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Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy has been used to investigate the effect of weak electromagnetic fields on the structure of L-glutamine (L-Gln) and L-phenylalnine (L-Phe) in aqueous solution. It has been found that the exposure to a DC field or a 50 Hz AC field, for a short time induces modifications in the spectra of exposed samples in agreement with our preceding observations on glutamic acid. Furthermore, the acid–base equilibrium has been investigated by using the ratio of the intensity of the deprotonated on protonated species. In the case of L-Phe, the exposure induces a measurable shift of acid dissociation constant pKa1 out of the experimental errors, while in case of L-Gln, the effect is under the limit detectable with this method. The phenomenon of the shift of the acid–base equilibrium has been connected elsewhere to modification of the water–water hydrogen bonds in the water around both the backbone and the residue (R). Here we suggest that the magnetic field modifies the water structure around the molecules and changes the hydrophobic interactions allowing the molecules of amino acids to aggregate. The differences observed in the behavior of L-Phe and L-Gln may be related to the differences in the polarity of their residues. Bioelectromagnetics. 35:129–135, 2014. © 2013 Wiley Periodicals, Inc.

The advent of scanning near-field optical microscopy (SNOM) has augmented at a microscopic level the usefulness of optical spectroscopy in the region between 300 nm and 10 mum. Two-dimensional imaging of chemical constituents makes this a very attractive and powerful new approach. In this paper we show SNOM results obtained in several geometrical configurations on boron clusters in silicon, Li clusters embedded in a LiF sample and BN growth on silicon. We also show some results on the wavelength dependence of the reflectivity (R) in the near infrared (IR) of biological cells in liquid environment with the observation of the local fluorescence. The SNOM images revealed features that were not present in the corresponding shear-force (SF) images and which were due to localized changes in the bulk properties of the sample. The size of the smallest detected features clearly demonstrated that near-field conditions were reached both in the visible and infrared region. (C) 2004 Elsevier B.V. All rights reserved.

Ultrasound (US) induced enhancement of plasma membrane permeability is a hugely promising tool for delivering exogenous vectors at the specific biological site in a safe and efficient way. In this respect, here we report effects of membrane permeability alteration on fibroblast-like cells undergoing very low-intensity of US. The change in permeability was pointed out in terms of high uptake efficiency of the fluoroprobe calcein, thus resembling internalization of small cell-impermeable model drugs, as measured by fluorescence microscopy and flow cytometry. Fluorescence evidences moreover suggests that the higher the time of exposure, the larger will be the size of molecules can be internalized. The uptake events were related to the cell viability and also with structural changes occurring at membrane level as revealed by infrared spectroscopy and preliminary membrane fluidity and atomic force microscopy (AFM) investigation. Thus, the question of whether the uptake of cell-impermeable molecules is consistent with the presence of disruptions on the cell membrane (sonopore formation) has been addressed. In this framework, our findings may constitute experimental evidence in support of sub-cavitation sonoporation models recently proposed, and they may also provide some hints towards the actual working condition of medical US dealing with the optimum risk to benefit therapeutic ratio.

Although medical ultrasound offers compelling opportunities to improve therapy in principle, progress in the field has been limited because of an insufficient understanding of the potential genotoxic and cytotoxic effects of ultrasound on biological systems. This paper is mainly focused on an in vitro study of effects with respect to genotoxicity and viability induced by 1- and 3-MHz medical ultrasound in murine fibroblasts (NIH-3T3) at low-intensity exposure (spatial peak temporal average intensity Ita

The essential question of whether the interactions within liquid water may best be described by either the continuum or the micro domain model has for some time been a matter of some debate within the scientific community. We studied isotopic exchange in H 2 O/D 2 O mixtures by the inspection of IR spectra, and found that it depends strongly on the correlation between an individual molecule and its environment. It is further found that in such mixtures a certain proportion of the water molecules is not involved in the mixing process at all. The physical properties of these molecules determine the behaviour of interfacial water that is often described in the biological literature.

IR spectra of mixtures of light and heavy water seem to provide a clear evidence for the existence of substructures, each of which may be assigned to a particular kind of water molecule on the basis of their correlation with the local environment. These substructures have been related to three different populations named correlated, non correlated and intermediate according to their degree of correlation. Experimental data analysis show that, in a mixture of H2O-D2O, each population participates differently to the solution process.

It has been claimed that weak extremely low frequency electromagnetic fields (ELF-EMFs) can affect biochemical reactions and a wide-ranging body of literature is available on this topic. Nevertheless, the physical nature of these effects remains largely unknown. We investigated the influence of ELF-EMF on glutamic acid solutions using Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectra. Samples were exposed for 10, 20, or 30 min to a weak EMF generated by Helmoltz coils, and then placed in a spectrometer. After exposure, those solutions that had a pH lower than the isoelectric point tended to show a shift toward the deprotonation of the carboxylic group, while solutions having a pH greater than the isoelectric point showed the deprotonation of the residual amine group. Moreover, at low pH values, we also detected a shift of the δantisym band of the amine. The effects lasted a few minutes after exposure before the native configuration was restored. The spectral modifications were observed after each independent exposure to EMFs, and the same effects were seen by varying the frequencies in the range of 0–7 kHz. Therefore, the hypothesis of the existence of a resonant frequency that has been proposed elsewhere cannot be supported by the results of this study. The most surprising characteristic of this effect is the long-lasting nature of the perturbation, which is hard to be explained in terms of short-living excitations in biological matter. Bioelectromagnetics 32:218–225, 2011. © 2010 Wiley-Liss, Inc.

The structural effect induced by therapeutic ultrasound on proteins in aqueous solution has been investigated with FTIR spectroscopy, UV-VIS spectroscopy, circular dichroism and light scattering. Six proteins (cytochrome, lysozyme, myoglobin, bovine serum albumin, trypsinogen, and alpha-chymotrypsinogen A) with different molecular weight and secondary structure have been studied. The experiment has been performed using an ultrasound source at resonant frequency of 1 MHz and sonication times of 10, 20, 30, 40, 50, and 60 min. A different behaviour of proteins under sonication depends on the dominant secondary structure type (alpha-helix or beta-sheets) and on the grade of the ordered structure. The results suggest that the free radicals, produced by water sonolysis, have an important role in the changes of structural order.

The reaction of bovine serum albumin (BSA) with [ trans-RuCl 4(Im)(dimethylsulfoxide)][ImH] (Im = imidazole) (NAMI-A), an experimental ruthenium(III) anticancer drug, and the formation of the respective NAMI-A/BSA adduct were investigated by X-ray absorption spectroscopy (XAS) at the sulfur and chlorine K-edges and at the ruthenium K- and L 3-edges. Ruthenium K and L 3-edge spectra proved unambiguously that the ruthenium center remains in the oxidation state +3 after protein binding. Comparative analysis of the chlorine K-edge XAS spectra of NAMI-A and NAMI-A/BSA, revealed that the chlorine environment is greatly perturbed upon protein binding. Only modest changes were observed in the sulfur K-edge spectra that are dominated by several protein sulfur groups. Overall, valuable information on the nature of this metallodrug/protein adduct and on the mechanism of its formation was gained; XAS spectroscopy turns out to be a very suitable method for the characterization of this kind of systems.

Cellulose undergoing accelerated hydrothermal ageing gives a pattern of carbonyl groups whose vibrational modes were observed in UV/VI/NIR, FTIR and Raman spectra. Indirectly their presence in degraded samples was observed traced by the changes in the degree of polymerization (DP) and acidity (pH). Conjugated ketonic groups found in FTIR and Raman spectra after accelerated ageing were correlated to the chromophores detected by UV/VIS. A simple model describing the formation of chromophores was put forward and verified by experiments.

The interaction of the cytotoxic metals cadmium, zinc, and lead with pancreatic cells was studied by atomic force/lateral Force microscopy (AFM/LFM), an approach that provides both topographic (with nanometer scale lateral resolution) and chemical information on the membrane. Different morphological modifications of the overall cell shape and roughness took place as consequence of 100 μM metal-dependent treatment. Furthermore, after exposure to Cd(Cl2) and Zn(Cl2), but not Pb(Cl2), the LFM images revealed several areas of the cell's surface showing lateral friction contrasts that have been interpreted as marker of different alterations of the cell physiology induced by the metal loading. Thus, the coupling of LFM detection to topographic AFM characterization allows to distinguish, through a nondestructive and surface characterising approach, between different metal-induced cytotoxic effects on cells. In this framework, the role of the LFM as an important tool to discriminate between different alteration of a biological system has to be highlighted. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc.

For the first time a comparative study on conformational differences between native oval­ buminand its heat-stable form, called S-ovalbumin. using small angle x-ray scattering, is reported. To detect a different pathway in the folding mechanism of the two proteins, scatter­ing measurements have been performed on ovalbumin and S-ovalbumin denatured with dif­ferent concentrations of guanidine hydrochloride, and by heating the proteins at acid pH. The intensity scattering curves provide evidence that the intermediate states in the unfolding process are globular for both proteins while their compactness changes. The reported experi­mental results suggest that the ovalbumin to S-ovalbumin transformation can be considered a protein-switch triggered by changes in the chemical conditions of the protein environment. Because the conformational changes are likely to be of functional importance, we infer that the occurrence in vivo of S-ovalbumin is thus determined by the transformation of ovalbumin, with a functional role for embryonic development, into a new protein with a dif­ferent function.