Selected papers from the latest issue:
Infrared Spectroscopic Study of the Model Metal-Ligand-Antibody Systems: What Information on the Structure and Stability of Systems Can Be Obtained?
06 March 2012, 01:13:41
Publication year: 2012
Source: Vibrational Spectroscopy, Available online 5 March 2012
Marie Reková, Pavel Matějka, Věra Jedináková-Křížová
In this study we investigated the possibility of using infrared spectroscopy for the characterization of the ligand (diethylenetriaminepentaacetic acid, DTPA) in various aqueous media (water and different buffers), the antibody (immunoglobulin G, IgG), the metal-ligand complexes (Y-DTPA and Lu-DTPA) and the metal-ligand-antibody conjugates (Y-DTPA-IgG and Lu-DTPA-IgG). The aim was to describe behaviour of individual components, and to find spectral markers of complexes and/or conjugates formation. The reason of the choice of Lu and Y was the potential use of their radionuclides to form radiopharmaceutical species for nuclear medicine. We performed kinetic measurements to describe the stability/instability of individual systems. Multivariate data analysis allowed finding out spectral regions related to different chemical processes. Hydrolysis effect of the diethylenetriaminepentaacetic acid dianhydride (cDTPAA) in water was confirmed in unbuffered aqueous solution. Nevertheless, the study of cDTPAA in various buffered media showed evident suppression of hydrolysis. Thus, appropriate buffers were selected as media for complexation reactions with Y and Lu. Characteristic marker bands of complexation were identified. Human IgG in phosphate buffer and its interaction with the metal-ligand complexes were studied. Observation of new bands, band shifts and intensity changes revealed formation of the metal-ligand-IgG conjugates together with a somewhat changed secondary structure of IgG. We demonstrated the possibility of vibrational spectroscopic monitoring of the preparation steps of the metal-ligand-antibody conjugates as potential radiopharmaceutical products.
Source: Vibrational Spectroscopy, Available online 5 March 2012
Marie Reková, Pavel Matějka, Věra Jedináková-Křížová
In this study we investigated the possibility of using infrared spectroscopy for the characterization of the ligand (diethylenetriaminepentaacetic acid, DTPA) in various aqueous media (water and different buffers), the antibody (immunoglobulin G, IgG), the metal-ligand complexes (Y-DTPA and Lu-DTPA) and the metal-ligand-antibody conjugates (Y-DTPA-IgG and Lu-DTPA-IgG). The aim was to describe behaviour of individual components, and to find spectral markers of complexes and/or conjugates formation. The reason of the choice of Lu and Y was the potential use of their radionuclides to form radiopharmaceutical species for nuclear medicine. We performed kinetic measurements to describe the stability/instability of individual systems. Multivariate data analysis allowed finding out spectral regions related to different chemical processes. Hydrolysis effect of the diethylenetriaminepentaacetic acid dianhydride (cDTPAA) in water was confirmed in unbuffered aqueous solution. Nevertheless, the study of cDTPAA in various buffered media showed evident suppression of hydrolysis. Thus, appropriate buffers were selected as media for complexation reactions with Y and Lu. Characteristic marker bands of complexation were identified. Human IgG in phosphate buffer and its interaction with the metal-ligand complexes were studied. Observation of new bands, band shifts and intensity changes revealed formation of the metal-ligand-IgG conjugates together with a somewhat changed secondary structure of IgG. We demonstrated the possibility of vibrational spectroscopic monitoring of the preparation steps of the metal-ligand-antibody conjugates as potential radiopharmaceutical products.
Preparation and characterization of multicore SERS labels by controlled aggregation of cold nanoparticles
03 March 2012, 22:44:35
Publication year: 2012
Source: Vibrational Spectroscopy, Available online 3 March 2012
Isabel Freitag, Ute Neugebauer, Andrea Csaki, Wolfgang Fritzsche, Christoph Krafft, ...
The preparation and characterization of multicore labels for surface enhanced Raman scattering (SERS) at 785 nm excitation are described. These labels consist of gold nanoparticles whose aggregation was controlled by a diamine. SERS reporters were attached that contain sulfur groups for covalent conjugation to the gold surface and aromatic ring structures for distinct Raman signatures. A thin silver layer was deposited onto aggregated gold nanoparticles to further enhance the SERS signals. Two polymers were deposited to prepare the surface for encapsulation by silica and stabilize nanoparticles. The thickness of the silica layer depended on ammonia concentration and was determined by transmission electron microscopy. Treatment with APTMS provided amino groups for subsequent conjugation with antibodies. N-H bending vibrations of amino silane were detected by infrared spectroscopy. Functionalization of the silica coated multicore labels by a FITC labeled antibody was confirmed by fluorescence microscopy. A Zetasizer determined an average radius of 60 nm. SERS spectra of labels with three different reporters and a SERS spectrum of mixed labels with exposure time between 10 ms and 1 s demonstrated the high sensitivity and multiplexing capacity. This design of multicore labels offers 785 nm near-infrared excitation for reduced laser-induced cell degradation, size above 100 nm for low toxicity under in vivo investigations as reported elsewhere, high stability due to silica encapsulation, and capability of antibody binding. These biocompatible properties make multicore labels with different reporters a promising candidate for diagnostic applications.
Source: Vibrational Spectroscopy, Available online 3 March 2012
Isabel Freitag, Ute Neugebauer, Andrea Csaki, Wolfgang Fritzsche, Christoph Krafft, ...
The preparation and characterization of multicore labels for surface enhanced Raman scattering (SERS) at 785 nm excitation are described. These labels consist of gold nanoparticles whose aggregation was controlled by a diamine. SERS reporters were attached that contain sulfur groups for covalent conjugation to the gold surface and aromatic ring structures for distinct Raman signatures. A thin silver layer was deposited onto aggregated gold nanoparticles to further enhance the SERS signals. Two polymers were deposited to prepare the surface for encapsulation by silica and stabilize nanoparticles. The thickness of the silica layer depended on ammonia concentration and was determined by transmission electron microscopy. Treatment with APTMS provided amino groups for subsequent conjugation with antibodies. N-H bending vibrations of amino silane were detected by infrared spectroscopy. Functionalization of the silica coated multicore labels by a FITC labeled antibody was confirmed by fluorescence microscopy. A Zetasizer determined an average radius of 60 nm. SERS spectra of labels with three different reporters and a SERS spectrum of mixed labels with exposure time between 10 ms and 1 s demonstrated the high sensitivity and multiplexing capacity. This design of multicore labels offers 785 nm near-infrared excitation for reduced laser-induced cell degradation, size above 100 nm for low toxicity under in vivo investigations as reported elsewhere, high stability due to silica encapsulation, and capability of antibody binding. These biocompatible properties make multicore labels with different reporters a promising candidate for diagnostic applications.
Thickness measurement of thin polymer films by total internal reflection Raman and attenuated total reflection infrared spectroscopy
02 March 2012, 00:03:16
Publication year: 2012
Source: Vibrational Spectroscopy, Available online 1 March 2012
Antti O. Kivioja, Anna-Stiina Jääskeläinen, Ville Ahtee, Tapani Vuorinen
For the first time total internal reflection (TIR) Raman spectroscopy was utilized for thickness measurements of thin isotropic polystyrene films on polypropylene substrate. In the presented method, the band intensity ratios of polystyrene to polypropylene were defined from the spectra, and the film thicknesses in a range from 50 nm to 350 nm were calculated mathematically from these ratios. The quantitativeness of the method was validated by applying the same principle to attenuated total reflection infrared (ATR-IR) spectroscopy and comparing the results to values obtained by ellipsometry and a spin-coating model. The results showed that the novel and non-invasive TIR Raman method reveals the film thickness quantitatively, and the method is applicable for thin films on soft substrates with similar refractive indices
Source: Vibrational Spectroscopy, Available online 1 March 2012
Antti O. Kivioja, Anna-Stiina Jääskeläinen, Ville Ahtee, Tapani Vuorinen
For the first time total internal reflection (TIR) Raman spectroscopy was utilized for thickness measurements of thin isotropic polystyrene films on polypropylene substrate. In the presented method, the band intensity ratios of polystyrene to polypropylene were defined from the spectra, and the film thicknesses in a range from 50 nm to 350 nm were calculated mathematically from these ratios. The quantitativeness of the method was validated by applying the same principle to attenuated total reflection infrared (ATR-IR) spectroscopy and comparing the results to values obtained by ellipsometry and a spin-coating model. The results showed that the novel and non-invasive TIR Raman method reveals the film thickness quantitatively, and the method is applicable for thin films on soft substrates with similar refractive indices
Isothermal melt crystallization behavior of neat poly(L-lactide) (PLLA) and PLLA/organically modified layered silicate (OMLS) nanocomposite studied by two-dimensional (2D) correlation spectroscopy
02 March 2012, 00:03:16
Publication year: 2012
Source: Vibrational Spectroscopy, Available online 1 March 2012
Yohei Ando, Harumi Sato, Hideyuki Shinzawa, Masami Okamoto, Isao Noda, ...
Isothermal melt crystallization behavior of neat poly(L-lactide) (PLLA) and PLLA/organically modified layered silicate (OMLS) nanocomposite was studied by using time-dependent infrared (IR) spectroscopy and transmission electron microscopy (TEM). Sets of time-dependent IR spectra reflecting the crystallization from the melt of the neat PLLA and PLLA/OMLS nanocomposite were collected at 105 °C. Fine details of the crystallization behaviors were analyzed by two-dimensional (2D) correlation spectroscopy, and significant differences in the crystallization behaviors depending on the presence of OMLS were revealed. Namely, it was found that the crystalline lamellae of the PLLA nanocomposite grow along the layered silicate, while the orientation of the neat PLLA resulted in more disordered orientation because of the absence of the OMLS. The result derived from the 2D correlation analysis of the time-dependent IR spectra of PLLA samples showed good agreement with corresponding TEM images.
Source: Vibrational Spectroscopy, Available online 1 March 2012
Yohei Ando, Harumi Sato, Hideyuki Shinzawa, Masami Okamoto, Isao Noda, ...
Isothermal melt crystallization behavior of neat poly(L-lactide) (PLLA) and PLLA/organically modified layered silicate (OMLS) nanocomposite was studied by using time-dependent infrared (IR) spectroscopy and transmission electron microscopy (TEM). Sets of time-dependent IR spectra reflecting the crystallization from the melt of the neat PLLA and PLLA/OMLS nanocomposite were collected at 105 °C. Fine details of the crystallization behaviors were analyzed by two-dimensional (2D) correlation spectroscopy, and significant differences in the crystallization behaviors depending on the presence of OMLS were revealed. Namely, it was found that the crystalline lamellae of the PLLA nanocomposite grow along the layered silicate, while the orientation of the neat PLLA resulted in more disordered orientation because of the absence of the OMLS. The result derived from the 2D correlation analysis of the time-dependent IR spectra of PLLA samples showed good agreement with corresponding TEM images.
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