Organic Matrixes Research Articles

Comparison of extraction and derivatization methods for fatty acid analysis in solid environmental matrixes

This study involved comparison of different extraction and derivatization methods for determining FAs in soil and in four highly organic matrixes (cattle manure, pig slurry, compost, and vermicompost), by application of a multifactor categorical design. Although some studies have been carried out regarding the application of FA analysis to highly organic matrixes, comparison and verification are still required to test which methods of extraction and derivatization of FAs function best for these matrixes. We compared three extraction methods (one in which the same extraction mixture as used in the Folch method was employed, a modification of the Bligh and Dyer method, and a microwave-assisted extraction) and two derivatization procedures (alkaline methanolysis and derivatization with trimethylsulfonium hydroxide (TMSH)). The highest yields of FAs belonging to different structural classes, and of individual FAs used as microbial biomarkers were obtained by application of the same extraction mixture as in the Folch method and use of TMSH as derivatization agent. These methods also involved a significant reduction in the complexity and time involved in sample preparation.

Comparison of nonporous silica‐based ion exchangers and monolithic ion exchangers in separations of inorganic anions

Low capacity anion exchangers for IC have been prepared by modification of nonporous uniformed silica MICRA microbeads and by modification of the organic polymeric monolithic matrixes prepared in situ in quarz capillary. Due to the small particle size (1.5 microm) high-performance adsorbents were prepared allowing to obtain up to 190,000 tp/m. However, the column possesses a very high back-pressure and can be used in a short length up to 50 mm only to meet the requirements of conventional chromatographic equipment. An analysis of a test mixture of seven anions was completed within 3 min with a back column pressure of about 350 bar (HETP of about 5.5 microm, where HETP is the height equivalent to the theoretical plate). Monolithic capillary columns provide lower efficiency per column unit length than MICRA columns; however, they can be used at a longer length because of their low flow resistance. Monolithic column of ca. 40 cm length has workable pressure below 10 bar and allows separation of a five anions test mixture within less than 10 min. A better efficiency of monolithic column (HETP approximately 75 microm) can be achieved at reduced flow rates when the analysis time is not a critical parameter.

Imidazole-Based Excited-State Intramolecular Proton-Transfer (ESIPT) Materials: Observation of Thermally Activated Delayed Fluorescence (TDF)

We report the first observation of thermally activated delayed fluorescence (TDF) from an excited-state intramolecular proton-transfer (ESIPT) molecule, a hydroxyl-substituted tetraphenyl imidazole derivative (HPI-Ac), in degassed solutions as well as in low-temperature organic matrixes. In the absence of oxygen, the blue emission of an identical spectral feature was observed in the nanosecond ( approximately 4.4 ns) and microsecond ( approximately 25 micros) time domains, and the fluorescence intensity increased with temperature. From the temperature dependence of the time-resolved spectra of HPI-Ac, the energy gap between the first-excited singlet state and the lowest triplet state was determined to be 7.6 +/- 0.3 kJ/mol (630 +/- 25 cm-1), and the limiting rate constant of intrinsic reverse intersystem crossing was estimated to be 1.3 (+/-0.5) x 107 s-1.

Dental Restorative Composites Fabricated from a Novel Organic Matrix without an Additional Diluent

Commercial organic matrixes of dental composites generally include diluents such as triethylene glycol dimethacrylate (TEGDMA) to reduce viscosity. However, the diluent exhibits adverse effects such as curing shrinkage and diminished mechanical properties of the dental composites. To overcome these adverse effects, organic monomers that can be used as an organic matrix may be developed. In this study, various novel organic monomers were developed by substituting alkoxy for hydroxyl groups in 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy)phenyl]propane (bis-GMA). Viscosities of the alkoxy-substituted monomers were decreased by increasing substituent size. The viscosity of 2,2-bis[4-(2-ethoxy-3-methacryloyloxy propoxy)phenyl]propane (bis-E-GMA) was higher than the control organic matrix (70 wt % bis-GMA and 30 wt % TEGDMA). However, those of 2,2-bis[4-(2-propoxy-3-methacryloyloxy propoxy)phenyl]propane (bis-Pr-GMA), 2,2-bis[4-(2-butoxy-3-methacryloyloxy propoxy)phenyl]propane (bis-B-GMA), and 2,2-bis[4-(2-pentoxy-3-methacryloyloxy propoxy)phenyl]propane (bis-P-GMA) were lower than the control organic matrix. To this end, these monomers could be used as organic matrixes of dental composites without an additional diluent. Among these monomers, bis-B-GMA exhibited the lowest curing shrinkage. In comparison to the control organic matrix, the curing shrinkage of the bis-B-GMA dental composite was approximately 40%. Additionally, dental composites prepared from bis-B-GMA exhibited excellent mechanical properties.

Nanomaterial Based Affinity Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for Biomolecules and Pathogenic Bacteria

This paper describes mass spectrometry (MS) using nanoparticles (NPs) for the analysis of biomolecules such as aminothiol compounds, drugs, peptides, proteins, and bacteria. Papers and patents dealing with preparation and use of several NPs in MS have been briefly reviewed, including carbon nanotubes, gold NPs, and magnetic NPs. The NPs or bioconjugated NPs were used for selective concentration and/or assisted matrices for desorption and ionization of analytes of interest. When compared to conventional organic matrixes, the NPs provide low MS background in low-mass region and low shot-to-shot variation. MS techniques using NPs and bioconjugated NPs for the analysis of disease-associated biomarkers and bacteria in real samples such as blood and urine are highlighted, showing the advantages of high sensitivity, reproducibility, and simplicity.

Analysis of Adenosine Triphosphate and Glutathione through Gold Nanoparticles Assisted Laser Desorption/Ionization Mass Spectrometry

This paper describes the use of aptamer-modified gold nanoparticles (Apt-AuNPs) as selective probes and AuNPs as the surface-assisted laser desorption/ionization (SALDI) matrixes for the determination of adenosine triphosphate (ATP) by mass spectrometry (MS). The aptamers were covalently attached to the surface of AuNPs to form Apt-AuNPs that provided selectivity toward ATP. However, Apt-AuNPs are less efficient laser desorption/ionization (LDI) matrixes when compared to AuNPs. By using Apt-AuNPs as selective probes and AuNPs as LDI matrixes, the MS approach provided the limit of detection (LOD) for ATP at a signal-to-noise ratio of 3 of 0.48 microM. When compared to conventional organic matrixes (e.g., 2,5-dihydroxybenzoic acid), AuNPs as LDI matrixes provide a number of advantages, including ease of preparation, selectivity, sensitivity, and repeatability. Sequential analysis of ATP and GSH in human cell lysates by SALDI with negative and positive MS modes, respectively, using Apt-AuNPs and AuNPs has been demonstrated. The present results demonstrate the practicality of the approach for monitoring the bioactivity of cells through determinations of the concentrations of ATP and GSH.

Artificial Nacre by Alternating Preparation of Layer-by-Layer Polymer Films and CaCO3Strata

In this paper, we described the fabrication of hybrid nanocomposite by bottom-up alternating preparation of organic and inorganic layers, toward the mimicking biomineralization process of natural nacre. The organic layers are layer-by-layer (LBL) polymer thin films of diazo-resins (DAR) and poly(acrylic acid) (PAA), with reactive DAR for cross-linking the thin films and PAA for providing a surface for facilitating the biomineralization. The inorganic layers are CaCO3 strata, which were prepared via the CO2 diffusion method. Scanning electron microscopy observations show that the nanocomposite fabricated in this way has the alternate organic−inorganic multilayered structure, similar to the natural nacre's brick-and-mortar structure. The thicknesses of CaCO3 strata can be controlled by selecting the diffusion time of CO2. Moreover, the thickness and content of organic matrixes may be adjusted by controlling the layer number of LBL polymer thin films. TGA analysis reveals that the content of organic composit...

Gold Nanoparticles as Assisted Matrix for Determining Neutral Small Carbohydrates through Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

A method for the analysis of small neutral carbohydrates by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) has been developed by using bare AuNPs as matrices. In comparison with citrate-capped and DDAB-capped AuNPs, bare AuNPs can capture the analytes on their surface; therefore, small neutral carbohydrates, which are difficult to ionize by matrix-assisted desorption/ionization mass spectrometry, could be cationized very efficiently by SALDI-MS with AuNPs as matrices. By using SALDI-MS in the positive ion mode, many molecular ions are obtained from monosaccharides and disaccharides. Without derivatization, the limits of detection at a S/N ratio of 3 are 82, 41, 144, and 151 nM for ribose, glucose, cellobiose, and maltose. In comparison with conventional organic matrixes (e.g., 2,5-dihydroxybenzoic acid), bare AuNPs as SALDI matrices offer many advantages, such as easy sample preparation, high ionization efficiency, and high shot-to-shot reproducibility. To validate the applicability of our method, a calibration curve is created from urine spiked with standard glucose (0.5-10 mM). We strongly believe that this approach can potentially be applied to diagnosis and glycomics.

Laser and Physical Properties of BODIPY Chromophores in New Fluorinated Polymeric Materials

We report on the synthesis and photophysical and lasing properties of new linear and cross-linked fluorinated polymeric materials doped with two BODIPY chromophores such as PM567 and PM597. The total fluorine content of the matrixes was varied adding to methyl methacrylate (MMA) different volumetric proportions of monomers with increased number of fluorine atoms: 2,2,2-trifluoromethyl methacrylate, 2,2,3,3,3,-pentafluoropropyl methacrylate (PFMA), and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate. The rigidity of the materials was modified adding to PFMA di-, tri-, and tetra-functionalized comonomers such as ethyleneglycol dimethacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate. When the fluorine-modified organic matrixes were transversally pumped at 532 nm, highly stable laser operation with high, not-optimized efficiencies up to 42% was obtained. The highest photostability was recorded for PM597 doped MMA/PFMA 70/30 linear matrix, with no sign of degradation in the laser output aft...

Formation of Transient Amorphous Calcium Carbonate Precursor in Quail Eggshell Mineralization: An In Vitro Study

To understand the mechanism of quail eggshell biomineralization, we have performed two CaCO(3) precipitation experiments. In the reprecipitation experiments, supersaturated Ca(HCO(3))(2) was prepared by bubbling CO(2) through a slurry of biogenic CaCO(3) obtained from bleach-treated eggshell followed by filtration to obtain a clear solution for crystallization experiments. The nucleated crystals were collected at various time intervals and analyzed. In the second experiment, the extracted SOM from the bleach-treated eggshell was added to the supersaturated clear solution of Ca(HCO(3))(2) solution obtained by bubbling CO(2) gas through a slurry of synthetic CaCO(3) followed by filtration. The crystals/precipitates collected at various time intervals were analyzed. Both experiments showed that amorphous CaCO(3) (ACC) was precipitated in the early stages, which then transformed to the most stable crystalline calcite phase. Amino acid analysis of the soluble organic matrixes (SOM) indicated the presence of high amounts of Glx and Asx amino acids. Ovomucoid--an acidic glycoprotein, and lysozyme--a basic protein, are the two major components along with a few low molecular weight peptides present in the SOM of quail eggshell matrix. Both ovomucoid and lysozyme did not induce precipitation of the ACC phase in in vitro conditions, while the fraction containing low molecular weight peptides induced the precipitation of ACC, suggesting that the latter play an important role in the eggshell biomineralization. Thus, organisms can produce inorganic minerals which assume nonequilibrium morphologies and intricate architecture by precipitating transient ACC, which then transformed into the crystalline phase. Altogether, these observations further demonstrate that this strategy may be common in both vertebrate and invertebrate mineralized structures.

Preparation and surface modification of uniform ZnO nanorods via a one-step process

Hydrophobic ZnO uniform nanorods were successfully produced via a one-step process through precipitation transformation reaction in aqueous solution of ZnSO 4, Na 2CO 3 and NaOH with sodium oleate (C 17H 33COONa) as a modifying agent. Sodium oleate was used to control the size and modify the surface property of the nanorods produced from the precipitation transformation reaction. Measurements of relative contact angle and active ratio indicated that ZnO nanorods were hydrophobic. Scanning electron microscope, X-ray diffraction, XPS analysis, and thermogravimetric analysis were applied. These results suggested that the hydrophobic property was attributed to the presence of a thin layer of zinc oleate, which was bonded onto the surface of ZnO nanorods during the reaction process. The effect of surface modification on morphology, and size of ZnO nanorods and the mechanism of surface modification were preliminary presented. This work provided an approach to control the uniform growth of ZnO nanorods and enhance interfacial compatibility between ZnO powders and organic matrixes by treating the surface with certain capping molecules.

Nanoscale characterization of nautilus shell structure: An example of natural self-assembly

Structural characterization at the nanometric scale of theNautilus spshell was carried out by high-resolution transmission electron microscopy and high-angle annular dark field to understand how the organic and inorganic components are related. The inorganic phase that built the shell is made of calcium carbonate (CaCO3), with the orthorhombic unit cell of the aragonite, in a texturized arrangement in such a way that thec-axis is always perpendicular to the shell surface. The organic material forms films through the plates. We observed for a very first time some aragonite nanocrystals embedded in the organic matrix. This observation supports the hypothesis that the proteins and other organic compounds guide the crystal growth because the organic matrixes are the places where the nanocrystals grow.

Preparation and properties of scintillating glass doped with organic activators

A series of scintillating glasses were developed by doping organic activators into low melting temperature glasses according to different ratios. The fluorescence spectra and the transmission spectra of some scintillating glasses were explored and the actual concentration organic in scintillating glass was estimated. The results show that it is feasible to prepare the scintillating glass by doing organic scintillating activators into the low-melting glasses. There are two main reasons for the weak optical properties of the scintillation glasses: one is that the actual concentration of organic activators doped in the glasses is very low, and the other is the existence of lots of defects formed in the scintillating glasses due to the evaporation of organic activator, lowering the transmission of glasses. The fluorescence emission peaks of the glasses move to a longer wavelength compared with those in organic matrixes. To increase the light output of the glass, the optical transmittance of the glasses must be improved and the concentration of activators in the glasses must be increased.

Nile Red-Adsorbed Gold Nanoparticle Matrixes for Determining Aminothiols through Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

This paper describes the use of Nile Red-adsorbed gold nanoparticles (NRAuNPs) as selective probes and matrixes for the determination of aminothiols through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The binding of three aminothiols-glutathione (GSH), cysteine (Cys), and homocysteine (HCys)-to the surfaces of these NRAuNPs induces their aggregation, which causes asubsequent changes in their color and fluorescence. Because arginine-a non-thiol amino acid-does not induce such aggregation, it is a straightforward process to use the NRAuNPs to selectively concentrate the aminothiols from a solution containing all four of these analytes; we were able to identify the three aminothiols in the precipitate, and arginine in the supernatant, directly through SALDI-MS measurements. Without using this preconcentration approach, the limits of detection (LODs) at a signal-to-noise ratio of 3 were 1.0, 2.0, and 1.3 microM for GSH, Cys, and HCys, respectively. In comparison, selective concentration using the NRAuNPs provided LODs of 25, 54, and 34 nM, for the determinations of GSH, Cys, and HCys, respectively. NRAuNP matrixes provide a number of advantages over the use of conventional organic matrixes (e.g., 2,5-dihydroxybenzoic acid), such as ease of preparation, selectivity, sensitivity, and repeatability. We validated the applicability of our method through the analyses of GSH in red blood cells and of Cys in plasma; we believe that this approach has great potential for diagnosis.

Synthesis of a Polyelectrolyte and Its Applications in Laser Desorption/Ionization

A novel laser energy-absorbing polymer derivatized from an energy-absorbing molecule has been synthesized. This polymer effectively eliminates the matrix addition step and the use of requisite small organic chemical matrixes from MALDI. The resulting polyelectrolyte-assisted laser desorption/ionization method has been proven to have some exceptional advantages over current MALDI methods. First, the matrix addition step from the LDI analytical process was eliminated. Second, the low molecular weight signal from energy-absorbing molecules was minimized by covalently linking the energy-absorbing molecules to the backbone of the polymer and other ionization-enhancing pendant groups on the backbone. Finally, the mass resolution of LDI was enhanced by minimizing chemical background noise throughout the spectrum. Polymeric linkage of energy-absorbing molecules aligns them with each other in an ordered structure, similar to MALDI matrix crystallization. Using the designed polymer film, laser desorption/ionization for proteins and peptides were successfully performed without the addition of any matrix. Analytical results for the synthesized monomer and polymers will be also presented.

Grafting of trialkoxysilane on the surface of nanoparticles by conventional wet alcoholic and supercritical carbon dioxide deposition methods

The problem of lack of interfacial interaction between inorganic fillers and organic matrixes needs to be solved in order to obtain stable hybrid composites. Interfacial interaction can be improved by modifying the surface of inorganic fillers with organic bifunctional molecules. Surface modification was addressed in this work through silanization. High quality siloxane monolayers are not easy to form using the traditional solution-phase methodology, mainly because of the difficulty in controlling the amount of water in the liquid medium. This article reports an anhydrous and generic SCCO 2 method for coating the surface of nanoparticulate materials through the deposition of self-assembled silane monolayers. The reaction of a trifunctional alkoxysilane with several micrometric and nanometric substrates was study. Three different inorganic materials were chosen as substrates: micrometric and nanometric hydroxyapatite, nanometric titanium dioxide and layered hectorite. The silanization performance of the anhydrous supercritical method was compared to that of a conventional wet alcoholic solution method. Using the wet conventional method, silane deposition resulted in the deposition of polycondensed structures that cemented the inorganic nanoparticles. Since the supercritical method is an anhydrous method, monolayer formation of thermally stable coatings was favored and multilayer formation could be avoided by controlling the processing time. The supercritical process provided a very effective approach to functionalize individual inorganic nanoparticles because of the enhanced diffusivity of the functional molecules in the agglomerated interparticle voids.

Distribution of Aged 14C−PCB and 14C−PAH Residues in Particle-Size and Humic Fractions of an Agricultural Soil

Organic matter is considered to be the single most importantfactor limiting availability and mobility of persistent organic pollutants (POPs) in soil. This study aimed to characterize the distribution of 14C-PCB (congeners 28 and 52) and 14C-PAH (fluoranthene and benzo[a]pyrene) residues in an Orthic Luvisol soil obtained from two lysimeter studies initiated in 1990 at the Agrosphere Institute (Forschungszentrum Jülich GmbH, Germany). The lysimeter soils contained a low-density OM fraction, isolated during soil washing, which contained a significant fraction (3-12%) of the total 14C-activity. Soils were also fractionated according to three particle sizes: >20, 20-2, and <2 microm. Relative affinity values of 14C-activity for the different particle sizes varied in the order 20-2 microm > (<2 microm) approximately (>20 microm) for the PCBs. Relative affinity values of 14C-activity for the different particle sizes varied in the order 20-2 microm > (<2 microm) > (>20 microm) for the PAHs. The distribution of 14C-PCB or 14C-PAH residues in the organic and inorganic matrixes of the particle-size fractions was determined using methyl isobutyl ketone (MIBK). 14C-PCB and 14C-PAH-associated activities were primarily located in the humin fraction of the 20-2 and <2 microm particle-size fractions of the soil. A small fraction was associated with the fulvic and humic acid fractions; these were quantitatively more important for the PAHs than the PCBs. There appeared to be a high degree of association of 14C-activity with the mineral fraction following MIBK separation of the humic fractions, ranging between 8 and 52% for 14C-PCBs and 57-80% for 14C-PAHs. The mineral (inorganic) component of the soils apparently played a significant (previously unreported) role in the sequestration of both PCBs 28 and 52 and the PAHs fluoranthene and benzo[a]pyrene.

Size-Selected (2−10 nm) Gold Nanoparticles for Matrix Assisted Laser Desorption Ionization of Peptides

In this report, first use of size-selected gold nanoparticles (AuNPs) as matrixes for matrix assisted laser desorption/ionization (MALDI) is described for peptides and proteins. In comparison with conventional organic acid MALDI matrixes, the optimum matrix-to-analyte ratio with AuNP matrixes is reduced by 10-14 orders of magnitude. Significant differences in the relative abundances of the ions observed in positive and negative mode MALDI-time-of-flight mass spectrometry (TOFMS) are revealed as the AuNP size distribution is decreased from 10 to 2 nm, whereby 2-nm AuNPs exhibit quantum confinement effects prevalent in quantum dots. AuNP matrixes allow for selective analyte ionization, as demonstrated in the selective MALDI-TOFMS of phosphotyrosine in a background of phosphoserine and phosphothreonine peptides.

Modulation of the Photophysical Properties of C60 by Electronic Confinement Effect

This research work reports on the incorporation of fullerene C60 in diverse inorganic and organic matrixes and how these different environments induce changes on the photophysical properties of the molecule depending on the cavity dimensions of the host. Indeed the fluorescence emission band of C60 experiences a progressive bathochromic shift with respect to C60 in solution as the cavity dimensions of the host decrease in going from the mesoporous material MCM41 to UTD-1 and Na-Y zeolites. This experimental observation, which has been documentarily confirmed by theoretical predictions and recent experimental results, is a reflection of the confinement effect imposed by the host. However, the most striking result reported in this work is that the fluorescence range accessible to this occluded species can be extraordinarily extended by confinement inside the neutral cages of a "dendritic box". The ability of the dendritic shell to create a microenvironment, modifying the properties of its functional core, allows the emission bands of C60 incorporated into a dendrimer to be effectively red-shifted with respect to their emission in solution, and, contrarily to other confined spaces of considerable hardness such as zeolites or the high surface material MCM41, the magnitude of this shifting is maximum and can be modulated under appropriate experimental conditions. This phenomenon has an enormous relevance since it can be exploited in future technological applications.

Excited-State Localization in a 3-Fold-Symmetric Molecule as Probed by Electroabsorption Spectroscopy

Excitation localization in a nominally 3-fold-symmetric molecule is probed using electroabsorption (Stark) spectroscopy in polymer and organic glass matrixes. The absolute value of the change in dipole moment of this molecule, referred to as the trimer, is found to be nearly identical to that of a model compound consisting of one of its three arms within experimental error. Electronic structure calculations presented in the companion paper to this one (Liu, L. A.; Peteanu, L. A.; Yaron, D. J. J. Phys. Chem. B 2004, 108, 16841) reveal that the value of measured in the trimer is consistent with absorption to a state localized on a single branch of the molecule. Previously, localization on the emission time scale had been demonstrated for these particular trimers. The localization evident from the electroabsorption spectrum results from ground-state geometrical disorder in the branches that renders their excitation energies nonequivalent and reduces the overall symmetry of the molecule.