Search

Significance: Optical fluorescence spectroscopy technique has been explored extensively to quantify both glucose uptake and mitochondrial metabolism with proper fluorescent probes in small tumor models in vivo. However, it remains a great challenge to rapidly quantify the intrinsic metabolic fluorophores from the optically measured fluorescence spectra that contain significant distortions due to tissue absorption and scattering. Aim: To enable rapid spectral data processing and quantify the in vivo metabolic parameters in real-time, we present an empirical ratio-metric method for rapid fluorescence spectra attenuation correction with high accuracy. Approach: A first-order approximation of intrinsic fluorescence spectra can be obtained by dividing the fluorescence spectra by diffuse reflectance spectra with some variable powers. We further developed this approximation for rapid extraction of intrinsic key metabolic probes (2-NBDG for glucose uptake and TMRE for mitochondrial function) by dividing the distorted fluorescence spectra by diffuse reflectance intensities recorded at excitation and emission peak with a pair of system-dependent powers. Tissue-mimicking phantom studies were conducted to evaluate the method. Results: The tissue-mimicking phantom studies demonstrated that our empirical method could quantify the key intrinsic metabolic probes in near real-time with an average percent error of ∼5%. Conclusions: An empirical method was demonstrated for rapid quantification of key metabolic probes from fluorescence spectra measured on a tissue-mimicking turbid medium. The proposed method will potentially facilitate real-time monitoring of key metabolic parameters of tumor models in vivo using optical spectroscopy, which will significantly advance translational cancer research.

Significance: Recent generation of bioengineered human skin allowed the efficient treatment of patients with severe skin defects. However, the optical and biomechanical properties of these models are not known. Aim: Three models of bioengineered human skin based on fibrin-agarose biomaterials (acellular, dermal skin substitutes, and complete dermoepidermal skin substitutes) were generated and analyzed. Approach: Optical and biomechanical properties of these artificial human skin substitutes were investigated using the inverse adding-doubling method and tensile tests, respectively. Results: The analysis of the optical properties revealed that the model that most resembled the optical behavior of the native human skin in terms of absorption and scattering properties was the dermoepidermal human skin substitutes after 7 to 14 days in culture. The time-course evaluation of the biomechanical parameters showed that the dermoepidermal substitutes displayed significant higher values than acellular and dermal skin substitutes for all parameters analyzed and did not differ from the control skin for traction deformation, stress, and strain at fracture break. Conclusions: We demonstrate the crucial role of the cells from a physical point of view, confirming that a bioengineered dermoepidermal human skin substitute based on fibrin-agarose biomaterials is able to fulfill the minimal requirements for skin transplants for future clinical use at early stages of in vitro development., Ministry of Science, Innovation and Universities of Spain PGC2018-101904-A-I0, Instituto de Salud Carlos III (ISCIII), Ministry of Science, Innovation and Universities, through AES 2017 AC17/00013, Instituto de Salud Carlos III (ISCIII), Ministry of Science, Innovation and Universities within EuroNanoMed framework, EU AC17/00013, University of Granada A.TEP.280.UGR18, Junta de Andalucía PE-0395-2019, Fundación Benéfica Anticancer San Francisco Javier y Santa Cándida, Granada, Spain, OTRI.35A-07

Introduction: Printing inks oil selection is related to the desired nature of the varnish in the ink production. Petroleum-derived mineral oils and vegetable oils can be used in offset inks. Methods: In this study, the behaviors of vegetable- and mineral oil-based inks on uncoated and coated paper surfaces were investigated in terms of printability. Solid tone test prints were done with offset printing of these inks. Print gloss of the printed samples was measured and a light fastness test was implemented on these samples in order to determine the resistance to fading. Absorption behavior and contact angles of the ink-printed films on the test papers were measured with the sessile water drop method depending on time, and surface energies were calculated. Results: On both paper types, linseed–soybean oil-based vegetable ink gave the highest brightness value. The lowest print gloss results on the paper were obtained from soybean oil-based inks. The lowest color change was recorded with mineral oil-based inks on gloss-coated papers. According to the ink-film–surface relation, when the contact angle is high, surface energy decreases and the absorbency of the ink-film is lower. Conclusions: In this study, the behaviors of vegetable- and mineral oil-based inks on different paper surfaces, and the effect on the quality of printability as well as differences, have been evaluated, taking environmental and health factors into consideration.

The optical properties and degradation of fir wood treated by different inorganic salts, which are components of waterborne wood preservatives, were studied before and after wet-thermal accelerated ageing (T=85 degrees C, RH=65%, for 30 days) using UV-Vis diffuse reflectance spectroscopy. The colour of all impregnated samples was due to the same chromophoric structures, thus revealing that the primary reactions leading to colour changes are essentially very similar. These chemically treated as well as standard (non-treated, unaged) and reference (treated only with distilled water, unaged/aged) samples have a significant absorption band at 358 nm, along with a shoulder near 265 nm of various intensity. The broad band at higher wavelength is attributed to the chromophoric structures derived especially from lignin, i.e. quinones, stilbenes, charge transfer complexes causing a bathochromic shift and other conjugated carbonyl structures. Coniferaldehyde is also a major contributor to this absorption. The band at 265 nm belongs to chromophores arising predominantly from carbohydrate degradation products, i.e. furan derivatives, quinone-type derivatives, catechol structures. Catechol structures (colourless) form coloured complexes with transition metal cations (Cu2+, Fe3+) or are oxidized to form highly coloured benzoquinone structures. Alkaline solutions of borax cause the reduction of conjugated and non-conjugated carbonyls and the degradation of coniferaldehyde. Generally, after ageing, the samples show higher absorptions in the visible region of the spectra in comparison. with the unaged ones, which explains their yellowing and loss of brightness after the action of elevated temperature and moisture.