Roll-to-roll graphene oxide radon barrier membranes.

Graphene oxide as a radon barrier in living environments was introduced by intercalating the polymer resin-coated layer inside a multilayer membrane with an area of 1 × 10 m and a thickness of 2.5 mm, prepared by the roll-to-roll method. A 5 µm-thick graphene oxide polymer resin (GOPR) layer was coated on polyethylene terephthalate (PET) film (100 µm) between the two styrene-butadiene-styrene (SBS)-modified bitumen asphalt layers fitted for construction sites. The inserted graphene oxide materials were characterized by means of infrared, Raman, and X-ray photoelectron spectroscopy (XPS). Dispersion-corrected density functional theory (DFT) calculations suggested weaker binding energies on the oxide surfaces and higher penetration energy barriers of graphene nanopores for radon (222Rn) than in the cases of the atmospheric gas molecules Ar, H2O, CO2, H2, O2, and N2. Theoretical calculations of the graphene nanopores supported the higher barrier energies of 222Rn than most ambient gases. The roll-to-roll prepared graphene materials exhibited good barrier properties for 222Rn as well as for the ambient gases. The purpose of our experimental and theoretical study is to provide a better understanding of using graphene-based materials to reduce the risk of carcinogenic radon gas in construction sites and residential buildings for practical applications.

Biodegradable shape-memory polymers using polycaprolactone and isosorbide based polyurethane blends.

Thermally responsive shape-memory polymers have received widespread attention in the biomedical field. In this study, biocompatible and biodegradable polyurethane (PU) and polycaprolactone (PCL) were blended to obtain shape-memory properties. Highly crystalline PCL was used as a hard segment, and PU synthesized from isosorbide, which is non-toxic and chemically and thermally stable, was used as a soft segment. The obtained PU/PCL blends containing the 30%, 50%, and 70% PU by weight were investigated for their thermal properties, mechanical properties, and shape-memory behavior. The 30%PU/PCL polymer has the best shape-memory characteristics and can be knotted by itself in the hot water bath, indicating that it can be applied in smart suture applications. The degradation test performed at 37 °C in phosphate buffered solution showed a mass loss of 2-4% for the obtained PU/PCL blends after 6 weeks. Finally, MC3T3-E1 cells cultured on PU/PCL blends showed high biocompatibility due to high adhesion and proliferation.

Facile preparation of antibacterial, highly elastic silvered polyurethane nanofiber fabrics using silver carbamate and their dermal wound healing properties.

In this study, polycarbonate diol/isosorbide-based antibacterial polyurethane nanofiber fabrics containing Ag nanoparticles were prepared by electrospinning process. Bio-based highly elastic polyurethane was prepared from hexamethylene diisocyanate and isosorbide/polycarbonate diol (8/2) by a simple one-shot bulk polymerization. Ag nanoparticles were formed using simple thermal reduction of silver 2-ethylhexylcarbamate at 120℃. The structural and morphological properties of polyurethane/Ag nanofibers were characterized by X-ray diffraction and scanning electron microscopy. The polyurethane nanofiber fabrics were flexible, with breaking strains from 355% to 950% under 7.28 to 23.1 MPa tensile stress. The antibacterial effects of the treated polyurethane/Ag fabrics against Staphylococcus aureus and methicillin resistant Staphylococcus aureus were examined and found to be excellent. Cell proliferation using the immortalized human keratinocyte HaCaT cell line was performed in order to determine cell viability in the presence of polyurethane and polyurethane/Ag fabrics, showing cytocompatiblility and a lack of toxicity.

Molecular Orbital Controlling Donor Moiety for High-Efficiency Thermally Activated Delayed Fluorescent Emitters.

A new donor moiety, 7,7,13,13-tetramethyl-7,13-dihydro-5H-indeno[1,2-b]acridine (IAc), was developed to control the highest occupied molecular orbital (HOMO) dispersion of thermally activated delayed fluorescent (TADF) emitters. The IAc unit expanded the HOMO dispersion of the emitters and increased the quantum efficiency of the TADF devices up to 20.9 %.

Synthesis, characterization, and biocompatible properties of alanine-grafted chitosan copolymers.

In order to overcome major problems regarding the lack of affinity to solvents and limited reactivity of the free amines of chitosan, introduction of appropriate spacer arms having terminal amine function is considered of interest. L-Alanine-N-carboxyanhydride was grafted onto chitosan via anionic ring-opening polymerization. The chemical and structural characterizations of L-alanine-grafted chitosan (Ala-g-Cts) were confirmed through Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy ((1)H NMR). In addition, the viscoelastic properties of Ala-g-Cts were examined by means of a rotational viscometer, and thermal analysis was carried out with a thermogravimetric analyzer and differential scanning calorimetry. Morphological changes in the chitosan L-alanine moiety were determined by x-ray diffraction. To determine the feasibility of using these films as biomedical materials, we investigated the effects of their L-alanine content on physical and mechanical properties. The biodegradation results of crosslinked Ala-g-Cts films were evaluated in phosphate-buffered solution containing lysozyme at 37℃. Proliferation of MC3T3-E1 cells on crosslinked Ala-g-Cts films was also investigated with use of the CCK-8 assay.

Synthesis of bio-based thermoplastic polyurethane elastomers containing isosorbide and polycarbonate diol and their biocompatible properties.

A new family of highly elastic polyurethanes (PUs) partially based on renewable isosorbide were prepared by reacting hexamethylene diisocyanate with a various ratios of isosorbide and polycarbonate diol 2000 (PCD) via a one-step bulk condensation polymerization without catalyst. The influence of the isorsorbide/PCD ratio on the properties of the PU was evaluated. The successful synthesis of the PUs was confirmed by Fourier transform-infrared spectroscopy and (1)H nuclear magnetic resonance. The resulting PUs showed high number-average molecular weights ranging from 56,320 to 126,000 g mol(-1) and tunable Tg values from -34 to -38℃. The thermal properties were determined by differential scanning calorimetry and thermogravimetric analysis. The PU films were flexible with breaking strains from 955% to 1795% at from 13.5 to 54.2 MPa tensile stress. All the PUs had 0.9-2.8% weight lost over 4 weeks and continual slow weight loss of 1.1-3.6% was observed within 8 weeks. Although the cells showed a slight lower rate of proliferation than that of the tissue culture polystyrene as a control, the PU films were considered to be cytocompatible and nontoxic. These thermoplastic PUs were soft, flexible and biocompatible polymers, which open up a range of opportunities for soft tissue augmentation and regeneration.

Preparation of silver-coated cotton fabrics using silver carbamate via thermal reduction and their properties.

In this study, cotton fabric was successfully coated with silver to have both antibacterial and conductive properties through a facile thermal reduction process at a low temperature using silver 2-ethylhexylcarbamate as the starting material. The cotton fabric modified with 3-mercaptopropyltriethoxysilane was padded with a solution of silver 2-ethylhexylcarbamate in methanol and then reduced for the in situ generation of Ag nanoparticles by only heating at 130°C. The silver-coated cotton fabrics (cotton/Ag) were examined by a scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analyses. The morphology of cotton/Ag nanocomposite fabrics conveyed a uniform and continuous layer of silver metal on the cotton surface. The results indicated that the silver nanoparticles were assembled on cotton fibers with a size range from 20 to 100 nm. The cotton/Ag imparts high conductivity to the textiles with electric resistance as low as 3.92±0.18 Ω. The antibacterial effects of the treated cotton fabric against Escherichia coli O157:H7 (ATCC 43889) and Staphylococcus aureus (ATCC 25923) were examined and found to be excellent.

Synthesis of highly elastic biocompatible polyurethanes based on bio-based isosorbide and poly(tetramethylene glycol) and their properties.

Bio-based high elastic polyurethanes were prepared from hexamethylene diisocyanate and various ratios of isosorbide to poly(tetramethylene glycol) as a diol by a simple one-shot bulk polymerization without a catalyst. Successful synthesis of the polyurethanes was confirmed by Fourier transform-infrared spectroscopy and (1)H nuclear magnetic resonance. Thermal properties were determined by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature was -47.8℃. The test results showed that the poly(tetramethylene glycol)/isosorbide-based elastomer exhibited not only excellent stress-strain properties but also superior resilience to the existing polyether-based polyurethane elastomers. The static and dynamic properties of the polyether/isosorbide-based thermoplastic elastomer were more suitable for dynamic applications. Moreover, such rigid diols impart biocompatible and bioactive properties to thermoplastic polyurethane elastomers. Degradation tests performed at 37℃ in phosphate buffer solution showed a mass loss of 4-9% after 8 weeks, except for the polyurethane with the lowest isosorbide content, which showed an initial rapid weight loss. These polyurethanes offer significant promise due to soft, flexible and biocompatible properties for soft tissue augmentation and regeneration.

New spiro[benzotetraphene-fluorene] derivatives: synthesis and application in sky-blue fluorescent host materials.

Blue light-emitting spiro[benzotetraphene-fluorene] (SBTF)-based host materials, 3-(1-naphthyl)-10-naphthylspiro[benzo[ij]tetraphene-7,9'-fluorene] (1), 3-(2-naphthyl)-10-naphthylspiro[benzo[ij]tetraphene-7,9'-fluorene] (2), and 3-[2-(6-phenyl)naphthyl]-10-naphthylspiro[benzo[ij]tetraphene-7,9'-fluorene] (3) were designed and prepared via multi-step Suzuki coupling reactions. Introducing various aromatic groups into SBTF core lead to a reduction in band gap and a determination of the color purity and luminescence efficiency. Typical sky-blue fluorescent organic light emitting diodes with the configuration of ITO/N,N'-di(1-naphthyl)-N,N'-bis[(4-diphenylamino)phenyl]-biphenyl-4,4'-diamie (60 nm)/N,N,N',N'-tetra(1-biphenyl)-biphenyl-4,4'-diamine (30 nm)/host: dopant (30 nm, 5%)/LG201 (electron transporting layer, 20 nm)/LiF/Al were developed using SBTF derivatives as a host material and p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-Ph) as a sky-blue dopant material. A device obtained from three materials doped with DSA-Ph showed color purity of 0.148 and 0.239, a luminance efficiency of 7.91 cd/A, and an external quantum efficiency >4.75% at 5 V.

Silk fibroin-polyurethane blends: physical properties and effect of silk fibroin content on viscoelasticity, biocompatibility and myoblast differentiation.

As a way to modify both the physical and biological properties of a highly elastic and degradable polyurethane (PU), silk fibroin (SF) was blended with the PU at differing ratios. With increasing SF content, the tensile strength decreased as did the strain at break; the stiffness increased to around 35 MPa for the highest silk content. C2C12 (a mouse myoblast cell line) cells were used for in vitro experiments and showed significantly improved cell responses with increasing SF content. With increasing SF content the number of non-adherent cells was reduced at both 4 and 8h compared to the sample with the lowest SF content. In addition, muscle marker genes were upregulated compared to the sample containing no SF, and in particular sarcomeric actin and α-actin.

Development, characterisation and biocompatibility testing of a cobalt-containing titanium phosphate-based glass for engineering of vascularized hard tissues.

There is a continuing need to develop scaffold materials that can promote vascularisation throughout the tissue engineered construct. This study investigated the effect of cobalt oxide (CoO) doped into titanium phosphate glasses on material properties, biocompatibility and vascular endothelial growth factor (VEGF) secretion by osteoblastic MG63 cells. Glasses composed of (P2O5)45(Na2O)20(TiO2)05(CaO)30-x(CoO)x(x=0, 5, 10, and 15 mol%) were fabricated and the effect of Co on physicochemical properties including density, glass transition temperature (Tg), degradation rate, ion release, and pH changes was assessed. The results showed that incorporation of CoO into the glass system produced an increase in density with little change in Tg. It was then confirmed that the pH did not change significantly when CoO was incorporated in the glass, and stayed constant at around 6.5-7.0 throughout the dissolution study period of 336 h. Ion release results followed a specific pattern with increasing amounts of CoO. In general, although incorporation of CoO into a titanium phosphate glass increased its density, other bulk and surface properties of the glass did not show any significant changes. Cell culture studies performed using MG63 cells over a 7-day period indicated that the glasses provide a stable surface for cell attachment and are biocompatible. Furthermore, VEGF secretion was significantly enhanced on all glasses compared with standard tissue culture plastic and Co doping enhanced this effect further. In conclusion, the developed Co-doped glasses are stable and biocompatible and thus offer enhanced potential for engineering vascularized tissue.

Application of high-strength biodegradable polyurethanes containing different ratios of biobased isomannide and poly (ϵ-caprolactone) diol.

Biodegradable-biocompatible polyurethanes were prepared with fixed hexamethylene diisocyanate and varying ratios of isomannide and poly(ϵ-caprolactone) diol using a simple one-step polymerization without a catalyst. The polyurethane structures were confirmed by 1H-nuclear magnetic resonance, Fourier transform infrared spectroscopy, and gel permeation chromatography. The glass transition temperatures were determined by thermal analysis to be between 25°C and 30°C. Degradation tests performed at 37°C in phosphate buffer produced mass losses of 5%-10% after 8 weeks. After 5 days of culture, using osteoblastic cells, the relative cell number on all the polyurethane films was only slightly lower than that of an optimized tissue culture plastic. These polymers offer significant promise with a simplistic synthesis and controlled degradation.

Catalyst-free synthesis of high elongation degradable polyurethanes containing varying ratios of isosorbide and polycaprolactone: physical properties and biocompatibility.

Biocompatible and biodegradable polyurethanes were prepared with fixed aliphatic diisocyanate level and varying ratios of isosorbide, and PCL diol via a simple one-shot polymerization without a catalyst. The successful synthesis of the polyurethanes was confirmed by gel permeation chromatography, (1)H-nuclear magnetic resonance and Fourier transform-infrared spectroscopies and the thermal properties were determined by differential scanning calorimetry and showed glass transition temperatures of around 30-35 °C. The degradation tests were performed at 37 °C in phosphate buffer solution (approx. pH 7.3) and showed a mass loss of around 5 % after 12 weeks, except for the polymer with the highest isosorbide content which showed an initial rapid mass loss. The in vitro cytocompatibility test results following culture of osteoblasts on the polymer surface showed that relative cell number on all of the polyurethane films after 5 days of cultured on polymer films was lower compared to the proliferation rate on the optimized tissue culture plastic. These polymers offer significant promise due to the simplicity of the synthesis and the controlled degradation.

Synthesis and biocompatibility properties of polyester containing various diacid based on isosorbide.

Biocompatible polyesters were prepared from isosorbide, various aliphatic diacid via a simple non-solvent polycondensation with a low toxicity catalyst. The successful synthesis of the polyesters was confirmed by gel permeation chromatography, (1)H-nuclear magnetic resonance and Fourier transform infrared spectroscopes, and differential scanning calorimetry. The degradation tests were performed at 37°C in phosphate buffer solution (approximately pH 7.3). The in vitro cytocompatibility test results following culture of osteoblasts on the polymer surface showed that relative cell number on poly(isosorbide sebacate) and poly(isosorbide adipate) films after 5 days of culture on polymer films proliferated at least as well as those on a culture plate.

Synthesis of elastic biodegradable polyesters of ethylene glycol and butylene glycol from sebacic acid.

High molecular weight biodegradable polyesters were prepared from sebacic acid, ethylene glycol and butylene glycol through a simple non-solvent polycondensation with a low toxicity catalyst. The successful synthesis of the polyesters was confirmed by gel permeation chromatography, (1)H-nuclear magnetic resonance and Fourier transform-infrared spectroscopies and differential scanning calorimetry. The degradation tests were performed at 37 °C in phosphate buffer solution (pH 7.4) and showed a mass loss of ~5% over 12 weeks compared with only 2% for polycaprolactone (PCL). Reverse transcription polymerase chain reaction results following culture of osteoblasts on the polymer surface showed that poly(ethylene sebacate) and poly(butylene sebacate) films were optimal for osteoblast formation in terms of Runx 2 and osteocalcin gene expression.

Size-dependent cellular toxicity of silver nanoparticles.

Silver nanoparticles (AgNPs) have found a variety of uses including biomedical materials; however, studies of the cytotoxicity of AgNPs by size effects are only in the beginning stage. In this study, we examined the size-dependent cellular toxicity of AgNPs using three different characteristic sizes (∼ 10, 50, and 100 nm) against several cell lines including MC3T3-E1 and PC12. The cytotoxic effect determined based on the cell viability, intracellular reactive oxygen species generation, lactate dehydrogenase release, ultrastructural changes in cell morphology, and upregulation of stress-related genes (ho-1 and MMP-3) was fairly size- and dose-dependent. In particular, AgNPs stimulated apoptosis in the MC3T3-E1 cells, but induced necrotic cell death in the PC12 cells. Furthermore, the smallest sized AgNPs (10 nm size) had a greater ability to induce apoptosis in the MC3T3-E1 cells than the other sized AgNPs (50 and 100 nm). These data suggest that the AgNPs-induced cytotoxic effects against tissue cells are particle size-dependent, and thus, the particle size needs careful consideration in the design of the nanoparticles for biomedical uses.

Water-resistive humidity sensor prepared by printing process using polyelectrolyte ink derived from new monomer.

A simple strategy was developed based on a new monomer containing both photocurable function and ammonium salt, N-(2-cinnamoyloxy)ethyl-N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl ammonium bromide (CMDAB) to obtain photocurable polyelectrolyte ink and stable humidity-sensitive membranes by printing process. Humidity-sensitive membranes are photocrosslinked polyelectrolytes obtained from copolymers of [2-(methacryloyloxy)ethyl] dimethyl propyl ammonium bromide (MEPAB), CMDAB and MMA. A flexible gold electrode/polyimide was pretreated with 2-(mercaptoethyl) cinnamamide (MEC) containing a thiol-coupling agent for the purpose of anchoring the humidity-sensitive polyelectrolyte to the gold electrode. The sensors using screen printing methods reduced the deflection of sensor characteristics showing humidity precision ±1%RH. The photocured copolymer MEPAB/CMDAB/MMA = 63/7/30 show good sensitivity (0.0586 logΩ/%RH) changing resistance approximately four orders of magnitude with relative humidity varying from 20% to 95% and fast response and recovery time. The resultant sensors showed acceptable linearity (Y = -0.04X + 7.0, R(2) = -0.9900) and small hysteresis. The reliability including water resistance and a long-term stability were estimated for the application of the flexible humidity sensor prepared by screen printing process.

In situ single cell monitoring by isocyanide-functionalized Ag and Au nanoprobe-based Raman spectroscopy.

The development of effective cellular imaging requires a specific labeling method for targeting, tracking, and monitoring cellular/molecular events in the living organism. For this purpose, we studied the cellular uptake of isocyanide functionalized silver and gold nanoparticles by surface enhanced Raman scattering (SERS). Inside a single mammalian cell, we could monitor the intracellular behavior of such nanoparticles by measuring the SERS spectra. The NC stretching band appeared clearly at approximately 2,100 cm-1 in the well-isolated spectral region from many organic constituents between 300 and 1,700 or 2,800 and 3,600 cm-1. The SERS marker band at approximately 2,100 cm-1 could be used to judge the location of the isocyanide-functionalized nanoparticles inside the cell without much spectral interference from other cellular constituents. Our results demonstrate that isocyanide-modified silver or gold nanoparticle-based SERS may have high potential for monitoring and imaging the biological processes at the single cell level.

Adsorption changes of cyclohexyl isothiocyanate on gold surfaces.

The adsorption and structure of cyclohexyl isothiocyanate (CHIT) on gold surfaces has been investigated by surface-enhanced Raman scattering (SERS) and scanning tunneling microscopy (STM). Depending on the concentration, the spectral changes of the NCS stretching vibration on gold nanoparticles appeared to be more conspicuous than those of cyclohexyl ring modes. Both equatorial and axial chair conformers of CHIT were found to exist at low bulk concentrations near the monolayer coverage limit, whereas the equatorial chair conformer appeared to be dominant at high bulk concentrations. It was also observed that the ring conversion of equatorial to axial conformers can easily occur at higher temperatures, and the mole fraction of the axial form is assumed to increase with increasing temperature from 30 to 60 degrees C. Alternatively, STM imaging revealed that the adsorption of CHIT molecules on Au(1 1 1) leads to the formation of disordered SAMs with a few vacancy islands, as opposed to the formation of well-ordered self-assembled monolayers (SAMs) by cyclohexanethiols.