Research Papers: General

Behavior of the thermal diffusivity of native and oxidized human low-density lipoprotein solutions studied by the Z-scan technique

[+] Author Affiliations
Priscila R. Santos, Andrea M. Monteiro, Antonio M. Figueiredo Neto

Universidade de São Paulo, Instituto de Física, Departamento de Física Experimental, Rua do Matão, Travessa R, 187, 05508-090, São Paulo, Brazil

Thiago C. Genaro-Mattos, Sayuri Miyamoto

Universidade de São Paulo, Instituto de Química, Departamento de Bioquímica, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo, SP, Brazil, Brazil

J. Biomed. Opt. 17(10), 105003 (Oct 01, 2012). doi:10.1117/1.JBO.17.10.105003
History: Received July 3, 2012; Revised August 6, 2012; Accepted September 5, 2012
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Abstract.  Modifications in low-density lipoprotein (LDL) have emerged as a major pathogenic factor of atherosclerosis, which is the main cause of morbidity and mortality in the western world. Measurements of the heat diffusivity of human LDL solutions in their native and in vitro oxidized states are presented by using the Z-Scan (ZS) technique. Other complementary techniques were used to obtain the physical parameters necessary to interpret the optical results, e.g., pycnometry, refractometry, calorimetry, and spectrophotometry, and to understand the oxidation phase of LDL particles. To determine the sample’s thermal diffusivity using the thermal lens model, an iterative one-parameter fitting method is proposed which takes into account several characteristic ZS time-dependent and the position-dependent transmittance measurements. Results show that the thermal diffusivity increases as a function of the LDL oxidation degree, which can be explained by the increase of the hydroperoxides production due to the oxidation process. The oxidation products go from one LDL to another, disseminating the oxidation process and caring the heat across the sample. This phenomenon leads to a quick thermal homogenization of the sample, avoiding the formation of the thermal lens in highly oxidized LDL solutions.

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© 2012 Society of Photo-Optical Instrumentation Engineers

Citation

Priscila R. Santos ; Thiago C. Genaro-Mattos ; Andrea M. Monteiro ; Sayuri Miyamoto and Antonio M. Figueiredo Neto
"Behavior of the thermal diffusivity of native and oxidized human low-density lipoprotein solutions studied by the Z-scan technique", J. Biomed. Opt. 17(10), 105003 (Oct 01, 2012). ; http://dx.doi.org/10.1117/1.JBO.17.10.105003


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