Total internal reflection ellipsometry as a label-free assessment method for optimization of the reactive surface of bioassay devices based on a functionalized cycloolefin polymer

Le, Nam Cao Hoai; Gubala, Vladimir; Gandhiraman, Ram P.; Coyle, Conor; Daniels, Stephen; Williams, David E.

doi:10.1007/s00216-010-4099-4

Cited by 25 publications

(26 citation statements)

References 36 publications

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“…Similar findings were observed by Yuan et al [45] using SPR when they tried to improve the immobilization capacity of anti-rabbit IgG and antigen binding using chitosan/alginate layer-by-layer self-assembled multilayer films. Le et al [46] also confirmed, by using total internal reflection ellipsometry, that an increase in surfaceadsorbed anti-R-hCG resulted in the reduction of hCG binding efficiency.…”

Section: Optimization Of Antigen Binding To the Immobilized Antibodiementioning

confidence: 88%

Label-free detection of human prostate-specific antigen (hPSA) using film bulk acoustic resonators (FBARs)

Zhao

Pan

Ashley

et al. 2014

Sensors and Actuators B: Chemical

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Label-free detection of cancer biomarkers using low cost biosensors has promising applications in clinical diagnostics. In this work, ZnO-based thin film bulk acoustic wave resonators (FBARs) with resonant frequency of ~1.5 GHz and mass sensitivity of 0.015 mg/m 2 (1.5 ng/cm 2) have been fabricated for their deployment as biosensors. Mouse monoclonal antibody, anti-human prostatespecific antigen (Anti-hPSA) has been used to bind human prostate-specific antigen (hPSA), a model cancer biomarker used in this study. Ellipsometry was used to characterize and optimise the antibody adsorption and biomarker antigen binding on gold surface. It was found that the best amount of antibody at the gold surface for effective antigen binding is around 1 mg/m 2 , above or below which resulted in the reduced antigen binding due to either the limited binding sites (below 1 mg/m 2) or increased steric effect (above 1 mg/m 2). The FBAR data were in good agreement with the data obtained from ellipsometry. Antigen binding experiments using FBAR sensors demonstrated that FBARs have the capability to precisely detect antigen binding, thereby making FBARs an attractive low cost alternative to existing cancer diagnostic sensors.

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Section: Optimization Of Antigen Binding To the Immobilized Antibodiementioning

confidence: 88%

Label-free detection of human prostate-specific antigen (hPSA) using film bulk acoustic resonators (FBARs)

Zhao

Pan

Ashley

et al. 2014

Sensors and Actuators B: Chemical

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“…PsiDelta 2 software (Jobin Yvon Horiba, France) was used for fitting the data from the measured Ψ and Δ spectra from TIRE to obtain the thickness of the ssDNA layers. Details of the fitting procedure were described elsewhere 18…”

Section: Methodsmentioning

confidence: 99%

Tetraethyl Orthosilicate and Acrylic Acid Forming Robust Carboxylic Functionalities on Plastic Surfaces for Biodiagnostics

Coyle

Gandiraman

Gubala

et al. 2011

Plasma Processes & Polymers

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properties of film that is formed as a result of sequential, plasma assisted fragmentation and deposition of vapours of acrylic acid and tetraethyl ortho silicate (TEOS). In this context, TEOS serves as an adhesion layer to the plastic substrate and also as a network-building layer for further cross-linking with acrylic acid. The presence of silanols (Si-OH) can facilitate large uptake of water molecules and cause significant hydration of the layer, which in combination with high total negative charge lowers the non specific binding of biomolecules..-2 -The reactivity of the carboxyl functionalities was confirmed by total internal reflection ellipsometry technique in a reaction with amino terminated ssDNA. Ageing studies of the film showed long term stability over 50 days. Overall, the specific combination of TEOS and acrylic acid deposited by plasma assisted vapour method results in film with an increased percentage of carboxyl groups to 16.4% as compared to that of 6.5% in acrylic acid as determined in the core level C 1s XPS spectrum and a significant increase in signal to noise ratio.

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“…The fabrication method of the PMMA flow-cell has been reported elsewhere [21]. For deposition of BSA and DOTAP, a standard COP slide was glue to the top PSA layer of a PMMA flow-cell to form a close channel as shown in Fig 1(b).…”

Section: Deposition Of Blocking Agents Into Pmma Microfluidic Flow-cellsmentioning

confidence: 99%

“…Fluorescent intensity was measured inside the microwells of the PMMA flow-cells to evaluate the effectiveness of each coatings against the non-specific adsorption of Cy5-labeled anti-IgG. Finally, total internal reflection ellipsometry (TIRE) [14][15][16][17][18][19][20][21] with spectra and kinetic data of adsorption of anti-a-human chorionic gonadotropin (anti-a-hCG) was used to evaluate the stability of the coatings under buffer rinsing. Our results could be useful when choosing a blocking agent, its deposition and characteristics, for suppression of non-specific binding of biomolecules on a PMMA surface.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Different Nonspecific Binding Blocking Agents Deposited Inside Poly(methyl methacrylate) Microfluidic Flow-Cells

Gubala

Gandhiraman

et al. 2011

Langmuir

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Poly(methyl methacrylate) (PMMA) flow-cells containing microwells were deposited with different nonspecific binding blocking agents namely bovine serum albumin (BSA), cationic lipid (DOTAP) and diethylene glycol dimethyl ether (DEGDME). Water contact angle (WCA) and atomic force microscope (AFM) measurements were carried out to confirm the successful depositions of BSA, DOTAP, DEGDME onto the PMMA surfaces. Fluorescent intensity measurements were performed to evaluate the degree of non-specific adsorption of Cy5-labeled anti-IgG proteins onto plain and oxygen plasma treated (PT) PMMA flow-cells as well as PMMA flow-cells deposited with different above-mentioned blocking agents. We then employed a label-free detection method called total internal reflection ellipsometry (TIRE) to evaluate the stability of the deposited blocking agents inside the PMMA flow-cells. It was found that while DOTAP was the best agent for blocking the non-specific adsorption, it could be removed from the PMMA surfaces of the flow-cells upon rinsing with phosphate buffer saline (PBS) and later deposited back onto the Au-coated glass sensing substrate of the TIRE. The removal of the blocking agents from PMMA surfaces and their deposition onto the sensing substrate were further manifested by measuring the kinetics and the amount of adsorbed anti-a-hCG proteins. Overall, the dry DEGDME coating by plasma enhanced chemical vapor deposition (PECVD) showed very good blocking and excellent stability for subsequent assay inside the microwells. Our results could be useful when one considers what blocking agents should be used for PMMA-based microfluidic immunosensor or biosensor devices by looking at both the blocking efficiency and the stability of the blocking agent.

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Total internal reflection ellipsometry as a label-free assessment method for optimization of the reactive surface of bioassay devices based on a functionalized cycloolefin polymer

Cited by 25 publications

References 36 publications

Label-free detection of human prostate-specific antigen (hPSA) using film bulk acoustic resonators (FBARs)

Label-free detection of human prostate-specific antigen (hPSA) using film bulk acoustic resonators (FBARs)

Tetraethyl Orthosilicate and Acrylic Acid Forming Robust Carboxylic Functionalities on Plastic Surfaces for Biodiagnostics

Evaluation of Different Nonspecific Binding Blocking Agents Deposited Inside Poly(methyl methacrylate) Microfluidic Flow-Cells

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