Solid-phase Synthesis Method Research Articles

Influence of PbTiO3 doping on semiconductor behavior of K0.5Bi0.5TiO3 ceramics

ABSTRACTHigh-quality ceramics of (1 − x)KBT–xPT (x = 0.18 and 0.5) were fabricated by a conventional solid-phase synthesis method. Both materials exhibit the features of perovskite solid solutions. The temperature dependence of dc, ac conductivity (, respectively), the Seebeck coefficient (α), the concentration of charge carriers (n) and their mobility (μ) were investigated. DC conductivity plot for both materials reveals four linear sections with four different activation energies Ea. The ac conductivity exhibits four linear sections for 0.82KBT–0.18PT and three for the second composition. The possible causes of the observed effects are examined. Finally, KBT–PT solid solutions are recommended for use in electronic applications.

Iluminated by foreign letters - Strategies for site-specific cyclopropene modification of large functional RNAs via in vitro transcription.

The synthesis of sequence-specifically modified long RNA molecules, which cannot entirely be prepared via solid phase synthesis methods is experimentally challenging. We are using a new approach based on an expanded genetic alphabet preparing site-specifically modified RNA molecules via standard in vitro transcription. In this report, the site-specific labeling of functional RNAs, in particular ribozymes and a long non-coding RNA with cyclopropene moieties, is presented. We provide detailed instructions for RNA labeling via in vitro transcription and include required analytical methods to verify production and identity of the transcript. We further present post-transcriptional inverse electron demand Diels-Alder cycloaddition reactions on the cyclopropene-modified sequences and discuss applications of the genetic alphabet expansion transcription for in vitro preparation of labeled functional RNAs with complex foldings. In detail, the glmS and CPEB3 ribozymes were site-specifically decorated with methyl cyclopropene moieties using the unnatural TPT3CP triphosphate and were proven to be still functional. In addition, the structurally complex A region of the Xist lncRNA (401nt) was site-specifically modified with methyl cyclopropene and detected by fluorescence after cycloaddition reaction with a tetrazine-BODIPY conjugate.

Biotin-transfer from a trifunctional crosslinker for identification of cell surface receptors of soluble protein ligands

Here we describe a novel crosslinker and its application as a biotin-transfer reagent to identify cell surface receptors of soluble protein ligands on live cells. This crosslinker contains three functional groups: an aldehyde-reactive aminooxy group, a sulfhydryl, and a biotin (ASB). It is readily synthesized via a 3-step addition reaction using standard solid-phase peptide synthesis methods and commercially available intermediates, allowing access to laboratories without specialized synthetic chemistry capabilities. For the biotin-transfer method, ASB is linked to a protein ligand through the sulfhydryl group in a two-step process that allows the introduction of a disulfide bond between the ligand and the crosslinker. Incubation of the labelled ligand with oxidized live cells leads to the formation of crosslinks with aldehyde-containing glycans on the cell surface receptor. Subsequent reduction of the disulfide bond results in biotin transfer from the ligand to the cell surface receptor. Protein biotinylation that is mediated by ligand binding to its receptor is differentiated from background biotinylation events by comparison with a similarly labelled control protein using comparative proteomic mass spectrometry to quantify streptavidin-bound proteins. Using this method, we successfully identified the cell surface receptors of a peptide hormone, a monoclonal antibody, and a single-domain antibody-Fc fusion construct.

Crystal structure, electrochemical and magnetic properties of a new binuclear copper(II) complex with benzoic acid as a ligand

A new complex [Cu2(L)4(DMF)2] (1) with benzoic acid (HL) as a ligand is synthesized by the solid phase synthesis method. Crystal data for the complex are as follows: monoclinic, space group P21/n, a = 10.593(2) A, b = 10.123(2) A, c = 16.336(3) A, β = 93.55(3)°, V = 1748.4(6) A3, D c = 1.439 g/cm–3, Z = 4, F(000) = 780, GOOF = 1.003, final discrepancy factors R 1 = 0.0624, wR 2 = 0.1559. In 1, the Cu(II) ion is coordinated by six oxygen atoms to give a distorted octahedral coordination geometry. The electrochemical, fluorescent, and magnetic properties of 1 are studied. The results show that the electron transfer of 1 is quasi reversible in the electrode reaction corresponding to Cu(II)/Cu(I), and 1 exhibits three relatively strong fluorescent emission peaks at 403, 425, and 454 nm. In addition, complex 1 displays antiferromagnetism in a temperature range of 300 ~ 10 K.

Lifetime of excess electrons in Cu–Zn–Sn–Se powders

The method of time-resolved microwave photoconductivity at a frequency of 36 GHz in the range of temperatures of 200–300 K is used to study the kinetics of the annihilation of charge carriers in Cu–Zn–Sn–Se powders obtained by the solid-phase method of synthesis in cells. The lifetime of excess electrons at room temperature is found to be shorter than 5 ns. The activation energy for the process of recombination amounted to Ea ~ 0.054 eV.

荧光稀土钨酸盐制备进展

随着显示、照明及荧光标记技术的不断发展进步，人们对应用于这些领域的发光材料也提出了更高的要求，例如低成本、高效率、无污染且制备简单的发光材料一直受到研究者的重视和研究。稀土离子激活的发光材料是发光及光谱学领域研究的重要内容，同时稀土离子掺杂的纳米发光材料更是研究的热点问题。稀土钨酸盐作为一种重要的新型功能材料应用与社会生活的各个领域，探索研究钨酸盐的合成制备方法及钨酸盐材料的性质称为材料的领域的热门的方向。本文介绍了稀土钨酸盐的几种合成方法，例如，水热法、溶胶凝胶法、高温煅烧、微波固相合成、顶部籽晶提拉法、微接触印刷路线、高温固相反应。 With the technical developments of display lighting and fluorescence labeling, the demands for the luminescent materials with advanced performance are placed on the desk of researchers. The luminescent materials with low producing cost, high efficiency and being free from pollution are still preferred by the scientists. Rare earth ions doped luminescent materials are key content in the studied scoped of optical spectroscopy. Earth ions luminescent nanomaterials became a hot issue which is concerned by the researchers. Tungstate as an important new functional materials used in various fields social life, to explore the synthesis of tungstate and the properties of tungstate materials are known as the hot areas of the field of materials. Some common preparation methods of tungstate are introduced, such as hydrothermal method, Sol-gel method, high temperature calcination, microwave solid phase synthesis method, Top seed crystal pulling method, microcontact printing route, high temperature solid phase reaction.

Structure–activity relationship of cyclic pentapeptide malformins as fibrinolysis enhancers

The formation of blood clots in blood vessels causes severe ischemic diseases such as cerebral infarction and myocardial infarction. While searching for microbial products that increase fibrinolytic activity using an in vitro fibrin degradation assay, we found malformin A1, a disulfide form of cyclo(–d-Cys-d-Cys-l-Val-d-Leu-l-Ile–), as an active compound. In this study, we synthesized malformin derivatives using a solid-phase peptide synthesis method and evaluated their fibrinolytic activity and cytotoxicity. Reduction of the disulfide bond and linearization of the cyclic peptide frame decreased the pro-fibrinolytic activity. Substitution of a branched-chain amino acid with lysine resulted in loss of activity. However, protection of the amino group in the lysine derivatives by the tert-butoxycarbonyl (Boc) group rescued the inactivity. Furthermore, the phenylalanine derivatives also exhibited a similar pro-fibrinolytic effect compared to malformin A1. These results suggest that the disulfide bond, the cyclic peptide frame, and the bulky hydrophobic side chains play a crucial role in the pro-fibrinolytic activity of malformin. The effective dose of the active derivatives for the in vitro fibrin degradation showed similar ranges (1–5μM), while the order of cytotoxic potency for the active derivatives was as follows: Phe-derivatives>BocLys-derivatives>malformin A1>reduced form. These results showed no correlation between pro-fibrinolytic activity and cytotoxicity, suggesting the possibility of the synthesis for non-toxic malformin derivatives possessing the activity.

Fabrication of Cu2ZnSnS4 (CZTS) absorber films based on different compound targets

CZTS has been considered to be a perfect suitable replacement for CuInGaSe2 (CIGS) which contains the rare elements. This work developed a novel route to fabricate CZTS absorber films based on the integration of non-vacuum and vacuum techniques. This was illustrated by first synthesizing CZTS powder with the method of solid-phase synthesis. Then three different compound targets made of CZTS precursors and pure CZTS powder were utilized to fabricate CZTS absorber films using Radio Frequency (RF) sputtering, followed by a sulfurization process. All synthesized samples were analyzed with respect to their crystal structure, vibrational property, morphology and chemical composition. The photoelectrical properties investigation of the sulfurized absorber films by UV-VIS spectrophotometer and Hall effect measurement can well meet the requirements for potential application in thin film solar cells, demonstrating this approach had great potential for CZTS solar cell production.

A method for solid phase synthesis of phosphors under increased pressure; creation of remote phosphors

A method for phosphors solid-phase synthesis under high pressure is proposed. Using the method, phosphors based on rare earth garnets were synthesized at a temperature considerably lower (1300 °C) than the temperature of the synthesis by conventional method (above 1650 °C). Using organic, inorganic ligaments and synthesized phosphors, remote phosphors were created. The chromaticity coordinates of created LEDs on the base of blue LEDs and remote phosphors fall into the bin of white and green colours. Luminous efficiency reaches 140 lm/W.

Glycosaminoglycan-Based Biohybrid Hydrogels: A Sweet and Smart Choice for Multifunctional Biomaterials.

Glycosaminoglycans (GAGs) govern important functional characteristics of the extracellular matrix (ECM) in living tissues. Incorporation of GAGs into biomaterials opens up new routes for the presentation of signaling molecules, providing control over development, homeostasis, inflammation, and tumor formation and progression. Recent approaches to GAG-based materials are reviewed, highlighting the formation of modular, tunable biohybrid hydrogels by covalent and non-covalent conjugation schemes, including both theory-driven design concepts and advanced processing technologies. Examples of the application of the resulting materials in biomedical studies are provided. For perspective, solid-phase and chemoenzymatic oligosaccharide synthesis methods for GAG-derived motifs, rational and high-throughput design strategies for GAG-based materials, and the utilization of the factor-scavenging characteristics of GAGs are highlighted.

Solid-Phase Purification of Synthetic DNA Sequences.

Although high-throughput methods for solid-phase synthesis of DNA sequences are currently available for synthetic biology applications and technologies for large-scale production of nucleic acid-based drugs have been exploited for various therapeutic indications, little has been done to develop high-throughput procedures for the purification of synthetic nucleic acid sequences. An efficient process for purification of phosphorothioate and native DNA sequences is described herein. This process consists of functionalizing commercial aminopropylated silica gel with aminooxyalkyl functions to enable capture of DNA sequences carrying a 5'-siloxyl ether linker with a "keto" function through an oximation reaction. Deoxyribonucleoside phosphoramidites functionalized with the 5'-siloxyl ether linker were prepared in yields of 75-83% and incorporated last into the solid-phase assembly of DNA sequences. Capture of nucleobase- and phosphate-deprotected DNA sequences released from the synthesis support is demonstrated to proceed near quantitatively. After shorter than full-length DNA sequences were washed from the capture support, the purified DNA sequences were released from this support upon treatment with tetra-n-butylammonium fluoride in dry DMSO. The purity of released DNA sequences exceeds 98%. The scalability and high-throughput features of the purification process are demonstrated without sacrificing purity of the DNA sequences.

An assessment tumor targeting ability of 177Lu labeled cyclic CCK analogue peptide by binding with cholecystokinin receptor

The cholecystokinin (CCK) receptor is known as a receptor that is overexpressed in many human tumors. The present study was designed to investigate the targeting ability of cyclic CCK analogue in AR42J pancreatic cells. The CCK analogues, DOTA-K(glucose)-Gly-Trp-Nle-Asp-Phe (DOTA-glucose-CCK) and DOTA-Nle-cyclo(Glu-Trp-Nle-Asp-Phe-Lys-NH2) (DOTA-[Nle]-cCCK), were synthesized and radiolabeled with 177Lu, and competitive binding was evaluated. The binding appearance of synthesized peptide with AR42J cells was evaluated by confocal microscopy. And bio-distribution was performed in AR42J xenografted mice. Synthesized peptides were prepared by a solid phase synthesis method, and their purity was over 98%. DOTA is the chelating agent for 177Lu-labeling, in which the peptides were radiolabeled with 177Lu by a high radiolabeling yield. A competitive displacement of 125I-CCK8 on the AR42J cells revealed that the 50% inhibitory concentration value (IC50) was 12.3 nM of DOTA-glucose-CCK and 1.7 nM of DOTA-[Nle]-cCCK. Radio-labeled peptides were accumulated in AR42J tumor in vivo, and %ID/g of the tumor was 0.4 and 0.9 at 2 h p.i. It was concluded that 177Lu-DOTA-[Nle]-cCCK has higher binding affinity than 177Lu-DOTA-glucose-CCK and can be a potential candidate as a targeting modality for a CCK receptor over-expressing tumors.

Solvothermal Synthesis of LiFePO4 with an Energy Saving Technique

Lithium iron phosphate (LiFePO4) with stable olivine structure is considered as a promising cathode material for rechargeable lithium batteries, due to its nontoxicity, high specific electrochemical capacity, excellent cycling stability and low cost. The LiFePO4, however, suffers from low power capacity attributed to its low electronic conductivity (about 10-9 S cm-1) and low ionic conductivity(about 1.8×10-14 cm2 S-1). Various approaches have been investigated to improve its electronic conductivity, such as carbon coating, higher valent cation doping, etc. Because of lithium ion’s one dimensional migration channel parallel to the b axis reducing particle sizes and crystal morphology control have been confirmed as the effective ways to improve LiFePO4 performances. Compared with conventional solid-phase synthesis method, hydrothermal/ solvothermal synthesis methods have shown advantages in controlling particle size and crystal orientation in synthesizing many materials including LiFePO4. hydrothermal/solvothermal synthesis technique is more complicated and more sensitive to reaction parameters compared with solid-phase method. Reaction parameters like feeding sequence, temperature and time have great influences on product LiFePO4’s crystallinity, morphology and especially electrochemical performances. As investigated ethylene glycol(EG) as a solvent or co-solvent have significant positive influences (for smaller crystal size and better electrochemical performance) on LiFePO4solvothermal process. In this work, we have applied a solvothermal process using ethylene glycol(EG) as solvent to investigate LiFePO4 crystallization. The synthesis of LiFePO4 was carried out in a 50ml Teflon vessel, which was sealed in a stainless-steel autoclave. The molar ration of Li:Fe:P in the precursor solution was 2.7:1:1, and the concentration of LiFePO4 in the reaction solution was controlled to be 0.2M. LiOH·H2O, FeSO4·7H2O and H3PO4 were chosen as Li, Fe, P sources, and EG was chosen as solvent for this solvothermal synthesis. The typical feeding sequence was chosen:. The reactor was heated in an air oven setting at 120, 140, 160, 180˚C for 1min. The heating and cooling rates were measured and collected. Fig. 1 shows the comparison of the temperature in and out of Teflon when air oven is set as 160 ˚C for 1min. The temperature of air in oven increased faster than the slurry in reactors. When oven was set at 160˚C for 1min,the highest temperature of the slurry is 89˚C instead. The result samples were characterized by XRD shown in Fig. 2. Crystallized LiFePO4 phase appeared associated with little Fe3(PO4)2·H2O and Li3PO4 when oven temperature was set at 160 ˚C for 1min. It indicates that the LiFePO4 nuclei could be formed as low as 89˚C (real temperature) in EG during solvothermal process. Then we tried to synthesize LiFePO4 samples in 85 and 80 ˚C for 10 hours. The XRD results show that LiFePO4 crystal phase can be formed even at as low as 80 ˚C in EG while in water the lowest temperature for LiFePO4crystallization is 105 ˚C. The decrease of LiFePO4 crystallization temperature is attributed to EG’s unique properties. There are 2 hydroxyl groups in EG’s chemical formula which have a strong hydrogen bonding ability. The two hydrogen bonds are not formed in one plane which results in a loose bonding structure and produces a low energy intermediate during crystallization reaction. It indicates a catalytic effect on LiFePO4 crystallization. And EG has a smaller solubility compared with water which leads to a higher degree of supersaturation at the same raw material concentration. LiFePO4 nucleis with slow crystal growth from diffusing solvents are because of the lower viscosity of EG. The results of this work provide deep insights into LiFePO4 crystallization in solvothermal synthesis process. Also it provides the probability of synthesis materials for lithium ion batteries on an energy saving mode. Figure 1

Sintesis Heptapeptida Linear (H-Tyr-Asp-Pro-Ala-Pro-Pro-Pro-Oh) dengan Menggunakan Dic/Oksima sebagai Reagen Pengkopling

A tetrapeptide, an analog of trypsin-modulating oostatic factor (TMOF), has been synthesised by using a method of solid-phase peptide synthesis on 2-chlorotrityl chloride resin. Fmoc strategy was applied on the synthesis. The formation of peptide bond was facilitated by DIC/oxime as coupling reagent. After all of amino acids were attached on the resin, tetrapeptidyl resin was added by a mixture of TFA:water:EDT(90:5:5) in dichloromethane to cleave the peptide.Crude peptide was purified by reverse-phase column chromatography and the purified peptide was analysed by TOF ES-MS spectroscopy .

Solid-phase synthesis of imprinted nanoparticles grafted on gold substrates for voltammetric sensing of 4-ethylphenol

A voltammetric sensor based on molecularly imprinted high affinity nanoparticles has been developed for the direct, selective, and label-free detection of 4-ethylphenol (4EP). The poorly functionalised template 4EP, was successfully imprinted by the recently developed method of solid-phase synthesis of molecularly imprinted nanoparticles. These nanoparticles were grafted to the surface of gold electrodes allowing for selective and sensitive detection of 4EP. Each step of the electrode modification process was characterised by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical response of the developed sensor was evaluated and a linear range between 0.24 and 5mgL−1 was obtained, together with good repeatability (RSD<10%). The sensor was proven to recognise specifically the target compound over structural analogues, including compounds that belong to the same metabolic pathway such as coumaric acid ethyl ester, coumaric acid and 4-vinylphenol, or other phenolic compounds such as 4-ethylguaiacol or paracetamol.

Thermal Stability of Aluminum Titanate Ceramics

The thermal stability of aluminum titanate (AT) ceramics is the main problem that restricted its extensive applications in many fields. In this paper, AT ceramics doped with single or composite additives of MgO, SiO2, mullite were fabricated by solid phase synthesis method. The thermal stability was tested by heated for 50h at 1100°C, and the phases of the samples were tested by X-ray diffraction (XRD) , and the microstructure were tested by SEM. The mechanism of the thermal stability of AT with additive was discussed based on DSC/TGA and electron back scatter diffraction pattern (EBSP). The results show that the adding of composite additives can improve the thermal stability of AT ceramics.

Synthesis of chiral fluorescence silver nano-clusters and study on the aggregation-induced emission enhancement and chiral flip

Using racemic GSH as ligand, AgNCs with aggregation-induced emission enhancement and chiral flip were synthesized with solid-phase synthesis method.

High-affinity sequence-selective DNA binding by iridium(III) polypyridyl organometallopeptides.

We demonstrate the application of solid-phase peptide synthesis methods for the straightforward assembly of polynuclear Ir(III) organometallopeptides, and show that their oligoarginine derivatives exhibit high DNA binding affinity, sequence selectivity, and high cytotoxicity towards a set of cancer cell lines.

Mussel-inspired adhesive epidermal growth factor for biological surface modification

Event Abstract Back to Event Mussel-inspired adhesive epidermal growth factor for biological surface modification Hongli Mao1, Shinhe Park1, 2*, Seiichi Tada1 and Yoshihiro Ito1, 2 1 RIKEN, Nano Medical Engineering Laboratory, Japan 2 Waseda University, Department of Life Science and Medical Bio-Science, Japan Introduction: Growth factor, as a fundamental requirement in tissue engineering, plays important roles in the regulation of a variety of cellular processes. It has been demonstrated that the immobilized growth factors on the material surfaces can stimulate the cognate receptors in the cell membrane and trigger the signal transduction. Although types of growth factors with binding ability to specific substrates were developed, simple and versatile strategies to modify growth factors for surface modification of multiple classes of materials are essential. Here inspired by underwater adhesive protein secreted by mussel, we incorporated the binding peptide sequence carrying 3,4-dihydroxyphenylalanine (DOPA) to the active sequence of epidermal growth factor (EGF). The binding affinity of the constructed growth factor (EGF-DOPA) to typical organic and inorganic materials and its biological activities were investigated. Materials and Methods: A peptide synthesizer ABI 433A was employed to synthesize the active sequence of EGF and the adhesive peptide carrying DOPAs and lysines (DOPA-Lys-DOPA-Lys-DOPA) by a solid-phase peptide synthesis method. Then the active sequence of EGF and the adhesive peptide was conjugated using three glycine residues as a spacer. After purification with a high performance liquid chromatography (HPLC), formulations of the synthesized peptide were confirmed by matrix-assisted laser desorption/ionization time-of-flight mass analysis (MALDI-TOF-MS). The binding affinity of EGF-DOPA to polystyrene (PSt) and titanium (Ti) surfaces was confirmed by using a quartz crystal microbalance with dissipation monitoring (QCM-D). The surface morphology and thickness of the substrates treated with EGF-DOPA was studied by atomic force microscopy (AFM), scanning electron microscopy (SEM) and ellipsometry. Rat kidney adherent fibroblast cell line, NRK49F, was cultured on the surfaces treated with EGF-DOPA. Cell growth and time course activation of cellular signal transduction was measured through WST-8 assay and phosphorylation analysis, respectively. Results and Discussion: MALDI-TOF-MS result showed that the expected 54-residue peptide (CPLSH-DGYCL-HDGVC-MYIEA-LDKYA-CNCVV-GYIGE-RCQYR-DLKWW-E-GGG-DOPA-K-DOPA-K-DOPA, EGF-DOPA) was successfully synthesized. QCM measurement showed that the binding affinity of EGF-DOPA on both PSt and Ti surfaces was significantly higher than that of EGF. Concentration and pH dependent binding affinity of EGF-DOPA was confirmed. This result was also proved by thickness measurement using SEM and ellipsometry. The measured thicknesses of EGF-DOPA bound on the substrates displayed the same trend as those calculated from the QCM measurement. AFM results showed that aggregation of the EGF-DOPA happened at high pH condition. Substrates treated with EGF-DOPA significantly improved cell growth and this result can attributed to the long activation period of bound EGF-DOPA on the substrates. Conclusions: Mussel-inspired adhesive EGF derivative (EGF-DOPA) was constructed. The binding affinity of EGF-DOPA to both PSt and Ti surfaces was dramatically higher than that of EGF. The bound EGF-DOPA significantly promoted cell growth. This mussel-inspired dopamine modification provides an effective method for preparation of adhesive materials that may be useful for surface modification and the development of medical devices.

A green technology for the synthesis of cellulose succinate for efficient adsorption of Cd(ii) and Pb(ii) ions

Cellulose succinate, directly prepared by a simple and green mechanical activation-assisted solid-phase synthesis method in a stirring ball mill, was used as environmental-friendly adsorbent for efficient adsorption of heavy metals.