A complex analysis was made of histological preparations of the large intestine without pathology, chronic colitis, and surgical material of primary colorectal adenocarcinoma with due allowance for recovery of the patients after standard treatment by confocal Raman spectroscopy with spatial resolution. It was shown that the main difference in the spectra of the normal and pathologically changed tissues are the positions and relative intensities of the vibrational bands at frequencies of 1248, 1537, 1587, and 1620 cm–1. The spectral changes were analyzed in terms of the Stark approach on the assumption of change of the local electric field in the epithelial cells during oncogenesis.

In aqueous solutions the spectral-kinetic parameters of quantum dots (QD) based on a mixture of semiconductors of groups I–III–VI, namely Ag–In–S and Ag–In–S 2 , with a layer of ZnS (AIS/ZnS QD), show a specific dependence on pH and on the local polarity caused by interaction with polyelectrolytes (spectral shifts, hyperchromism, and hypochromism in the absorption and photoluminescence spectra, changes of the average photoluminescence life time). It was found that the change in the properties of the AIS/ZnS QDs with variation of the pH of the solution is caused by reversible recharging of ampholyte ion groups, which alters the structure of the Helmholtz double layer at the surface of the QD covered by glutathione molecules. It was shown that the second derivative of the QD absorption spectra both in an acidic medium and during interaction with polyelectrolytes corresponds to a linear Stark effect due to the formation of an induced dipole moment in the QD. The obtained results can be used to develop selective markers based on AIS/ZnS QDs for testing local pH and polarity in biomedicine.

In water solutions, spectral-kinetic parameters of quantum dots based on the mixture of semiconductors of I-III-VI groups, namely Ag-In-S, Ag-In-S 2 with ZnS layer (QD AIS/ZnS), show a specific dependence on pH and the local polarity caused by the interaction with polyelectrolytes (spectral shifts, hyperchromism and hypochromism in absorption and photoluminescence spectra, changes of the photoluminescence mean decay). It was argued that changes of QD AIS/ZnS upon variation of the solution pH are caused by the reversible recharging of ampholyte ion groups, which thus alters the structure of the Helmholtz binary layer at the QD surface covered by glutathione molecules. It is shown that the second derivative of QD absorption spectra both in an acid medium and upon interaction with polyelectrolytes corresponds to the Stark linear effect caused by the formation of the QD induced dipole moment. The results obtained and the corresponding conclusions on their basis may be used to develop selective markers for testing local pH and polarity in biomedicine using QD AIS/ZnS.

Effective enhancement of the fluorescence signal of chromophores adsorbed directly onto plasmonic films can be observed under conditions of strong spectral resonance between plasmon and chromophore absorptions. This effect seems to contradict the established mechanisms of complete quenching of the fluorescence of chromophores under their adsorbtion directly onto the metal surface. However, under certain conditions, enhancement of the fluorescence signal is observed for both inorganic and organic chromophores. To understand the effect and conditions of its observation, we propose to use the quantum concept of virtual photon exchange in the near optical field - dressed photons. This concept is borrowed from the physics of elementary particles and is already well adapted to the problems of nanophotonics by M. Otsu. In this paper, we discuss exclusively the key factors responsible for enhancement of fluorescence of CdSe/ZnS nanocrystals and the effective dressed photons exchange: the size of nanoparticles, the distance between them, and the presence of spectral overlap indicating the possibility of resonant interactions between plasmons and chromophores.

We discuss the fluorescence spectra from a set of points in histological sections of colon tissue with different levels of pathology that were stained with hydrophilic semiconductor CdSe/ZnS nanoparticles that were modified by a unique method at the phase interface. The shifts in the fluorescence spectra that were recorded for stained cells at different pathologies are described using the electrochromism of the nanoparticles. Aqueous solutions of the CdSe/ZnS nanoparticles with different pH values are used as systems that model the acidity of a biological medium. It has been shown that the shifts of the fluorescence bands of the CdSe/ZnS nanoparticles are caused by a change in the local electrical field that is induced by solvated ions near their surface at different pH values of the solutions. The application of the CdSe/ZnS nanoparticles as nanoprobes for the local pH in biological tissue is discussed in the context of this model.

Флуоресцентные наночастицы CdSe/ZnS как нанозонды локального pH в диагностике онкологических заболеваний

The spectral and kinetic characteristics of CdSe/ZnS nanoparticles (NPs) surface-modified with cysteamine by two different methods are considered upon interaction with polyelectrolytes. With the use of steady-state and time-resolved fluorescence spectroscopies, it is shown that the fluorescence intensity and stability of NPs in the presence of polyelectrolytes depend on the surface-modification method. It is found that hydrophilic NPs obtained at the interface between two immiscible liquids (chloroform–water) are more resistant to aggregation.

Влияние технологии модификации поверхности на спектральные характеристики гидрофильных наночастиц CdSe/ZnS при взаимодействии с полиэлектролитами

Computer modeling (DFT B3LYP/6-31G(d,p)/SDD) of the structure and spectral characteristics of photochromic 1,3,3,8′-tetramethyl-6′-formylspiro[indoline-2,2′-[2 H ]-chromene] and 1,3,3-trimethyl-6′-methoxy-8′-formyl[spiroindoline-2,2′-[2 H ]-chromene] complexes adsorbed onto the surface of a 10-atom silver cluster has been performed. It has been demonstrated that, depending on the position of the formyl group in the quinoline ring and the isomeric form of the spirocyclic compound, the change in the band intensity in Raman spectra caused by complexation with the silver cluster can reach three orders of magnitude.

The influence of the cysteamine surfactant concentration on the stability of CdSe/ZnS nanoparticles (NPs) solubilized by this compound at the phase interface between two immiscible liquids is considered. The steady-state and time-resolved fluorescence spectroscopy data show that the fluorescence quantum yield of cysteamine-coated NPs and their stability to aggregation in a potassium phosphate buffer are determined by the balance between the concentrations of surfactant in the aqueous phase and hydrophobic NPs in the nonpolar phase (chloroform, toluene, etc.). It is found that the brightest and most stable hydrophilic NPs can be obtained by completely coating them by cysteamine molecules without a surfactant deficit or excess in the reaction at the phase interface.

We consider the dependence of the spectral properties of eosin and hematoxylin (dyes routinely used in histology as contrast agents) on their localization in biological tissues with different levels of pathology: benign and malignant neoplasms and sigmoid colonic crypts. We have analyzed the fluorescent images and fluorescence spectra of the parenchyma and stromal elements. We have established that on going from physiologically normal cells to tumor cells, the contribution to the absorption cross section of histologic sections due to hematoxylin increases. In pathologically altered cells in a colonic crypt, we observe a hypsochromic effect in the fluorescence spectra of the samples with appreciable quenching of the fluorescence, while in the model systems the reverse effect occurs: a shift of the fluorescence maximum toward the red region. We discuss the influence on the indicated effects from local pH and the polarity of the dye environment in the model systems and histologic sections. As the systems modeling the polarity and acidity of the biological media, we use aqueous solutions of the dyes with different pH values and synthetic polyelectrolytes.

Absorption and Raman spectra of the tetra(4-sulfonatophenyl)porphyrin (TSPP) zwitterion in aqueous solutions under conditions at which porphyrin nanotubes (PNT) form (pH 1) are presented. TSPP was immobilized on the surface of plasmonic silver films (PSF) via quick transfer of a suspension of the molecules into a solution at pH 5 and onto the film surface in order to avoid degrading the film. Images of PNT and spheroidal TSPP aggregates on the PSF surface were visualized using confocal microscopy. Spatially resolved surface-enhanced Raman spectra (SERS) of these objects were recorded. Differences in SERS of PNT and TSPP globular aggregates are discussed based on quantum-chemical calculations of TSPP vibrational spectra. Vibrational bands sensitive to the tube–spherulite transition are found.

We present the results of x-ray fluorescence analysis of tissues from healthy ovaries and from ovaries with different pathologies: benign and borderline tumors, mucinous and endometrioid cancers, serous carcinomas. We determine the average copper, zinc, calcium, selenium, cadmium, lead, and mercury levels. We observed that in the benign ovarian tumors, we see a significant decrease in the cadmium, mercury, and lead levels compared with healthy tissues. In the borderline neoplasms, the copper level is reduced relative to zinc (Cu/Zn), cadmium, mercury, and lead, and also the zinc concentration is increased. In the ovarian carcinomas, we observed changes in the ratio of the chemical elements in the tumor tissues, depending on the histologic type. The results obtained can be used for differentiation, diagnosis, and adjustment of treatment for different ovarian neoplasms.

We have studied the absorption spectra and micrographs of sections of cells of the epithelium and andenocarcinoma of the large intestine, immobilized between standard glass slides and cover glasses and plasmonic silver films. We have shown that when we use a microtome technique and specially selected plasmonic silver films, we can achieve enhancement of the image contrast in analysis of the cell morphology as a result of the increase in the light absorption and scattering cross sections with the contrasting stains hematoxylin and eosin.

The germanium on silicon (Ge-on-Si) semiconductor nanostructures with a vacuum-deposited silver coating are tested as substrates for detecting microamounts of inorganic crystalline ultramarine pigment by enhanced Raman scattering (SERS). At least tenfold enhancement of Raman lines is obtained. The quantum-chemical calculations are performed and used to assign the bands in the Raman spectra. A significant electrooptic anharmonicity of vibrations of chromophore groups in the presence of an SERS-active compound is found.

Semiconductor self-assembled Ge-on-Si quantum dot structures coated with Au film were successfully employed as surface-enhanced Raman scattering (SERS) substrates to characterize ultramarine blue inorganic art pigment. To assign the bands and to reveal the enhancement mechanisms, the quantum-chemical calculations of vibration spectra of linear and cyclic model compound of SiO4 and AlO4 tetrahedra were carried out. The overtones are observed in the SERS spectra and the unharmonicity constants were estimated. The development of a series of new bands in SERS spectra of ultramarine are discussed in terms of electro-optical unharmonicity.