Facile Surface Modification Research Articles

(Invited) Gold Nanowire Electronic Skins for Wearable Biochemical Monitoring

Next generation of electronic devices will be not only flexible but also stretchable, enabling applications impossible to achieve with existing rigid circuit board technologies. This needs new materials and new design principles. Among various materials of choices, gold has advantages of biocompatibity, chemical inertness, facile synthesis/Surface functionalisation and band-gap-matching with a lot of semiconductors materials. In this talk, I will discuss our newly developed standing gold nanowire-based soft electrochemical biosensing platform in the forms of patches, fibers and tattoos. The unique Janus structures, high surface area and facile surface modification offer materials attributes for next-generation wearable biodianostics for real-time monitoring vitals such as glucose, latctate and catitionic ions.

Antifouling low-pressure highly permeable single step produced loose nanofiltration polysulfone membrane for efficient Erichrome Black T/divalent salts fractionation

Nanofiltration (NF) membranes are effective in treating wastewater containing organics, dyes, and divalent salts; however, lacking the capability of fractionating the dyes/divalent salts, which is crucial for the treatment of the textile wastewater. Loose NF with excellent permeability is highly required to effectively fractionate the dye and divalent salts. Herein, a facile surface modification of ultrafiltration (UF) membranes with the loose layer of nanosilver immobilized polydopamine have been reported. The self-initiated dopamine polymerization on the polysulfone (PS) coordinated with the silver (Ag) to form a loosely held layer of the silver immobilized polydopamine functionalized polysulfone membrane (L-Ag-PDA-PS-membrane). The original polysulfone membrane had a contact angle of ~ 65° that was reduced to ~ 25° after nanosilver immobilization. Fabricated membranes were thoroughly investigated by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), and contact analyzer. High rejection of 99.9% of Eriochrome Black T (EBT) was witnessed with the exceptionally high permeation flux of 39.2 LMH using L-Ag-PDA-PS-membrane. The polydopamine (PDA)-silver modified membranes showed higher permselectivity than the PDA-only counterparts, the former rejecting the dye altogether while letting most of the divalent ions (Mg2+, SO42-) pass through. Long-term fouling runs in the presence of bovine serum albumin (BSA) showed that the presence of Ag/PDA slowed down the rate of flux decline considerably, and flux decline was only 15.6% after 6 h of continuous operation in the presence of the foulants. The designed membrane is an excellent example for fractionating the dye and divalent salts.

Sustainable green functional nano aluminium fumarate-MOF decorated on 3D low-cost natural diatoms for the removal of Congo red dye and fabric whitening agent from wastewater: Batch & continuous adsorption process

Industrial contaminants such as dyes being released into water streams, making the water unfit for the domestic purposes. Treatment of such dye contaminants still remains as a challenge which transformed as leading issues in environment remediation. Some of the important limitations involved in the dye adsorption includes cumbersome synthetic routes, high cost adsorbents, more contact time, lack of efficiencies and usage of more adsorbents. To address these drawbacks, present work involves facile surface modification of 3D diatoms (DE) with 2D aluminium fumarate metal-organic framework (Al-MOF) as a sustainable approach to obtain hybrid materials for the removal of industrial important toxic dyes. It is significant to note that the surface area of diatoms increased dramatically from 16.6 to 1330.8 m2g−1 revealing that the surface modifications with Al-MOF played a significant role in tuning the surface properties of DE. The developed hybrid materials were investigated for batch adsorption studies for the removal of CR dye which displayed outstanding 98.13% removal efficiency for just 20 mg of adsorbent with rapid contact time of 15 min. Moreover, the maximum adsorption capacity (qm) was found to be 181.82 mg/g, which is of better significance. Further, hybrid materials were adapted as powder-based membranes a continuous flow adsorption studies where 100 mg of materials showed excellent 99.65% of rejection performances with flux rate of 1747.1 Lm−2h−1. To demonstrate their capability in real-time sample analysis, 100 mg of hybrid materials were used for the removal of fabric whitening agent through batch adsorption and continuous flow studies exhibited with effective 94% and 99.2% efficiencies respectively. Additionally, the reusability test of adsorbents showed it could be used up to 6 cycles where the adsorbents can be regenerated with facile methanol wash. The developed hybrid materials could be one of the potential candidates for the removal of hazardous textile dye from wastewater since the adsorbent displayed rapid adsorption, efficient removal, utilization of minimal adsorbents, better reusability and finally substantiated with real time sample analysis.

Functional gradient coating of alumina on net shaped zirconia implant: Improved strength, aging resistance, and role of residual stress

Aging of zirconia in vivo has been widely discussed as a potential cause of implant degradation over time. Hydrothermal degradation is sensitive to composition, process conditions, and microstructure leading to an emphasis on secondary phases, and grain boundary engineering for aging resistance. However, surface coatings, resultant residual stress, and associated physical constraint for phase stabilization are insufficiently explored. Herein a novel ceramic dough processing facilitated the formation of a functional gradient alumina coating (20–50 µm) below the critical thickness, on net-shaped green zirconia dental implant while preserving the fine machined threads. Residual stress (~ −0.8 GPa) after sintering improved the characteristic strength by ~ 45% with a simultaneous contribution to profound phase preservation after in vitro aging. Thus, the compositional gradient coating on green zirconia components using alumina-based slurries is a facile surface modification technique to inhibit moisture-induced aging.

Enhanced luminescence and dispersion stability of lead halide perovskite nanocrystals by surface modification via O/W emulsion

Metal halide perovskite nanocrystals (NCs) attract tremendous research attentions as next-generation functional materials due to their excellent photophysical nature. A common disadvantage of perovskite NCs is very poor stability and dispersibility in polar solvents. Then, we encapsulate CsPbBr3 NCs into an oil-in-water (O/W) emulsion formed with sodium bis(2-ethylhexyl)sulfosuccinate (AOT) to improve their dispersion property and chemical stability. X-ray diffraction and X-ray photoemission spectroscopy indicate that the non-luminescent Cs4PbBr6 NC precursor converted to luminescent CsPbBr3 NCs in the O/W emulsion process, as excess CsBr dissociated at emulsion interfaces. CsPbBr3 NCs encapsulated with an AOT-based emulsion shell (AOT-modified CsPbBr3 NCs) were obtained after freeze-drying the O/W emulsion, exhibiting good dispersibility in hydrophilic polar solvents such as alcohols and water. The photoluminescence intensity of AOT-modified CsPbBr3 NCs remained 40–56% even after dispersion in water for 180 min, while unmodified ones rapidly degraded within 30 min. These results suggest that the interfacial molecular order of the O/W emulsion should be condensed on the surfaces of CsPbBr3 NCs and enhance their affinity and stability to polar solvents. The present findings provide a facile surface modification approach to attain perovskite and related halide compounds NCs applicable to polar solvents or water environments.

Facile Surface Modification of Ultrathin Gold Nanowires Film with Hydrogen Sulfide for Improvement of Stability

Ultrathin gold nanowires (AuNWs) have an important role and promising applications in areas of wearable sensors, matter detection, and flexible transparent electronic materials. But oleylamine (OAm) ligand on the ultrathin AuNWs surface leads to high junction resistance and the inherent Rayleigh instability leads to decomposition into gold spheres within a few days. To eliminate these two disadvantages, herein, the implementation of one facile H2S gas treatment method to improve the conductivity and stability of ultrathin AuNWs is tried. The conductivity of AuNWs on the interdigital electrode can be improved by 4 × 107 times because the AuNWs became bent and cross‐linked, due to the H2S exchange of the ligand OAm. In addition, the conductivity of the three‐layer ultrathin AuNW film on polyethylene terephthalate (PET) can be improved by at least 2000 times. The ultrafine structure of AuNWs can be maintained for more than 1 week at room temperature, which attributes to H2S that can protect the surface structure of AuNWs. The findings highlight a new method of the ultrathin AuNWs for exceeding improvement in electronic conduction and stability.

Nanofiltration performance of glutaraldehyde crosslinked graphene oxide-cellulose nanofiber membrane

Cellulose nanofibers have been widely used in membrane fabrication due to their unique structure, hydrophilicity, sustainability, facile surface modification, and low cost. In this study, the efficient combination of the precise molecular sieving characteristics of graphene oxide (GO) and the high permeability of the cellulose nanofibers (CNFs) network is demonstrated. GO nanosheets were incorporated into the CNF matrix using a facile vacuum filtration technique followed by chemical cross-linking. Cross-linking with glutaraldehyde not only resisted membrane swelling but also improved molecular selectivity. The nanofiltration performance of prepared membranes was evaluated in both aqueous and organic solutions. The optimized crosslinked membranes exhibited a pure solvent flux of 13.9 ± 1.9 Lm−2h−1bar−1 and 4.1 ± 0.35 Lm−2h−1bar−1 for water and ethanol respectively, while maintaining a rejection above 90% for Rose Bengal and Brilliant Blue dyes.

Boosting Electrochemical Activity of Porous Transparent Conductive Oxides Electrodes Prepared by Sequential Infiltration Synthesis (Small 12/2022)

Electrochemistry Electrodes In article number 2105898, Nari Jeon and co-workers present the fabrication of porous, conductive, transparent indium zinc oxides thin films using sequential infiltration synthesis. Their potential as electrodes for electrochemical applications is owed to their excellent chemical inertness, large electrochemically active surface areas, and facile surface modification with ferrocene derivatives.

Bifunctional Asymmetric Fabric with Tailored Thermal Conduction and Radiation for Personal Cooling and Warming

Abstract Personal thermal management is emerging as a promising strategy to provide thermal comfort for the human body while conserving energy. By improving control over the heat dissipating from the human body, personal thermal management can provide effective personal cooling and warming. Here, we propose a facile surface modification approach to tailor the thermal conduction and radiation properties based on commercially available fabric, to realize better management of the whole heat transport pathway from the human body to the ambient. A bifunctional asymmetric fabric (BAF) offering both a cooling and a warming effect is demonstrated. Due to the advantages of roughness asymmetry and surface modification, the BAF demonstrates an effective cooling effect through enhanced heat conduction and radiation in the cooling mode; in the warming mode, heat dissipation along both routes is reduced for personal warming. As a result, a 4.6 °C skin temperature difference is measured between the cooling and warming BAF modes, indicating that the thermal comfort zone of the human body can be enlarged with one piece of BAF clothing. We expect this work to present new insights for the design of personal thermal management textiles as well as a novel solution for the facile modification of available fabrics for both personal cooling and warming.

Facile and tunable method for polymeric surface modification of magnetic nanoparticles via RAFT polymerization: Preparation, characterization, and drug release properties

Herein, the facile and tunable technique for the preparation of novel multi-stimuli-responsive nanocomposites via RAFT polymerization for DOX delivery is reported. The influence of the molecular weight of pH- and thermo-sensitive poly (acrylic acid-co-NIPAM) (PNAx), as a macro-RAFT agent, on the nanocomposites size and drug release rate was investigated. The outcome of this study reveals that macro-RAFT agent with lower molecular weight can be attached to the surface of magnetic nanoparticles with higher content of polymeric layer than can macro-RAFT agent with higher molecular weight. Also, it was observed that the particle size, polymer grafting density, DOX loading capacity, and DOX release rate could well be influenced by the molecular weight of PNAx. The in vitro drug release of doxorubicin was examined in various conditions (pH and temperature) and the results established a strong pH and thermal dependence. The order of drug-loading and releasing level rate for synthesized nanocarriers toward PNAx molecular weight are PNA3 < PNA2 < PNA1. These magnetic nanocarriers displayed excellent biocompatibility, stability, and dispersibility in aqueous solutions. Therefore, experimental data and results showed that nanocarriers synthesized with various molecular weights of PNAx by RAFT polymerization could be deployed for practical biomedicine applications and that the RAFT polymerization ushers in an excellent technique for tunable and facile surface modification of various nanoparticles with distinct sizes and morphologies.

Design of Ordered Mesoporous CeO2-YSZ Nanocomposite Thin Films with Mixed Ionic/Electronic Conductivity via Surface Engineering.

Mixed ionic and electronic conductors represent a technologically relevant materials system for electrochemical device applications in the field of energy storage and conversion. Here, we report about the design of mixed-conducting nanocomposites by facile surface modification using atomic layer deposition (ALD). ALD is the method of choice, as it allows coating of even complex surfaces. Thermally stable mesoporous thin films of 8 mol-% yttria-stabilized zirconia (YSZ) with different pore sizes of 17, 24, and 40 nm were prepared through an evaporation-induced self-assembly process. The free surface of the YSZ films was uniformly coated via ALD with a ceria layer of either 3 or 7 nm thickness. Electrochemical impedance spectroscopy was utilized to probe the influence of the coating on the charge-transport properties. Interestingly, the porosity is found to have no effect at all. In contrast, the thickness of the ceria surface layer plays an important role. While the nanocomposites with a 7 nm coating only show ionic conductivity, those with a 3 nm coating exhibit mixed conductivity. The results highlight the possibility of tailoring the electrical transport properties by varying the coating thickness, thereby providing innovative design principles for the next-generation electrochemical devices.

Amino acid-mediated negatively charged surface improve antifouling and tribological characteristics for medical applications

To prevent infections associated with biomedical catheters, various antimicrobial coatings have been investigated. However, those materials do not provide consistent antibacterial effects or biocompatibility, generally, due to degradation of the coating materials, in vivo. Additionally, biomedical catheters must have low surface friction to reduce tribological damage. In this study, we developed an antifouling surface composed of biocompatible amino acids (leucine, taurine, and aspartic acid) on polyimide, via modification using a series of facile immersion steps with waterborne reactions. The naturally derived amino acid could be formed highly biostable amide bonds on the polyimide surface like peptides. The amino acid-modified surface formed a water layer with antifouling performance through the hydrophilic properties of amino acids. Amino acid-mediated modification reduced adhesion up to 84.45% and 94.81% against Escherichia coli and Staphylococcus epidermidis, respectively, and exhibited an excellent prevention to adhesion against the proteins, albumin and fibrinogen. Evaluation of the surface friction of the catheter revealed a dramatic reduction in the tribological force after amino acid modification on polyimide that of 0.81 N to aspartic acid of 0.44 N. These results clearly demonstrate a reduced occurrence of infections, thrombi and tribological damage following the relatively facile surface modification of catheters. The proposed modification method can be used in a continuous manufacturing process via using the same time of modification steps for the easy producing the product. Moreover, the method uses biocompatible naturally derived materials and can be applied to medical equipment that requires biocompatibility and biofunctionality with polyimide surfaces.

Enhancing storage performance of P2-type Na2/3Fe1/2Mn1/2O2 cathode materials by Al2O3 coating

The P2-type Na2/3Fe1/2Mn1/2O2 materials were synthesized by an ultrasonic spray pyrolysis followed by solid-state sintering method. The structures, morphologies and electrochemical performances of Na2/3Fe1/2Mn1/2O2 materials were characterized thoroughly by means of X-ray diffractometer, scanning electron microscope and electrochemical charge/discharge instruments. Moreover, a thin layer of Al2O3, which was formed on the surface of Na2/3Fe1/2Mn1/2O2, can enhance the storage performance by preventing the formation of Na2CO3·H2O, which is believed to enhance the electrochemical performances of Na2/3Fe1/2Mn1/2O2 materials. This facile surface modification method may pave a way to synthesize advanced cathode materials for sodium-ion batteries.

Dentritic hemaitite thinfilms with ferrous lactate overlayers for efficient photoelectrochemical water splitting

Hematite (α-Fe2O3) has been intensively studied as a promising photoanonde material for water splitting. This paper reports a facile method to prepare dendritic hematite nanorods and an active catalytic interface was constructed by coordinating ferrous lactate layers. A negative shift of 100 mV for onset potential and significant enhancement (200%) of photocurrent were observed for the modified hematite photoanodes. It was found that ferrous lactate decorated samples showed distinct catalytic effect for water oxidation only in illuminated condition. XPS and a series photo-electrochemical analysis reveal that Fe (II) site in the surface bonded ferrous lactate possessed distinguished photo-generated charge transfer properties and excellent stability during the reaction. The corresponding mechanism for water oxidation over catalytic surface was proposed. The result provides a facile and reliable surface modification method for efficient PEC water oxidation.

Surface engineering of Ti3C2Tx MXene by oxygen plasma irradiation as room temperature ethanol sensor

In this work, a surface modification strategy by oxygen plasma irradiation was introduced for the first time to significantly improve the room temperature sensing performance of Ti3C2T[Formula: see text] MXene. Oxygen plasma irradiation induced TiO2formation on the Ti3C2T[Formula: see text] surface, produced lattice distortion, increased the specific surface area, and provided mesoporous structures. The gas sensitivity performance characterization results show the gas response value of Ti3C2T[Formula: see text] irradiated for 0.5 h (Ti3C2T[Formula: see text]0.5P) was hundreds of times better than the pristine Ti3C2T[Formula: see text]alongside with its sufficient response time (280 s) and rapid recovery time (11 s). The excellent sensing performance is attributed to the formation of more reactive sites on the edge and basal planes of Ti3C2T[Formula: see text] and mesoporous structures which greatly improved the adsorption of ethanol. Additionally, the relatively low work function of TiO2facilitates the formation of a Schottky junction for easy migration of charge carrier, the thereby shortening the sensing response time. This strategy offers a facile and controllable surface modification of other 2D materials, without damaging their structures.

Poly(ethylene oxide)-ethylene carbonate solid binary electrolyte with higher conductivity, lower operating temperature and fully impregnated separator for all solid-state lithium ion batteries

Poly(ethylene oxide) (PEO) solid electrolyte suffers from the low conductivity and the high operating temperature owing to the cation is trapped in the highly crystalline domains and enmeshed in amorphous domains. Therefore, a tactic was attempted by forming the solid binary electrolyte with the solid cosolvent, ethylene carbonate (EC). X-ray diffraction revealed the crystallinity of the electrolyte progressively degraded at room temperature as EC was added, eventually disappeared, accompanying the endothermic peak continuously shifted to the lower temperature and then vanished in differential scanning calorimetry. Fourier transform infrared spectroscopy also indicated the surroundings around PEO chains mutated after addition of 50% EC (in EO ratio). More importantly, the conductivity was significantly improved ten times after 60% EC was added, still three times at 25 °C than the pristine electrolyte at 60 °C, which was further corroborated with cyclic voltammogram of LiFePO4 micro electrode. Based on the rate discharge, no less than 60% EC content was recommended for the application in the medium rate (<2C) at 25 °C. Additionally, another barrier, the poor wettability of polyolefin separator with the solid state electrolyte was also overcome completely by the facile surface modification.

TRANSPLANTATION OF GOLD NANOPARTICLES WITH OR WITHOUT BONE MARROW STEM CELLS FOR REGENERATION OF SURGICALLY INDUCED TONGUE DEFECT IN RATS

The ultimate goal of tongue reconstruction is restoring the tongue integrity while preserve its critical functions(i.e., articulation, mastication, and deglutition) and minimize the morbidity profile of a selected reconstructive technique. Mesenchymal stem cells (MSCs) used in tissue engineering became a therapeutic selectiondue to numerous advantagesas regeneration of damaged tissues withhigh quality without the formation of fibrous tissue, minimal donor site morbidity in comparison withautografts and a low risk ofdisease transmition and autoimmune rejection. Bone marrow stem cells (BMSCs) areexpandable stem, self-renewing,embedded at the site of injury and motivate tissue regeneration and wound healing. In oral wounds, they revealgreater re-epithelialization, intracellular matrix formation,cellularity, and neoangiogenesis, thusspeed up wound healing.Gold nanoparticles (GNPs) application in medical fields is growingdue to the chemical and physical properties like biocompatibility, optical properties,facile surface modification and stability.GNP usage in regenerative medicine is safe if the implanted tissue is replacing a tissue/organresectedbecause of tumor.

Superparamagnetic SiO2@Fe3O4 core/shell fabrication via low-temperature electroless deposition

Magnetite (Fe3O4) coated nanoparticles combine magnetic properties of magnetite with low density of core particles. This category of magnetic responsive core/shell particles takes advantage of the physical and chemical properties of particle core and can be used in numerous suspension-based applications such as biosensors, cargo particles and in magnetorheological (MR) fluids. A facile, controllable, and scalable particle surface modification methodology is required to synthesize magnetite-coated nanoparticles. In this study, we fabricated a monodisperse magnetic particle using low-temperature electroless deposition technique to deposit a magnetite layer on the surface of silica (SiO2) particle. Silica particle was synthesized, functionalized with amine as the intermediate agent and catalyst, and subsequently dispersed in a solution of iron (III) salt and a reducing agent. This technique implemented at low temperatures in a simple experimental setup can be applied to generate magnetite layer on wide varieties of particles made of inorganic materials or polymers and is scalable for mass manufacture. The fabricated SiO2@Fe3O4 core/shell particle was responsive to the magnetic field, forming persistent structures that make it a good candidate for magnetorheological fluid application.

Enhanced electromechanical performance of natural rubber dielectric elastomers achieved by in situ synthesis of silver nanoparticles on TiO 2 nanoparticles

Dielectric elastomers (DEs) could transduce electrical energy to mechanical energy, but their applications are currently limited by the elevated driving voltages. To obtain satisfactory actuated strains at low voltages, titanate oxide@tannic acid-ferric ion@silver (labelled as TiO2@TA-Fe3+@Ag) satellite-structure nanoparticles were obtained in this study by in situ synthesis followed by incorporating the nanoparticles into natural rubber (NR) to prepare DE composites (denoted as TiO2@TA-Fe3+@Ag/NR). The presence of surface coating of TA-Fe3+ and Ag nanoparticles improved the electromechanical performance of TiO2@TA-Fe3+@Ag/NR composites. Among the samples, 30 wt% TiO2@TA-Fe3+@Ag/NR composite displayed a relatively high actuated strain of 9.09% at a relatively low electric field of 22.78 kV/mm. In sum, the green, facile, and cost-effective surface modification method looks promising for improving the electromechanical properties of particulate-filled polymer composites.

Rapid and Robust Surface Treatment for Simultaneous Solid and Liquid Repellency.

A wide range of liquid and solid contaminants can adhere to everyday functional surfaces and dramatically alter their performance. Numerous surface modification strategies have been developed that can reduce the fouling of some solids or repel certain liquids but are generally limited to specific contaminants or class of foulants. This is due to the typically distinct mechanisms that are employed to repel liquids vs solids. Here, we demonstrate a rapid and facile surface modification technique that yields a thin film of linear chain siloxane molecules covalently tethered to a surface. We investigate and characterize the liquid-like morphology of these surfaces in detail as the key contributing factor to their anti-fouling performance. This surface treatment is extremely durable and readily repels a broad range of liquids with varying surface tensions and polarities, including water, oils, organic solvents, and even fluorinated solvents. Additionally, the flexible, liquid-like nature of these surfaces enables interfacial slippage, which dramatically reduces adhesion to various types of solids, including ice, wax, calcined gypsum, and cyanoacrylate adhesives, and also minimizes the nucleation of inorganic scale. The developed surfaces are durable and simple to fabricate, and they minimize fouling by both liquids and solids simultaneously.