Репозиторий Университета

© 2019 Elsevier B.V. Application of restructured collagen-based biomaterials is generally restricted by their poor mechanical properties, which ideally must be close to those of a tissue being repaired. Here, we present an approach to the formation of a robust biomaterial using laser-induced curing of a photosensitive star-shaped polylactide. The created collagen-based structures demonstrated an increase in the Young's modulus by more than an order of magnitude with introduction of reinforcing patterns (from 0.15 ± 0.02 MPa for the untreated collagen to 51.2 ± 5.6 MPa for the reinforced collagen). It was shown that the geometrical configuration of the created reinforcing pattern affected the scaffold's mechanical properties only in the case of a relatively high laser radiation power density, when the effect of accumulated thermomechanical stresses in the photocured regions was significant. Photo-crosslinking of polylactide did not compromise the scaffold's cytotoxicity and provided fluorescent regions in the collagen matrix, that create a potential for noninvasive monitoring of such materials' biodegradation kinetics in vivo.

© 2018, V.A. Negovsky Research Institute of General Reanimatology. All rights reserved. The purpose of the study - to determine the feasibility of using the succinate-based antioxidant for the in vitro reduction of excessive methemoglobin to oxyhemoglobin in blood. Materials and Methods. Blood sampling was performed in five healthy donors in microvettes containing EDTA during prophylactic examinations. NaNO2 solution was added to blood samples in vitro in order to yield methemoglobin (MetHb). The complex drug containing the following active ingredients: succinic acid, inosine, riboflavin, nicotinamide, was used as an antioxidant. The absorption spectrum of red cell suspensions with different drug content Dl(λl) exper was measured with 1 nm increments. The non-linear regression method was used to calculate concentrations of hemoglobin derivatives in suspensions. Results. In our experiments, when methemoglobin reacted with drug the optical density of peaks typical for oxyhemoglobin increased and the spectral peak of methemoglobin decreased. The greater the concentration of drug, the more was the incubation time, the more efficient was the process of reduction of MetHb to HbO2. Conclusion. We proved experimentally that while the baseline concentration of MetHb was an average of 91-93%, addition of drug decreased its concentration to 25-7%. Without drug, due to autoreduction, the concentration of MetHb decreases only to 84%. The revealed effect provide a potential for practical applications in critical illness, during the storage of donor blood, in blood transfusions, and under the action of physico-chemical factors on blood.

© 2017 Astro Ltd. A two-photon laser femtosecond crosslinking process at the wavelength of 525 nm was studied in a human donor cornea in the presence of riboflavin using two-photon optical microscopy and nanoindentation. It was shown that such an approach results in efficient crosslinking of the corneal collagen and a significant (three-fold) increase in the Young's modulus of the corneal structure. Application of a femtosecond laser with the wavelength of 525 nm allows a drastic enhancement of efficiency in the presence of riboflavin on human corneas and a 50-fold reduction of the laser treatment duration in comparison with the use of a femtosecond laser with the wavelength of 760 nm. We relate this effect to a significant growth in the coefficient of two-photon absorption due to the laser wavelength falling within the edge of the photoinitiator (riboflavin) absorption band. Our studies on a donor human cornea demonstrate the good potential for the clinical application of a femtosecond laser with the wavelength of 525 nm for increasing the cornea rigidity using the two-photon laser femtosecond crosslinking technique.