Three-dimensional computational model of a blood oxygenator reconstructed from micro-CT scans

Cardiopulmonary bypass procedures are one of the most common operations and blood oxygenators are the centre piece for the heart-lung machines. Blood oxygenators have been tested as entire devices but intricate details on the flow field inside the oxygenators remain unknown. In this study, a novel method is presented to analyse the flow field inside oxygenators based on micro Computed Tomography (μCT) scans. Two Hollow Fibre Membrane (HFM) oxygenator prototypes were scanned and three-dimensional full scale models that capture the device-specific fibre distributions are set up for computational fluid dynamics analysis. The blood flow through the oxygenator is modelled as a non-Newtonian fluid. The results were compared against the flow solution through an ideal fibre distribution and show the importance of a uniform distribution of fibres and that the oxygenators analysed are not susceptible to flow directionality as mass flow versus area remain the same. However the pressure drop across the oxygenator is dependent on flow rate and direction. By comparing residence time of blood against the time frame to fully saturate blood with oxygen we highlight the potential of this method as design optimisation tool.In conclusion, image-based reconstruction is found to be a feasible route to assess oxygenator performance through flow modelling. It offers the possibility to review a product as manufactured rather than as designed, which is a valuable insight as a precursor to the approval processes. Finally, the flow analysis presented may be extended, at computational cost, to include species transport in further studies

The effect of pre-incubation of Allium cepa L. roots in the ATH-rich extract on Pb uptake and localization

The positive influence of anthocyanin (ATH) on toxic metal-treated plant material is well documented; however, it is still not explained if it is caused by changes in element absorption and distribution. Therefore, detailed analysis of the effect of the ATH-rich extract from red cabbage leaves on Pb uptake and localization at morphological, anatomical and ultrastructural level was the goal of this study. Two-day-old adventitious roots of Allium cepa L. (cv. Polanowska) were treated for 2 h with the aqueous solution of Pb(NO3)2 at the concentration of 100 μM with or without preliminary incubation in the anthocyanin-rich extract from Brassica oleracea L. var. capitata rubra leaves (250 μM, 3 h). The red cabbage extract did not change the total Pb uptake but it enhanced the translocation of accumulated metal from roots to shoots. Within the pretreated roots, more Pb was deposited in their basal part and definitely smaller amount of the metal was bound in the apoplast of the outer layers of cortex cells. The ultrastructural analysis (transmission electron microscopy and X-ray microanalysis) revealed that the ATH-rich extract lowered the number of Pb deposits in intracellular spaces, cell wall and cytoplasm of root meristematic cells as well as in such organelles important to cell metabolism as mitochondria, plastids and nucleus. The Pb deposits were preferably localised in those vacuoles where ATH also occurred. This sequestration of Pb in vacuoles is probably responsible for reduction of metal cytotoxicity and consequently could lead to better plant growth.This work was supported by the grant of the University of Lodz, no. 505/04038

Ligand design and nuclearity variation towards dual emissive Pt(ii) complexes for singlet oxygen generation, dual channel bioimaging, and theranostics

Organic ligands comprising thiophene ring(s) afford complexes of transition metals, such as Pt(II) and Ir(III), with photoluminescence readily tunable via ligand modifications. In this work we demonstrate the targeted design of a NC-CN type ditopic ligand with a central thiophene ring as the cyclometalating core and variation of the nuclearity of the complex to fine-tune the photophysical properties of the material. The mononuclear complex Pt-1 shows red T-1 -> S-0 phosphorescence with the emission maximum at lambda = 660 nm. The dinuclear complex Pt-2 shows near infrared (NIR) T-1 -> S-0 phosphorescence peaking at lambda = 710 nm. In both cases the phosphorescence is quenched by molecular oxygen generating singlet oxygen molecules with high efficiencies of phi(Delta) approximate to 83% (Pt-1) and phi(Delta)approximate to 70% (Pt-2, respectively) in air-equilibrated CH2Cl2 solutions under ambient conditions. The red phosphorescence of Pt-1 is accompanied by green S-1 -> S-0 fluorescence with the maximum at lambda = 495 nm. This makes Pt-1 a dual emissive material with two emissions stemming from a single chromophore moiety. Transient absorption studies revealed a relatively low rate of ISC from the S-1 state to the triplet manifold with a time constant tau(ISC) of about 4 ps. The slow ISC in Pt-1 is rationalized by a specific electronic structure with a relatively large energy gap Delta E(S-1 -> T-1) approximate to 0.63 eV and the higher triplet state T-2 being higher in energy than the singlet state S-1. In dinuclear Pt-2, state T-2 lies below S-1 opening fast T-2 -> S-1 ISC paths with a time constant tau of only approximate to 0.13 ps. The unique dual emission of Pt-1 was beneficial for its imaging in HeLa cells as it enabled switching between green fluorescence and red phosphorescence channels of detection in the time-span of the single confocal luminescence microscopy experiment. Pt-1 represents a prototype of new theranostic agents combining cytotoxic activity with a unique dual wavelength mode of detection

The impact of ruthenium terminated carbosilane dendrimers on cell membranes

Медицинская биофизик

Cytotoxicity of anticancer carbosilane metallodendrimers in human leukemia (HL-60) cells

Медицинская биофизик