization against NIH 3T3 cell lines. These results suggest that these backbone thermo and pH dual-responsive hyperbranched poly(amine-ether)s are promising materials for biomedicine. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Hyperbranched polymers (HBPs), invented at the end of 1980s, are one important subclass of the fourth generation macromolecular architectures following the linear, branched, and crosslinking polymers. Due to their unique topological structure and interesting physical/chemical properties, HBPs have attracted wide attention from both academia and industry. HBPs are composed of linear units, dendritic units, and terminal units. The degree of branching (DB), a term to describe the composition of these three structure units and thus the branching architecture of polymers, is one of the most important intrinsic parameters for HBPs. This review has summarized the effect of the DB on the physical and chemical properties of HBPs, including the rheological property, crystallization and melting behaviors, glass transition, thermal and hydrolytic degradations, phase characteristics, lower critical solution temperature phase transition, optoelectronic properties, encapsulation capability, self-assembly behavior, biomedical applications, and so on. Such a structure and property relationship will build a bridge between the syntheses and applications of HBPs, especially in the application areas of functional materials, biomedical materials, and nanotechnology. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1277–1286, 2011

Hyperbranched polymers (HBPs) are highly branched macromolecules with a three-dimensional dendritic architecture. Due to their unique topological structure and interesting physical/chemical properties, HBPs have attracted wide attention from both academia and industry. In this paper, the recent developments in HBP self-assembly and their biomedical applications have been comprehensively reviewed. Many delicate supramolecular structures from zero-dimension (0D) to three-dimension (3D), such as micelles, fibers, tubes, vesicles, membranes, large compound vesicles and physical gels, have been prepared through the solution or interfacial self-assembly of amphiphilic HBPs. In addition, these supramolecular structures have shown promising applications in the biomedical areas including drug delivery, protein purification/detection/delivery, gene transfection, antibacterial/antifouling materials and cytomimetic chemistry. Such developments promote the interdiscipline researches among surpramolecular chemistry, biomedical chemistry, nano­technology and functional materials.

A self-assembly approach to tuning the optical properties of a star copolymer is reported herein. The star copolymer HCP-star-PEG with a hyperbranched conjugated polymer (HCP) core and many linear poly(ethylene glycol) (PEG) arms has been prepared successfully. The HCP core was synthesized by Wittig coupling of N-(n-hexyl)-3,6-diformylcarbazole and 1,3,5-bis[(triphenylphosphonio)methyl]benzene tribromide. Subsequently, the linear PEG arms were grafted onto the HCP core by acylhydrazone connection. It was found that the optical properties of HCP-star-PEG in chloroform solution changed on addition of acid. Both ¹H NMR and UV/Vis spectroscopic investigations confirmed that the variation of the optical properties was related to the complexation of the acid and the imine bond in the acylhydrazone group. HCP-star-PEG self-assembled into core–shell micelles in the mixed solvent of chloroform and acetonitrile, which affected the protonation of the imine bond. Therefore the optical properties of HCP-star-PEG can be readily controlled by self-assembly.

Hybrid polymerization of glycidyl methacrylate (GMA) with potassium hydride (KH) and various oligo(ethylene glycol)s as the initiating system, in which both vinyl polymerization and ring-opening polymerization occur simultaneously, generates hyperbranched poly(ether-ester)s. The reaction process has been followed by an in situ nuclear magnetic resonance technique. The experimental results indicate that both the vinyl and epoxy groups of GMA undergo polymerization, with the reactivity of the latter being much higher than that of the former. Interestingly, the resulting hyperbranched polymers exhibit a sharp phase transition in water at the lower critical solution temperature (LCST). Significantly, the LCST values can be accurately controlled from 0 to 100 °C by changing the hydrophilic/hydrophobic balance of GMA and various oligo(ethylene glycol)s or by modification of the precursor polymer through acetylation. This novel stimuli-responsive hyperbranched polymer is a promising candidate for a new generation of commercially viable thermoresponsive polymers following on from the widely used poly(N-isopropylacrylamide) (PNIPAM).

Poly(ethylene glycol) (PEG) can form either the inclusion complex with α-cyclodextrins (α-CDs) through host–guest interactions or the interpolymer complex with poly(acrylic acid) (PAA) through hydrogen-bonding interaction. Mixing α-CD, PEG, and PAA ternary components in an aqueous solution, the competition between host–guest and hydrogen-bonding interactions occurs. Increasing feed ratio of α-CD:EG:AA from 0:1:1 to 0.2:1:1 (molar ratio), various interesting supramolecular polymer systems, such as hydrogen-bonding complex, dynamic polyrotaxane, crystalline inclusion complex, and thermoresponsive hydrogel, are successively obtained. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1114–1120, 2008