In-situ and label-free optical monitoring of the adhesion and spreading of primary monocytes isolated from human blood: dependence on serum concentration levels

Orgován, Norbert and Salánki, Rita and Sándor, Noémi and Bajtay, Zsuzsa and Erdei, Anna and Szabó, Bálint and Horváth, Róbert (2013) In-situ and label-free optical monitoring of the adhesion and spreading of primary monocytes isolated from human blood: dependence on serum concentration levels. BIOSENSORS & BIOELECTRONICS, 54. pp. 339-344. ISSN 0956-5663

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Adhesion and spreading of primary monocytes isolated from human blood were monitored utilizing optical waveguide lightmode spectroscopy (OWLS); a highly sensitive label-free biosensor technique using evanescent optical waves generated at a biocompatible surface. Appropriate development on a custom built setup enabled the OWLS cuvette to be operated as a 1.5 ml mini-incubator, controlling both temperature and CO2 levels. The incubator-equipped OWLS is readily applicable for delicate and long-term studies on sensitive primary cells, demonstrated here through monitoring the serum dependence of the adhesion and spreading of human monocytes. Moreover, the custom-built setup enables the simultaneous monitoring of the position and overall width of the OWLS resonant peaks. This unique feature makes it possible to distinguish the refractive index variations induced by the adsorption of secreted material from refractive index changes provoked by cellular spreading. A definite attachment and spreading activity was observed on the substratum (glassy silica-titania), when the serum level of the culturing medium was 0.0-0.01%. Increasing serum concentration resulted in a steep fall in monocyte surface adhesion and spreading. 1.0% serum level practically abolished all spreading activity measured by OWLS, and the number of attached cells was significantly decreased, too. Serum addition to fully spread cells provoked a reduction in the cell-substratum contact area, clearly detectable by the biosensor. Cell spreading was inhibited by pre-coating the sensor surface with considerable amounts of serum proteins. These findings suggest that monocyte spreading is inhibited by the adsorption of serum biomolecules to the substratum, rather than by soluble factors present in the serum. All of these results were obtained completely non-invasively with real time monitoring; demonstrating the capabilities of OWLS to sensitively monitor the adhesion properties of immune cells isolated from human blood. The current study is, therefore, a significant step towards the application of label-free optical biosensors in medical diagnostics.

Item Type: Article
Uncontrolled Keywords: label-free optical biosensor Optical Waveguide Lightmode Spectroscopy mini-incubator primary monocyte cellular adhesion serum dependence
Subjects: Q Science / természettudomány > QH Natural history / természetrajz > QH301 Biology / biológia
Depositing User: Andrea Bolgár
Date Deposited: 12 Mar 2014 11:24
Last Modified: 12 Mar 2014 11:24

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