The influence of freezing rates on bovine pericardium tissue Freeze-drying

Borgognoni, Camila Figueiredo; Tattini, Virgílio; Ayrosa, Ana Maria Irene Bartolomeu; Polakiewicz, Bronislaw; Leirner, Adolfo A.; Maizato, Marina Junko Shiotsu; Higa, Olga Zazuco; Beppu, Marisa Masumi; Pitombo, Ronaldo Nogueira de Moraes

doi:10.1590/s1516-89132009000600021

Cited by 15 publications

(10 citation statements)

References 26 publications

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“…In Fig. A, the amide bands, especially the prominent amide I, did not appear indicating structural changes and denaturation of the membrane proteins and hemoglobin . However, residues of hemoglobin are confirmed through the bands near 565 cm −1 by Fe‐O 2 bonding and 1360 and 1543 cm −1 due to the Soret band excitation of heme proteins .…”

Section: Resultsmentioning

confidence: 93%

Platinum electrode modification: Unique surface carbonization approach to improve performance and sensitivity

2015

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Many microfluidic devices, also known as lab-on-a-chip devices, employ electrochemical detection methods using microelectrodes. Miniaturizing electrodes inevitably reduces electrode sensitivity and decreases the S/N, which limits applications within microfluidic devices. However, microelectrode surface modification can increase the surface area and sensitivity. In the present work, we report substantial improvement in platinum electrode performance and sensitivity by coating with carbon from red blood cells. The larger goal of this work was to measure DC electrical resistances of red blood cell suspensions in a microchannel for hematocrit determination. It was observed that as current responses of red blood cell suspensions were measured, the platinum electrode performance (reproducibility and S/N) improved with time. The platinum electrode electrocatalytic activity for red blood cell current measurements improved by 140%. Systematic experimentation revealed that red blood cells adsorb and carbonize the platinum electrode surfaces. The electrode surfaces before and after performance improvements were analyzed by field emission scanning electron microscopy, energy dispersive spectrometry, and Raman spectrometry. The formed carbon layers on the electrode surfaces were found to be proteomic and increased surface area with a porous three-dimensional structure, thus improving performance and stabilizing currents.

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Section: Resultsmentioning

confidence: 93%

Platinum electrode modification: Unique surface carbonization approach to improve performance and sensitivity

2015

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“…Before being used, BP was washed with saline solution (NaCl 0.9% w/v) to remove glycerol excess. The samples were freeze-dried in a FTS Systems (TDS-00209-A) [35].…”

Section: Bovine Pericardium Preparationmentioning

confidence: 99%

Inhibition of calcification of bovine pericardium after treatment with biopolymers, E-beam irradiation and in vitro endothelization

Polak

Rodas

Chicoma

et al. 2013

Materials Science and Engineering: C

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“…Several BP tissue lyophilization protocols have been evaluated, and the protocol using annealing (heat treatment) produced the best results (15). Using this protocol, BP biological valve prostheses were lyophilized for subsequent implantation in a chronic animal model.…”

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confidence: 99%

Behavior of Lyophilized Biological Valves in a Chronic Animal Model

et al. 2013

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Glutaraldehyde is used in order to improve the mechanical and immunogenic properties of biological tissues, such as bovine pericardium membranes, used to manufacture heart valve bioprostheses. Lyophilization, also known as freeze-drying, preserves biological material without damage by freezing the water content and removing ice by sublimation. Through this process, dehydrated products of high quality may be obtained; also, the material may be easily handled. The lyophilization process reduces aldehyde residues in biological tissue previously treated with glutaraldehyde, thus promoting reduction of cytotoxicity, increasing resistance to inflammation, and possibly decreasing the potential for tissue calcification. The objective of this study was to chronically evaluate the calcification of bovine pericardium heart valve prostheses, previously lyophilized or not, in an animal model. Six-month-old sheep received implants of lyophilized and unlyophilized heart valve prostheses in the pulmonary position with right bypass. The study followed 16 animals for a period of 90 days. Right ventricle-pulmonary artery (RV/PA) transvalvular pressure gradient was evaluated before and immediately after implantation and before explantation, as were tissue calcium, inflammation intensity, and thrombosis and pannus formation. The t-test was used for statistical analysis. Twelve animals survived to the end of the experiment, but one of the animals in the control group had endocarditis and was excluded from the data. Four animals died early. The mean RV/PA gradient on implantation was 2.0 ± 1.6 mm Hg in the control group and 6.2 ± 4.1 mm Hg in the lyophilized group (P = 0.064). This mean gradient increased at explantation to 7.7 ± 3.9 mm Hg and 8.6 ± 5.8 mm Hg, respectively (P = 0.777). The average calcium content in the tissue leaflets after 3 months was 21.6 ± 39.1 mg Ca(2+)/g dry weight in the control group, compared with an average content of 41.2 ± 46.9 mg Ca(2+)/g dry weight in the lyophilized group (P = 0.478). In this experimental study there was no reduction of calcification after lyophilization. However, histological analysis showed less inflammation over the lyophilized tissue when compared with the control.

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The influence of freezing rates on bovine pericardium tissue Freeze-drying

Abstract: The bovine pericardium has been used as biomaterial in developing bioprostheses. Freeze-drying is a drying process that could be used for heart valve's preservation.

Cited by 15 publications

References 26 publications

Platinum electrode modification: Unique surface carbonization approach to improve performance and sensitivity

Platinum electrode modification: Unique surface carbonization approach to improve performance and sensitivity

Inhibition of calcification of bovine pericardium after treatment with biopolymers, E-beam irradiation and in vitro endothelization

Behavior of Lyophilized Biological Valves in a Chronic Animal Model

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