Multivalent binding is a key for many critical biological processes and unique recognition and specificity in binding enables many of different glycans and proteins to work in a great harmony within the human body. In this study, the binding kinetics of synthetic glycopolypeptides to the dendritic cell lectin DC‐SIGN and their inhibition potential for DC‐SIGN interactions with the gp120 envelope glycoprotein of HIV‐1 (gp120) are investigated.
Molecular bottle‐brush functionalized single‐walled carbon nanotubes (SWCNTs) with superior dispersibility in water are prepared by a one‐pot synthetic methodology. Elongating the main‐chain and side‐chain length of molecular bottle‐brushes can further increase SWCNT dispersibility. They show significant enhancement of SWCNT dispersibility up to four times higher than those of linear molecular functionalized SWCNTs.
Stratified polymer brushes are fabricated using microcontact printing (μCP) of initiator integrated polydopamine (PDOPBr) on polymer brush surfaces and the following surface initiated atom transfer radical polymerization (SI‐ATRP). It is found that the surface energy, chemically active groups, and the antifouling ability of the polymer brushes affect transfer efficiency and adhesive stability of the polydopamine film. The stickiness of the PDOPBr pattern on polymer brush surfaces is stable enough to perform continuous μCP and SI‐ATRP to prepare stratified polymer brushes with a 3D topography, which have broad applications in cell and protein patterning, biosensors, and hybrid surfaces.
A free‐standing polymer brush film with tailored thicknesses based on a colorless polydopamine (PDA) thin layer is prepared and characterized. The surface‐initiated atom transfer radical polymerization (ATRP) of 2‐hydroxyethyl methacrylate (HEMA) is performed on a PDA layer with thickness of ca. 6 nm, which generated an optically transparent and colorless free‐standing PHEMA brush film (1.5 cm × 1.5 cm). Because the cross‐linked PDA layer is used as the base for the polymer brushes, the reported method does not require cross‐linking the polymer brushes. The free‐standing film thicknesses of ≈16–75 nm are controlled by simply changing the ATRP reaction time. The results show that the free‐standing PHEMA brush film transferred onto a plate exhibits a relatively smooth surface and is stable in any solvent.
The functionalization of zinc oxide (ZnO) nanoparticles by poly(3‐hexylthiophene) (P3HT) brush is completed by the combination of a mussel inspired biomimetic anchoring group and Huisgen cyclo‐addition “click chemistry.” Herein, the direct coupling of an azide modified catechol derivative with an alkyne end‐functionalized P3HT is described. This macromolecular binding agent is used to access core@corona ZnO@P3HT with a stable and homogeneous conjugated organic corona. Preliminary photoluminescence measurement proves an efficient electron transfer from the donor P3HT to the acceptor ZnO nanoparticles upon grafting, thus demonstrating the potential of such a combination in organic electronics.
Thin, phenylboronic acid‐containing polymer coatings are potentially attractive sensory layers for a range of glucose monitoring systems. This contribution presents the synthesis and properties of glucose‐sensitive polymer brushes obtained via surface RAFT polymerization of 3‐methacrylamido phenylboronic acid (MAPBA). This synthetic strategy is attractive since it allows the controlled growth of PMAPBA brushes with film thicknesses of up to 20 nm via direct polymerization of MAPBA without the need for additional post‐polymerization modification or deprotection steps. QCM‐D sensor chips modified with a PMAPBA layer respond with a linear change in the shift of the fundamental resonance frequency over a range of physiologically relevant glucose concentrations and are insensitive toward the presence of fructose, thus validating the potential of these polymer brush films as glucose sensory thin coatings.
Thermoresponsive polymer brushes are grafted on micro/nanostructured polymer substrates as new intelligent interfaces that synergistically enhance wettability changes in response to external temperature stimuli. Thermoplastic poly(styrene‐co‐4‐vinylbenzyl chloride) [P(St‐co‐VBC)] is synthesized using radical polymerization and spin‐coated on a glass substrate. Micro/nanopillar and hole patterns are imprinted on the P(St‐co‐VBC) layer using thermal nanoimprint lithography. Poly(N‐isopropylacrylamide) (PIPAAm) brushes are grafted on the micro/nanostructured P(St‐co‐VBC) layer through surface‐initiated atom‐transfer radical polymerization using 4‐vinylbenzyl chloride as the initiator. The imprinted micro/nanostructures and grafted PIPAAm brush chain lengths affect the surface wettability. Combinations of nanopillars or nanoholes (diameter 500 nm) and longer PIPAAm brushes enhance hydrophobic/hydrophilic changes in response to temperature changes, compared with the flat substrate. The thermoresponsive hydrophobic/hydrophilic transition is synergistically enhanced by the nanostructured surface changing from Cassie–Baxter to Wenzel states. This PIPAAm‐brush‐modified micro/nanostructured P(St‐co‐VBC) is a new intelligent interface that effectively changes wettability in response to external temperature changes.
Three different series of brush polymers bearing glucosyl, maltosyl, or maltotriosyl moiety at the bristle end are successfully prepared by using cationic ring‐opening polymerization and two sequential postmodification reactions. All brush polymers, except for the polymer containing 100 mol% maltotriosyl moiety, demonstrate the formation of multibilayer structure in films, always providing saccharide‐enriched surface. These self‐assembling features are remarkable, regarding the bulkiness of saccharide moieties and the kink in the bristle due to the triazole linker. The saccharide‐enriched film surfaces reveal exceptionally high specific binding affinity to concanavalin A but suppress nonspecific binding of plasma proteins severely. Overall, the brush polymers bearing saccharide moieties of various kinds in this study are highly suitable materials for biomedical applications including biosensors.
The synthesis of poly(ionic liquid) (PIL) nanoparticles grafted with a poly(N‐isopropyl acrylamide) (PNIPAM) brush shell is reported, which shows responsiveness to temperature and ionic strength in an aqueous solution. The PIL nanoparticles are first prepared via aqueous dispersion polymerization of a vinyl imidazolium‐based ionic liquid monomer, which is purposely designed to bear a distal atom transfer radical polymerization (ATRP) initiating group attached to the long alkyl chain via esterification reaction. The size of the PIL nanoparticles can be readily tuned from 25 to 120 nm by polymerization at different monomer concentrations. PNIPAM brushes are successfully grafted from the surface of the poly(ionic liquid) nanoparticles via ATRP. The stimuli‐responsive behavior of the poly(ionic liquid) nanoparticles grafted with PNIPAM brushes (NP‐g‐PNIPAM) in aqueous phase is studied in detail. Enhanced colloidal stability of the NP‐g‐PNIPAM brush particles at high ionic strength compared to pure PIL nanoparticles at room temperature is achieved. Above the lower critical solution temperature (LCST) of PNIPAM, the brush particles remain stable, but a decrease in hydrodynamic radius due to the collapse of the PNIPAM brush onto the PIL nanoparticle surface is observed.
Simulated‐sunlight induced atom transfer radical polymerization is used for spatial control over polymer brush growth by in situ photo‐generation of the CuI/L activator complex from its higher oxidation state CuII/L deactivator complex using dye sensitized titanium dioxide nanoparticles. The polymerization is well controlled under sunlight irradiation. Another attractive feature of this method is the possibility of creating various patterned surfaces of brushes using photomasks. When a nanoporous alumina oxide membrane is used as the template for confinement diffusion of photogenerated CuI/L catalyst, patterns with sub‐50 nm resolution are obtained.
A heterotritopic copillar[5]arene monomer by introducing effective neutral guest moieties (methylene chains end‐capped with cyano and triazole groups) to a pillar[5]arene macrocycle is prepared. This well‐designed AB2‐type copillar[5]arene contains strong host–guest recognition motifs that are connected with relatively flexible and long linkers, thus efficiently assembles to form supramolecular hyperbranched polymer (SHP) in chloroform solution, which is characterized by various techniques including 1H NMR, DOSY, viscosity, DLS, and TEM. Particularly, this supramolecular polymer can be effectively depolymerized by adding a competitive butanedinitrile guest.
Poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA)‐based brush poly(phosphoamidate)s are successfully synthesized by a combination of ring‐opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP) following either a commutative two‐step procedure or a straightforward one‐pot process using Grubbs ruthenium‐based catalysts for tandem catalysis. Compared with the traditional polymerization method, combining ROMP and ATRP in a one‐pot process allows the preparation of brush copolymers characterized by a relatively moderate molecular weight distribution and quantitative conversion of monomer. Moreover, the surface morphologies and aggregation behaviors of these polymers are studied by AFM and TEM measurements.
A new multivalent glycopolymer platform for lectin recognition is introduced in this work by combining the controlled growth of glycopolymer brushes with highly specific glycosylation reactions. Glycopolymer brushes, synthetic polymers with pendant saccharides, are prepared by surface‐initiated atom transfer radical polymerization (SI‐ATRP) of 2‐O‐(N‐acetyl‐β‐d ‐glucosamine)ethyl methacrylate (GlcNAcEMA). Here, the fabrication of multivalent glycopolymers consisting of poly(GlcNAcEMA) is reported with additional biocatalytic elongation of the glycans directly on the silicon substrate by specific glycosylation using recombinant glycosyltransferases. The bioactivity of the surface‐grafted glycans is investigated by fluorescence‐linked lectin assay. Due to the multivalency of glycan ligands, the glycopolymer brushes show very selective, specific, and strong interactions with lectins. The multiarrays of the glycopolymer brushes have a large potential as a screening device to define optimal‐binding environments of specific lectins or as new simplified diagnostic tools for the detection of cancer‐related lectins in blood serum.
The different mechanisms contributing to adhesion between two polymer surfaces are summarized and described in individual examples, which represent either seminal works in the field of adhesion science or novel approaches to achieve polymer–polymer adhesion. A further objective of this article is the development of new methodologies to achieve strong adhesion between low surface energy polymers.
A simple strategy is provided to construct a novel pH‐ and sugar‐induced shape memory hydrogel based on dynamic phenylboronic acid (PBA)–diol interactions formed by PBA‐modified sodium alginate (Alg‐PBA) and poly(vinyl alcohol) (PVA). The dynamic PBA–diol ester bonds serve as temporary cross‐links and stabilize the deformed shape of the hydrogel. The disassociation of the PBA–diol ester bonds is explored in acidic conditions and aqueous solutions of glucose and fructose, which endow the hydrogel with shape memory performances.
Imitating the natural “energy cascade” architecture, we present a single‐molecular rod‐like nano‐light harvester (NLH) based on a cylindrical polymer brush. Block copolymer side chains carrying (9,9‐diethylfluoren‐2‐yl)methyl methacrylate units as light absorbing antennae (energy donors) are tethered to a linear polymer backbone containing 9‐anthracenemethyl methacrylate units as emitting groups (energy acceptors). These NLHs exhibit very efficient energy absorption and transfer. Moreover, we manipulate the energy transfer by tuning the donor–acceptor distance.
A novel one‐component type II polymeric photoinitiator, poly(vinyl alcohol)–thioxanthone (PVA–TX), is synthesized by a simple acetalization process and characterized. PVA–TX enables photopolymerization of methyl methacrylate and acrylamide in both organic and aqueous media. Photopolymerization proceeds even in the absence of a co‐initiator since PVA–TX possesses both chromophoric and hydrogen donating sites in the structure.
A facile and versatile approach to constructing colorless surface coatings based on green tea polyphenols is reported, which can further act as a photoinitiating layer to initiate radical polymerization. These colorless green tea polyphenol coatings are capable of successfully photografting polymer brushes, and the resulting polymer brush patterns show spatial shape adjustability by masked UV irradiation. Both surface modifications and photografted polymer brushes do not alter the original color of the substrates. This method could be promising for the development of surface modifications.
Thioxanthone (TX) and its derivatives, which are widely used as photoinitiators in UV curing technology, hold promising research interest in biological applications. In particular, the use of TXs as anticancer agent has recently been manifested as an outstanding additional property of this class of molecules. Incorporation of TX molecules into specially designed polymers widens their practical use in such applications. In this study, two water‐soluble, biocompatible, and stable polymers, namely poly(vinyl alcohol) and poly(ethylene glycol), possessing TX moieties at the side chains and chain ends, respectively, are prepared and used as anticancer and radiotherapy agents. The findings confirm that both polymers are potential candidates for therapeutic agents as they possess useful features including water‐solubility, radiosensitizer effect, and anticancer activity in a polymeric scaffold.
Electrohydrodynamic cojetting has been employed to synthesize compartmentalized microfibers from thermally responsive hydrogels. The synthesis of the hydrogels as well as their transformation into compartmentalized microcylinders is discussed. After programmable shape‐shifting, snail‐like particles are obtained that undergo functional and structural reconfiguration in response to a change in temperature.
