Ultrathin and smooth poly(methyl methacrylate) (PMMA) films for label-free biomolecule detection with total internal reflection ellipsometry (TIRE) (original) (raw)
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Analytical and Bioanalytical Chemistry, 2010
We report a label-free optical detection technique, called total internal reflection ellipsometry (TIRE), which can be applied to study the interactions between biomolecules and a functionalized polymer surface. Zeonor (ZR), a cycloolefin polymer with low autofluorescence, high optical transmittance and excellent chemical resistance, is a highly suitable material for optical biosensor platforms owing to the ease of fabrication. It can also be modified with a range of reactive chemical groups for surface functionalization. We demonstrate the applications of TIRE in monitoring DNA hybridization assays and human chorionic gonadotrophin sandwich immunoassays on the ZR surface functionalized with carboxyl groups. The < and Δ spectra obtained after the binding of each layer of analyte have been fitted to a four-layer ellipsometric model to quantitatively determine the amount of analytes bound specifically to the functionalized ZR surface. Our proposed TIRE technique with its very low analyte consumption and its microfluidic array format could be a useful tool for evaluating several crucial parameters in immunoassays, DNA interactions, adsorption of biomolecules to solid surfaces, or assessment of the reactivity of a functionalized polymer surface towards a specific analyte.
Total internal reflection ellipsometry based SPR sensor for studying biomolecular interaction
Materials Today: Proceedings, 2020
We report a label-free, highly sensitive plasmonic sensor integrated with a self-fabricated micro-fluidic flow cell, based on surface plasmon resonance (SPR) generated from the evanescent field by total internal reflection (TIR) of the incident light. Surface plasmon excitation on the sensor chip was studied with spectroscopic ellipsometry parameters W and D. Incident light was made to fall on sensor chip through Dove prism via total internal reflection, and it also helped to interact with the sample indirectly, which led to noise-free measurements. Ellipsometry parameter D gives the relative phase change of reflected polarized light and has a greater response to any interaction between sensor-chip and chemical/biomolecule as compared to other conventional parameters (absorbance, reflectance, etc.). Bulk refractive index sensitivity for W and D was calculated using an aqueous solution of glycerol at different concentrations (refractive indices from 1.338 to 1.364). Furthermore, we also report label-free dynamic measurements at a fixed wavelength to study specific interactions between Rabbit-IgG and Anti Rabbit-IgG proteins at a concentration of 10 mM and 300 nM, respectively. The proposed technique is self-referencing and allows us to detect the biomolecules at ultra-low concentration. Hence it could be a promising biosensing tool.
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Thin Solid Films, 2011
The biosensor based on the total internal reflection imaging ellipsometry (TIRIE) is realized as an automatic analysis method for protein interaction processes in real-time, with high throughput and label-free. An evanescent wave is used as the optical probe to monitor bio-molecular interactions on a chip surface with a high sensitivity due to its phase sensitive property. In this paper, the technique is optimized with a polarization setting, a spectroscopic light source and a low noise CCD detector to improve the performance of the biosensor in sensitivity and detection limit, as evidenced by a quantitative detection of Hepatitis B virus surface antigen (HbsAg) with concentrations of 8, 16, 32, 64, 125 and 250 ng/ml. The sensitivity is increased by one order of magnitude and the detection limit has been extended more than 50 times for HbsAg detection.
Polymer thin film structures for ultra-low cost biosensing
Optik - International Journal for Light and Electron Optics, 2012
Reflectance change due to binding of molecules on thin film structures has been exploited for biomolecular sensing by several groups due to its potential in the development of sensitive, low cost, easy to fabricate, large area sensors with high multiplexing capabilities. However, all of these sensing platforms have been developed using traditional semiconductor materials and processing techniques, which are expensive. This article presents a method to fabricate disposable thin film reflectance biosensors using polymers, such as polycarbonate, which are 2-3 orders of magnitude cheaper than conventional semiconductor and dielectric materials and can be processed by alternate low cost methods, leading to significant reduction in consumable costs associated with diagnostic biosensing.