Fourier Transform Infrared Spectroscopy Data Research Articles

Hydration dynamics in zeolite A – An X-ray diffraction and infrared spectroscopic study

The structural evolution of sodium zeolite A with increasing hydration has been studied by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The lattice parameter and cell volume, determined from time resolved XRD patterns during hydration at ambient conditions, display contraction followed by expansion, suggestive of a hydration-driven flexibility transition, with a two phase region separating hydrated zeolite A from its dehydrated form. Details of bonding dynamics of water molecules with sodium ions and characteristic building units of zeolite Na-A were studied using time resolved FTIR as the sample underwent hydration. The O-H stretching vibration shifts from 3450 cm−1 representing chemisorption to 3350 cm−1 indicating physisorption with increasing hydration. The FTIR data strongly suggest that both water and sodium ions change their locations and bonding as a function of water content. The structural and dynamic observations support our earlier calorimetric studies of the enthalpy of water absorption, pointing to a phase transition related to framework flexibility in response to hydration and to variable water content in both the less hydrated and the more hydrated phase.

Deposition time dependence of the morphology and properties of tin-catalyzed silicon oxide nanowires synthesized by the gas-jet electron beam plasma chemical vapor deposition method

SiOx nanowires (SiOxNWs, x ≤ 2) were grown by gas-jet electron beam plasma chemical vapor deposition method according to the vapor-liquid-solid mechanism at different synthesis times (tdep = 0.5–5 min) using tin particles as a catalyst. Microropes of SiOxNWs were obtained at tdep of more than 1 min. The average growth rate of nanowires was about 19 nm/s. Fourier transform infrared (FTIR) spectroscopy shows that SiOxNWs synthesized at different tdep are very similar in chemical composition (x ≈ 2) and in the bonding network of SiOx. FTIR spectroscopy data on the chemical composition of nanowires are in good agreement with the results of X-ray energy dispersive spectroscopy (EDS) analysis. EDS mapping of silicon and oxygen indicates that the atoms are uniformly distributed in the nanowires. Also, FTIR measurements showed that a significant number of water-adsorbing silanol groups formed on the surface of the nanowires. Photoluminescence spectra of nanowires obtained at different tdep are typical of SiO2 and exhibit a broad band in the region 400–600 nm centered at ~475 nm. The contact angle for SiOxNWs is <21° and decreases to 4.4° with increasing tdep, indicating a superhydrophilic coating.

FTIR spectral analysis of bituminous binders: reproducibility and impact of ageing temperature

This RILEM round robin study with nine participating laboratories investigated bitumen ageing, its effect on chemical properties and its reproducibility. The impact of temperature used for short-term (RTFOT) binder ageing on the combined short- and long-term (PAV) aged samples was investigated; thereby the effect of reduced mixing temperature such as those relevant for warm mix asphalt technologies on long term ageing was examined. Four 70/100 penetration graded bituminous binders from different sources were selected. In addition to the standard RTFOT temperature of 163 °C, two additional temperatures, 143 and 123 °C were used. The Fourier transform infrared spectroscopy (FTIR) analysis was carried out using an integration method which considers the area below the absorbance spectrum around a band maximum using baseline and tangential approaches. A statistical investigation into the reproducibility of FTIR spectra analysis based on the accumulated data was done. To assess the reproducibility, the coefficient of variation (CV) was taken as a benchmark parameter. Carbonyl and sulfoxide indices were calculated using different baseline correction methods and tangential and baseline integration, respectively. It was shown that the tangential method was not influenced by the applied baseline correction. However, in all considered cases, the tangential method led to significantly worse reproducibility (CVs ranging from 20 to 120%) compared to the baseline method. The sulfoxide indices calculated by both methods were not affected by the baseline correction method used. Impacts of changes in the short-term ageing temperature on short- or long-term aged samples could not be found whereas differences between different binder sources could be detected. RTFOT temperature and therefore mix production temperature had a stronger impact on the formation of sulfoxide structures than for carbonyl structures. The findings from this study show the most reproducible of all considered methods when more than one laboratory is providing FTIR data.

Development of rapid method to assess microbial quality of minimally processed pomegranate arils using FTIR

Fourier transform infrared spectroscopy (FTIR) spectra were correlated with microbial quality of minimally processed pomegranate (Punica granatum) arils stored at 10 °C using chemometrics. FTIR data processed in three ways i.e. FTIR spectrum, first derivative for FTIR spectrum and peak integrated data of FTIR spectrum was used as independent variables for preparing regression models by partial Least Square Regression (PLS-R) and artificial neural networks (ANN) for predicting the total viable count (TVC) and yeast and mold count (Y&M). Models built with both ANN and PLS-R using FTIR data demonstrated a high correlation value of R2 > 0.85. Analysis of PLS-R results suggested the production of alcohols and acids with utilization of sugars during storage. This is a first report demonstrating use of FTIR as a nondestructive rapid method for microbial quality analysis of minimally processed fruits.

Ex-Situ Synthesis of Polyvinyl alcohol(PVA)-coated Fe3O4 Nanoparticles by Coprecipitation-Ultrasonication Method

In this study, the synthesis of Fe3O4 nanoparticles was done with surface modification using PVA with coprecipitation-ultrasonication method. Time variations and PVA concentrations were added to determine the effect on crystallite size and lattice parameters on the synthesis of Fe3O4-PVA nanoparticles. Fe3O4 characterization was done using X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) instruments. FTIR was employed to determine PVA coating on the surface of Fe3O4 nanoparticles. The crystallite size and lattice parameters were analyzed using XRD. From the FTIR data, it is known that the interaction between PVA and Fe3O4 nanoparticles is characterized by Fe-O-C group at 1100 cm-1 region which is characteristic of Fe3O4-PVA nanoparticles, C-H groups of PVA in the range of 2950 cm-1 wave number, C-C of PVA regions of wave number 1405 cm-1, Fe3O4 and Fe3O4-PVA samples are in the range of 565 cm-1. In addition, the variation of ultrasonication time and the addition of PVA concentration have an effect on the crystallite size change and the lattice parameter observed from the XRD data. The use of ultrasonication time will affect the size of the crystallite become smaller and the grating lattice parameters obtained are wider. The effect of addition of PVA showed that higher concentration of PVA resulted in smaller crystallite size and larger lattice parameters. These results indicated that ultrasonication time and addition of PVA concentration greatly affect the characteristics of nanoparticles.

Facile Synthesis and Characterization of Monodisperse Silver Colloidal Nanoparticles Stabilized by Sodium Laurate

A facile process was present in this paper for synthesizing nano silver particles colloidal in aqueous solutions using silver nitrate, sodium laurate, and hydrazine hydrate as silver precursor, stabilizer, and reducing agents, respectively. The generation of nano silver particles was confirmed by change of color from milk white to brown or dark. The prepared silver nanoparticles were analyzed by scanning electron microscope (SEM), transmission electron microscope (TEM), UV–Visible spectroscopy (UV–Vis), X-ray diffraction (XRD), and Fourier transform infrared spectroscopic (FT-IR). The SEM and TEM images indicated that the prepared silver nanoparticles have spherical shape, average size of 6 nm, and with a narrow distribution from 2 to 8 nm. The XRD information exhibited that the obtained metallic nanoparticles were highly crystalline in nature. FT-IR data demonstrated that the sodium laurate absorbed on the surface of silver nanoparticles. The effects of the sodium laurate and hydrazine hydrate on the silver nanoparticle formation were studied. The mechanism of the formation silver nanoparticles was discussed. The process raised in this study can be considered as an excellent candidate for the preparation of silver nanoparticles in a large-scale production. The simple method can be extended to synthesis of other noble metal nanoparticles.

FORMULATION AND EVALUATION OF TRANSDERMAL PATCH OF INDOMETHACIN CONTAINING PATCHOULI OIL AS NATURAL PENETRATION ENHANCER

Objective: To develop a transdermal patch of Indomethacin using patchouli oil as a natural enhancer to increase transdermal permeation of the drug from the matrix system across rat epidermis.Materials and Methods: The chemical characterization of patchouli oil was done by gas chromatography-mass spectrometry. Transdermal patches of indomethacin were formulated after studying the drug-excipient compatibility studies by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). The transdermal patches were evaluated for various physiochemical properties. In-vitro transdermal permeation was carried using modified Keshary-Chein diffusion cell across rat epidermis. FTIR studies of rat epidermis were done to understand the mechanism of the permeation enhancing effect of the oil from the matrix patch.Result: The results of physiochemical parameters of the transdermal patch were found satisfactory. The transdermal flux obtained of the different concentration of patchouli oil tend to increase with increasing concentration of the oil and the maximum transdermal flux of 61.92 ± 0.89 μg/cm2/hr was obtained with formulation F7 (containing 1% w/v of patchouli oil) which is similar to the flux of the formulation F2 containing standard enhancer dimethyl sulphoxide. The skin irritation test did not show any edema and the FTIR data of rat epidermis indicated that patchouli oil enhances transdermal permeation of indomethacin by partial extraction of lipids in the stratum corneum.Conclusion: Thus, the results showed a potential enhancing effect of patchouli oil on the transdermal permeation of the model drug indomethacin and may be used as natural permeation enhancer in transdermal drug delivery systems.

Revealing the chemical characterization of asphaltenes fractions produced by N-methylpyrrolidone using FTIR, molecular fluorescence, 1H NMR, and ESI(±)FT-ICR MS

Heavy oil fractions studies are of great importance for the oil industry, receiving particular attention in recent decades due to interest in obtaining compounds with higher added value derived from heavy oil fractions. Moreover, these studies also aim to offer solutions to problems caused by these fractions during all oil processing steps. Asphaltenes placed in n-methylpyrrolidone (NMP) produce two fractions with distinct characteristics, soluble and insoluble in NMP (called NS and NI, respectively). In previously studies it was suggested that the NI fraction presents low content of aromatic compounds, opening a new debate on the composition of asphaltene as is widely discussed in the literature. Here, we show the deep characterization of three set of asphaltenes fractions obtained in NMP using Fourier transform ion cyclotron resonance mass spectrometry coupled to positive and negative-ions mode electrospray ionization (ESI(±)-FT-ICR MS), Fourier transform infrared spectroscopy (FTIR), molecular fluorescence and proton nuclear magnetic resonance (1H NMR) spectroscopy. FTIR, 1H NMR and molecular fluorescence demonstrated differences among asphaltene fractions studied, in which, NS fractions exhibited a more polar and aromatic character. On the other hand, NI fractions showed nonpolar profile, being proved by the presence of high amounts of alkyl and naphthenic hydrocarbons showing high abundance of alkyl and naphthenic hydrocarbon related compounds. ESI(±)FT-ICR MS data corroborate the FTIR, 1H NMR and molecular fluorescence data, which show NS fractions with a high proportion of heteroatomic species and higher aromaticity (higher DBE values) compared with NI fractions.

Brassinosteroid improves lipid productivity and stress tolerance of Chlorella cells induced by high temperature

The application of exogenous brassinosteroids (BRs) against high-temperature stress in algae is poorly studied. The present work aims to assess the function of 2,4-epibrassinolide (EBL) on lipid production during the stress phase of Chlorella vulgaris cultivation induced by high temperature. The maximum growth rate was reached by the treatment with EBL at the optimum temperature of 25 °C, while the highest lipid content was obtained by the treatment with EBL at 30 °C, indicating that EBL significantly increases the lipid content of algae subjected to the stress induced by high temperature. Therefore, the maximum lipid productivity was obtained by cells in the media with EBL under optimum temperature (25 °C). The application of Fourier transform infrared spectroscopy (FTIR) in this work demonstrated that this technique can effectively and rapidly determine the changes in lipid and carbohydrate. Principal component analysis (PCA) can provide a full view of multivariate shift of cell compositions (i.e., lipids, carbohydrates, and proteins), which is much faster than individual band comparison. Based on FTIR data and PCA analysis, we successfully demonstrated that overall composition changes in algal cell, including lipid, protein, and carbohydrate, in response to the assimilation of high temperature and plant hormones.

Comparative adsorption of amylase, protease and lipase on ZnFe2O4: kinetics, isothermal and thermodynamics studies.

The role of enzyme engineering in biotechnology, biological and pharmaceutical process cannot be over emphasized. This study compared the adsorption of digestives enzymes; amylase, protease and lipase on to Zn-ferrite (ZnFe2O4). The metal ferrite was synthesized via a sol-gel technique and characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), Electron paramagnetic resonance (EPR) and Fourier transform infrared spectroscopy (FTIR). The adsorption was studied in a batch process and the data were subjected to kinetics and isotherm models. Characterization shows that the particle has a nanoporous structure, with pore sizes of about 5.4nm and good magnetic properties. The FTIR data showed the presence of M-O bond, which is a characteristic of metal ferrites. The adsorption of the amylase, lipase and protease on ZnFe2O4 follow first-order kinetic model with rate constants increasing with concentration. The maximum adsorption capacities as revealed by the generalized adsorption isotherms are 7.20, 42.90 and 22.24mgg-1 for amylase, lipase and protease, respectively, with cooperative binding. The Dubinin-Radushkevich model gave the maximum adsorption energies, E of 3.74kJmol-1 for amylase, 2.01kJmol-1 for lipase and 1.51kJmol-1 for the protease adsorption, showing that the process is physisorption dominated. The isotherms fit the adsorption data in the order of Freundlinch>Generalized>Guggenheim-Anderson-de Boer>Tempkin isotherm>Dubinin-Radushkevich. Thermodynamic study revealed a spontaneous adsorption process with increased entropy. ZnFe2O4, therefore, is a very good adsorbent for the purification of enzymes and can be used as a supporter for enzymatic process that required immobilization of the enzymes.

Carbon Dot Assisted Synthesis of Nanostructured Polyaniline for Dye Sensitized Solar Cells

Herein, we have reported a facile method to synthesize surface passivated carbon dots (CDs) with high quantum yield. The structure and optical properties of the CDs are successfully investigated using high-resolution transmission electron microscopy; dynamic light scattering; and UV–vis, fluorescence, and Fourier transform infrared spectroscopy (FTIR). The synthesized CDs with excellent water solubility have been utilized to prepare nanostructured polyaniline (PANI) where CDs act both as a dopant as well as nucleating agent. The synthesis of PANI is achieved through a simple and one pot chemical oxidative polymerization. The UV–vis and FTIR data clearly indicates the formation of highly doped PANI (emeraldine salt form), which will really be helpful for fabricating photovoltaic device. We have examined the current–voltage characteristics of CD-PANI samples both in dark and illuminated state, which evidently designates the enhancement of current in the illuminated state. Hence, we have employed the CD-PANI samples for photovoltaic study, and the DSSCs are studied under illumination of 100 mW/cm2. Among the CD-PANI samples, CDPA10 shows a maximum power conversion efficiency of 3.65%.

Rice Husk Ash Modified with Vanadium Pentoxide

Rice husk collected in Barreiras City, Bahia, Brazil was converted to rice husk ash (RHA) by acidic or basic leaching, followed by calcination. The resulting RHA was modified with vanadium pentoxide (2, 5, or 10 mass% of V 2 O 5 ). The modified RHA samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). RHA exhibited FTIR bands associated with silica. After modification of acid-leached RHA with vanadium, the XRD data indicated the formation of V 2 O 5 phases. Base-leached RHA modified with vanadium pentoxide showed the presence of the V 2 O 5 phase only in the sample containing 10 mass% V 2 O 5 . The FTIR data indicated the formation of cristobalite, where bands associated with Si-O-V interactions were observed only for the sample with 10 mass% V 2 O 5 prepared with acid-leached RHA. DOI: http://dx.doi.org/10.17807/orbital.v9i2.916

Neem extract as a green inhibitor for microbiologically influenced corrosion of carbon steel API 5LX in a hypersaline environments

In this study, the efficiency of neem extract to inhibit the corrosion of carbon steel API 5LX in the presence of different bacterial strains (Bacillus subtilis A1, Streptomyces parvus B7, Pseudomonas stutzeri NA3 and Acinetobacter baumannii MN3) were evaluated. 150ppm of Azadirachta indica leave extract (AILE) was identified as minimal inhibitory concentration for the bacterial strains B. subtilis A1, S. parvus B7, P. stutzeri NA3 and A. baumannii MN3. Weight loss, electrochemical studies including potential measurements, potentiodynamic polarization and impedance and surface analysis includes Fourier transform infrared spectroscopy (FT-IR) were used to examine the corrosion inhibition efficiency (IE) of AILE on carbon steel API 5LX. The individual bacterial strains and mixed consortium had showed severe corrosion of carbon steel API 5LX in hypersaline environment. In contrast with AILE, the IE of abiotic control and mixed consortia were about 81% and 72% respectively. The corrosion rate was observed as increased trends in presence of all bacterial strains (0.179mm/y) when compared to abiotic system with AILE system (0.012mm/y). X-ray diffraction spectroscopy (XRD) confirms that all bacterial strains has accelerates the corrosion by the production of higher intensity peaks of corrosion products when compared to AILE systems. FT-IR data reveals that AILE extracts consists of azadirachtin and other phytochemical compound which was play a key role in control of bacterial biofilm on metal surface and thus leads to inhibit corrosion process. This is the first report on the application of AILE as a natural, eco-friendly corrosion inhibitor with antibacterial activities to control microbiologically influenced corrosion in hypersaline environment of oil reservoir.

Spectroscopic Investigation of the Formation and Disruption of Hydrogen Bonds in Pharmaceutical Semicrystalline Dispersions

We recently found that indomethacin (IMC) can effectively act as a powerful crystallization inhibitor for polyethylene glycol 6000 (PEG) despite the fact that the absence of interactions between the drug and the carrier in the solid state was reported in the literature. However, in the present study, we investigate the possibility of drug-carrier interactions in the liquid state to explain the polymer crystallization inhibition effect of IMC. We also aim to discover other potential PEG crystallization inhibitors. Drug-carrier interactions in both liquid and solid state are characterized by variable temperature Fourier transform infrared spectroscopy (FTIR) and cross-polarization magic angle spinning 13C nuclear magnetic resonance spectroscopy (CP/MAS NMR). In the liquid state, FTIR data show evidence of the breaking of hydrogen bonding between IMC molecules to form interactions of the IMC monomer with PEG. The drug-carrier interactions are disrupted upon storage and polymer crystallization, resulting in segregation of IMC from PEG crystals that can be observed under polarized light microscopy. This process is further confirmed by 13C NMR since in the liquid state, when the IMC/PEG monomer units ratio is below 2:1, IMC signals are undetectable because of the loss of cross-polarization efficiency in the mobile IMC molecules upon attachment to PEG chains via hydrogen bonding. This suggests that each ether oxygen of the PEG unit can form hydrogen bonds with two IMC molecules. The NMR spectrum of IMC shows no change in solid dispersions with PEG upon storage, indicating the absence of interactions in the solid state, hence confirming previous studies. The drug-carrier interactions in the liquid state elucidate the crystallization inhibition effect of IMC on PEG as well as other semicrystalline polymers such as poloxamer and Gelucire. However, hydrogen bonding is a necessary but apparently not a sufficient condition for the polymer crystallization inhibition. Screening of crystallization inhibitors of semicrystalline polymers discovers numerous candidates that exhibit the same behavior as IMC, demonstrating a general pattern of polymer crystallization inhibition rather than a particular case. Furthermore, the crystallization inhibition effect of drugs on PEG is independent of the carrier molecular weight. These mechanistic findings on the formation and disruption of hydrogen bonds in semicrystalline dispersions can be extended to amorphous dispersions and are of significant importance for preparation of solid dispersions with consistent and reproducible physicochemical properties.

Microarc oxidation discharge types and bio properties of the coating synthesized on zirconium

This study is an attempt for gaining a better understanding on relationship between microarc oxidation (MAO) coating discharge types and bioactivity of an oxide-based coating synthesized on a Zr substrate. The discharge types and the coating growth mechanism were identified by the examination of the real cross-section image of the coating microstructure. The coating was conducted by using MAO in an electrolyte containing Na2SiO3, Ca(CH3COO)2 and C3H7Na2O6P, for different durations of 2.5, 5, 15, and 30mins. The effect of the process duration on the different discharge model types (Type-A, B, and C) and bioactivity of the coatings were investigated by using X-ray Diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy-Energy-Dispersive X-ray spectroscopy measurements (SEM-EDS) and Optical Surface Profilometry (OSP). It was found that the increasing MAO duration resulted in thicker and rougher coatings. The XRD data revealed that all the samples prepared at different process durations contained the t-ZrO2 (tetragonal zirconia) phase. During the MAO process, non-crystalline hydroxyapatite (HA) formed, which was confirmed from the FTIR data. The surface morphology, the amount and distribution of the features of the coating surface were modified by increasing voltage. The simulated body fluid (SBF) tests showed that the more bioactive surface with more HA crystals formed owing to chemical composition and high surface roughness of the coating. The pore, crack and discharge structures played a key role in apatite nucleation and growth, and provided ingrowth of apatite into discharge channels on the coating surface.

Activity and Stability of Trypsin Immobilized onto Chitosan Magnetic Nanoparticles

The aim of this study was to develop a thermally and operationally stable trypsin through covalent immobilization onto chitosan magnetic nanoparticles (Fe3O4 @CTS). The successful preparation of the Fe3O4 @CTS nanoparticles was verified by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM), which indicated that the prepared Fe3O4 @CTS nanoparticles have superparamagnetic properties, with an average size of approximately 17 nm. Then, trypsin was covalently immobilized onto the Fe3O4 @CTS nanoparticles at a high loading capacity (149.25 mg/g). The FTIR data demonstrated that the trypsin had undergone a conformational change compared with free trypsin, and the Michaelis constant (Km) and the maximum hydrolysis reaction rate (Vmax) showed that the trypsin immobilized on the Fe3O4 @CTS had a lower affinity for BAEE and lower activity compared with free trypsin. However, the immobilized trypsin showed higher activity than free trypsin at pH 6.0 and in alkaline conditions and retained more than 84% of its initial activity at 60°C after 8 h incubation. Its excellent performance across a broader pH range and high thermal stability, as well as its effective hydrolysis of bovine serum albumin (BSA) and its reusability, make it more attractive than free trypsin for application in protein digestion.

Potassium Oleate as a Dissolution and Corrosion Inhibitor during Chemical Mechanical Planarization of Chemical Vapor Deposited Co Films for Interconnect Applications

1,2-4 Triazole (TAZ), N-lauroylsarcosine sodium salt (NLS) and potassium oleate (PO) were tested as passivating additives to previously developed H2O2 and citric acid-based silica dispersions for the polishing of chemical vapor deposited Co films for interconnect applications. In comparison to TAZ and NLS, Co corrosion currents are ∼1 to 2 order of magnitude lower (∼1–3 μA cm−2) at pH 7 with PO and post-polish surface quality was much better. The galvanic corrosion currents between Co-Ti and Ti-TiN couples with PO were also very low (∼0.1 μA cm−2), making the previously developed silica and citric acid-based dispersion, now containing PO, suitable for both bulk removal of Co (step I) and for planarizing Co/Ti/TiN structures (step II) with excellent selectivity while stopping on low-k dielectric. Langmuir adsorption isotherm model analysis showed that the standard free energies of adsorption values were ∼−40 kJ/mol for PO suggesting chemisorption. Fourier transform infra-red (FTIR) and attenuated FTIR spectroscopy data show bridging coordination between the carboxylate ligand of PO and the Co surface.

Dipentaerythritol penta-acrylate phosphate - an alternative phosphate ester monomer for bonding of methacrylates to zirconia.

The present work examined the effects of dipentaerythritol penta-acrylate phosphate (PENTA) as an alternative phosphate ester monomer for bonding of methacrylate-based resins to yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and further investigated the potential bonding mechanism involved. Shear bond strength testing was performed to evaluate the efficacy of experimental PENTA-containing primers (5, 10, 15, 20 or 30 wt% PENTA in acetone) in improving resin-Y-TZP bond strength. Bonding without the use of a PENTA-containing served as the negative control, and a Methacryloyloxidecyl dihydrogenphosphate(MDP)-containing primer was used as the positive control. Inductively coupled plasma-mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) were used to investigate the potential existence of chemical affinity between PENTA and Y-TZP. Shear bond strengths were significant higher in the 15 and 20 wt% PENTA groups. The ICP-MS, XPS and FTIR data indicated that the P content on the Y-TZP surface increased as the concentration of PENTA increased in the experimental primers, via the formation of Zr–O–P bond. Taken together, the results attest that PENTA improves resin bonding of Y-TZP through chemical reaction with Y-TZP. Increasing the concentration of PENTA augments its binding affinity but not its bonding efficacy with zirconia.

Evaluation of folic acid release from spray dried powder particles of pectin-whey protein nano-capsules

Our main goal was to evaluate release kinetics of nano-encapsulated folic acid within a double W1/O/W2 emulsion. First, W1/O nano-emulsions loaded with folic acid were prepared and re-emulsified into an aqueous phase (W2) containing single whey protein concentrate (WPC) layer or double layer complex of WPC-pectin to form W1/O/W2 emulsions. Final double emulsions were spray dried and their microstructure was analyzed in terms of scanning electron microscopy (SEM), and Fourier Transform Infrared spectroscopy (FTIR). Also the release trends of folic acid were determined and fitted with experimental models of zero and first order, Higuchi, and Hixson-Crowell. It was revealed that folic acid nano-capsules made with Span as the surfactant had the lowest release rate in acidic conditions (pH=4) and highest release in the alkaline conditions (pH=11). The best model fitting for folic acid release data was observed for single layer WPC encapsulated powders with the highest R2. Our FTIR data showed there was no chemical interaction between WPC and pectin in double layered capsules and based on SEM results, single WPC layered capsules resulted in smooth and uniform particles which by incorporating pectin, some wrinkles and shrinkage were found in the surface of spray dried powder particles.

Unravelling the Binding Mechanism of a Poly(cationic) Anthracenyl Fluorescent Probe with High Affinity toward Double-Stranded DNA.

We report the synthesis, spectroscopy, and the DNA binding properties of a biocompatible, water-soluble, polycationic two-photon absorbing anthracenyl derivative (Ant-PIm) specifically designed for biorelated applications. Detailed insights into the Ant-PIm-DNA binding interaction are provided by using several spectroscopic approaches, including UV-vis absorption, circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR), steady-state, and time-resolved fluorescence techniques. Absorption and fluorescence quantitative data analysis show a strong Ant-PIm-duplex interaction with binding constants of Kf = 4.7 ± 0.2 × 105 M-1, 7.1 ± 0.3 × 105 M-1, and 1.0 ± 0.1 × 106 M-1 at 298, 304, and 310 K, respectively. Spectral changes observed upon DNA binding provide evidence for a complex formation with off-on fluorescence pattern, which can be related to two consecutive binding equilibria. Results of DNA binders displacement and iodide quenching experimental assays unambiguously point to the groove binding mode of Ant-PIm to the DNA-helicate. Thermodynamic and chemical denaturation studies suggest that long-range interactions of hydrophobic nature regulate the association of Ant-PIm with the biopolymer. The ionic strength dependence of the binding constant shows that electrostatic component has an important contribution to the overall Gibbs free energy. FTIR and CD data provide evidence of partial modification of the B-DNA secondary structure, while the increase in the melting temperature clearly indicates the enhancement of the thermal stability of the duplex. Furthermore, the two-photon absorption cross section spectrum determined using the two-photon excited fluorescence (TPEF) technique shows a strong 2PA maximum at 820 nm with a σ2 > 800 GM, which emphasizes the advantageous combination of biological and optical properties possessed by this positively charged bioprobe.