Phenotyping Metastatic Brain Tumors Applying Spectrochemical Analyses: Segregation of Different Cancer Types

Metastatic brain tumors represent a significant proportion of tumors identified intraoperatively. A rapid diagnostic method, circumventing the need for histopathology studies, could prove clinically useful. As many spectroscopic studies have shown ability to differentitate between different tumor types, this technique was evaluated for use within metastatic brain tumors. Spectrochemical approaches [Raman and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) spectroscopy] were applied to determine how readily they may identify the primary site for the metastatic tumor. Metastases were from primary adenocarcinomas of lung (n?=?7) and colorectum (n?=?7), and for comparison, metastatic melanoma (n?=?7). The objective was to determine if Raman or ATR-FTIR spectroscopy could delineate the origin of the primary tumor. The results demonstrate that there are marked similarities between the two adenocarcinoma groups and whilst Raman and ATR-FTIR can distinguish the three groups with limited success, classification accuracy is greatly improved when combining the adenocarcinoma groups. The use of such techniques in the clinical setting is more likely to be found intraoperatively, determining the presence of a tumor and suggesting the tumor class; however, traditional histopathology would still be needed to identify the primary origin of the tumor.     

Chemical and structural changes at the ABS polymer-copper metal interface

Creating oxygen containing moieties (hydroxyl or carbonyl) on polymer substrate surfaces is known to increase the adhesion strength of polymers to metals. However, we noticed adhesion increase with time even though no pre- or post-treatment of the polymer substrate was done. In the case of sputtered and galvanically strengthened copper coatings on acrylonitrile-butadiene-styrene polymer (ABS) substrate, the adhesion strength increased from approximately 6 J/m² to 53 J/m² during a 1008-h period. During this period structural and chemical changes of the polymer near the interface take place. Carbonyl functionalities developed on the ABS surface are most likely responsible for the large increase in the adhesion strength. Chemical changes of the polymer are probably a consequence of the galvanic deposition and a close contact of ABS with copper which is known to facilitate the oxidation of ABS.     

In situ monitoring of coordination copolymerization of butadiene and isoprene via ATR-FTIR spectroscopy

<正>FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance(ATR) immersion probe was utilized to study in situ the copolymerization of butadiene(Bd) and isoprene(Ip) with neodymium-based catalyst in hexane. The relationship between the signal intensity of monomer and its concentration was investigated.The kinetic study of copolymerization of Bd and Ip was further conducted,and the monomer reactivity ratios were determined via in situ ATR FTIR.The signal band at 1010 cm~(-1) was assigned to wagging vibration of Bd and its intensity was proportional to Bd concentration([Bd]) in the range of 0.46-3.88 mol·L~(-1).The signal bands at 890 and 989 cm~(-1) were assigned to wagging vibration of Ip and the signal intensity was also proportional to Ip concentration([Ip]) in the range of 0.08-4.73 mol·L~(-1) at 890 cm~(-1) and 0.08-7.49 mol·L~(-1) at 989 cm~(-1),respectively.Thus the signal band at 1010 cm~(-1) was chosen to monitor Bd concentration and bands at 989 and 890 cm~(-1) to monitor Ip concentration during the copolymerization,respectively.It was demonstrated that the conversions of Bd and Ip calculated from FTIR data agreed very well with those obtained gravimetrically.The polymerization rates were first order with respect to both[Bd]and[Ip],respectively at different polymerization temperatures.The apparent propagation activation energy for Bd and Ip could be determined to be 54.4 kJ·mol~(-1) and 57.7 kJ·mol~(-1),respectively.The monomer reactivity ratios were calculated to be 1.08 for Bd(r_(Bd)) and 0.48 for IP(r_(Ip)) based on FTIR data.The Bd-Ip copolymer products with random sequence could be obtained with only one glass transition temperature.     

Chemical degradation of crosslinked ethylene-propylene-diene rubber in an acidic environment. Part II. Effect of peroxide crosslinking in the presence of a coagent

An investigation on the time-dependent chemical degradation of ethylene-propylene diene rubber containing 5-ethylidene-2-norbornene as diene cured by peroxide crosslinking in the presence of a coagent in an acidic environment (20% Cr/H₂SO₄) has been made. Two types of rubber, with comparable monomer composition, but having significant differences in molar mass and levels of long chain branching were tested. Dicumyl peroxide and triallylcyanurate under similar conditions were used for curing the rubbers. The molecular mechanisms of chemical degradation at the surface were studied using X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy, which demonstrate that several oxygenated species evolve during exposure. The primary process of degradation is hydrolytic attack on the crosslink sites, which is manifested by a decrease in crosslink density. The surface degradation is found to be strong enough to alter the bulk mechanical properties as observed by the change in retention in tensile strength, elongation at break, modulus at 50% elongation and, the change in micro-hardness. Retention in modulus at 50% elongation is found to follow a negative linear correlation with decrease in crosslink density. With higher molar mass and level of long chain branching more crosslinking occurs and thus comparatively more hydrolytic attack ensues. Scanning electron microscopy shows that the surface topography is significantly altered upon exposure and supports the notion of the dependence of degradation on the crosslinking density of the samples. Importantly, the coagent used in this study is shown to enhance the chemical degradation through formation of weaker sites for hydrolysis. The results also show that upon prolonged exposure the resulting oxygenated species tend to combine with each other.     

Prediction of glycoprotein secondary structure using ATR-FTIR

Glycoproteins are important biomolecules with a diverse array of structural and signaling functions in biology. Determination of glycoprotein secondary structure is becoming increasingly important in aiding the understanding of how these molecules function in biological environments and disease. Furthermore, glycoproteins such as mucins are being evaluated in various nano-engineering processes that require knowledge of how the underlying secondary structure might alter in different target environments. We have developed an analytical procedure for predicting the secondary structures of glycoprotein using ATR-FTIR on dry film. Using Bovine submaxillary mucin (BSM) as a glycoprotein model, we determined the additive infrared spectral pattern of acetyl amino sugars and amino acids that could contribute to the absorbance in the Amide I band of BSM through empirical data. We show through subtraction of these spectra how the absorbance pattern of the protein backbone can be determined in order to predict glycoprotein secondary structure. The analysis predicted a predominant pattern of random coil, beta sheet and beta turn secondary structure for BSM after carbohydrate and amino acid spectral subtraction in agreement with other methods. Our relatively simple approach can be applied to predict secondary structure in other glycoproteins.     

一种包装膜的ATR-FTIR的剖析

在FTIR中,使用透射谱及水平ATR对进口的一种包装膜进行分析,该膜的厚度大约为0.034m/m,膜的两面分别由等规聚丙烯和聚对苯二甲酸乙二醇酯组成。     

Application of Polyelectrolytic Temperature-Responsive Hydrogels in Chemical Sensors

Summary: A rapidly expanding field of on-line process monitoring and on-line control in biotechnology, food industry, pharmaceutical industry, process chemistry, environmental measuring technology, water treatment and sewage processing requires the development of new micro fabricated reliable chemical and biosensors that are specific for particular species and can attain the analytic information in a faster, simpler and cheaper manner. Using a functionalised polymer coating in sensors provides the possibility to detect, transmit and record the information regarding the concentration change or the presence of a specific analyte (a chemical or biological substance that needs to be measured) by producing a signal proportional to the concentration of the target analyte. However, the sensor response time and signal reproducibility are limited by the visco-elastical and hysteresis behaviour of the polymer material. We propose some methods improving the properties of the chemical sensors on the basis of thermo-shrinking N-isopropylacrylamide (NIPAAm) copolymer gels.     

The effect of monolithic zirconia thickness on the degree of conversion of dental resin cements: ATR-FTIR spectroscopic analysis

The purpose of this study was to evaluate the effect of monolithic zirconia thickness on degree of conversion (DC) of different resin cements. Five groups (1 mm, 1.5 mm, 2 mm monolithic zirconia, veneered zirconia substructure, and lithium disilicate) of disk-shaped ceramic specimens (14 mm in diameter) were prepared (n = 6). Three dental resin cements (Variolink II light-cured, Variolink II dual-cured and Zirconite dual-cured) were tested to evaluate their DC under each ceramic group. FTIR spectra were recorded using Attenuated Total Reflectance-Fourier Transform Infrared Spectrometer (ATR-FTIR). The DC% was calculated by ratio of infrared absorbance values of aliphatic and aromatic peaks for uncured and cured states. Data were statistically analyzed by Analysis of Variance (ANOVA) and post hoc Tukey tests (a = 0.05). DC of dental resin cement specimens under monolithic zirconia decreased with increasing thickness. For Variolink II light-cured cement, the highest DC found under lithium disilicate and the lowest DC observed under veneered zirconia specimens. Zirconite which is recommended for cementation of zirconia revealed the highest DC when polymerized under monolithic or veneered zirconia. Under lithium disilicate specimens, DC of Zirconite was similar with light-cured resin cement.     

Spectral characteristics of ethylene sorbed by silver-containing ionic liquids studied by in situ ATR-FTIR spectroscopy

The spectral characteristics of ethylene absorbed by ionic liquids (ILs) containing silver ions were studied by in situ ATR-FTIR spectroscopy at high pressure. Three different states of ethylene were observed based on the band shift of out-of-plane bending vibrations (ωCH₂) due to van der Waals interactions, hydrogen bonds, and π-complex formation with silver ions. Thus, ethylene can be used as an IR-sensitive probe molecule for characterizing interactions with ILs and other substances.     

Epoxy/POSS organic-inorganic hybrids: ATR-FTIR and DSC studies

Organic-inorganic hybrid nanocomposites were prepared by reaction of an octaepoxy-silsesquioxane, OECh, with an epoxy-amine system. OECh was used to partially replace the thermosetting resin, diglycidyl ether of bisphenol A, DGEBA, in its reaction with an aromatic diamine, 4,4′-(1,3-phenylenediisopropylidene) bisaniline, BSA. The OECh was characterized by different techniques. The curing kinetics of ternary systems formed by DGEBA, OECh and BSA, was followed by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy, ATR-FTIR. All the mixtures were prepared with a stoichiometric ratio between epoxy and amine groups. The degree of reaction of glycidyl epoxy ring along the curing cycle selected was obtained from the infrared spectra. A peak-height method based on the ratio of the height of the characteristic to reference absorbance peak was used. The curing kinetic of different blends was obtained by differential scanning calorimetry, DSC. Three different methods, the differential of Kissinger, the integral of Flynn-Wall-Ozawa and the phenomenological model of Kamal, were used in order to obtain the kinetic parameters of the cure reaction. It is observed that the presence of POSS accelerates the rate of opening of glycidyl epoxy rings from DGEBA. The behaviour of the mixture during the curing process can be explained with an autocatalytical model, corrected with the contribution of the diffusion of the molecules during the course of the reaction.