Hydrophilic Polymer Chains Research Articles

Hydrophilic molecularly imprinted thermal-responsive polymers based sorbent for ambient ionization mass spectrometric analysis of sulfonamide antibiotics from food samples

The thermal-responsive magnetic molecularly imprinted polymer (TrMMIP) sorbent was synthesized by surface imprinting method, and then used for magnetic solid-phase extraction (MSPE) and subsequent integrated into the ion source for elution and ionization. The shrinking-strength states change of the thermal-responsive polymer chain on TrMMIP alters the wettability of the sorbent when the working temperature crosses the lower critical solution temperature (LCST) of the polymer, and thus affects its behavior of in the extraction and clean-up process. The targeted analytes could be effectively extracted due to the high selectivity of MIPs and well dispersibility of polymer chain under the open state. Additionally, a hydrophilic polymer chain wrapped on the sorbent surface further protected target substances from co-elution during cleanup. Analytical methods for sulfonamide antibiotics (SAs) detection in complex food samples (milk, honey, fish) were developed, demonstrating potential for rapid and sensitive SAs analysis in diverse food and biological samples.

Synthesis and Structure Optimization of Star Copolymers as Tunable Macromolecular Carriers for Minimal Immunogen Vaccine Delivery.

Minimal immunogen vaccines are being developed to focus antibody responses against otherwise challenging targets, including human immunodeficiency virus (HIV), but multimerization of the minimal peptide immunogen on a carrier platform is required for activity. Star copolymers comprising multiple hydrophilic polymer chains ("arms") radiating from a central dendrimer unit ("core") were recently reported to be an effective platform for arraying minimal immunogens for inducing antibody responses in mice and primates. However, the impact of different parameters of the star copolymer (e.g., minimal immunogen density and hydrodynamic size) on antibody responses and the optimal synthetic route for controlling those parameters remains to be fully explored. We synthesized a library of star copolymers composed of poly[N-(2-hydroxypropyl)methacrylamide] hydrophilic arms extending from poly(amidoamine) dendrimer cores with the aim of identifying the optimal composition for use as minimal immunogen vaccines. Our results show that the length of the polymer arms has a crucial impact on the star copolymer hydrodynamic size and is precisely tunable over a range of 20-50 nm diameter, while the dendrimer generation affects the maximum number of arms (and therefore minimal immunogens) that can be attached to the surface of the dendrimer. In addition, high-resolution images of selected star copolymer taken by a custom-modified environmental scanning electron microscope enabled the acquisition of high-resolution images, providing new insights into the star copolymer structure. Finally, in vivo studies assessing a star copolymer vaccine comprising an HIV minimal immunogen showed the criticality of polymer arm length in promoting antibody responses and highlighting the importance of composition tunability to yield the desired biological effect.

High Antifouling Performance of Weakly Hydrophilic Polymer Brushes: A Molecular Dynamics Study.

The antifouling performance of polymer brushes usually improves with increasing hydrophilicity of the grafted polymer. However, in some cases, less hydrophilic polymers show comparable or better antifouling performance than do more hydrophilic polymers. We investigate the mechanism of this anomalous behavior using molecular dynamics (MD) simulations of coarse-grained (CG) models of weakly and strongly hydrophilic polymers. The antifouling performance is evaluated from the potential of mean force of a model protein. The strongly hydrophilic polymer exhibits a better antifouling performance than the weakly hydrophilic polymer when the substrate of the polymer brush is repulsive. However, when the substrate is sufficiently attractive, the weakly hydrophilic polymer brush becomes more effective than the strongly hydrophilic brush in a certain range of grafting density. This is because the weakly hydrophilic polymer chains form a tightly packed layer that prevents the adsorbate molecule from contacting the substrate. We also perform all-atom (AA) MD simulations for several standard polymers to examine the correspondence with the CG polymer models. The weakly hydrophilic CG polymer is found to be similar to poly[N-(2-hydroxypropyl)methacrylamide] and poly(2-hydroxyethyl methacrylate), both of which have a hydroxyl group in a monomer unit. The strongly hydrophilic CG polymer resembles zwitterionic poly(carboxybetaine methacrylate). A discussion referring to the adsorption free energies of proteins on surfaces calculated in previous AA MD studies suggests that the higher antifouling performance of less hydrophilic polymer brushes can be realized for various combinations of protein and surface.

Engineering shrinkage resistance of nano-structured hydrogels in seawater for fast uranium capture

Synthetic hydrogels, which are 3D networks composed of crosslinked hydrophilic polymer chains, have been created using various crosslinked ways for uranium capture due to full exposure of chelate functional groups. However, the conventional honeycomb-like hydrogels exhibit non-connected micropore structure, which locks abundant water molecules and hence is unfavorable for mass transfer. Herein, we demonstrate a simple synthesis of the nano-structured hydrogel with activated nanogels as nano-crosslinkers (denoted as PGP hydrogel), and probe into the relationship between hydrogel structural parameters and uranium adsorption kinetics. It is found that the PGP hydrogel with a low crosslinking density of ∼0.02 mol/m3 possesses interconnected micropores, thereby facilitating diffusion of uranyl ions (UO22+) in 3D polymeric networks. Furthermore, a freeze-assisted soaking strategy is proposed to endow PGP hydrogel (denoted as target hydrogel) with strong shrinkage resistance in natural seawater, resulting in a ∼40 % increase in water permeance to reach 369 Lm−2h−1MPa−1. Correspondingly, the adsorption equilibrium time is shortened to ∼11 days. Although the uranium uptake capacity of PGP hydrogels with and without freeze-assisted soaking treatment remain basically unchanged (∼9.73 mg-U/g-Ads), a high uranium adsorption rate of 0.88 mg/g/d for the target hydrogel surpasses most currently available polymer adsorbents. The presented strategy is generalizable to a broader range of applications involving the adsorption of economically valuable ions in seawater or brine lake.

Quantitative Comparison of the Hydration Capacity of Surface-Bound Dextran and Polyethylene Glycol.

We have quantified and compared the hydration capacity (i.e., capability to incorporate water molecules) of the two surface-bound hydrophilic polymer chains, dextran (dex) and poly(ethylene glycol) (PEG), in the form of poly(l-lysine)-graft-dextran (PLL-g-dex) and poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), respectively. The copolymers were attached to a negatively charged silica-titania surface through the electrostatic interaction between the PLL backbone and the surface in neutral aqueous media. While the molecular weights of PLL and PEG were fixed, that of dex and the grafting density of PEG or dex on the PLL were varied. The hydration capacity of the polymer chains was quantified through the combined experimental approach of optical waveguide lightmode spectroscopy (OWLS) and quartz crystal microbalance with dissipation monitoring (QCM-D) to yield a value for areal solvation (Ψ), i.e., mass of associated solvent molecules within the polymer chains per unit substrate area. For the two series of copolymers with comparable stretched chain lengths of hydrophilic polymers, namely, PLL(20)-g-PEG(5) and PLL(20)-g-dex(10), the Ψ values gradually increased as the initial grafting density on the PLL backbone increased or as g decreased. However, the rate of increase in Ψ was higher for PEG than dextran chains, which was attributed to higher stiffness of the dextran chains. More importantly, the number of water molecules per hydrophilic group was clearly higher for PEG chains. Given that the -CH2CH2O- units that make up the PEG chains form a cage-like structure with 2-3 water molecules, these "strongly bound" water molecules can account for the slightly more favorable behavior of PEG compared to dextran in both aqueous lubrication and antifouling behavior of the copolymers.

Chitosan-Type-A-Gelatin Hydrogels Used as Potential Platforms in Tissue Engineering for Drug Delivery.

Hydrogels are materials made of crosslinked 3D networks of hydrophilic polymer chains that can absorb and retain significant amounts of water due to their hydrophilic structure without being dissolved. In relation to alternative biomaterials, hydrogels offer increased biocompatibility and biodegradability, giving them distinct advantages. Thus, hydrogel platforms are considered to have the potential for the development of biomedical applications. In this study, the main objective was the development of hybrid hydrogels to act as a drug delivery platform. These hydrogels were made from chitosan (CH) and type A gelatin (G), two natural polymers that provide a supportive environment for cellular attachment, viability, and growth, thanks to their unique properties. Particularly, the use of gelatins for drug delivery systems provides biodegradability, biocompatibility, and non-toxicity, which are excellent properties to be used in the human body. However, gelatins have some limitations, such as thermal instability and poor mechanical properties. In order to improve those properties, the aim of this work was the development and characterization of hybrid hydrogels with different ratios of CH-G (100-0, 75-25, 50-50, 25-75, 0-100). Hydrogels were characterized through multiple techniques, including Fourier transform infrared (FTIR) spectroscopy, rheological and microstructural studies, among others. Moreover, a model hydrophilic drug molecule (tetracycline) was incorporated to evaluate the feasibility of this platform to sustain the release of hydrophilic drugs, by being tested in a solution of Phosphate Buffer Solution at a pH of 7.2 and at 37 °C. The results revealed that the synergy between chitosan and type A gelatin improved the mechanical properties as well as the thermal stability of it, revealing that the best ratios of the biopolymers are 50-50 CH-G and 75-25 CH-G. Thereby, these systems were evaluated in a controlled release of tetracycline, showing a controlled drug delivery of 6 h and highlighting their promising application as a platform for controlled drug release.

Surface Reconstruction of Silicone-Based Amphiphilic Polymers for Mitigating Marine Biofouling.

Poly(dimethylsiloxane) (PDMS) coatings are considered to be environmentally friendly antifouling coatings. However, the presence of hydrophobic surfaces can enhance the adhesion rate of proteins, bacteria and microalgae, posing a challenge for biofouling removal. In this study, hydrophilic polymer chains were synthesised from methyl methacrylate (MMA), Poly(ethylene glycol) methyl ether methacrylate (PEG-MA) and 3-(trimethoxysilyl) propyl methacrylate (TPMA). The crosslinking reaction between TPMA and PDMS results in the formation of a silicone-based amphiphilic co-network with surface reconstruction properties. The hydrophilic and hydrophobic domains are covalently bonded by condensation reactions, while the hydrophilic polymers migrate under water to induce surface reconstruction and form hydrogen bonds with water molecules to form a dense hydrated layer. This design effectively mitigates the adhesion of proteins, bacteria, algae and other marine organisms to the coating. The antifouling performance of the coatings was evaluated by assessing their adhesion rates to proteins (BSA-FITC), bacteria (B. subtilis and P. ruthenica) and algae (P. tricornutum). The results show that the amphiphilic co-network coating (e.g., P-AM-15) exhibits excellent antifouling properties against protein, bacterial and microalgal fouling. Furthermore, an overall assessment of its antifouling performance and stability was conducted in the East China Sea from 16 May to 12 September 2023, which showed that this silicon-based amphiphilic co-network coating remained intact with almost no marine organisms adhering to it. This study provides a novel approach for the development of high-performance silicone-based antifouling coatings.

Prussian Blue Encapsulated with Brush-like Polyorganosiloxane Nanospheres with Tunable Functionality

Faced with higher demands of pigments in various applications, the performance of pigments in a specific system is in urgent need of optimization and improvement. Polyorganosiloxane (POS) stands out among various encapsulating polymeric materials for pigment modification due to its superior thermal stability and alkali resistance. However, the inherent hydrophobicity of POS causes poor stability in aqueous systems, which is usually applied in environmentally friendly applications. Grafting hydrophilic polymer chains on the surface of POS could improve water dispersity. In addition, the encapsulated pigment can also be endowed with various functionalities by selecting or combining grafted polymers. Herein, we reported a strategy to encapsulate Prussian blue (PB27) with POS grafted with poly(acrylic acid) (PAA) or poly(N-(2-hydroxyethyl) acrylamide) (PHEAA) to allow better stability and functionality of the composite pigment particles, denoted as PB27@POS@PAA or PB27@POS@PHEAA, respectively. The effect of the number of monomers and the amount of initiator potassium persulfate (KPS) on the brush thickness of the grafted polymers was studied, along with various performance properties and the functionality of PB27@POS@PAA and PB27@POS@PHEAA. The dispersity, alkali resistance, and high-temperature stability are studied. The brush-like composite pigment performs better after centrifugation (5000 rpm, 30 min) or treatment under 90 °C when the dosage of grafting monomer AA or HEAA reaches 400 wt%. Optimal alkali resistance was obtained for PB27@POS@PAA (AA, 200 wt%) with a particle size variation of only 31 nm after 8 h. Comparably, PB27@POS@PHEAA behaved worse under similar conditions. Moreover, PB27@POS grafted with PAA was responsive to pH and that with PHEAA showed excellent antifouling properties, which could also be replaced by other functional monomers if needed.

A thermodynamic theory coupling photo-chemo-mechano interactions for light-responsive hydrogel

Light-responsive hydrogel, as a typical functional hydrogel, is composed of crosslinked hydrophilic polymer chains, photosensitive molecules and water. Under illumination, the photosensitive molecules exhibit a transition in hydrophilic/ hydrophobic properties, leading to migration of water molecules and deformation of the hydrogel based on the temporal and spatial distribution of light. In this study, we propose a nonequilibrium thermodynamic framework to study the photo-chemo-mechano behaviors of light-responsive hydrogel. We firstly describe the light propagation in the hydrogel and the photochemical reaction kinetics. New free energy functions to expound the relationship between the photochemical reaction and thermodynamic process are established, and the constitutive equations are derived. Subsequently, we implant the model into a multi-field coupling analysis software, COMSOL, to conduct a spatio-temporal analysis of the hydrogel's response under uniform light exposure. Finally, we simulate the inhomogeneous deformation of light-responsive hydrogel strips under different illumination conditions and compare the results with experiments. The results highlight the importance of the photochemical reaction rate and the redistribution of light field caused by deformation. The present research holds potential for the precise manipulation and optimal design of light-responsive hydrogel in prospective applications, and offers insights for the synthesis of similar materials as well as the design of pertinent devices.

Hydrogel microspheres based on Bletilla striata polysaccharide as a promising cervical positioning drug delivery system

Due to female cervical mucosa is smooth and covered with a mucous layer, so the spreadability and mucoadhesion are crucial for the development of cervical positioning drug delivery system (CPDDS). In this work, the natural polymer Bletilla striata polysaccharide (BSP) as a hydrogel matrix-forming material was used for the preparing of hydrogel microspheres (HMs) by an improved emulsion crosslinking method. The prepared HMs have a spherical or quasi-spherical shape with a size of 115 ± 27 μm, resulting a good fluidity for spreading well at the administration site. By the physical entanglements of hydrophilic polymer chains of BSP, the matrix of HMs presents a microporous structure. With microporous matrix, the HMs could absorb water from mucous layer and achieve an optimum hydration required for mucoadhesion when they contact the cervical mucosa, also could keep their mucoadhesion behavior and morphology for a long time even after absorbing more water. As a result, the cervical positioning drug release behavior and long retention time at the cervical mucosa obtained. The loaded drug release profile of HMs include a low initial burst release and subsequent a longer sustained release, this is beneficial for the local treatment of cervical diseases. Owing to the BSP is a natural biodegradable polymer, the HMs have better biocompatibility with mucosal tissues and without causing irritation. In conclusion, this work suggest that the HMs based on BSP polymer is a promising CPDDS for clinical applications.

Biomass-derived 3D evaporator with antifouling and salt-rejecting toward solar-enabled steam generation, desalination, and electricity generation

Solar-driven interfacial evaporation is currently considered as one of the most effective and sustainable strategies to address water scarcity and energy shortages issues. Whereas, challenges in developing durable, eco-friendly, and low-cost solar evaporators from readily available materials still exist. Herein, we have reported a facile strategy to construct a robust natural sorghum stalk pith solar evaporator. With advantageous features of gradient honeycomb structure and hydrophilic polymer chains, the constructed evaporator exhibits broadband light absorption, efficient light to heat conversion, fast water transport, and multi-channel release of steam performances, leading to an ultrahigh evaporation rate of 3.79 kg m−2h−1 under one sun irradiation and outstanding salt-resistant ability at a high evaporation rate of 2.6 kg·m−2·h−1 in a highly concentrated brine (20 wt% NaCl), accompanied with anti-oil-fouling performances, as well as high oil removal efficiency (>99.8 %) for oil-in-water emulsion, outperforming most previously reported solar evaporators. Additionally, solar irradiation can further promote the directional water flow, contributing to a high photovoltage of 68 mV under one sun illumination. This paves the way for designing durable biomass-based steam generators, not only scaling up sustainable clean water production, sewage depuration and desalination, but also discovering promising application in the field of electricity generation.

UV-Initiated Frontal Polymerization for the Fast Synthesis of Bubble-Free, Self-Propagating Hydrogel Anticorrosive Coatings.

Hydrogels are formed through the cross-linking of hydrophilic polymer chains within an aqueous microenvironment. A novel synthesis strategy, UV-initiated frontal polymerization to quickly synthesize bubble-free, self-propagating hydrogel anticorrosive coatings in aqueous conditions, was presented, in which the self-propagating polymerization rate reached 16.7 mm min-1. SEM, AFM, FTIR, EIS, IC, XPS, and ultra-depth-of-field microscopy were used to characterize the surface morphology and anti-corrosion properties of the hydrogel coating. The addition of nano-SiO2 formed dense hydrogen bonds, and the stability of the three-dimensional network was enhanced. Underwater, the hydrogel coating could physically block corrosive media from reaching steel surfaces, and it was 75% effective at blocking chloride ions after 7 days under osmotic pressure. In addition, 1,2,4-triazole accumulated on the steel surface, and then the active anti-corrosion function took effect. This paper provides the basis for the in situ synthesis of hydrogel anticorrosive coatings on the surface of mild steel in a wet or underwater state.

Hydrogel with Robust Adhesion in Various Liquid Environments by Electrostatic-Induced Hydrophilic and Hydrophobic Polymer Chains Migration and Rearrangement.

Hydrogels with wet adhesion are promising interfacial adhesive materials; however, their adhesion in water, oil, or organic solvents remains a major challenge. To address this, a pressure-sensitive P(AAm-co-C18 )/PTA-Fe hydrogel is fabricated, which exhibits robust adhesion to various substrates in both aqueous solutions and oil environments. It is demonstrated that the key to wet adhesion under liquid conditions is the removal of the interfacial liquid, which can be achieved through rational molecular composition regulation. By complexing with hydrophilic polymer networks, phosphotungstic acid (PTA) is introduced into the hydrogel network as a physical cross-linker and anchor point to improve the cohesion strength and drive the migration of polymer chains. The migration and rearrangement of hydrophilic and hydrophobic polymer chains on the hydrogel surface are induced by the electrostatic interactions of Fe3+ , which create a surface with interfacial water- and oil-removing properties. By co-regulating the hydrophilic and hydrophobic polymer chains, the P(AAm-co-C18 )/PTA-Fe hydrogel is able to act as a pressure-sensitive adhesive under water and oils with adhesion strength of 92.6 and 90.0kPa, respectively. It is anticipated that this regulation strategy for polymer chains will promote the development of wet adhesion hydrogels, which can have a wide range of applications.

Janus polymer-grafted nanoparticles mimicking membrane repair proteins for the prevention of lipid membrane rupture.

Plasma membrane rupture often leads to cell damage, especially when there is a lack of membrane repair proteins near the wounds due to genetic mutations in organisms. To efficiently promote the repair of the injured lipid membrane, nanomedicines may act as a promising alternative to membrane repair proteins, but the related research is still in its infancy. Herein, using dissipative particle dynamics simulations, we designed a class of Janus polymer-grafted nanoparticles (PGNPs) that can mimic the function of membrane repair proteins. The Janus PGNPs comprise both hydrophobic and hydrophilic polymer chains grafted on nanoparticles (NPs). We track the dynamic process of the adsorption of Janus PGNPs at the damaged site in the lipid membrane and systematically assess the driving forces for this process. Our results reveal that tuning the length of the grafted polymer chains and the surface polarity of the NPs can efficiently enhance the adsorption of Janus PGNPs at the site of the damaged membrane to reduce membrane stress. After repair, the adsorbed Janus PGNPs can be successfully detached from the membrane, leaving the membrane untouched. These results provide valuable guidelines for designing advanced nanomaterials for the repair of damaged lipid membranes.

Temporally programmed polymer – solvent interactions using a chemical reaction network

Out of equilibrium operation of chemical reaction networks (CRNs) enables artificial materials to autonomously respond to their environment by activation and deactivation of intermolecular interactions. Generally, their activation can be driven by various chemical conversions, yet their deactivation to non-interacting building blocks remains largely limited to hydrolysis and internal pH change. To achieve control over deactivation, we present a new, modular CRN that enables reversible formation of positive charges on a tertiary amine substrate, which are removed using nucleophilic signals that control the deactivation kinetics. The modular nature of the CRN enables incorporation in diverse polymer materials, leading to a temporally programmed transition from collapsed and hydrophobic to solvated, hydrophilic polymer chains by controlling polymer-solvent interactions. Depending on the layout of the CRN, we can create stimuli-responsive or autonomously responding materials. This concept will not only offer new opportunities in molecular cargo delivery but also pave the way for next-generation interactive materials.

Multifunctional Composite Hydrogels for Bacterial Capture, Growth/Elimination, and Sensing Applications.

Hydrogels are cross-linked networks of hydrophilic polymer chains with a three-dimensional structure. Owing to their unique features, the application of hydrogels for bacterial/antibacterial studies and bacterial infection management has grown in importance in recent years. This trend is likely to continue due to the rise in bacterial infections and antimicrobial resistance. By exploiting their physicochemical characteristics and inherent nature, hydrogels have been developed to achieve bacterial capture and detection, bacterial growth or elimination, antibiotic delivery, or bacterial sensing. Traditionally, the development of hydrogels for bacterial/antibacterial studies has focused on achieving a single function such as antibiotic delivery, antibacterial activity, bacterial growth, or bacterial detection. However, recent studies demonstrate the fabrication of multifunctional hydrogels, where a single hydrogel is capable of performing more than one bacterial/antibacterial function, or composite hydrogels consisting of a number of single functionalized hydrogels, which exhibit bacterial/antibacterial function synergistically. In this review, we first highlight the hydrogel features critical for bacterial studies and infection management. Then, we specifically address unique hydrogel properties, their surface/network functionalization, and their mode of action for bacterial capture, adhesion/growth, antibacterial activity, and bacterial sensing, respectively. Finally, we provide insights into different strategies for developing multifunctional hydrogels and how such systems can help tackle, manage, and understand bacterial infections and antimicrobial resistance. We also note that the strategies highlighted in this review can be adapted to other cell types and are therefore likely to find applications beyond the field of microbiology.

Hydrogel scaffolds in diabetic wound healing: A mini review

A sedentary lifestyle has paved a rapid upsurge in diabetes prevalence worldwide and is often allied with defective wound healing and impaired reparative responses. Hydrogel-based biomaterials are designed to mimic natural extracellular matrix to promote cell invasion, angiogenesis, re-epithelialization and inhibit persistent inflammation thereby accelerating the wound healing process. Hydrogels are hydrophilic polymer chains cross-linked to a three-dimensional solid using physical and chemical crosslinks ensuring the structural integrity of the hydrogels that can clench a large amount of water. These skin substitutes are fine-tuned to reiterate the aspects of the wound healing cascade to facilitate complete skin repair with restored function and tissue integrity. This study reviews and discusses the various aspects of hydrogels and their role in diabetic wound healing.

Preparation of nickel-chelated iminodiacetate-functionalized macroporous agarose monolith using modular and clickable building blocks for affinity separation of histidine-tagged recombinant proteins

Selective separation and purification of protein from complex medium is required to completely investigate the structure and function of the target protein. In this study, a composite macroporous agarose monolith containing iminodiacetate-chelated Ni2+ ligands was synthesized for selective separation and purification of histidine-tagged recombinant proteins. The large and interconnected pores in the monolith enabled fast binding of proteins with high matrix tolerance in treating complex mediums. To realize the selective protein binding, the iminodiacetate was directly conjugated to epoxy-functionalized agarose monolith via simple chemical reactions between epoxy and imino groups. After chelated Ni2+, the composite monolith could bind histidine-tagged recombinant proteins through the coordination interaction between transition metal ions and the imidazole ring of histidine. To further increase the binding capacities of the monolith, a hydrophilic intermediate polymer chain containing multiple iminodiacetate immobilization sites was conjugated to the azide-functionalized agarose monolith via Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The morphology and chemical composition of the composite agarose monolith were characterized systematically. The protein binding capacities of the obtained composite agarose monolith were subsequently investigated. The binding capacities of the composite agarose monolith towards the model proteins Gp10 and Lys84 were 0.93 and 0.51 mg/mL, respectively. The protein binding of the composite agarose monolith could be manipulated by adjusting the temperature and concentrations of imidazole. These results demonstrate that the composite agarose monolith could be used as an affinity medium for rapid separation and purification of histidine-tagged recombinant proteins from biological samples.

Significant Interfacial Dielectric Relaxation of Covalently Bonded Ice-Hydrogels.

Hydrogels are composed of a three-dimensional network of cross-linked hydrophilic polymer chains and large amounts of water. The physicochemical properties of the polymer-water interface in hydrogels draw our attention. Due to the complex structure of hydrogel systems, it is still a challenge to investigate the interfacial layer properties of hydrogels through experiments. In this work, we investigate the properties of the covalently bonded chitosan-based ice-hydrogels interfacial layer by dielectric relaxation spectroscopy (DRS) techniques in the presence of avoided electrode polarization. The DRS data exhibit that the polymer-water interfacial layer has a strong dielectric signal response, which indicates that a large number of polar electric dipoles or polar molecules may be contained in the interfacial layer. The variable temperature dielectric relaxation behavior of a series of chitosan-base ice-hydrogels showed that the value of dielectric activation energy for different water contents is about 180 kJ/mol, which is much larger than that of the polymer and ice phases, suggesting a strong coupling of polar electric dipoles within the interfacial layer. This work demonstrates the important role of the polymer-water interface in covalently bonded hydrogels, which will provide assistance in the design and application of covalently bonded hydrogels.

Collagen and Keratin as a Components of Hydrogels

Abstract Smart hydrogels, or stimuli-responsive hydrogels, can and should play an important role as excellent drug carriers. These three-dimensional structure materials are composed of crosslinked hydrophilic polymer chains that are able to dramatically change their volume and other properties in response to environmental stimuli, such as pH, temperature and solvent changes. The main goal of individual research projects was the development of new hydrogels based on polypeptides. These hybrid materials are crosslinked hydrophilic polymers capable of absorbing large amounts of water, saline or physiological solutions. Superabsorbent hydrogels based on natural materials are non-toxic, biocompatible and biodegradable. Unfortunately, their mechanical properties in the swollen state are weak. In this article, we present a review of literature on the synthesis of smart hydrogels based on keratin or collagen with synthetic materials.