Abstract
Thrombin generation is a complex and finely regulated pathway that provokes dynamical changes of thrombin concentration in blood when a vascular injury occurs. In order to characterize the initiation phase of such process, when thrombin concentration is in the nM range, a label-free optical aptasensor is proposed here. This aptasensor combines a 1D photonic crystal structure consisting of a silicon corrugated waveguide with thrombin binding aptamers on its surface as bioreceptors. As a result, this aptasensor has been demonstrated to specifically detect thrombin concentrations ranging from 270 pM to 27 nM with an estimated detection limit of 33.5 pM and a response time of ~2 min. Furthermore, it has also been demonstrated that this aptasensor is able to continuously respond to consecutive increasing concentrations of thrombin and to detect binding events as they occur. All these features make this aptasensor a good candidate to continuously study how thrombin concentration progressively increases during the initiation phase of the coagulation cascade.
Highlights
Thrombin is a pleiotropic enzyme with a central role in blood coagulation
We begin trying to demonstrate the detection of a thrombin concentration of 27 nM (1 μg/mL), a value that is near the upper concentration of the initiation phase [4]
The microfluidic cell is attached to the photonic chip and the optical response of each sensing structure is checked while flowing 1× Phosphate-Buffered Saline (PBS)
Summary
Thrombin is a pleiotropic enzyme with a central role in blood coagulation. In normal conditions it is absent in blood. Some works have reported the development of aptasensors able to detect lower concentrations of thrombin, for example, in research of Chen, X. et al [26] and Cho, H. et al [27] They require the incubation of thrombin and the TBA as well as the use of dyes to measure the final TBA-thrombin complexes, not offering the possibility of performing a continuous and label-free monitoring of the binding events as reported in the current work. Combining both TBA and our PC structures, it is demonstrated that a direct detection of thrombin concentrations as low as 270 pM can be performed by monitoring in real time the binding events while they occur. It is evinced that a continuous increase of the concentration of thrombin can be continuously detected, which makes this optical aptasensor a good candidate to monitor the formation of thrombin during the initiation phase of the thrombin generation process
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