Dual Molecular Recognition Leading to a Protein-Polymer Conjugate and Further Self-Assembly

Hydrogel-to-Nanoparticle Transition with Immune Cell Activation Controlled by Dual Supramolecular Interactions

Biomolecules may undergo dynamic transitions between different aggregation states in order to adapt to the microenvironment. As a result, appropriate biofunctions can be performed only under certain states. This feature inspires exploration for constructing and regulating environmentally adaptive materials through supramolecular ways. Herein, we propose a strategy to employ a special pair of supramolecular interactions, a very strong binding between fluorescent proteins and their nanobodies together with a rather weak and dynamic binding of α-cyclodextrin and poly(ethylene glycol), to construct protein-containing polymeric hydrogel with a hydrogel-to-particle transition. The dynamic property of the originally homogeneous hydrogel was demonstrated by dilution under physiological conditions, when the complete dissociation of the hydrogel to nanoparticles was observed. This fascinating property was achieved via the very special coupling of strong protein-nanobody binding and dynamic polypseudorotaxane, which supported the hydrogel-to-particle transition and stability of the resultant particles. Such hydrogel-to-particle transition was found to efficiently promote migration of immune cells and activate them to secrete proinflammatory cytokines, indicating a bright future in immunotherapy.

One-Pot Fabrication of Supramolecular Synthetic Protein Hydrogel with Tissue-like Integrated Dynamic Features

Protein-incorporated soft networks have received remarkable attention during the past several years. They possess desirable properties similar to native tissues and organs and exhibit unique advantages in applications. However, fabrication of protein-based hydrogels usually suffers from complex protein mutation and modification or chemical synthesis, which limited the scale and yield of production. Meanwhile, the lack of rationally designed noncovalent interactions in networks may result in a deficiency of the dynamic features of materials. Therefore, a highly efficient method is needed to include supramolecular interactions into protein hydrogel to generate a highly dynamic hydrogel possessing integrated tissue-like properties. Here, we report the design and construction of native protein-based supramolecular synthetic protein hydrogels through a simple and efficient one-pot polymerization of acrylamide and ligand monomers in the presence of a ligand-binding protein. The supramolecular interactions in the network yield integrated dynamic properties, including remarkable stretchability over 10,000% of their original length, ultrafast self-healing abilities within 3-4 s, tissue-like fast stress relaxation, satisfactory ability of adhesion to different living and nonliving substrates, injectability, and high biocompatibility. Furthermore, this material demonstrated potential as a biosensor to monitor small finger movements. This strategy provides a new avenue for fabricating synthetic protein hydrogels with integrated features.

A brief insight to the role of glyconanotechnology in modern day diagnostics and therapeutics

Carbohydrate-protein and carbohydrate-carbohydrate interactions are very important for various biological processes. Although the magnitude of these interactions is low compared to that of protein-protein interaction, the magnitude can be boosted by multivalent approach known as glycocluster effect. Nanoparticle platform is one of the best ways to present diverse glycoforms in multivalent manner and thus, the field of glyconanotechnology has emerged as an important field of research considering their potential applications in diagnostics and therapeutics. Considerable advances in the field have been achieved through development of novel techniques, use of diverse metallic and non-metallic cores for better efficacy and application of ever-increasing number of carbohydrate ligands for site-specific interaction. The present review encompasses the recent developments in the area of glyconanotechnology and their future promise as diagnostic and therapeutic tools.

Preparation, characterization and biological evaluation of β-cyclodextrin-biotin conjugate based podophyllotoxin complex

Podophyllotoxin is a natural occurring aryltetralin lignin with pronounced cytotoxic activity. However, its clinical application for cancer treatment has been blocked due to its poor water solubility and selectivity. In this work, biotin as a tumor specific ligand was coupled with β-cyclodextrin and the resulting biotin modified β-cyclodextrin was used to complex with podophyllotoxin to improve its aqueous solubility and tumor selectivity. The solubility of β-cyclodextrin was greatly enhanced(>16 times) by conjugating with biotin. podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin inclusion complex was prepared by freeze-drying method and the complex behavior between mono-6-biotin-amino-6-deoxy-β-cyclodextrin and podophyllotoxin was studied by water solubility, phase solubility, Job's plot, UV spectroscopy, Proton Nuclear Magnetic Resonance, Rotating-frame Overhauser Effect Spectroscopy, Powder X-ray diffraction and Scanning electron microscopy. The solubility of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was greatly improved(9 times) compared with Podophyllotoxin. The stability constant of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex (K_s= 415.29 M^-1) was 3.2 times that of podophyllotoxin/β-cyclodextrin complex. The possible inclusion mode of podophyllotoxin/mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was inferred from the Proton Nuclear Magnetic Resonance and Rotating-frame Overhauser Effect Spectroscopy. The cellular uptake study showed that the introduction of biotin increased the cellular uptake of rhodamine-B/mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex. Moreover, cell cytotoxicity study showed that the antitumor activity of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was more potent than podophyllotoxin/β-cyclodextrin complex and free podophyllotoxin. The superior water solubility and enhanced cytotoxicity suggested that the mono-6-biotin-amino-6-deoxy-β-cyclodextrin associated inclusion complex might be a potential and promising delivery system for hydrophobic chemotherapeutics such as podophyllotoxin.

Cyclodextrin-Based Functional Glyconanomaterials

Cyclodextrins (CDs) have long occupied a prominent position in most pharmaceutical laboratories as "off-the-shelve" tools to manipulate the pharmacokinetics of a broad range of active principles, due to their unique combination of biocompatibility and inclusion abilities. The development of precision chemical methods for their selective functionalization, in combination with "click" multiconjugation procedures, have further leveraged the nanoscaffold nature of these oligosaccharides, creating a direct link between the glyco and the nano worlds. CDs have greatly contributed to understand and exploit the interactions between multivalent glycodisplays and carbohydrate-binding proteins (lectins) and to improve the drug-loading and functional properties of nanomaterials through host-guest strategies. The whole range of capabilities can be enabled through self-assembly, template-assisted assembly or covalent connection of CD/glycan building blocks. This review discusses the advancements made in this field during the last decade and the amazing variety of functional glyconanomaterials empowered by the versatility of the CD component.

Exploring and Controlling the Polymorphism in Supramolecular Assemblies of Carbohydrates and Proteins

In biology, polymorphism is a well-known phenomenon by which a discrete biomacromolecule can adopt multiple specific conformations in response to its environment. This term can be extended to the ability of biomacromolecules to pack into different ordered patterns. Thus, exploration and control of the polymorphism of biomacromolecules via supramolecular methods have been key steps in achieving bioinspired structures, developing bioinspired functional materials, and exploring the mechanisms of these self-assembly processes, which are models for more complex biological systems. This task could be difficult for proteins and carbohydrates due to the complicated multiple noncovalent interactions of these two species which can hardly be manipulated.In this account, dealing with the structural polymorphisms from biomacromolecular assemblies, we will first briefly comment on the problems that carbohydrate/protein assemblies are facing, and then on the basis of our long-term research on carbohydrate self-assemblies, we will summarize the new strategies that we have developed in our laboratory in recent years to explore and control the polymorphism of carbohydrate/protein assemblies.Considering the inherent ability of carbohydrates to recognize lectin, we proposed the "inducing ligand" strategy to assemble natural proteins into various nanostructures with highly ordered packing patterns. The newly developed inducing ligand approach opened a new window for protein assembly where dual noncovalent interactions (i.e., carbohydrate-protein interactions and dimerization of rhodamine) instead of the traditionally used protein-protein interactions direct the assembly pattern of proteins. As a result, various polymorphisms of protein assemblies have been constructed by simply changing the ligand chemical structure and/or the rhodamine dimerization.Another concept that we proposed for glycopolymer self-assembly is DISA (i.e., deprotection-induced glycopolymer self-assembly). It is well known that protection-deprotection chemistry has been employed to construct complex oligosaccharide structures. However, its application in glycopolymer self-assembly has been overlooked. We initiated this new strategy with diblock copolymers. Such copolymers with a carbohydrate block having protected pendent groups exist as single chains in organic media. The self-assembly can be initiated by the deprotection of the pendent groups. The process was nicely controlled by introducing various protective groups with different deprotection rates. Later on, the DISA process has been proven practical in water and even in the cellular environment, which opens a new avenue for the development of polymeric glycomaterials.Finally, the resultant polymeric glyco-materials, as a new type of biomimetic materials, provide a nice platform for investigating the functions of glycocalyx. The glycocalyx-mimicking nanoparticles achieved unprecedent functions which exceed their carbohydrate precursors. Here, the reversion of tumor-associated macrophages induced by glycocalyx-mimicking nanoparticles will be discussed with potential applications in cancer immunotherapy, where such a reversion effect could be combined with other methods (e.g., tumor checkpoint blockade).

A super-stretchable, self-healing and injectable supramolecular hydrogel constructed by a host–guest crosslinker

Supramolecular hydrogels based on host–guest interactions have drawn considerable attention due to their unique properties and promising applications.

Construction of supramolecular hydrogels using imidazolidinyl urea as hydrogen bonding reinforced factor

A new hydrogen bonding reinforced factor was introduced into polymer design for the preparation of supramolecular hydrogels with advanced properties.

Pillar[5]arene-based, dual pH and enzyme responsive supramolecular vesicles for targeted antibiotic delivery against intracellular MRSA

A rationally designed mannosylated amphiphilic pillar[5]arene (Man@AP5) self-assembles into supramolecular vesicles with encapsulated vancomycin (Man@AP5-Van), enhancing vancomycin's antibacterial efficacy against intracellular MRSA.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

Morphology-Variable Aggregates Prepared from Cholesterol-Containing Amphiphilic Glycopolymers: Their Protein Recognition/Adsorption and Drug Delivery Applications

In this study, a series of diblock glycopolymers, poly(6-O-methacryloyl-d-galactopyranose)-b-poly(6-cholesteryloxyhexyl methacrylate) (PMAgala-b-PMAChols), with cholesterol/galactose grafts were prepared through a sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and deprotection process. The glycopolymers could self-assemble into aggregates with various morphologies depending on cholesterol/galactose-containing block weight ratios, as determined by transmission electronic microscopy (TEM) and dynamic laser light scattering (DLS). In addition, the lectin (Ricinus communis agglutinin II, RCA120) recognition and bovine serum albumin (BSA) adsorption of the PMAgala-b-PMAChol aggregates were evaluated. The SK-Hep-1 tumor cell inhibition properties of the PMAgala-b-PMAChol/doxorubicin (DOX) complex aggregates were further examined in vitro. Results indicate that the PMAgala-b-PMAChol aggregates with various morphologies showed different interaction/recognition features with RCA120 and BSA. Spherical aggregates (d ≈ 92 nm) possessed the highest RCA120 recognition ability and lowest BSA protein adsorption. In addition, the DOX-loaded spherical complex aggregates exhibited a better tumor cell inhibition property than those of nanofibrous complex aggregates. The morphology-variable aggregates derived from the amphiphilic glycopolymers may serve as multifunctional biomaterials with biomolecular recognition and drug delivery features.

Promoting neural differentiation of embryonic stem cells using β-cyclodextrin sulfonate

Promoting neural differentiation of embryonic stem cells using inclusion complexes formed between β-cyclodextrin sulfonate and all-trans retinoic acid.

Mechanically resilient, injectable, and bioadhesive supramolecular gelatin hydrogels crosslinked by weak host-guest interactions assist cell infiltration and in situ tissue regeneration

Although considered promising materials for assisting organ regeneration, few hydrogels meet the stringent requirements of clinical translation on the preparation, application, mechanical property, bioadhesion, and biocompatibility of the hydrogels. Herein, we describe a facile supramolecular approach for preparing gelatin hydrogels with a wide array of desirable properties. Briefly, we first prepare a supramolecular gelatin macromer via the efficient host-guest complexation between the aromatic residues of gelatin and free diffusing photo-crosslinkable acrylated β-cyclodextrin (β-CD) monomers. The subsequent crosslinking of the macromers produces highly resilient supramolecular gelatin hydrogels that are solely crosslinked by the weak host-guest interactions between the gelatinous aromatic residues and β-cyclodextrin (β-CD). The obtained hydrogels are capable of sustaining excessive compressive and tensile strain, and they are capable of quick self healing after mechanical disruption. These hydrogels can be injected in the gelation state through surgical needles and re-molded to the targeted geometries while protecting the encapsulated cells. Moreover, the weak host-guest crosslinking likely facilitate the infiltration and migration of cells into the hydrogels. The excess β-CDs in the hydrogels enable the hydrogel-tissue adhesion and enhance the loading and sustained delivery of hydrophobic drugs. The cell and animal studies show that such hydrogels support cell recruitment, differentiation, and bone regeneration, making them promising carrier biomaterials of therapeutic cells and drugs via minimally invasive procedures.

Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation

The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazene bases. In addition, the commercially relevant double-metal cyanide (DMC) catalyst systems are discussed. Besides the synthetic progress, new types of multifunctional linear PEG (mf-PEG) and PPO structures accessible by copolymerization of EO or PO with functional epoxide comonomers are presented as well as complex branched, hyperbranched, and dendrimer like polyethers. Amphiphilic block copolymers based on PEO and PPO (Poloxamers and Pluronics) and advances in the area of PEGylation as the most important bioconjugation strategy are also summarized. With the ever growing toolbox for epoxide polymerization, a "polyether universe" may be envisaged that in its structural diversity parallels the immense variety of structural options available for polymers based on vinyl monomers with a purely carbon-based backbone.

Regulation of Protein Binding Capability of Surfaces via Host-Guest Interactions: Effects of Localized and Average Ligand Density

The protein binding capability of biomaterial surfaces can significantly affect subsequent biological responses, and appropriate ligand presentation is often required to guarantee the best functions. Herein, a new facile method for regulating this capability by varying the localized and average ligand density is presented. Binding between lysine and plasminogen relevant to a fibrinolysis system was chosen as a model. We integrated different lysine-modified β-cyclodextrin (β-CD) derivatives onto bioinert copolymer brushes via host-guest interactions. The localized and average lysine density can be conveniently modulated by changing the lysine valency on β-CD scaffolds and by diluting lysine-persubstituted β-CD with pure β-CD, respectively. Both the plasminogen adsorption and the plasminogen binding affinity were enhanced by lysine-persubstituted β-CD compared with those of lysine-monosubstituted β-CD, which is possibly due to the higher localized lysine density and the multivalent binding of plasminogen on lysine-persubstituted β-CD surfaces. With a change in the ratio of lysine-persubstituted β-CD to β-CD, the average lysine density can be tuned, leading to the linear regulation of the adsorption of plasminogen on surfaces.

Multistimuli Responsive and Electroactive Supramolecular Gels Based on Ionic Liquid Gemini Guest

Electroactive supramolecular gels with multistimuli responsiveness were fabricated through host-guest interactions between a host polymer containing β-cyclodextrin (CD) and an ionic liquid (IL) type asymmetric gemini guest, which contains both ferrocene (Fc) and bis(trifluoromethyl-sulfonyl)imide (TFSI^-) as the respective α- and ω-guest groups. Owing to the multiple stimuli-responsiveness of the host-guest interactions, reversible sol-gel phase transition could be triggered by various stimuli, including temperature, electrochemical/chemical redox and anion-exchange reactions. Due to the intrinsically conductive properties of the IL gemini guest, the sol-gel transition behavior could be electrochemically controlled by the applied voltage, without using additional supporting electrolyte.

Progressive macromolecular self-assembly: from biomimetic chemistry to bio-inspired materials

Macromolecular self-assembly (MSA) has been an active and fruitful research field since the 1980s, especially in this new century, which is promoted by the remarkable developments in controlled radical polymerization in polymer chemistry, etc. and driven by the demands in bio-related investigations and applications. In this review, we try to summarize the trends and recent progress in MSA in relation to biomimetic chemistry and bio-inspired materials. Our paper covers representative achievements in the fabrication of artificial building blocks for life, cell-inspired biomimetic materials, and macromolecular assemblies mimicking the functions of natural materials and their applications. It is true that the current status of the deliberately designed and obtained nano-objects based on MSA including a variety of micelles, multicompartment vesicles, and some hybrid and complex nano-objects is at their very first stage to mimic nature, but significant and encouraging progress has been made in achieving a certain similarity in morphologies or properties to that of natural ones. Such achievements also demonstrate that MSA has played an important and irreplaceable role in the grand and long-standing research of biomimetic and bio-inspired materials, the future success of which depends on mutual and persistent efforts in polymer science, material science, supramolecular chemistry, and biology.

Structure and enzymatic properties of molecular dendronized polymer-enzyme conjugates and their entrapment inside giant vesicles

Macromolecular hybrid structures were prepared in which two types of enzymes, horseradish peroxidase (HRP) and bovine erythrocytes Cu,Zn-superoxide dismutase (SOD), were linked to a fluorescently labeled, polycationic, dendronized polymer (denpol). Two homologous denpols of first and second generation were used and compared, and the activities of HRP and SOD of the conjugates were measured in aqueous solution separately and in combination. In the latter case the efficiency of the two enzymes in catalyzing a two-step cascade reaction was evaluated. Both enzymes in the two types of conjugates were highly active and comparable to free enzymes, although the efficiency of the enzymes bound to the second-generation denpol was significantly lower (up to a factor of 2) than the efficiency of HRP and SOD linked to the first-generation denpol. Both conjugates were analyzed by atomic force microscopy (AFM), confirming the expected increase in object size compared to free denpols and demonstrating the presence of enzyme molecules localized along the denpol chains. Finally, giant phospholipid vesicles with diameters of up to about 20 μm containing in their aqueous interior pool a first-generation denpol-HRP conjugate were prepared. The HRP of the entrapped conjugate was shown to remain active toward externally added, membrane-permeable substrates, an important prerequisite for the development of vesicular multienzyme reaction systems.