Silica sol-gel matrix doped with Photolon molecules for sensing and medical therapy purposes.

Photolon is one of the new photosensitisers that has found application in photodynamic therapy (PDT). Its chemical structure has a partially reduced porphyrin moiety and its molecular structure is comparable to chlorin e(6), which can be isolated after hydrolysis of the 5-membered exocyclic beta-ketoester moiety of pheophorbide a. For this study, a Photolon doped sol-gel matrix was produced in the form of coatings deposited on silica fibers cores. The material was produced from sols prepared from the silicate precursor TEOS mixed with ethyl alcohol. The sol-gel films were prepared with factor R=20, where R denotes the solvent-to-precursor molar ratio. Hydrochloric acid was added as a catalyst in the correct proportion to ensure acid hydrolysis (pH approximately 2). The mixture was stirred at room temperature for 4h using a magnetic stirrer (speed 400 rpm). The coated fibers were examined in different environments, liquid and gaseous, at different pH values and with various zinc cation concentrations. The chemical reactions were studied by means of spectroscopic methods, whereby the fluorescence response was studied. It was demonstrated that Photolon immobilized in a sol-gel matrix is accessible for the environment and shows visible response to the external changes. Furthermore, it was observed that these reactions are reversible. These biomaterials are also examined as carriers for PDT. It was also proved that a toxic effect is observed an environment with microorganisms, meaning that doped coatings have photodynamic activity.

[The influence of laser irradiation of low-power density on an experimental cartilage damage in rabbit knee-joints: an in vivo investigation considering macroscopic, histological and immunohistochemical changes]. / Der Einfluss von Laserlichtbestrahlung niedriger Leistungsdichte auf einen experimentellen Knorpelschaden im Kniegelenk des Kaninchens: eine in vivo-Untersuchung unter Berücksichtigung makroskopischer, histologischer und immunhistochemischer Veränderungen.

In a total of 45 rabbits, knee-joint arthrosis was induced according to the Hulth & Telhag model. Depending on the post-operative survival time, the cartilage was investigated macroscopically, histologically and immunohistochemically (within a period of 10 days to 8 months). Thereafter, the influence of laser irradiation at a wavelength of 692.6 nm and energy densities of 1 and 4 J/cm2 on the cartilage morphology seven days following the exposure was examined. After joint instability surgery it was found out that the cartilage changes in the main stress area (MSA) and in regions outside the main stress area (ROMSA) progressed differently. Various qualitative and semi-quantitative changes were found for collagens I, II, IV and V, and for the glycoproteins fibronectin and tenascin. Immunohistochemically, there was a growing expression of collagen I in the apical layers, collagen II showed a stronger pericellular expression, and collagen IV showed, after an initial growth of the pericellular expression, a reduced territorial expression and a stronger apical-interterritorial expression in the osteoarthrotic cartilage. For fibronectin, the cellular expression turned out to grow in the ROMSA. In the MSA it decreased, but at the same time the interterritorial expression grew. For Tanascin, there was a decrease of the interterritorial expression in the radial zone while the pericellular and interterritorial expression of the apical layers of the osteoarthrotic cartilage grew. Lasing proved to significantly influence the osteoarthrotically changed cartilage when applied at an energy density of 1 J/cm2, i.e., the morphological changes had not yet progressed to the extent the control group had. Both the chondrocyte density and the glucosaminoglycan content turned out to be higher. When lasing was applied at higher energy densities, no significant difference among the control groups was found. Thus, it could be demonstrated in vivo that an arthrotic process decelerates through the influence of laser light of low-energy densities.

Fiber-optical and microscopic detection of malignant tissue by use of infrared spectrometry.

Several investigations were performed in order to develop an in vivo endoscopic method to differentiate between malignant and healthy tissue working on the assumption that each diseased state of biological tissue has its own characteristic infrared (IR) spectral pattern. The technical design of the laboratory setup is presented here together with the experimental details and the results. Two regions (1245-1195) and (1045-995) cm(-1) within the fingerprint (<1500 cm(-1)) region were selected for analysis. Lead salt diode lasers were used as excitation sources and IR radiation was transmitted via silver halide wave guides to the tissue to be investigated. The IR radiation is returned to a mercury-cadmium-telluride detector by another IR cable. The measurements were carried out in attenuated total reflectance and diffuse reflection/remission. Human colon carcinoma tissue, under humid conditions, was used as a target for experiments to simulate in vivo conditions. Specimens were mapped using a stepper, motor powered, x/y/z-translation stage with a spatial resolution of 1 microm. The results were compared with similar measurements from a Fourier transform IR (FTIR) interferometer/FTIR microscope setup in the wave number region of 4000-900 cm(-1).