•KH-560 molecules have been successfully grafted on the GNPs’ surface.•Thermal conductivity of fGNPs/E-51 nanocomposite with 30wt% fGNPs is 1.698W/mK.•Thermal stabilities of the nanocomposites are ...increased with the addition of fGNPs.
Graphite nanoplatelets (GNPs) are performed to fabricate GNPs/bisphenol-A epoxy resin (GNPs/E-51) nanocomposites with high thermal conductivity via casting method. And the “two-step” method of methanesulfonic acid/γ-glycidoxypropyltrimethoxysilane (MSA/KH-560) is introduced to functionalize the surface of GNPs (fGNPs). The KH-560 molecules have been successfully grafted onto the surface of GNPs. The thermal conductivities of the fGNPs/E-51 nanocomposites are increased with the increasing addition of fGNPs, and the corresponding thermally conductive coefficient of the fGNPs/E-51 nanocomposites is improved to 1.698W/mK with 30wt% fGNPs, 8 times higher than that of original E-51 matrix. The flexural strength and impact strength of the fGNPs/E-51 nanocomposites are optimal with 0.5wt% fGNPs. The thermal stabilities of the fGNPs/E-51 nanocomposites are also increased with the increasing addition of fGNPs. For a given GNPs loading, the surface functionalization of GNPs by MSA/KH-560 exhibits a positive effect on the thermal conductivities and mechanical properties of the nanocomposites.
Developing carbon quantum dots (CQDs) from bio-waste lignin for effectively detecting Cu2+ is of great significance for promoting the value-added utilization of lignin resources. However, the limited ...amount of surface-active groups and low quantum yield of lignin-based CQDs hinder their application in this regard. Herein, bio-waste lignin was converted into value-added amine functionalized CQDs using a facile two-step hydrothermal approach. The as-synthesized CQDs modified with amino groups exhibit bright green fluorescence, abundant surface functional groups, high water solubility and uniform particle size (3.9 nm). Systematic analysis demonstrates that the rich NH2 groups (~12.3 %) on the CQDs backbone improve their fluorescence properties (quantum yield increased from 3.4 % to 21.1 %) and specific detection ability for Cu2+. The developed NH2-CQDs serve as an efficient fluorescent probe, displaying high sensitivity and selectivity towards Cu2+ in aqueous system, with a detection limit of 2.42 μmol/L, which is lower than the maximum permitted amount of Cu2+ in drinking water (20 μmol/L). The detection mechanism of NH2-CQDs for Cu2+ is attributed to the synergy of static quenching and photo-induced electron transfer. This study provides a valuable reference for the synthesis of high-quality fluorescent CQDs from lignin resources and the effective detection of trace Cu2+ in aquatic environments.
•Bio-waste lignin was converted into NH2-CQDs by a two-step hydrothermal approach.•The surface modification of the amino group enhanced the QY of CQDs.•NH2-CQDs showed high selectivity and sensitivity towards Cu2+ in an aqueous system.•The detection mechanism is the synergistic effect of static quenching and PET.
Advanced PDMS-based materials: Fabrication, modification, functionalization and applications.
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•Newly bulk modification methods for advanced PDMS materials.•The effect of chemical ...groups on PDMS properties were discussed.•Various surface treatments for their functional applications.•Challenges and opportunities of advance PDMS-based materials.
With the rapid progress of artificial intelligence, robot and medical services, soft polymers with changeable modulus and flexible machinability have become an important kind of strategic materials. Among them, a polydimethylsiloxane (PDMS)-based material is regarded as a promising one due to its flexible chemistry and biocompatibility. Two modification methods are always involved in practical applications of PDMS-based materials, i.e., bulk modifications and surface functionalizations. The former mainly aims to improve the poor mechanical strength of PDMS, while the latter is conducted to meet some functional requirements in the field of smart structures, e.g., surface wettability, anti-freezing, self-cleaning and strong adhesion. As a result, design and fabrication procedures in the modification of PDMS-based materials arise as important and attractive hotspots. In this review, we summarize the recent advances in not only bulk modification strategies for PDMS-based materials but also in the functionalizing methods to realize various surface functions. Correlations between material properties and structural factors including chemical constitution and micro/nano structures are further extracted for guiding the modification of PDMS-based materials. The challenges and prospects in developing surface-functionalized PDMS-based materials are also presented and concluded. It is hoped that this review could help to better understand modification technologies of PDMS-based materials and even stimulate some new thoughts for design and preparation of smart soft materials.
Here we present the use of surface nanopatterning of covalently immobilized BMP-2 and integrin selective ligands to determine the specificity of their interactions in regulating cell adhesion and ...focal adhesion assembly. Gold nanoparticle arrays carrying single BMP-2 dimers are prepared by block-copolymer micellar nanolithography and azide-functionalized integrin ligands (cyclic-RGD peptides or α5β1 integrin peptidomimetics) are immobilized on the surrounding polyethylene glycol alkyne by click chemistry. Compared to BMP-2 added to the media, surface immobilized BMP-2 (iBMP-2) favors the spatial segregation of adhesion clusters and enhances focal adhesion (FA) size in cells adhering to α5β1 integrin selective ligands. Moreover, iBMP-2 copresented with α5β1 integrin ligands induces the recruitment of αvβ3 integrins in FAs. When copresented with RGD, iBMP-2 induces the assembly of a higher number of FAs, which are not affected by α5β1 integrin blocking. Our dual-functionalized platforms offer the possibility to study the crosstalk between integrins and BMP receptors, and more in general they could be used to address the spatial regulation of growth factors and adhesion receptors crosstalk on biomimetic surfaces.
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Heavy metal-containing wastewater can be treated by adsorption technology to obtain ultra-low concentration or high-quality treated effluent. Due to the constraints of the specific surface area, ...surface electrical structure and spatial effect of conventional adsorbents, it is often difficult to obtain adsorbents within high adsorption capacity. Graphene has characteristics of large specific surface area, small particle size, and high adsorption efficiency. It is considered as one of the research hotspots in recent years. However, despite graphene’s unique properties, graphene-based adsorbents still have some drawbacks, i.e. graphene nanosheets are easier to be stacked with each other via π–π stacking and van der Waals interactions, which affect the site exposure, impede the rapid mass transport and limit its adsorption performance. Special strategy is needed to overcome its drawbacks. This work summarizes recent literatures on utilization of three strategies-surface functionalization regulation, morphology and structure control and material composite, to improve the adsorption properties of graphene-based adsorbent towards heavy metal removal. A brief summary, perspective on strategies to improving adsorption properties of graphene-based materials for heavy metal adsorption are also presented. Certainly, this review will be useful for designing and manufacturing of graphene-based nanomaterials for water treatment.
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•Role of surface functionalization regulation for heavy metal removal were summarized.•Effect of morphology and structure control for heavy metal removal were discussed.•Function of material composite for heavy metal removal were summarized.•Perspectives of future research directions for graphene-based adsorbent was presented.
Electrospun polymer nanofibers have received much attention in tissue engineering due to their valuable properties such as biocompatibility, biodegradation ability, appropriate mechanical properties, ...and, most importantly, fibrous structure, which resembles the morphology of extracellular matrix (ECM) proteins. However, they are usually hydrophobic and suffer from a lack of bioactive molecules, which provide good cell adhesion to the scaffold surface. Post-electrospinning surface functionalization allows overcoming these limitations through polar groups covalent incorporation to the fibers surface, with subsequent functionalization with biologically active molecules or direct deposition of the biomolecule solution. Hydrophilic surface functionalization methods are classified into chemical approaches, including wet chemical functionalization and covalent grafting, a physiochemical approach with the use of a plasma treatment, and a physical approach that might be divided into physical adsorption and layer-by-layer assembly. This review discusses the state-of-the-art of hydrophilic surface functionalization strategies of electrospun nanofibers for tissue engineering applications. We highlighted the major advantages and drawbacks of each method, at the same time, pointing out future perspectives and solutions in the hydrophilic functionalization strategies.
Upconversion nanoparticles (UCNPs) offer a myriad of opportunities for bioanalytical applications, well beyond those of their down-converting counterparts (QDs, organic dyes, etc.). It is due to ...their several unique photophysical attributes of UCNPs, including: large anti-Stokes shift, improved penetration depth in biological tissues, resistance to photobleaching, low autofluorescence background, remarkable chemical stability, and low toxicity. Plenty of articles have provided details on UCNP synthesis, photophysical characteristics, and their use in therapeutics. Herein, we provide a comprehensive description on their analytical applications in light of the surge in UCNP research over last few years. Beginning with a brief overview on concepts related to the luminescent properties of UCNPs, it leads into the essential surface-functionalization strategies that have been adopted thus far in designing UCNP probes. Subsequently, a comprehensive detail of recent advancements in UCNP probe development is provided. Finally, current challenges in UCNP research and future prospects have been discussed.
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•NIR excitation and anti-Stokes emissions of UCNPs are used for probes.•Donor-acceptor distance is critical in designing UCNPs for luminescent RET.•Facile surface modifications incorporate versatile moieties on UCNPs.•The UCNP based probes have been used for sensing over a wide range of analytes.•UCNPs are placed into point-of-care devices via sandwich assay modes.
High-performance chemiresistor gas sensor made of sulfide porous GaN decorated with Pt nanoparticles, which shows tunable sensor response and enhanced sensitivity. The fabricated gas sensors show ...detection of H2 down to 30 ppm at 23 °C after sulfide treatment and Pt decorated porous GaN. The response time and recovery time were equal to 47 s and 113 s, respectively. Density functional theory simulations were used to support the detection mechanism based on sulfide treatment. Adsorption energy calculations showed that H adsorption energy is lowered by the simultaneous presence of S and Pt on the GaN (0001) surface. The density of states (DOS) calculations revealed possibility of bond strengthening when Pt and S is adsorbed on GaN surface along with H, arising from the hybridization of d and p orbitals of Pt and S with that of H 1s orbitals.
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•High performance sulfide treated Pt/porous GaN gas sensors has been developed.•H2 gas sensor was working at room temperature, selective, simple, and low cost.•Detection mechanism was investigated and supported by DFT simulations.•A bond strengthening when Pt and S is adsorbed on porous GaN surface along with H.•Sulfide treatment improve significantly H2 detection at room temperature.
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