Types Of Organic Groups Research Articles

Utilization of Prunus serrulata leaf extract for the synthesis and characterization of ZnO nanoparticles

Using a green route for the synthesis of nanoparticles has become popular in recent years due to its easier, eco-friendly, faster and cheaper nature. This study explores the synthesis of ZnO nanoparticles utilizing, for the first time, Prunus serrulata (Japanese Cherry Blossom) leaf extract as both a reducing and capping agent. The characterization of the nanoparticles was performed by employing several instrumental techniques. The X-Ray Diffraction (XRD) method was utilized to identify the amorphous crystal structure of the ZnO nanoparticles. Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM) were used to determine the homogenous and spherical geometry, having a size of 5–10 nm. X-Ray Photoelectron Spectroscopy (XPS) was used to observe the surface of the nanoparticles, which were present in the metal oxide form. Fourier Transform-Infrared spectroscopy (FT-IR) was also utilized to understand which types of organic groups are responsible for the stabilization of the nanoparticles.

Use of Materials Based on Polymeric Silica as Bone-Targeted Drug Delivery Systems for Metronidazole.

Mesostructured ordered silica-based materials are the promising candidates for local drug delivery systems in bone disease due to their uniform pore size and distribution, and high surface area which affect their excellent adsorption properties, good biocompatibility and bioactivity, and versatile functionalization so that their properties can be controlled. Ordered mesoporous silica (MCM-41 type) was synthesized by a surfactant-assisted sol-gel process using tetraethoxysilane as a silica precursor and hexadecyltrimethylammonium bromide as the structure-directing agent. Functionalized silica materials containing various types of organic groups (3-aminopropyl, 3-mercaptopropyl, or 3-glycidyloxypropyl groups) were synthesized by the post-grafting method onto pre-made mesoporous silica. Comparative studies of their structural characteristics, the surface mineralization activity and release properties for the model drug Metronidazole (MT) were then conducted. It has been found that porosity parameters, mineralization activity and adsorption/release of metronidazole from mesoporous channels of silica can be regulated using functional groups which are chemically bounded with an outer silica surface. The preferential mineral nucleation was found on negatively charged surfaces—MCM-41, and mercaptopropyl and glycidyloxypropyl functionalized silica (MCM-SH and MCM-epoxy, respectively) in simulated body fluid (SBF solution), as well as a sustained release of MT. In contrast to them, aminopropyl-functionalized samples (MCM-NH2) achieved a high MT release rate. These results confirm the potential of silica-based materials for local therapeutic applications (as drug carriers and bone substitutes) in bone disease.

Chemical Crosslinking: Role in Protein and Peptide Science.

Chemical crosslinking refers to intermolecular or intramolecular joining of two or more molecules by a covalent bond. The reagents that are used for the purpose are referred to as 'crosslinking reagents' or 'crosslinkers'. Based on factors like reactivity and spacer length these are classified into different types, each having its own specific function and application. In recent times, chemical crosslinking has emerged as an efficient tool for the study of biomolecules like proteins. It finds its application in various studies including the attachment of proteins to a solid support for the study of membrane receptors, protein-protein complexes, protein-DNA complexes, and others. When coupled with techniques like mass spectroscopy, it has been used not only for the determination of three dimensional structures of proteins but also for the study of protein-protein interactions and determination of interesting sites. This combination of mass spectrometry techniques and bioinformatics, added yet another dimension to our present day understanding of protein chemistry. Thus, chemical crosslinking has multitude uses that it can be put to. We undertook a systematic search of bibliographic databases and search engine such as Google Scholar, Scifinder, Scopus, Mendeley etc for review of research literature. We excluded research paper which only reported synthesis of crosslinker molecules and did not involve any mass spectrometry studies. Sixty-four papers were included in the review. The majority of references were taken from last ten years as there has been an immense progress in this area in the recent years. Eleven classical papers in this field were included which talk about basic of this methodology. Thirty-two papers discussed about various types of organic groups used for designing chemical cross-linkers and various methodologies which were used to enhance the crosslinking efficiency. These papers also highlight various strategies used to enhance detection of cross-linked proteins and various computer software used to detect cross-linking sites from mass data. Twenty-one papers showed the proof concept application of this methodology to detect protein crosslinking in-vivo and in-vitro. The findings of this review confirm the importance chemical crosslinking combined with mass spectroscopy as a low cost alternative to understand protein-protein interaction. The information generated by this methodology can help in better understating of various diseases and for the development of better drugs for them.

Sol-gel based photochromic coating for solar responsive smart window

Transparent photochromic (PC) films can be used for smart window applications to partially block the sunlight and provide comfort vision. However, for large area applications, the high cost and delicate manufacturing processes are the major challenges faced by the prior-art technologies. This paper reports a development of cost effective PC coatings with effective reduction of visible light transmission and total energy transmittance at tinted states. The coating material was prepared by embedding organic PC dyes, 1,2-b Naphthopyran, in sol-gel based organic-inorganic mesoporous coating matrix. The degree of crosslinking of coating matrix and types of organic groups can effectively influence the visible light transmittance and bleaching speed. Visible light transmission reduction at tinted state can be tuned from 30% to 60% by varying the dye concentration in coating and coating thickness. The thermal properties of the PC coatings are evaluated by UV–Vis-NIR and FTIR measurements and further calculation to obtain solar heat gain coefficient (G value) and thermal transmittance (U value). For a glass in thickness of 3mm coated with a PC layer in thickness of 12μm, the G value at tinted state was reduced to 0.78 as compared with a G value of 0.87 for an uncoated glass. A double glazed smart window prototype consisting of a commercial low-E glass and a PC coated glass showed G value of 0.26, and U value of 1.58 as compared to the G value of 0.87 and U value of 5.2 of a single uncoated glass. This demonstrates a significant reduction of energy transmittance through the smart window resulting in high potential energy saving for end users especially in tropical climate.

ChemInform Abstract: Preparative Routes to Organozinc Reagents Used for Organic Synthesis

Organozinc reagents have become extremely important synthetic tools in recent years, and the useful and practical preparative routes to such reagents have been reviewed. The methods have been classified into four broad categories, (1) oxidative zincation method, (2) transmetalation method, (3) halogenzinc exchange, and (4) others. Each categories are subdivided according to the type of organic groups on the zinc atom (alkyl, alkenyl, etc.).

Functionalized mesoporous materials for adsorption and release of different drug molecules: A comparative study

The adsorption capacity and release properties of mesoporous materials for drug molecules can be improved by functionalizing their surfaces with judiciously chosen organic groups. Functionalized ordered mesoporous materials containing various types of organic groups via a co-condensation synthetic method from 15% organosilane and by post-grafting organosilanes onto a pre-made mesoporous silica were synthesized. Comparative studies of their adsorption and release properties for various model drug molecules were then conducted. Functional groups including 3-aminopropyl, 3-mercaptopropyl, vinyl, and secondary amine groups were used to functionalize the mesoporous materials while rhodamine 6G and ibuprofen were utilized to investigate the materials’ relative adsorption and release properties. The self-assembly of the mesoporous materials was carried out in the presence of cetyltrimethylammonium bromide (CTAB) surfactant, which produced MCM-41 type materials with pore diameters of ∼2.7–3.3 nm and moderate to high surface areas up to ∼1000 m 2/g. The different functional groups introduced into the materials dictated their adsorption capacity and release properties. While mercaptopropyl and vinyl functionalized samples showed high adsorption capacity for rhodamine 6G, amine functionalized samples exhibited higher adsorption capacity for ibuprofen. While the diffusional release of ibuprofen was fitted on the Fickian diffusion model, the release of rhodamine 6G followed Super Case-II transport model.

Characterization of Nanostructured Organic-Inorganic Hybrid Materials Using Advanced Solid-State NMR Spectroscopy

AbstractWe demonstrate the applications of several novel techniques in solid-state nuclear magnetic resonance spectroscopy (SSNMR) to the structural studies of mesoporous organic-inorganic hybrid catalytic materials. Most of these latest capabilities of solid-state NMR were made possible by combining fast magic angle spinning (at ≥ 40 kHz) with new multiple RF pulse sequences. Remarkable gains in sensitivity have been achieved in heteronuclear correlation (HETCOR) spectroscopy through the detection of high-λ (1H) rather than low-λ (e.g., 13C, 15N) nuclei. This so-called indirect detection technique can yield through-space 2D 13C-1H HETCOR spectra of surface species under natural abundance within minutes, a result that earlier has been out of reach. The 15N-1H correlation spectra of species bound to a surface can now be acquired, also without isotope enrichment. The first indirectly detected through-bond 2D 13C-1H spectra of solid samples are shown, as well. In the case of 1D and 2D 29Si NMR, the possibility of generating multiple Carr-Purcell-Meiboom-Gill (CPMG) echoes during data acquisition offered time savings by a factor of ten to one hundred. Examples of the studied materials involve mesoporous silica and mixed oxide nanoparticles functionalized with various types of organic groups, where solid-state NMR provides the definitive characterization.

Novel Two-Dimensional Molecular Space Material with Regular Double Bonds

A novel layered material acrylamidephenylsilica (AAPhS) with regular double bonds in a layer structure was synthesized by liquid−solid reaction between layered aminophenylsilica (APhTMS-Cl) and acrylic acid. A series of novel layered materials can be synthesized by hybridizing various types of organic groups in the layer structure of layered acrylamidephenylsilica.

Proton conductivity and methanol permeation in Nafion™/ORMOSIL prepared with various organic silanes

Using TEOS and organic silane agent, we could prepare the Nafion™/ORMOSIL hybrid membranes with varying hydrophilicity and morphology by controlling the number and the type of organic groups. Water uptake was dominated by the hydrophilicity of hybrid membranes. On the other hand, methanol uptake was determined by the interconnectivity and the compatibility of ORMOSIL phase. It is due to the difference of polarity between water and methanol. Methanol permeability was directly correlated with the uptakes of both water and methanol which reflect how many paths for the methanol diffusion were formed. The methanol sorption was directly related to methanol uptake. In addition, the higher the methanol diffusion, the higher the wet porosity of membranes in methanol–water solvent. The type of organic groups as well as the hydrophilicity and the distribution of ORMOSIL phase could affect proton conductivity. Nafion™/[ORMOSIL (TEOS:TEVS=1:1)] had much lower proton conductivity while Nafion™/[ORMOSIL (TEOS:DEDMS=0:1)] had much higher proton conductivity.

Development of Quantum dot Reporters for Immunoassay Applications

ABSTRACTMulti-pathogen biosensors that take advantage of sandwich immunoassay detection schemes usually rely on spatial resolution patterns of capture antibodies on a detector plate for pathogen recognition, and typically utilize fluorescent, organic dyes as optical labels to identify captured pathogens. An immunoassay-based, fiber optic detector that utilizes varying sized fluorescent semiconductor quantum dots (QDs) as the reporter labels for different antibodies would have the ability to detect multiple pathogens within a single fiber, using a single excitation source. Such a detector requires that QDs be attached to antibody proteins, such that the specificity of the antibody is maintained. We have been involved in efforts to develop a reproducible method for attaching QDs to antibodies for use in such a biosensor.We synthesized CdSe/ZnS core-shell QDs of differing size, functionalized their surfaces with several types of organic groups for water solubility, and covalently attached these functionalized QDs to rabbit anti-ovalbumin antibody protein. We also demonstrated that these labeled antibodies exhibit selective binding to ovalbumin antigen. We characterized the QDs at each step in the overall synthesis by UV-VIS absorption spectroscopy and by picosecond (psec) transient photoluminescence (TPL) spectroscopy. TPL spectroscopy measurements indicate that QD lifetime depends on the size of the QD, the intensity of their optical excitation, and whether or not they are functionalized and conjugated to antibody. We describe details of these experiments and discuss the impact of our results on our biosensor program.

Solvent Extraction with Quaternary Ammonium Halides.

The solvent extraction of metal ions by quaternary ammonium halides dissolved in 1,2-dichloroethane is described. The extraction is dependent upon the ion association of the quaternary ammonium ion with labile chloro anionic complexes of Fe (III), Co(II), Zn(H), and Tl(III) or with the oxyanions of Hf(PJ), Ta(V), and Mo(VI) in concentrated hydrochloric acid or lithium chloride. The effects of metal ion concentration, contacting time, and type of quaternary ammonium halide are investigated with the cobalt ion. Extractions of >50% for cobalt are possible only if the distribution ratio of the quaternary ammonium halide itself is very large. The value of the distribution ratio of the cobalt ion is dependent upon the quaternary ammonium ions' size, shape, and type of organic groups. An analogy between solvent extraction with quaternary ammonium halides and anion exchange of metal ions in concentrated hydrochloric acid is demonstrated. (auth)