High efficiency amine functionalization of cycloolefin polymer surfaces for biodiagnostics

Gandhiraman, Ram P.; Volcke, Cédric; Gubala, Vladimir; Doyle, Carol; Basabe‐Desmonts, Lourdes; Dotzler, C.; Toney, Michael F.; Iacono, Marcello; Nooney, Robert; Daniels, Stephen; James, Bryony; Williams, David E.

doi:10.1039/b925737c

Cited by 54 publications

(61 citation statements)

References 51 publications

(52 reference statements)

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“…However, these particles typically have a negatively charged surface due to surfactants used to stabilize them and avoid aggregation [10,11]. This can cause particles to bind non-specifically due to charge attraction to surfaces commonly used for protein absorption such as 3-aminopropyltriethoxy silane (APTES) [12][13][14]. As illustrated on Scheme 1, APTES coated substrates contain a high density of amine groups that are in equilibrium between the charged ÐNH 3 + and neutral ÐNH 2 form.…”

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TIRF microscopy as a screening method for non-specific binding on surfaces

Charlton

Gubala

Gandhiraman

et al. 2011

Journal of Colloid and Interface Science

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We report a method for studying nanoparticle-biosensor surface interactions based on Total Internal Reflection Fluorescence (TIRF) Microscopy. We demonstrate that this simple technique allows for high throughput screening of non-specific adsorption (NSA) of nanoparticles on surfaces of different chemical composition. Binding events between fluorescent nanoparticles and functionalized Zeonor¨ surfaces are observed in real-time, giving a measure of the attractive or repulsive properties of the surface and the kinetics of the interaction. Three types of coatings have been studied: one containing a polymerized aminosilane network with terminal ÐNH 2 groups, a second film with a high density of Ð COOH surface groups and the third with sterically restraining branched poly(ethylene)glycol (PEG) functionality. TIRF microscopy revealed that the NSA of nanoparticles with negative surface charge on such modified coatings decreased in the following order ÐNH 2 > -branched PEG > -COOH. The surface specificity of the technique also allows discrimination of the degree of NSA of the same surface at different pH. KeywordsTotal Internal Reflection, Fluorescence, Microscopy, Non-Specific Binding, SurfaceParticle Interaction IntroductionCurrent research in biomedical diagnostics is directed at inexpensive, highly sensitive, miniaturized devices, in which usually disposable substrates or chips are used. Such devices are required to measure analytes in microliter volume samples, typically at picomolar level. In fluorescence-based assays, the signal can be greatly enhanced with the use of dye doped nanoparticles as fluorescent labels [1][2][3][4]. However, in a successful diagnostics device, signal-to-noise ratio is paramount to its performance and effectively controls the sensitivity. Controlling the noise and background contribution, dictated by non-specific binding of the non-analyte constituents of the sample remains very challenging. The chemical composition of the substrate surface and its interactions with the active surface area of the dye-doped nanoparticles, therefore, play a key role in the performance of diagnostic platform. In this work, we focus on surface functionalization of the substrate ZeonorÒ, a cyclo-olefin polymer (COP), which is characterized by ease of injection molding for biochip fabrication and relatively low autofluorescence, which is an important factor for fluorescence-based applications including TIRF microscopy.Total Internal Reflection Fluorescence (TIRF) microscopy [5] is presented here as a very useful and fast method to compare non-specific adsorption of detection molecules on different surfaces. This method allowed for rapid screening of surfaces to find their ability to prevent non-specific binding. Total internal reflection occurs an any interface between materials of different refractive index inside the material of higher refractive index provided the angle of incidence of the light is above the critical angle defined as:where n 1 is the refractive index of the high refractive index mat...

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TIRF microscopy as a screening method for non-specific binding on surfaces

Charlton

Gubala

Gandhiraman

et al. 2011

Journal of Colloid and Interface Science

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“…85 They are then adsorbed onto the surface and form chemical bonds at favourable sites to create an amorphous network. We have recently proposed a reasonable mechanism on the formation of a siloxane-silicone network in APTES deposition by PECVD in the presence of traces of water 20 . We reason 90 that the siloxane-silicone network formation could be initiated by fragmentation of APTES into aminosiloxane radicals that condense and polymerise on the surface.…”

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“…The instrument measures the phase retardation of the guided 15 light caused by interaction of the evanescent field with coatings on the top waveguide, by measurement of an interference pattern developed between the sample beam and the un-retarded reference beam passing through the bottom waveguide. It utilises the different evanescent field 20 penetration depth of light polarised perpendicular-and parallel-to the waveguide surface to derive thickness and refractive index information about the surface coatings. DPI has been verified using standard protein systems and has been demonstrated in the successful monitoring of biochemical 25 interactions, e.g., protein adsorption 16,17 and lipid membrane formation 18,19 .…”

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confidence: 99%

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Functionalization of cycloolefin polymer surfaces by plasma-enhanced chemical vapour deposition: comprehensive characterization and analysis of the contact surface and the bulk of aminosiloxane coatings

Gubala

Gandhiraman

Volcke

et al. 2010

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“…[22][23][24] One key advantage of our chip is that it does not require an enzymatic amplification step to achieve high sensitivity, but rather uses fluorescently labeled detection antibodies (phycoerythrin), which helps reduce the cost and complexity of the assay.…”

Section: Benchmark Of Elisa Vs Serum Analyzer Chipmentioning

confidence: 99%

A 1024-sample serum analyzer chip for cancer diagnostics

García-Cordero

Maerkl

2014

Lab Chip

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We present a platform that combines microarrays and microfluidic techniques to measure four protein biomarkers in 1024 serum samples for a total of 4096 assays per device. Detection is based on a surface fluorescence sandwich immunoassay with a limit of detection of~1 pM for most of the proteins measured: PSA, TNF-α, IL-1β, and IL-6. To validate the utility of our platform, we measured these four biomarkers in 20 clinical human serum samples, 10 from prostate cancer patients and 10 female and male controls. We compared the results of our platform to a conventional ELISA and found a good correlation between them. However, compared to a classical ELISA, our device reduces the total cost of reagents by 4 orders of magnitude while increasing throughput by 2 orders of magnitude. Overall, we demonstrate an integrated approach to perform low-cost and rapid quantification of protein biomarkers from over one thousand serum samples. This new high-throughput technology will have a significant impact on disease diagnosis and management.

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High efficiency amine functionalization of cycloolefin polymer surfaces for biodiagnostics

Cited by 54 publications

References 51 publications

TIRF microscopy as a screening method for non-specific binding on surfaces

TIRF microscopy as a screening method for non-specific binding on surfaces

Functionalization of cycloolefin polymer surfaces by plasma-enhanced chemical vapour deposition: comprehensive characterization and analysis of the contact surface and the bulk of aminosiloxane coatings

A 1024-sample serum analyzer chip for cancer diagnostics

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