The Elaboration of Effective Coatings for Photonic Crystal Chips in Optical Biosensors

Here, we propose and study several types of quartz surface coatings designed for the high-performance sorption of biomolecules and their subsequent detection by a photonic crystal surface mode (PC SM) biosensor. The deposition and sorption of biomolecules are revealed by analyzing changes in the propagation parameters of optical modes on the surface of a photonic crystal (PC). The method makes it possible to measure molecular and cellular affinity interactions in real time by independently recording the values of the angle of total internal reflection and the angle of excitation of the surface wave on the surface of the PC. A series of dextrans with various anchor groups (aldehyde, carboxy, epoxy) suitable for binding with bioligands have been studied. We have carried out comparative experiments with dextrans with other molecular weights. The results confirmed that dextran with a Mw of 500 kDa and anchor epoxy groups have a promising potential as a matrix for the detection of proteins in optical biosensors. The proposed approach would make it possible to enhance the sensitivity of the PC SM biosensor and also permit studying the binding process of low molecular weight molecules in real time.

Polyacrylonitrile/Crown Ether Composite Nanofibres With High Efficiency for Adsorbing Li(I): Experiments and Theoretical Calculations

Lithium, as the lightest alkali metal, is widely used in military and new energy applications. With the rapid growth in demand for lithium resources, it has become necessary to improve the effectiveness of extraction thereof. By using chemical grafting and electrospinning techniques, nanofibres containing crown ether were developed for adsorbing Li(I) from the brine in salt lakes, so as to selectively adsorb Li(I) on the premise of retaining specific vacancies of epoxy groups in crown ether. In lithium-containing solution, the adsorbing materials can reach adsorption equilibrium within three hours, and the maximum adsorption capacity is 4.8 mg g−1. The adsorption mechanisms of the adsorbing materials for Li(I) were revealed by combining Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) with density functional theory (DFT) calculation. The results indicated that in crown ether, O in epoxy groups was coordinated with Li(I) to form Li–O and four O atoms in the epoxy groups were used as electron donors. After coordination, two O atoms protruded from the plane and formed a tetrahedral structure with Li(I), realising the specific capture of Li(I). By desorbing fibres that adsorbed Li(I) with 0.5-M HCl, the adsorption capacity only decreased by 10.4% after five cycles, proving ability to regenerate such materials. The nanofibres containing crown ether synthesised by chemical grafting and electrospinning have the potential to be used in extracting lithium resources from the brine in salt lakes.

KINETICS OF FORMATION AND PROPERTIES OF PHOTOCURED SIMULTANEOUS EPOXY-ACRYLATE IPNS WITH THE PREVAILING CONTENT OF AN EPOXY COMPONENT

The distinct features of UV induced polymerization of epoxy-acrylate blends leading to the formation of simultaneous interpenetrating polymer networks (IPNs) have been studied. Different ratios of components within a prevailing content of an epoxy one have been used for the synthesis. Such a content of epoxy monomer is required to create a barrier preventing oxygen diffusion into a curing sample. It allows retardation of the well-known oxygen-inhibition effect, which acrylate monomers are susceptible to. Hence, the conduction of their polymerization in open-air conditions is possible. The proceeding of the polymerization reactions of acrylate (TEGDM) via free radical mechanism and of epoxy (UP-650D) via cationic one have been monitored by FTIR-spectroscopy. Namely, the conversion degrees have been calculated for double bonds of TEGDM and for epoxy groups of UP-650D respectively. A mixture of triphenylsulfonium hexafluorophosphate salts, which is capable of generating both free radical and cationic reactive species, have been used as a single photoinitiator for the formulations being investigated. Almost complete conversion of acrylate double bonds was reached after 60 min of UV irradiation irrespective of epoxy content. On the contrary, conversion of epoxy groups of aliphatic epoxy, which is known to be rather unreactive towards cationic photopolymerization, when mixed may be either higher or lower compared to the neat epoxy network. Such results are attributed to dual influence of acrylate network on the formation of epoxy one. Firstly, cationic polymerization of epoxy component is sensitized by acrylate macroradicals in terms of free radical promoted cationic polymerization. On the other hand, the mobility of epoxy macrocations is restricted by the rapid build-up of acrylate network. At the weight ratio of UP-650D and TEGDM 70/30 the sensitizing effect of acrylate is revealed to be dominant, so the given composition may be considered as optimal. Regardless of low conversion of epoxy groups, the content of the estimated gel fraction is high, and the epoxy component is found not to be leached in the process of extraction in acetone. Furthermore, physicomechanical properties of obtained UV-cured IPNs have been investigated. The results of the measurements, namely, impact resistance by the Gardner test, crosshatch adhesion test to different substrates (including silicon), and accelerated weathering test in a climatic chamber, show that all the samples exhibit good operational properties essential for effective protecting coatings of outdoor exposure.

Antibiocorrosive Hybrid Materials with High Durability

We have developed novel antibiocorrosive multifunctional hybrid materials based on functionalizedperfluoroalkylmethacrylate copolymerswith epoxy groups in main chainsand selected biologically active compounds.The hybrids are transparent, showgood adhesion to various surfaces (plastic, wood),high viscoelastic recovery in scratch testing,low wear rates and glass transitions above 323 K. No phase separation is seen in scanning electron micrography. Enhanced mechanical strength and good abrasion resistance are advantages for uses of our protective and antibiocorrosive coatings in various applications including protection of cultural heritage.

Aqueous dispersions of epoxy oligomers: Stability and rheological properties

In this study, the stability of the aqueous dispersions of epoxy oligomers was investigated. The following epoxy oligomers with various numbers of epoxy groups were used for the characterization: NPEL 127, NPEL 128, NPEL 134, NPPN 631, EPOXY 520 and DEG-1. A non-ionic surfactant Emulsogen LCN-287 based on alkyl polyethylene glycol ether was used as an emulsifier. The dispersions of epoxy resins were fabricated by changing the content of a non-ionic surfactant (emulsifier) in a range from 2 to 6 wt.%. It was demonstrated that the stability of aqueous emulsions depends not only on the type of resin, but also on the content of the oil phase and the concentration of the emulsifier. The rheological properties of the aqueous dispersions of epoxy oligomers were investigated as well.

Glycidyl methacrylate-crosslinked fish swim bladder as a novel cardiovascular biomaterial with improved antithrombotic and anticalcification properties

At present, commercial artificial biological valves are mostly prepared by crosslinking bovine or porcine pericardia with glutaraldehyde. Swim bladder has similar components and lower immunogenicity compared to bovine or porcine pericardium. In this study, we used a glycidyl methacrylate (GMA)–based radical polymerization method to crosslink decellularized swim bladders. Amino and carboxyl groups in the swim bladder were reacted with epoxy groups on GMA to introduce carbon–carbon double bonds to the swim bladder. The results showed that the platelet adhesion of GMA-crosslinked swim bladders (GMA-SBs) decreased by 35%, as compared to that of glutaraldehyde-crosslinked swim bladders (GLUT-SBs). Moreover, the superior anticoagulant property was further verified by the ex vivo arteriovenous shunt assay. Meanwhile, the subcutaneous implantation in rats showed that GMA-SBs were able to effectively inhibit the calcification compared with GLUT-SBs. In conclusion, GMA-SBs showed improved antithrombotic and anticalcification properties compared to GLUT-SBs.

Rosin-Based Epoxy Vitrimers with Dynamic Boronic Ester Bonds

Rosin is an abundantly available natural product. In this paper, for the first time, a rosin derivative is employed as the main monomer for preparation of epoxy vitrimers to improve the mechanical properties of vitrimers. Novel epoxy vitrimer networks with dynamic reversible covalent boronic ester bonds are constructed by a reaction between thiols in 2,2′–(1,4–phenylene)–bis (4–mercaptan–1,3,2–dioxaborolane) (BDB) as a curing agent and epoxy groups in the rosin derivative. The rosin-based epoxy vitrimer networks are fully characterized by Fourier transform infrared spectroscopy (FTIR), an equilibrium swelling experiment, and dynamic mechanical analysis (DMA). The obtained rosin-based epoxy vitrimers possess superior thermostability and good mechanical properties. Due to transesterification of boronic ester bonds, rosin epoxy vitrimer network topologies can be altered, giving welding, recycle, self-healing, and shape memory abilities to the fabricated polymer. Besides, the effects of treating time and temperature on welding capability is investigated, and it is found that the welding efficiency of the 20% C-FPAE sample is >93% after treatment for 12 h at 160 °C. Moreover, through a hot press, the pulverized samples of 20% C-FPAE can be reshaped several times and most mechanical properties are restored after reprocessing at 200 °C for 60 min. Finally, chemical degradation is researched for the rosin-based epoxy vitrimers.

Effect of Silica Nanoparticles Blocked with Epoxy Groups on the Crosslinking and Surface Properties of PEG Hydrogel Films

Silica nanoparticles (G-SiNPs) blocked with 3-glycidoxypropyl trimethoxysilane (GPTS) were newly applied to hydrogel films for improving film coating properties and to distribute the epoxy groups on the film surface. The effects of the content of epoxy-functionalized G-SiNPs on the crosslinking features by photo-induced radical polymerization and the surface mechanical properties of the hydrogel films containing poly(ethylene glycol) dimethacrylate (PEGDMA) and glycidyl methacrylate (GMA) were investigated. The real-time elastic modulus of various PEG hydrogel mixtures with prepared particles was monitored using a rotational rheometer. The distribution of epoxy groups on the crosslinked film surface was directly and indirectly estimated by the elemental analysis of Si and Br. The surface mechanical properties of various hydrogel films were measured by nano-indentation and nano-scratch tests. The relationship between the rheological and surface properties of PEG-based hydrogel films suggests that the use of small amounts of G-SiNPs enhances the surface hardness and crosslinked network of the film and uniformly distributes sufficient epoxy groups on the film surface for further coating applications.