Introduction Of Hydroxyl Group Research Articles

Inhibition of Dipeptidyl Peptidase-4 by Flavonoids: Structure-Activity Relationship, Kinetics and Interaction Mechanism.

With the aim to establish a structure-inhibitory activity relationship of flavonoids against dipeptidyl peptidase-4 (DPP-4) and elucidate the interaction mechanisms between them, a pannel of 70 structurally diverse flavonoids was used to evaluate their inhibitory activities against DPP-4, among which myricetin, hyperoside, narcissoside, cyanidin 3-O-glucoside, and isoliquiritigenin showed higher inhibitory activities in a concentration-dependent manner. Structure-activity relationship analysis revealed that introducing hydroxyl groups to C3', C4', and C6 of the flavonoid structure was beneficial to improving the inhibitory efficacy against DPP-4, whereas the hydroxylation at position 3 of ring C in the flavonoid structure was unfavorable for the inhibition. Besides, the methylation of the hydroxyl groups at C3', C4', and C7 of the flavonoid structure tended to lower the inhibitory activity against DPP-4, and the 2,3-double bond and 4-carbonyl group on ring C of the flavonoid structure was essential for the inhibition. Glycosylation affected the inhibitory activity diversely, depending on the structure of flavonoid aglycone, type of glycoside, as well as the position of substitution. Inhibition kinetic analysis suggested that myricetin reversibly inhibited DPP-4 in a non-competitive mode, whereas hyperoside, narcissoside, cyanidin 3-O-glucoside, and isoliquiritigenin all reversibly inhibited DPP-4 in a mixed type. Moreover, the fluorescence quenching analysis indicated that all the five flavonoid compounds could effectively quench the intrinsic fluorescence of DPP-4 by spontaneously binding with it to form an unstable complex. Hydrogen bonds and van der Waals were the predominant forces to maintain the complex of myricetin with DPP-4, and electrostatic forces might play an important role in stabilizing the complexes of the remaining four flavonoids with DPP-4. The binding of the tested flavonoids to DPP-4 could also induce the conformation change of DPP-4 and thus led to inhibition on the enzyme. Molecular docking simulation further ascertained the binding interactions between DPP-4 and the selected five flavonoids, among which hyperoside, narcissoside, cyaniding 3-O-glucoside, and isoliquiritigenin inserted into the active site cavity of DPP-4 and interacted with the key amino acid residues of the active site, whereas the binding site of myricetin was located in a minor cavity close to the active pockets of DPP-4.

Post-modification of metal-organic framework for improved CO2 photoreduction efficiency

Utilizing metal-organic frameworks (MOFs) to design photocatalysts for CO2 reduction catalysts is an excellent idea but currently restricted by the relatively low activity. Enhancing CO2 affinity and tuning the oxidation state of metal clusters in MOFs might be a solution to improve the catalytic performance. Herein, the Cl-bridge atoms in the metal clusters of a cobalt MOF were easily exchanged with OH−, which simultaneously oxidized a portion of Co(II) to Co(III) and resulted in a much enhanced photocatalytic activity for CO2 reduction. In contrast, the original framework does not exhibit such superior activity. Comprehensive characterizations on their physicochemical properties revealed that the introduction of hydroxyl group not only greatly increases the CO2 affinity but also alters the oxidation state of metal clusters, resulting in significantly improved photocatalytic activities for CO2 reduction. This work provides important insight into the design of efficient photocatalysts.

Mixed polyamines promotes CO2 adsorption from air

The deployment of large-scale direct air capture (DAC) technology relies on the development of energy-efficient and cost-effective CO2 capture materials. The high desorption temperature of the current DAC adsorbents, especially the supported polyamines, is undesirable. In this work, the "mixed-polyamines" concept was adopted to prepare class 1 adsorbents by impregnating both tetraethylenepentamine (TEPA) and diethanolamine (DEA) into the mesoporous SBA-15. The synergy of TEPA and DEA influences the reaction mechanism between CO2 and amines sites, resulting in higher amine efficiency and lower regeneration temperature. Moreover, CO2 adsorption and desorption kinetics are enhanced by the introduction of hydroxyl groups from DEA. The desorption process of solid polyamines-loaded adsorbents fits well with the Avrami model under ultra-dilute CO2 concentrations. SBA-15 loaded mixed polyamine with a weight ratio of TEPA to DEA equaling to 4 shows a maximum CO2 adsorption amount of 1.93 mmol/g at 400 ppm CO2 and 25 °C, a fast adsorption rate of 1.82 mmol/(g·h), and a desorption rate of 0.26 mmol/(g·min) at 80 °C within the first 5 min, which is believed to be a promising DAC adsorbent for practical application.

Hematite decorated functional porous graphitic carbon nitride binary nanohybrid: Mechanistic insight into the formation and arsenic adsorption study

Here, hydroxyl functionalized porous graphitic carbon nitride (gCN) decorated with hematite (α-Fe2O3) nanoparticles (NPs) (P-gCN-OH/α-Fe2O3) were synthesized by an eco-friendly hydrothermal and thermal polycondensation process. The physicochemical investigation and mechanistic approach signified that glucose is responsible for porosity formation and potassium (K) ions from KCl are responsible for breaking the periodic chemical structure of gCN; while a trace amount of H2O in melamine helps in introducing hydroxyl groups in the P-gCN matrix. Apart from this, α-Fe2O3 NPs were also successfully introduced into the P-gCN-OH. The synthesized P-gCN-OH/α-Fe2O3 binary nanohybrid shows enhanced adsorption performance towards both arsenite (As(III)) and arsenate (As(V)) ions due to their greater specific surface area (242.5 m2/g). About > 96% and > 98% of As(III) and As(V) were adsorbed with an adsorption capacity of 22.22 mg/g and 27.80 mg/g respectively. The proposed adsorption mechanism was supported by the combined results of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It is demonstrated that arsenic (As) adsorption onto the P-gCN-OH/α-Fe2O3 surface was due to electrostatic attraction, simultaneous As(III) oxidation & adsorption, and monodentate & bidentate complex formation.

Molecule Dynamics Simulation of the Effect of Oxidative Aging on Properties of Nitrile Rubber.

The effects of oxidative aging on the static and dynamic properties of nitrile rubber at the molecular scale were investigated by molecular dynamics simulation. The aged nitrile rubber models were constructed by introducing hydroxyl groups and carbonyl groups into rubber molecular chains to mimic oxidative aging. The static and dynamic properties of the unaged and aged nitrile rubber under different conditions were evaluated by mean square displacement, self-diffusion coefficients, hydrogen bond, fractional free volume, radial distribution function, cohesive energy density and solubility parameter. The results show that the elevated temperature intensified significantly the mobility of rubber molecular chains and fractional free volume, while the compressive strain displayed the opposite effect resulting in packing and rearrangement of rubber chains. The introduction of hydroxyl groups and carbonyl groups enhanced the polarity, intermolecular interactions, the volume and rigidity of molecular chains, implying weaker mobility of molecular chains as compared to unaged models. The compressive strain and oxidative aging both decreased the fractional free volume, which inhibited gaseous and liquid diffusion into the rubber materials, and slowed down the oxidative aging rate. This study provides insights to better understand the effect of molecular changes due to oxidative aging on the structural and dynamic properties of rubber materials at the molecular level.

Low Interface Trapped Charge Density for AlO/β-GaO (001) Metal-Insulator-Semiconductor Capacitor

In this letter, high-performance Al2O3/β-Ga2O3 (001) metal-insulator-semiconductor (MIS) capacitor has been demonstrated. The capacitance-voltage (C.V) curves of the Al2O3/β-Ga2O3 (001) MIS capacitor remain stable under different measurement frequencies. The leakage current density is lower than 2.0 × 10-8 A/cm2 when the gate voltage is in the range of –5 13 V. The fixed charge and trapped charge densities in Al2O3 film are 4.4 × 1012 and 6.0 × 1011 cm-2, respectively. Average and minimum interface trapped charge density (Dit) for Al2O3/β-Ga2O3 (001) interface has been extracted to be as low as 3.3 × 1011 and 2.3 × 1011 cm-2 eV-1 via the Terman method, respectively. The low Dit is probably attributed to the modification of vacancy defects and the introduction of hydroxyl groups at the Al2O3/β-Ga2O3 (001) interface after piranha solution pretreatment for β-Ga2O3.

Nitro-substituted aurones as xanthine oxidase inhibitors

Aurone derivatives possessing a wide range of biological activities are of high interest in medicinal chemistry. Carboxylated aurones were found previously to inhibit xanthine oxidase, which is a potential target for treatment of hyperuricemia and gout. In this paper, a series of B-ring nitro-substituted aurone derivatives were studied in vitro as inhibitors of this enzyme. The introduction of hydroxyl group into the B-ring of nitro-functionalized aurones resulted in significant increase of their inhibitory potency. At the same time, aurones chlorinated at ring A and containing nitro and hydroxyl groups at ring B showed only slightly increased inhibition effect. The kinetic studies and molecular docking calculations were carried out to explain the inhibition mechanism of xanthine oxidase by the nitro-substituted aurone derivatives

Adsorption of 1,2-Dichlorobenzene from the Aqueous Phase onto Activated Carbons and Modified Carbon Nanotubes.

This study aimed to describe the adsorption process of ortho-dichlorobenzene (o-DCB) onto activated carbons (ACs) and modified carbon nanotubes (CNTs) from the aqueous phase. The starting material NC_7000 carbon nanotubes were modified by chlorination (NC_C) and then by the introduction of hydroxyl groups (NC_C_B). The concentration of o-DCB in solutions was performed by UV-VIS spectrophotometry. After adsorption, the activated carbons were regenerated by extraction with organic solvents such as acetone, methanol, ethanol, and 1-propanol; the carbon nanotubes were regenerated by methanol. The degree of adsorbate recovery was determined by gas chromatography (GC) with flame ionization detection, using ethylbenzene as an internal standard. The equilibrium isotherm data of adsorption were satisfactorily fitted by the Langmuir equations. The results indicate that carbon adsorbents are effective porous materials for removing o-DCB from the aqueous phase. Additionally, activated carbons are more regenerative adsorbents than carbon nanotubes. The recoveries of o-DCB from ACs were in the range of 76–85%, whereas the recoveries from CNTs were in the range of 23–46%. Modifications of CNTs affect the improvement of their adsorption properties towards o-DCB compared to unmodified CNTs. However, the introduction of new functional groups on carbon nanotube surfaces makes the regeneration process less effective.

Large-scale production of 4MoO3·2NH3·H2O nanosheets through antisolvent crystallization for highly efficient removal of cationic dyes

This article describes a practical approach for the rational design and large-scale production of different morphologies and sizes of 4MoO 3 ·2NH 3 H 2 O (MAH) nanosheets. The optimized MAH-20 shows the best adsorption capacities for various cationic dyes such as methylene blue (1169.2 mg·g −1 ) and rhodamine B (1452.8 mg·g −1 ), benefiting from its high Mo 5+ centres concentration, negative surface charge, small nanosheet thickness, and high surface-to-volume ratio. We reveal that the adsorption behaviour of MAH-20 is mainly driven by electrostatic interactions, while also affirming the existence of coordination interactions between surface coordination-unsaturated Mo and dye molecules. • Large-scale preparation of 4MoO 3 ·2NH 3 ·H 2 O (MAH) nanocrystal was realized. • The MAH-x nanosheets showed selective adsorption capacity for cationic dyes. • High adsorption capacity was realized because of the existence of Mo 5+ centers. • MAH-20 membrane remained highly durability in reuse experiments. A facile method for the large-scale production of 4MoO 3 ·2NH 3 ·H 2 O (MAH) nanocrystal with tunable size and morphology is developed through an antisolvent crystallization approach. The introduction of hydroxyl groups during crystallization promotes the formation of oxygen vacancies on the MAH. Due to the high concentration of Mo 5+ centres, small nanosheet thickness, and sandwich-like crystal structure, MAH-20 exhibits an outstanding adsorption capability toward cationic dyes, with the maximum adsorption capacities up to 1169.2 mg·g −1 for methylene blue (MB) and 1452.8 mg·g −1 for rhodamine B (RhB), which are almost 10 times as that of MAH-0. An electrostatic adsorption mechanism is proposed to interpret the highly selective adsorption activity toward cationic dyes. Moreover, a fast and recyclable treatment and adsorbent regeneration are realized based on a continuous flow filtration device.

Non-bonding energy directed designing of HDAC2 inhibitors through molecular dynamics simulation

Designing an inhibitor having strong affinity in the active site pocket is the cherished goal of structure based drug designing. To achieve this, it is considerably important to predict which structural scaffold is better suited for change to increase affinity. We have explored five HDAC2 co-crystals having PDB ligand code—SHH (vorinostat), LLX, 20Y, IWX (BRD4884) and 6EZ (BRD7232). For analyzing protein-ligand interaction at an atomistic level, we have employed the NAMD molecular dynamics (MD) package. The obtained 100 ns long MD trajectories were subjected to quantitative estimations of non-bonding energies (NBEs) for inferring their interactions with the whole protein or its composite active site (CAS). In addition, relative ΔGbind was calculated to rank the inhibitors. These inhibitors’ NBEs reveal that the phenyl moieties are the major structural scaffold where modifications should be attempted. We designed new compounds (NCs) via introducing hydroxyl groups at 4,5 position of the phenyl moiety of 6EZ, called NC1. Improvement in NC1 further encouraged us for CAP modification by isochromane and isoindoline moieties in place of oxabicyclooctane in NC1, resulting in NC2 and NC3. We also explored trifluoromethyl oxadiazole in 6EZ (NC4 and NC5) and SHH (NC6 and NC7). This moiety acts as a ZBG in NC4 while acting as a part of the foot-pocket in the rest. NC2 and NC6 have highest favorable NBEs among all studied ligands due increased favorable electrostatic contribution. We expect these NBEs data will provide atomistic level insights and benefit in designing new and improved HDAC2 inhibitors. Communicated by Ramaswamy H. Sarma

HYDROGEL ANTIBACTERIAL COATING FOR SILICONE MEDICAL DEVICES

Effective antibacterial coatings are in demand in medicine, especially for urological medical devices such as catheters and stents. We propose the production method of an antibacterial hydrogel coating on polydimethylsiloxane (PDMS, silicone), a popular surface for medical materials. The coating process consists of the following steps: PDMS surface activation (introduction of hydroxyl groups), silanisation (introduction of amine groups) and application of chitosan/alginate hydrogel with the addition of lysozyme as an antibacterial agent using the layer-by-layer method. We investigated the effect of polyion concentration on the coating mass, swelling ratio and stability. We analysed the adsorption of Micrococcus luteus, Escherichia coli and Proteus rettgeri on a PDMS surface using confocal laser scanning microscopy. The chitosan/alginate hydrogel coating with immobilised lysozyme protected the PDMS surface against adhesion for all three tested bacterial strains.

Molecular-functionalized engineering of porous carbon nitride nanosheets for wide-spectrum responsive solar fuel generation

Carbon nitride (C3N4) is a promising metal-free photocatalyst for solar-to-energy conversion, but bulk carbon nitride (BCN) shows insufficient light absorption, sluggish photocarrier transfer and moderate activity for photocatalysis. Herein, a facile strategy to significantly increase solar spectrum absorption of the functionalized porous carbon nitride nanosheets (MFPCN) via molecule self-assembly engineering coupled thermal polymerization is reported. This strategy can greatly enhance the wide-solar-spectrum absorption of MFPCN up to 1000 nm than most reported carbon nitride-based photocatalysts. Experimental characterizations and theoretical calculations together display that this strategy could introduce hydroxyl groups into the structure of MFPCN as well as the rich pores and active sites at the edges of framework, which can narrow the bandgap and accelerate the transfer and separation of photoinduced carries. As a result, the optimal MFPCN photocatalyst exhibit the excellent photocatalytic hydrogen evolution rate of 7.745 mmol g-1h−1 under simulated solar irradiation, which is ≈13 times that of BCN with remarkable durable CO2 reduction activities. New findings in this work will provide an approach to extend solar spectrum absorption of metal-free catalysts for solar fuel cascades.

Robust Cr(VI) reduction over hydroxyl modified UiO-66 photocatalyst constructed from mixed ligands: Performances and mechanism insight with or without tartaric acid

Hydroxyl modified UiO-66 ((OH)2-UiO-66-X%, X represents the mass content ratio of introduced 2,5-dihydroxyterephthalic acid) was prepared via a solvothermal reaction between zirconium tetrachloride, benzene-1,4-dicarboxylic acid (H2BDC), as well as 2,5-dihydroxyterephthalic acid (H2BDC-(OH)2). It was found that hydroxyl groups can act as the intramolecular hole scavenger to boost the photo-induced charge carrier separation to enhance Cr(VI) reduction. The photocatalytic Cr(VI) reduction activities of (OH)2-UiO-66-X% were investigated upon the irradiation of low-power ultraviolet LED light. The findings demonstrated that (OH)2-UiO-66-20% with good cyclicity and stability exhibited superior photocatalytic performances to both UiO-66 and (OH)2-UiO-66. The introduction of hydroxyl groups can also extend the light absorption region to longer wavelength in visible range, which provides possibility for displaying photocatalytic activities under sunlight. The effect of small molecule organic acid (SOAs), pH value, and co-existing inorganic ions on photocatalytic performances of (OH)2-UiO-66-20% were investigated. Tartaric acid (TA) as typical SOAs was introduced to the reaction system to further boost the photocatalytic Cr(VI) reduction via acting as hole scavenger, constructing charge-transfer-complex for quick electron transportation, and producing COO·- radicals. This work opened a new opportunity for modified MOFs for boosted elimination activities for environmental pollutants.

Efficient Electroreduction of CO2 to CO on Porous ZnO Nanosheets with Hydroxyl Groups in Ionic Liquid‐based Electrolytes

AbstractElectrochemical reduction of CO2 is a very promising route to realize carbon cycle and alleviate energy shortage. Herein, the porous zinc oxide nanosheets with hydroxyl groups on carbon paper substrates (ZnO(OH)/CP‐x,×represents the deposition time) were proved to be excellent catalysts for CO2 electroreduction to CO. As far as we know, the hydroxyl groups were first introduced into ZnO catalysts for this reaction, which can enhance the surface areas and improve the capacity of binding CO2 by the formation of hydrogen bond. Especially, the total current density could reach 44.3 mA cm−2 with 97.8 % Faradaic efficiency (FE) of CO over ZnO(OH)/CP‐600 catalysts with moderate hydroxyl groups in 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([Bmim]PF6, 30 wt%)/acetonitrile/H2O (5 wt%) ternary electrolytes at −2.0 V versus Ag/Ag+, although the self‐reduction of the catalysts could be occurred simultaneously during electrolysis. Besides, the composition of the electrolytes also can significantly modulate the catalytic activity and selectivity of CO. The outstanding performance of ZnO(OH)/CP‐600 catalyst resulted mainly from the introduction of hydroxyl groups, high surface area, good contact with the substrate, and synergy effect between the catalyst and the electrolyte.

Bio-inspired hydroxylation imidazole linked covalent organic polymers for uranium extraction from aqueous phases

• High selectivity imidazole was introduced as linkage in varying degree hydroxylation covalent organic polymers. • Benefiting from the introduction of hydroxyl groups, the uranium adsorption capacities were largely enhanced. • The TpDAB endowed prominent selectivity towards multiple metal ions including vanadium. • The hydroxyl groups significantly influenced the uranium coordination mechanism of imidazole functional group. Highly effective and reliable adsorbents for uranium extraction are vital significant for environmental protection and social development. Herein, inspired by the interaction between imidazole affinity ligand of histidine and uranium, a series of varying degree hydroxylation imidazole linked covalent organic polymers were developed for the first time via one step facile reaction without any post treatment between 2,4,6-triformylphloroglucinol (Tp), 2,4,6-triformylresorcinol (Bd), 2,4,6-triformylphenol (Hb) and 3,3′-diaminobenzidine (DAB), denoted as TpDAB, BdDAB, and HbDAB, respectively. Benefiting from the hierarchical structure of the covalent organic polymer and synergistic effects originating from hydroxyl groups and imidazole linkages, TpDAB, BdDAB, and HbDAB displayed as the promising adsorbents for uranium extraction with high extraction ability and fast capture kinetics. X-ray photoelectron spectroscopy results revealed that both nitrogen atoms in imidazole and oxygen atom in hydroxyl took part in uranium coordination. With the increasing of hydroxyl group amounts, TpDAB achieved highest extraction capacity of uranium. Furthermore, TpDAB with imidazole affinity group possessed eminent selectivity for uranium in the multiple metal ions solution, and especially overcome the unavoidable problem of vanadium interfering with amidoxime adsorption uranium. This work provided a promising uranium extraction strategy with high selectivity and easy preparation for environmental protection and human health.

Introducing hydroxyl groups as cellulose-binding sites into polymeric solid acids to improve their catalytic performance in hydrolyzing cellulose

Effective hydrolysis of cellulose to glucose is a crucial step to produce fuels and chemicals from lignocellulosic biomass. Solid acids are promising alternatives of cellulases and homogenous acids for hydrolyzing cellulose. In this study, porous polymeric solid acids bearing hydroxyl and sulfonic acid groups were fabricated for cellulose hydrolysis in water through the low-cost Friedel-Crafts “knitting” polymerization of hydroxyl-containing aromatic monomers followed by sulfonation. The synthesized bifunctional solid acids could effectively hydrolyze microcrystalline cellulose (Avicel) to glucose by as high as 93 % at 120 °C within 48 h and ball-milled Avicel by 98 % at 120 °C in 24 h. The evidence from this study indicated that the outstanding catalytic performance of the solid acids was attributed to the porous structure (large surface area) and the presence of the hydroxyl (cellulose-binding group) in the solid acids.

Removal of lead ions by two Fe[sbnd]Mn oxide substrate adsorbents

Lead pollution has become a global concern due to its ubiquity and persistence. This study describes two FeMn oxide substrate adsorbents, namely, FeMn binary oxides (FMBO) and mesoporous FeMn binary oxide (MFMBO) covered with tannic acid film (FMBO@TA-Fe3+ and MFMBO@TA-Fe3+), for the treatment of Pb2+ in water. The characterization results showed that TA was successfully coated onto the surfaces of FMBO and MFMBO. The maximum capacities of Pb2+ on FMBO@TA-Fe3+ and MFMBO@TA-Fe3+ were 322.08 and 357.14 mg g−1, respectively, which were twice those of FMBO and MFMBO. The adsorption of Pb2+ on the adsorbents was a spontaneous, endothermic process with increasing disorder through thermodynamics studies. An overall mechanism was proposed for Pb2+ adsorption, the improved adsorption performance of FMBO@TA-Fe3+ and MFMBO@TA-Fe3+ is ascribed to the mesoporous characteristics and the introduction of hydroxyl groups. Further investigation indicated the adsorption of Pb2+ could be attributed to electrostatic interactions on FMBO@TA-Fe3+ and MFMBO@TA-Fe3+, and cation exchange existed through the formation of these internal surface complexes. The Pb2+-loaded adsorbents could be effectively desorbed in a dilute hydrochloric acid solution, promoting recycling and reuse of the regenerated adsorbents. These results warrant the promising application of FMBO@TA-Fe3+ and MFMBO@TA-Fe3+ for the removal of Pb2+, and this work first proposed TA film-modified FMBO and MFMBO to improve its adsorption capacity in the application of environmental remediation.

The Impact of Ground Tire Rubber Oxidation with H2O2 and KMnO4 on the Structure and Performance of Flexible Polyurethane/Ground Tire Rubber Composite Foams.

The use of waste tires is a very critical issue, considering their environmental and economic implications. One of the simplest and the least harmful methods is conversion of tires into ground tire rubber (GTR), which can be introduced into different polymer matrices as a filler. However, these applications often require proper modifications to provide compatibility with the polymer matrix. In this study, we examined the impact of GTR oxidation with hydrogen peroxide and potassium permanganate on the processing and properties of flexible polyurethane/GTR composite foams. Applied treatments caused oxidation and introduction of hydroxyl groups onto the surface of rubber particles, expressed by the broad range of their hydroxyl numbers. It resulted in noticeable differences in the processing of the polyurethane system and affected the structure of flexible composite foams. Treatment with H2O2 resulted in a 31% rise of apparent density, while the catalytic activity of potassium ions enhanced foaming of system decreased density by 25% and increased the open cell content. Better mechanical performance was noted for H2O2 modifications (even by 100% higher normalized compressive strength), because of the voids in cell walls and incompletely developed structure during polymerization, accelerated by KMnO4 treatment. This paper shows that modification of ground tire rubber is a very promising approach, and when properly performed may be applied to engineer the structure and performance of polyurethane composite foams.

Interfacial performance enhancement of carbon fiber/epoxy composites by a two-step surface treatment

Carbon fiber-reinforced polymer composites (CFRPs) have many features, such as lightweight, high specific strength, and excellent chemical resistance. However, the adhesion at the interface of the CFRPs, which are composed of fiber and resin, is poor. Thus, de-lamination and interfacial peeling occur, and the mechanical properties, such as intrinsic strength and rigidity, decrease. Fiber surface modification by plasma and silane coupling treatments has attracted much attention to improve these properties. In this study, argon and oxygen mixed gas plasma treatment was used as pretreatment to introduce hydroxyl group on the fiber surface. This method was utilized to improve the adhesion between the fiber and resin. A silane coupling treatment was conducted to bond the carbon fiber and epoxy resin by chemical covalent bonding. The effect of silane coupling treatment on the interfacial property of CFRPs was investigated. Elemental analysis of the surface modified carbon fiber was explored through energy dispersive X-ray spectrometry. The functional groups of different carbon fiber surfaces were analyzed through X-ray photoelectron spectroscopy. The wettability of the treated carbon fiber was examined with a contact angle meter. The interlaminar shear strength was determined with a short beam method.

Detection of Uncharged 5-Fluorouracil Exploiting Sequential Adsorption of 5-Fluorouracil-Modified Bovine Serum Albumin Using Field Effect Transistor Biosensor

The dosage of 5-fluorouracil (5-FU), which is a widely used for cancer medication, is determined based on body surface area, although efficacy largely depends on the liver function of the individual, resulting that only 21% patients are given an optimal dose of 5-FU in these years. The measurement of the 5-FU concentration in the blood enables us to adjust individual dose adjustment. Conventional methods for 5-FU detection such as an enzyme-linked immunosorbent assay (ELISA) and liquid chromatography are not very suitable for clinical applications because they need time-consuming procedure with expensive equipments. Detection of 5-FU using a field effect transistor (FET) biosensor, which enables rapid and simple measurement, is expected to solve such problems. However, FET biosensor, which detects changes in its surface density due to the adsorption of charged molecules, was unable to detect uncharged 5-FU. In this study, a method for the FET biosensing to detect 5-FU exploiting sequential adsorption of 5-FU modified bovine serum albumin (BSA/5-FU) was proposed. By using this method, FET responses caused by the adsorption of negatively charged BSA/5-FU depending on the 5-FU concentration were detected. The SiO2 surface of the FET gate insulator was exposed to O2 plasma to introduce hydroxyl groups. After the exposure, the surface was exposed to 3-aminopropyltriethoixysilane (APTES), followed by the modification of the cross-linker, glutaraldehyde (GA). A single chain variable fragments (ScFv) and antigen binding fragments (Fab) were allowed to react with each activated GA-modified FET. After the immobilization, the residual aldehyde-groups were treated by ethanolamine to suppress the non-specific adsorption. V g-I d characteristics were measured before and after dripping of both 5-FU and BSA/5-FU on the ScFv- and Fab-immobilized FET biosensors. Finally, threshold voltage shifts (∆V g) caused by the adsorption of BSA/5-FU were obtained. To compare the capture capability of ScFv and Fab, the electrical responses of the FET biosensors functionalized with the two receptors due to the adsorption of BSA/5-FU were measured. The responses of ScFv- and Fab-immobilized FET biosensor caused by dripping of 25 μg/mL BSA/5-FU were +25 mV and +40 mV, respectively. The difference between ΔV g values for these two FET sensors using ScFv or Fab can be ascribed to the difference of affinity [1]. To verify the specificity of Fab-immobilized FET biosensor, ∆V g was measured when human serum albumin (HSA) was dropped on the FET biosensor, and the ∆V g was hardly observed. Additionally, the atomic force microscopic (AFM) images on the FET gate surface shows that the size of observed particles matches the size of BSA/5-FU, while the surface morphology and roughness are not significantly changed. These results indicated that Fab-immobilized surface specifically captured BSA/5-FU. To investigate the quantitative detectability of the Fab-immobilized FET biosensor, we measured the FET responses corresponding to the amount of adsorbed BSA/5-FU, which was related with the concentrations of 5-FU. As a result, the magnitude of ∆V g by dripping of 1000 ng/mL 5-FU and 25 μg/mL BSA/5-FU was reduced to +12 mV compared with the response of 25 µg/mL BSA/5-FU (Figure 1). These results can be attributed to that the adsorbed 5-FU inhibited the adsorption of BSA/5-FU to the Fab-immobilized surface. Therefore, we conclude that the detection of 5-FU using the FET biosensors by applying the charged BSA/5-FU is a promising simple method for monitoring the concentration of 5-FU.Reference:[1] Y. Reiter, et al., J. Biol. Chem., 269, 28, 18327-18331 (1994).Figure 1 V g-I d characteristics of Fab-immobilized FET biosensor before and after dripping of (a) 0 ng/mL 5-FU and 25 µg/mL BSA/5-FU or (b) 1000 ng/mL 5-FU and 25 µg/mL BSA/5-FU. Figure 1