A surface plasmon resonance (SPR) expression after hybridization of chitosan–gold nanoparticle‐antibody ( CS ‐ AuNPs‐Ab ) based on: i) metal‐free click chemistry, and, ii) in water system as an approach for a rapid antigen sensing, is proposed. The chitosan‐hydroxybenzyl triazole complex enables us to carry out the conjugation of mPEG and trifluoromethylated oxanorbornadiene ( OND ) in water. CS‐mPEG‐OND further allows metal‐free click to hybridize chitosan ( CS ) with azido‐modified gold nanoparticles ( azido‐AuNPs ) in aqueous solution at room temperature. The CS‐mPEG‐OND conjugated with LipL32 antibody ( Ab ) not only effectively binds with LipL32 antigen ( Ag ) but also performs the cycloaddition with azido‐AuNPs to display a change in color within 2 min. The phenomenon leads to a simple and efficient naked‐eye antigen detection technique.
Redox‐responsive micelles with cores crosslinked via click chemistry are developed to improve the stability of polymer micelles. Amphiphilic block copolymer mPEG‐b‐P(DTC‐ADTC) with pendant azido groups on the hydrophobic chains is synthesized by the ring‐opening polymerization of 2,2‐bis(azidomethyl)trimethylene carbonate (ADTC) and 2,2‐dimethyltrimethylene carbonate (DTC) with monomethoxy poly(ethylene glycol) (mPEG) as an initiator. mPEG‐b‐P(DTC‐ADTC) self‐assemble to form the micelles in aqueous solution and the cores of the micelles are crosslinked via click chemistry to afford redox‐responsive core‐crosslinked micelles. Core‐crosslinking enhances the stability of the micelles in aqueous solution and improve the drug‐loading property. The redox‐responsive core‐crosslinked micelles can be reduced by the addition of reducing agents such as dithiothreitol (DTT), and thus release the loaded drug quickly in the presence of DTT.
Pillararene‐containing thermoresponsive polymers are synthesized via reversible addition–fragmentation chain transfer polymerization using pillararene derivatives as the effective chain transfer agents for the first time. These polymers can self‐assemble into micelles and form vesicles after guest molecules are added. Furthermore, such functional polymers can be further applied to prepare hybrid gold nanoparticles, which integrate the thermoresponsivity of polymers and molecular recognition of pillararenes.
A novel oral delivery system consisting of thermoresponsive zwitterionic poly(sulfobetaine methacrylate) (PSBMA) and pH‐responsive poly(2‐(diisopropylamino)ethyl methacrylate) (PDPA) is synthesized via free radical polymerization. This copolymer can self‐aggregate into nanoparticles via electrostatic attraction between ammonium cation and sulfo‐anion of PSBMA and successfully encapsulate anticancer drug, curcumin (CUR), with highest loading content of 2.6% in the P(SBMA‐co‐DPA) nanoparticles. The stimuli‐responsive phase transition behaviors of P(SBMA‐co‐DPA) copolymers at different pH buffer solution show pH‐dependent upper critical solution temperature (UCST) attributed to the influence of protonation/deprotonation of the pH‐responsive DPA segments. Through the delicate adjustment of the PSBMA/PDPA molar ratios, the stimuli‐responsive phase transition could be suitable for physiological environment. The kinetic drug release profiles demonstrate that P(SBMA‐co‐DPA) nanoparticles have the potential as oral delivery carriers due to their effective release of entrapped drugs in the stimulated intestinal fluid and preventing the deterioration of drug in stimulated gastric fluid.
Biodegradable and bioabsorbable poly(lactic acid)s are one of the most important biomedical materials. However, it is difficult to introduce the functional groups into poly(lactic acid)s in order to improve their hydrophilicity and degradation rate. Here the authors describe the synthesis of functionalized cyclic lactide monomer 3,6‐bis(benzyloxymethyl)‐1,4‐dioxane‐2,5‐dione (BnLA) using an advanced synthetic route. Water‐soluble hydroxyl‐functionalized homopoly(lactic acid) (P(OH)LA) is synthesized via ring‐opening polymerization (ROP) of BnLA, followed by a hydrogenolytic deprotection reaction. Amphiphilic diblock poly(lactic acid) (P(OH)LA‐PLA) is synthesized via ROP of DL‐lactide using PBnLA as an initiator, followed by a hydrogenolytic deprotection reaction. P(OH)LA‐PLA is able to form polymeric micelles with the diameter of sub‐100 nm.
A novel and robust route for the synthesis of a new amphiphilic brush copolymer, poly(glycidyl methacrylate)‐graft‐polyethylene glycol (PGMA‐g‐PEG), with high grafting densities of 97%–98% through a “grafting onto” method via carbon dioxide chemistry is reported. PGMA‐g‐PEG can self‐assemble and form stable spherical core–shell micelles in aqueous solution. Besides, the obtained PGMA‐g‐PEG polymer contains hydroxyurethane structures as the junction sites between the PGMA backbone and PEG side chain, which can be used for further modification.
A thermo‐controlled pesticide release system composed of poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) thin film grafted polydopamine (PDA) (PDMAEMA‐g‐PDA) microcapsules is reported. SiO2 microparticles are used as a template to prepare PDA‐coated SiO2 microparticles. The thermally‐responsive PDMAEMA thin films are grafted on PDA surfaces using a metal‐free surface‐initiated photopolymerization approach without adding any photoinitiator or photosensitizer under UV light irradiation. The subsequent acid etching yields PDMAEMA‐g‐PDA hollow microcapsules. PDMAEMA‐g‐PDA microcapsules exhibit well‐controlled release of avermectin (Av). The results show that the loading ability of PDMAEMA‐g‐PDA microcapsules of Av is up to 52.7% (w/w). The release kinetics of Av demonstrate that Av@PDMAEMA‐g‐PDA microcapsules exhibit temperature‐controlled release performance. This work is significant for controlled release systems. This simple design is expected to be used in various applications, such as in controlled drug release and agriculture‐related fields.
For most stimuli‐responsive polymer materials (SRPMs), such as polymer gels, micelles, and brushes, the responsive mechanism is based on the solubility or compatibility with liquid media. That basis always results in distorting or collapsing the material's appearance and relies on external liquids. Here, a novel kind of SRPMs is proposed. Unlike most SRPMs, liquid is stored within special domains rather than expelled, so it is deforming‐free and relying on no external liquid, which is referred to as self‐storage SRPMs (SS‐SRPMs). The facile and universal route to fabricate SS‐SRPMs allows for another novel family of SRPMs. Furthermore, it is validated that SS‐SRPMs can drastically respond to outside temperature like switchers, especially for optical and electrochemical responses. Those features hold prospects for applications in functional devices, such as smart optical lenses or anti‐self‐discharge electrolytes for energy devices.
The first polymer bearing exTTF units intended for the use in electrical charge storage is presented. The polymer undergoes a redox reaction involving two electrons at −0.20 V vs Fc/Fc+ and is applied as active cathode material in a Li‐organic battery. The received coin cells feature a theoretical capacity of 132 mAh g−1, a cell potential of 3.5 V, and a lifetime exceeding more than 250 cycles.
The combination of dendritic and linear polymeric structures in the same macromolecule opens up new possibilities for the design of block copolymers and for applications of functional polymers that have self‐assembly properties. There are three main strategies for the synthesis of linear‐dendritic block copolymers (LDBCs) and, in particular, the emergence of click chemistry has made the coupling of preformed blocks one of the most efficient ways of obtaining libraries of LDBCs. In these materials, the periphery of the dendron can be precisely functionalised to obtain functional LDBCs with self‐assembly properties of interest in different technological areas. The incorporation of stimuli‐responsive moieties gives rise to smart materials that are generally processed as self‐assemblies of amphiphilic LDBCs with a morphology that can be controlled by an external stimulus. Particular emphasis is placed on light‐responsive LDBCs. Furthermore, a brief review of the biomedical or materials science applications of LDBCs is presented.
Well‐defined nanogels have become quite attractive as safe and stable carriers for siRNA delivery. However, to avoid nanoparticle accumulation, they need to provide a stimuli‐responsive degradation mechanism that can be activated at the payload's site of action. In this work, the synthetic concept for generating well‐defined nanohydrogel particles is extended to incorporate disulfide cross‐linkers into a cationic nanonetwork for redox‐triggered release of oligonucleotide payload as well as nanoparticle degradation under reductive conditions of the cytoplasm. Therefore, a novel disulfide‐modified spermine cross‐linker is designed that both allows disassembly of the nanogel as well as removal of cationic charge from residual polymer fragments. The degradation process is monitored by scanning electron microscopy (SEM) and fluorescence correlation spectroscopy (FCS). Moreover, siRNA release is analyzed by agarose gel electrophoresis and a fluorescent RNA detection assay. The results exemplify the versatility of the applied nanogel manufacturing process, which allows alternative stimuli‐responsive core cross‐linkers to be integrated for triggered oligonucleotide release as well as effective biodegradation for reduced nanotoxicity.
Chirality is one of the most fascinating and ubiquitous features in nature, especially in biological systems. The effects of chiral surfaces, especially in combination with degradable materials of good biocompatibility, on stem cell behaviors has not yet been tackled. In this communication, the chiral monomers N‐acryloyl‐l (d )‐valine (l (d )‐AV) are synthesized and are polymerized to obtain chiral (l (d )‐PAV‐SH) oligomers, which are covalently immobilized onto electron‐deficient poly(propylene fumarate) polyurethane (PPFU) via Michael addition. The PPFU‐l ‐PAV can interact more strongly and actively with bone marrow stem cells (BMSCs) than PPFU‐d ‐PAV, leading to a larger cell spreading area, faster migration velocity, and stronger osteodifferentiation tendency.
Here, a novel multi‐stimuli‐responsive fluorescence probe is developed by incorporating spiropyran group into the coumarin‐substituted polydiacetylene (PDA) vesicles. The fluorescence of PDA can be turned on upon heating, and can be quenched upon exposure to UV light irradiation or pH stimuli owing to the fluorescene resonance energy transfer (FRET) between the red‐phase PDA and the open merocyanine (MC) form of spiropyran. Moreover, we have designed and experimentally realized a set of logic gate operations for the first time based on the fluorescence modulation of the designed system upon thermal, photo, and pH stimuli. This novel type of resettable logic gates augur well for practical applications in information storage, optical recording, and sensing in complicated microenvironments.
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.
This work deals with the in‐depth investigation of thiol‐yne based network formation and its effect on thermomechanical properties and impact strength. The results show that the bifunctional alkyne monomer di(but‐1‐yne‐4‐yl)carbonate ( DBC ) provides significantly lower cytotoxicity than the comparable acrylate, 1,4‐butanediol diacrylate ( BDA ). Real‐time near infrared photorheology measurements reveal that gel formation is shifted to higher conversions for DBC /thiol resins leading to lower shrinkage stress and higher overall monomer conversion than BDA . Glass transition temperature (Tg), shrinkage stress, as well as network density determined by double quantum solid state NMR, increase proportionally with the thiol functionality. Most importantly, highly cross‐linked DBC /dipentaerythritol hexa(3‐mercaptopropionate) networks (Tg ≈ 61 °C) provide a 5.3 times higher impact strength than BDA , which is explained by the unique network homogeneity of thiol‐yne photopolymers.
Anisometric polymer colloids are likely to behave differently when compared with centrosymmetric particles. Their study may not only shine new light on the organization of matter; they may also serve as building units with specific symmetries and complexity to build new materials from them. Polymer colloids of well‐defined complex geometries can be obtained by packing a limited number of spherical polymer particles into clusters with defined configurations. Such supracolloidal architectures can be fabricated at larger scales using narrowly dispersed emulsion droplets as templates. Assemblies built from at least two different types of particles as elementary building units open perspectives in selective targeting of colloids with specific properties, aiming for mesoscale building blocks with tailor‐made morphologies and multifunctionality. Polymer colloids with defined geometries are also ideal to study shape‐dependent properties such as the diffusion of complex particles.
To enhance the limited degradability of poly(ethylene glycol) (PEG), a straightforward method of synthesizing poly[(ethylene glycol)‐co‐(glycolic acid)] (P(EG‐co‐GA)) via a ruthenium‐catalyzed, post‐polymerization oxyfunctionalization of various PEGs is developed. Using this method, a set of copolymers with GA compositions of up to 8 mol% are prepared with minimal reduction in molecular weight (<10%) when compared to their commercially available starting materials. The P(EG‐co‐GA) copolymers are shown to undergo hydrolysis under mild conditions.
Similar to the traditional self‐assembly strategy, polymerization induced self‐assembly and reorganization (PISR) can produce a myriad of polymeric morphologies through morphology transitions. Besides the chain length ratio (R) of the hydrophobic to the hydrophilic blocks, the chain mobility in the intermediate nano‐objects, which is a requisite for morphology transition, is a determining factor in the formation of the final morphology. Although various morphologies have been fabricated, hexagonally packed hollow hoops (HHHs) with highly ordered internal structure have not, to the best of our knowledge, been prepared by PISR. In this article, the fabrication of HHHs through morphology transition from large compound vesicles to HHHs is reported. HHHs with highly regular internal structure may have significance in theoretical research and practical applications of nanomaterials.
The step‐wise solution self‐assembly of double crystalline organometallic poly(ferrocenyldimethylsilane)‐block‐poly(2‐iso‐propyl‐2‐oxazoline) (PFDMS‐b‐PiPrOx) diblock copolymers is demonstrated. Two block copolymers are obtained by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), featuring PFDMS/PiPrOx weight fractions of 46/54 (PFDMS30‐b‐PiPrOx75) and 30/70 (PFDMS30‐b‐PiPrOx155). Nonsolvent induced crystallization of PFDMS in acetone leads in both cases to cylindrical micelles with a PFDMS core. Afterward, the structures are transferred into water for sequential temperature‐induced crystallization of the PiPrOx corona, leading to hierarchical double crystalline superstructures, which are investigated using scanning electron microscopy, wide angle X‐ray scattering, and differential scanning calorimetry.
In this article, a synthetic concept for the preparation of polyamides with functional side groups is described. First, the synthesis of a bis(thiolactone) monomer is shown in a concise three‐step route from itaconic acid and DL‐homocysteine thiolactone. The reactivity of the resulting bis(thiolactone) toward hexyl amine is examined. Next, the bis(thiolactone) is reacted as A,A‐type monomer with different B,B‐type comonomers (1,12‐diaminododecane and 1,3‐bis(aminopropyl)tetramethyldisiloxane). Ring opening of the thiolactones by the diamines leads to polyamides with pendant thiol groups. Using two diamines in different ratios, the properties of the resulting polyamides are tuned (thermal properties are determined) and different molecular weights are acquired. Subsequently, the thiol groups are reacted with methyl acrylate via Michael addition to functionalize the polyamides. Functionalization of thiol‐functional polyamides using poly(ethylene glycol) monomethyl ether (mPEG) acrylates ( = 480 and 1700 g mol−1) results in water‐soluble amphiphilic polyamides with molecular weights higher than 10 000 g mol−1.
