Nanotoxicity of two-dimensional nanomaterials on human skin and the structural evolution of keratin protein.

Two-dimensional (2D) materials have been increasingly widely used in biomedical and cosmetical products nowadays, yet their safe usage in human body and environment necessitates a comprehensive understanding of their nanotoxicity. In this work, the effect of pristine graphene and graphene oxide (GO) on the adsorption and conformational changes of skin keratin using molecular dynamics simulations. It is found that skin keratin can be absorbed through various noncovalent driving forces, such as van der Waals (vdW) and electrostatics. In the case of GO, the oxygen-containing groups prevent tighter contact between skin keratin and the graphene basal plane through steric effects and electrostatic repulsion. On the other hand, electrostatic attraction and hydrogen bonding enhance their binding affinity to positively charged residues such as lysine and arginine. The secondary structure of skin keratin is better preserved in GO system, suggesting that GO has good biocompatibility. The charged groups on GO surface perform as the hydrogen bond acceptors, which is like to the natural receptors of keratin in this physiological environment. This work contributes to a better knowledge of the nanotoxicity of cutting-edge 2D materials on human health, thereby advancing their potential biological applications.

Thermal and Rheological Performances Evaluation of a Modified Biopolymer for Fracturing Fluid System.

Developing an efficient fracturing fluid system is an enduring hot topic in the petrochemical industries, especially regarding the exploitation of limited oil. Biopolymers, especially polysaccharides (e.g., konjac gum, guar gum), are widely applied as fracturing fluids in fracturing as a result of their advantages. Herein, we propose an easy method of modifying konjac gum (KGM) using isopropanol, sodium hydroxide, and chloroacetic acid to obtain modified konjac glum (MKGM). The MKGM and KGM gels were also obtained by using the self-prepared organic titanium high-temperature stabilizer and organic borate cross-linker. The prepared MKGM was characterized by multiscale techniques, including attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and rheology properties. The ATR-FTIR results showed that the etherification modification reaction occurred as designed. The XRD results showed that the regularity of KGM was destroyed after modification. The TGA and DSC results showed that the thermal stability improved. Rheology measurements illustrated that the temperature and shear resistance of MKGM were better than those of KGM. The MKGM gel could be applied in fracturing fluid systems at a lower frequency through viscoelastic measurements.

Molecularly Imprinted Materials for Selective Biological Recognition.

Molecular imprinting is an approach of generating imprinting cavities in polymer structures that are compatible with the target molecules. The cavities have memory for shape and chemical recognition, similar to the recognition mechanism of antigen-antibody in organisms. Their structures are also called biomimetic receptors or synthetic receptors. Owing to the excellent selectivity and unique structural predictability of molecularly imprinted materials (MIMs), practical MIMs have become a rapidly evolving research area providing key factors for understanding separation, recognition, and regenerative properties toward biological small molecules to biomacromolecules, even cell and microorganism. In this review, the characteristics, morphologies, and applicability of currently popular carrier materials for molecular imprinting, especially the fundamental role of hydrogels, porous materials, hierarchical nanoparticles, and 2D materials in the separation and recognition of biological templates are discussed. Moreover, through a series of case studies, emphasis is given on introducing imprinting strategies for biological templates with different molecular scales. In particular, the differences and connections between small molecular imprinting (bulk imprinting, "dummy" template imprinting, etc.), large molecular imprinting (surface imprinting, interfacial imprinting, etc.), and cell imprinting strategies are demonstrated in detail. Finally, future research directions are provided.

Enhancing adsorption capacity while maintaining specific recognition performance of mesoporous silica: a novel imprinting strategy with amphiphilic ionic liquid as surfactant.

In order to facilitate the broad applications of molecular recognition materials in biomedical areas, it is critical to enhance their adsorption capacity while maintaining their excellent recognition performance. In this work, we designed and synthesized well-defined peptide-imprinted mesoporous silica (PIMS) for specific recognition of an immunostimulating hexapeptide from human casein (IHHC) by using amphiphilic ionic liquid as the surfactant to anchor IHHC via a combination of one-step sol-gel method and docking oriented imprinting approach. Thereinto, theoretical calculation was employed to reveal the multiple binding interactions and dual-template configuration between amphiphilic ionic liquid and IHHC. The fabricated PIMS was characterized and an in-depth analysis of specific recognition mechanism was conducted. Results revealed that both adsorption and recognition capabilities of PIMS far exceeded that of the NIMS's. More significantly, the PIMS exhibited a superior binding capacity (60.5 mg g-1), which could increase 18.9% than the previous work. The corresponding imprinting factor and selectivity coefficient could reach up to 4.51 and 3.30, respectively. The PIMS also possessed lickety-split kinetic binding for IHHC, where the equilibrium time was only 10 min. All of these merits were due to the high surface area and the synergistic effect of multiple interactions (including hydrogen bonding, π-π stacking, ion-ion electrostatic interactions and van der Waals interactions, etc) between PIMS and IHHC in imprinted sites. The present work suggests the potential application of PIMS for large-scale and high-effective separation of IHHC, which may lead to their broad applications in drug/gene deliver, biosensors, catalyst and so on.

Preparation of l-phenylalanine-imprinted solid-phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l-phenylalanine from human urine.

A novel l-phenylalanine molecularly imprinted solid-phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion-pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid-phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l-phenylalanine. Under the optimized conditions of the procedure, an analytical method for l-phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse-phase silica gel, the obtained molecularly imprinted polymer as an solid-phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L(-1) ) for the isolation of l-phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion-pair dummy template imprinting is effective for preparing selective solid-phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples.

Preparation of "dummy" l-phenylalanine molecularly imprinted microspheres by using ionic liquid as a template and functional monomer.

In this study, dummy imprinting technology was employed for the preparation of l-phenylalanine-imprinted microspheres. Ionic liquids were utilized as both a "dummy" template and functional monomer, and 4-vinylpyridine and ethylene glycol dimethacrylate were used as the assistant monomer and cross-linker, respectively, for preparing a surface-imprinted polymer on poly(divinylbenzene) microspheres. By the results obtained by theoretical investigation, the interaction between the template and monomer complex was improved as compared with that between the template and the traditional l-phenylalanine-imprinted polymer. The batch experiments indicated that the imprinting factor reached 2.5. Scatchard analysis demonstrated that the obtained "dummy" molecularly imprinted microspheres exhibited an affinity of 77.4 M·10-4 , significantly higher that of a traditional polymer directly prepared by l-phenylalanine, which is in agreement with theoretical results. Competitive adsorption experiments also showed that the molecularly imprinted polymer with the dummy template effectively isolated l-phenylalanine from l-histidine and l-tryptophan with separation factors of 5.68 and 2.68, respectively. All these results demonstrated that the polymerizable ionic liquid as the dummy template could enhance the affinity and selectivity of molecularly imprinted polymer, thereby promoting the development of imprinting technology for biomolecules.

Thermal preparation of lysozyme-imprinted microspheres by using ionic liquid as a stabilizer.

Thermal preparation of lysozyme-imprinted microspheres was firstly investigated by using biocompatible ionic liquid (IL) as a thermal stabilizer. The imprinted microspheres made with IL could obtain the good recognition ability to template protein, whereas the imprinted polymer synthesized in the absence of it had a similar adsorption capacity to the non-imprinted one. Furthermore, the preparation conditions of imprinted polymers (MIPs) including the content of IL, temperature of polymerization, and types of functional monomers and crosslinkers were systematically analyzed via circular dichroism spectrum and activity assay. The results illustrated that using hydroxyethyl acrylate as the functional monomer, ethylene glycol dimethacrylate as the crosslinker, 5 % IL as the stabilizer, and 75 °C as the reaction temperature could retain the structure of template protein as much as possible. The obtained MIPs showed excellent recognition ability to the template protein with the separation factor and selectivity factor value of 4.30 and 2.21, respectively. Consequently, it is an effective way to accurately imprint and separate template protein by cooperatively using circular dichroism spectroscopy and activity assay during the preparation of protein MIPs. The method of utilizing IL to stabilizing protein at high temperature would offer a good opportunity for various technologies to improve the development of macromolecules imprinting.

Fluorescent Carbon Dioxide-Based Polycarbonates Probe for Rapid Detection of Aniline in the Environment and Its Biomarkers in Urine.

Aniline compounds, as a class of widely used but highly toxic chemical raw materials, are increasingly being released and accumulated in the environment, posing serious threats to environmental safety and human health. Therefore, developing detection methods for aniline compounds is of particular significance. Herein, we synthesized the fluorescent third monomer cyano-stilbene epoxide M and ternary copolymerized it with carbon dioxide (CO2) and propylene oxide (PO) to synthesize carbon dioxide-based polycarbonate (PPCM) with fluorescence recognition functions, as well as excellent performance, for the first time. The results revealed that the PPCM fluorescent probe exhibited typical aggregation-induced luminescence properties and could be quenched by aniline compounds. The probe presented anti-interference-specific selectivity for aniline compounds, and the detection limit was 1.69 × 10-4 M. Moreover, it was found to be a highly sensitive aniline detection probe. At the same time, the aniline biomarker p-aminophenol in urine could also be detected, which could expand the potential applications of polymers in the fluorescence-sensing field.

On the interface between biomaterials and two-dimensional materials for biomedical applications.

Two-dimensional (2D) materials have garnered significant attention due to their ultrathin 2D structures with a high degree of anisotropy and functionality. Reliable manipulation of interfaces between 2D materials and biomaterials is a new frontier for biomedical nanoscience and combining biomaterials with 2D materials offers a promising way to fabricate innovative 2D biomaterials composites with distinct functionality for biomedical applications. Here, we focus exclusively on a summary of the current work in the interface investigation of 2D biomaterials. Specifically, we highlight extraordinary features that make 2D materials so desirable, as well as the molecular level interactions between 2D materials and biomaterials that have been studied thus far. Furthermore, the approaches for investigating the interface characteristics of 2D biomaterials are presented and described in depth. To capture the emerging trend in mass manufacturing of 2D materials, we review the research progress on biomaterial-assisted exfoliation. Finally, we present a critical assessment of newly developed 2D biomaterials in biomedical applications.

Enhanced Stability and Mechanical Properties of a Graphene-Protein Nanocomposite Film by a Facile Non-Covalent Self-Assembly Approach.

Graphene-based nanocomposite films (NCFs) are in high demand due to their superior photoelectric and thermal properties, but their stability and mechanical properties form a bottleneck. Herein, a facile approach was used to prepare nacre-mimetic NCFs through the non-covalent self-assembly of graphene oxide (GO) and biocompatible proteins. Various characterization techniques were employed to characterize the as-prepared NCFs and to track the interactions between GO and proteins. The conformational changes of various proteins induced by GO determined the film-forming ability of NCFs, and the binding of bull serum albumin (BSA)/hemoglobin (HB) on GO's surface was beneficial for improving the stability of as-prepared NCFs. Compared with the GO film without any additive, the indentation hardness and equivalent elastic modulus could be improved by 50.0% and 68.6% for GO-BSA NCF; and 100% and 87.5% for GO-HB NCF. Our strategy should be facile and effective for fabricating well-designed bio-nanocomposites for universal functional applications.

Zero-Waste Recycling of Fiber/Epoxy from Scrap Wind Turbine Blades for Effective Resource Utilization.

The number of scrap wind turbines is expanding globally as the wind power industry develops rapidly. Zero-waste recycling of scrap wind turbine blades (WTB) is the key for wind power firms to achieve green and sustainable development on the premise of satisfying environmental protection criteria. In this work, the pyrolysis of fiber/epoxy composites obtained from scrap WTB in oxidizing inert atmospheres was investigated. Various characterization methods were employed to characterize the microstructure and chemical characteristics of the heat-treated fiber/epoxy and to reveal the pyrolysis mechanism. In addition, the heat-treated fibers/epoxy were used as reinforcing agents to investigate their impact on the elastic deformation of butadiene styrene rubber-based flexible composites, and the reinforcing mechanism was revealed. The results revealed that the constituents of fiber/epoxy composites were mostly fiberglass (SiO2, CaCO3) and cured epoxy resin, with covalent bonding being the interaction between the fiberglass and epoxy resin. The total weight of the epoxy resin in the fiber/epoxy composites was 22%, and the 11% weight loss was achieved at around 350 °C, regardless of the presence of oxygen; however, the features of heat-treated fibers/epoxy were associated with the pyrolysis atmosphere at a higher temperature. The pyrolysis products in inert atmospheres, with water contact angles of 58.8°, can considerably improve the tensile properties of flexible composites at the elastic stage. Furthermore, the flexible composite granules were prepared to plug large channels in sand-filled pipes, and the plugging rate had the potential to reach 81.1% with an injection volume of 5.0 PV. The plugging performance was essentially unaffected by water salinity, owing to the high stability of flexible composite granules in mineralized water. The findings of this study present a realistic route to the industrial application of fiber/epoxy, as well as a novel approach for encouraging the efficient use of scrap wind turbines on a large scale.

Non-covalent loading of ionic liquid-functionalized nanoparticles for bovine serum albumin: experiments and theoretical analysis.

Biomacromolecule-based nanomaterials have attracted much attention due to their excellent function in sensing, catalysis, medicine, biology and recognition. In this work, a silane-coupling ionic liquid, 1-(3-trimethoxysilylpropyl)-3-methylimidazolium chloride ([TMIM]Cl), was synthesized and applied to prepare ionic liquid-functionalized nanoparticles (SiO2@IL) using surface grafting technology. By employing multiple non-covalent interactions, including electrostatic interactions, hydrogen bonding and π-π stacking, the obtained functional nanoparticles were able to bind bovine serum albumin (BSA) with strong binding affinity, which has been illustrated through experiments and theoretical calculations. Moreover, the stability of SiO2@IL further demonstrated that it is promising in applications for biomacromolecule immobilization.

Bottom-Up Formation of Carbon-Based Magnetic Honeycomb Material from Metal-Organic Framework-Guest Polyhedra for the Capture of Rhodamine B.

Three-dimensional carbon-based porous materials have proven to be quite useful for tailoring material properties in the energy conservation and environmental protection applications. In view of the three-dimensional and well-defined structure of metal-organic frameworks (MOFs), a novel carbon-based magnetic porous material (HKUST-Fe3O4) has been designed and constructed by MOF-guest interactions of high-temperature pyrolysis. The obtained HKUST-Fe3O4 exhibited the unique features of superparamagnetism, a macro/mesoporous structure, environmental protection (inexistence of toxic heavy metal ions), and physicochemical stability and has shown high adsorption capacity and rapid adsorption for carcinogenic organic pollutants (for example, rhodamine B) with an environmentally friendly character and excellent reusability. We demonstrate that the unique/superior advantages of HKUST-Fe3O4 could meet the requirements of environment cleaning, especially for removing the targeted organic pollutant from water. Moreover, the specific HKUST-Fe3O4 and organic pollutant interaction mechanism has been analyzed in detail via parameter-free calculations. This study proposes a promising strategy for constructing novel carbon-based magnetic nanomaterials for various applications, not limitated to pollutant removal.

Three-dimensional Cu/C porous composite: Facile fabrication and efficient catalytic reduction of 4-nitrophenol.

Developing a facile method to fabricate new heterogeneous Metal-Organic Framework (MOFs) based catalysts with high catalytic activity and stability has drawn significant attention. Herein, we demonstrate a simple in-situ pyrolysis reduction strategy to fabricate a novel three-dimensional (3D) Cu-based catalyst, which displays an outstanding performance for the decomposition of 4-nitrophenol (4-NP). Detailed characterization including SEM, FTIR, XPS, ICP-OES, HRTEM, SAED, XRD and BET confirmed the formation of the Cu/C porous composites (Cu/C-PC). Taking advantage of enormous Cu particles in the composite as well as ultrahigh surface area (196.7 m2/g) of carbon support, Cu/C-PC presents prominent catalytic activity for the hydrogenation reduction 4-NP to 4-aminophenol (4-AP) with apparent rate constant (Kapp) of 0.0267 s-1 (the ratio of Kapp to the catalyst amount is 119 s-1 g-1), which is dramatically higher than that previous reports. On the contrary, after being washed successively (Cu/C-PC-AW) by FeCl3, HCl aqueous solution and deionized water, the Cu/C porous composite materials exhibit fairly weak catalytic activity. The catalytic performance of Cu/C-PC is better than Cu, Cu2O and CuO nanoparticles as well as other catalysts in previous reports. Furthermore, Cu/C-PC shows excellent reusability, indicating its potential applications in treatment of water pollution.

Synergetically understanding the interaction between nano/microspheres and peptide for controllable drug loading via experimental and theoretical approaches.

In this paper we systematically investigate the loading capacity of raspberry-like nano/microspheres with highly cross-linked structure for the peptide, immunostimulating hexapeptide from human (IHH), by integrating both experimental and simulation efforts. The experimental results indicate that the loading capacities of raspberry-like nano/microspheres with different functionalized chains vary drastically. To provide theoretical insights into the observed phenomenon, the typical raspberry-like nano/microspheres were simplified as effective functionalized groups, thereby the interactions between them and IHH were accurately calculated by ab initio method. The ab initio results agree well with the experimental observations, and the underlying binding mechanism is analyzed in great details. It is shown that hydrogen bonding plays an important role and the binding affinity strongly depends on the functionalized motifs. Therefore, this work provides insightful guidance to controlling the drug loading by design of the functionalized surface of nanomaterials.

Surface modification of imprinted polymer microspheres with ultrathin hydrophilic shells to improve selective recognition of glutathione in aqueous media.

A universal, effective approach addressing the classical limitations of hydrophobic molecularly imprinted polymer (MIP) microspheres was described. Two water-compatible MIP microspheres with ultrathin hydrophilic shells were synthesized by controllable surface-graft polymerization using a charged monomer (methacrylic acid) and uncharged monomer (N-isopropylacrylamide) as the hydrophilic functional monomers for the recognition of glutathione in the aqueous medium. The morphological and chemical characteristics of the as-prepared water-compatible MIP microspheres were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Their selective recognition properties were investigated by static binding tests and compared with those of the ungrafted MIP microspheres. The results of this study showed that the both as-prepared water-compatible MIP microspheres effectively decreased non-specific binding and enhanced the imprinting factor significantly, and the water-compatible MIP microspheres prepared using N-isopropylacrylamide as monomer exhibited a more remarkable recognition property. In addition, the thickness of surface-grafted hydrophilic layer was well controlled by adjusting the irradiation time to obtain the excellent recognition property. Finally, the applicability of the as-prepared water-compatible MIP microspheres as solid-phase extraction materials was investigated by competitive binding tests using a mixture of glutathione and its analogs.

Preparation of surface-imprinted microspheres effectively controlled by orientated template immobilization using highly cross-linked raspberry-like microspheres for the selective recognition of an immunostimulating peptide.

Surface-imprinted microspheres were controllably synthesized using ionic liquid-functionalized microspheres with a highly cross-linked raspberry-like structure as the matrix via surface molecular self-assembly and precipitation polymerization in aqueous media at room temperature. An immunostimulating hexapeptide from human (IHH) with medical properties was chosen as a template molecule in the preparation of different molecularly imprinted microspheres (MIMs). The experiment process was tracked and the as-prepared microspheres were well characterized. Results reveal that the adsorption capacity and selective recognition of MIMs have a direct relationship with the properties of the functional chain of the ionic liquid-functionalized microspheres. Moreover, MIMs that have both high adsorption capacity and good selective recognition were used in competitive rebinding tests and analysis of urine samples, which demonstrated their potential use for IHH enrichment and in real samples.

Water-compatible surface-imprinted microspheres for high adsorption and selective recognition of peptide drug from aqueous media.

Novel water-compatible ionic liquid-functionalized microspheres with molecularly imprinted shell layer were controllably synthesized via precipitation polymerization and surface imprinting technique. Here, a room-temperature ionic liquid was synthesized to prepare these surface-imprinted microspheres with excellent water solubility and multiple binding sites with template molecules. The peptide drug thymopentin (TP5) was chosen as a template molecule, which is known as an immunomodulating agent. The as-prepared microspheres were fully characterized. Results reveal that ionic liquid incorporation significantly improves the adsorption of TP5. Moreover, the adsorption property and recognition capability towards TP5 are closely related to the synergetic effect of electrostatic interaction and hydrogen bonding. Through employing the synergetic effect of directional and non-directional interactions, the surface-imprinted microspheres exhibit high adsorption capacity, good selective recognition, and rapid binding ability for TP5. The surface-imprinted microspheres demonstrate potential usage for TP5 enrichment from other biomolecules, and the proposed method was successfully applied for TP5 determination in thymopentin injection and urine.

The effectively specific recognition of bovine serum albumin imprinted silica nanoparticles by utilizing a macromolecularly functional monomer to stabilize and imprint template.

Structural stability of the template is one of the most important considerations during the preparation of protein imprinting technology. To address this limitation, we propose a novel and versatile strategy of utilizing macromolecularly functional monomers to imprint biomacromolecules. Results from circular dichroism and synchronous fluorescence experiments reflect the macromolecularly functional monomers tendency to interact with the protein surface instead of permeating it and destroying the hydrogen bonds that maintain the protein's structural stability, therefore stabilizing the template protein structure during the preparation of imprinted polymers. The imprinted polymers composed of macromolecularly functional monomers or their equivalent micromolecularly functional monomers over silica nanoparticles were characterized and carried out in batch rebinding test and competitive adsorption experiments. In batch rebinding test, the imprinted particles prepared with macromolecularly functional monomers exhibited an imprinting factor of 5.8 compared to those prepared by micromolecularly functional monomers with the imprinting factor of 3.4. The selective and competitive adsorption experiments also demonstrated the imprinted particles made by macromolecularly functional monomers possessed much better selectivity and specific recognition ability for template protein. Therefore, using macromolecularly functional monomers to imprint may overcome the mutability of biomacromolecule typically observed during the preparation of imprinted polymers, and thus promote the further development of imprinting technology.