Absolute quantities and equilibrium kinetics of macromolecular adsorption measured by fluorescence photobleaching in total internal reflection

Zimmermann, R.; Schmidt, Christoph F.; Gaub, Hermann E.

doi:10.1016/0021-9797(90)90462-w

Cited by 27 publications

(20 citation statements)

References 21 publications

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“…[18,19] Among these SAMs, octadecyltrichlorosilane (OTS, Cl 3 -Si-(CH 2 ) 17 -CH 3 ) is the most extensively used surface active reagent for generating SAMs on a variety of substrates. [20 -23] While OTS, with CH 3 -terminated groups, has a high impact on the preparation of reverse phase high performance liquid chromatography (HPLC) columns, [24,25] many emerging fields have begun to employ OTS treated hydroxylic substrates including biomedical studies, [26] ultra-thin imaging layer, [27] boundary lubricants, [28 -30] bio-and chemical sensors, [31,32] environmental studies, [33] glass reinforced composites, [34] electrochemical studies; [35,36] and finally, resist materials. [37 -41] Recent years have seen a tremendous impact on gold nanoparticles (Au NPs) and their optical response in biological assays, detection, labeling, sensing, etc.…”

Section: Introductionmentioning

confidence: 99%

Octadecyltrichlorosilane (OTS): a resist for OMCVD gold nanoparticle growth

Rezaee

Davidson

Manifar

et al. 2009

Surface & Interface Analysis

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One application of octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) is its use as thin film resists. In this work, we demonstrated that OTS SAMs can be reliable resists for organo-metallic chemical vapor deposition (OMCVD) grown gold nanoparticles (Au NPs). In optical sensing applications based on Au NPs, one candidate system consists of patterned OTS SAMs and precisely grown OMCVD Au NPs for achieving a high sensitivity. As an initial step, the OTS SAMs need to perfectly resist the OMCVD Au NP growth. Hence the optimized formation of the OTS SAMs affected by different assembly times and baking temperatures was studied by contact angle, ellipsometry, XPS, SEM, and atomic force microscopy (AFM). To demonstrate the ability of the OTS SAMs to resist OMCVD Au NP growth, the OMCVD process was carried out on two sets of samples: OTS SAMs fabricated under optimized conditions on one set and the other set without OTS SAMs. High-resolution XPS, RBS, SEM, and ultraviolet-visible (UV-Vis) spectroscopy were applied to study the growth of Au NPs on the samples with and without OTS SAM resists.

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Section: Introductionmentioning

confidence: 99%

Octadecyltrichlorosilane (OTS): a resist for OMCVD gold nanoparticle growth

Rezaee

Davidson

Manifar

et al. 2009

Surface & Interface Analysis

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“…5 In published reports, the characterization of protein adsorption onto surfaces has been accomplished using mainly radiolabeling (surface and solution techniques) 6 and spectroscopic techniques, including infrared spectroscopy 7,8 and fluorescence (e.g., TIRF). [9][10][11][12] These techniques measure average quantities of large numbers of adsorption events, yet because material properties and features as small as molecular scale may affect adsorption, it is of interest to observe individual adsorption events. With the advent of atomic force microscopy (AFM), direct observation of individual adsorption events has been achieved in situ with minimal sample preparation, unlike other imaging techniques with similar resolution that require sample preparation and/or ambient or vacuum imaging environments.…”

Section: Introductionmentioning

confidence: 99%

Individual plasma proteins detected on rough biomaterials by phase imaging AFM

Holland

Marchant

2000

J. Biomed. Mater. Res.

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In the past several years, atomic force microscopy (AFM) has provided topographic images of adsorbed plasma proteins in situ at unprecedented resolution. Imaging has been limited to adsorbed protein on relatively smooth model substrates such as mica, graphite, or self-assembled monolayers on which the small height of the protein can be observed from the background. The inherent roughness of biomaterial surfaces has prevented observation of adsorbed proteins in topographic images. We report imaging isolated fibrinogen molecules adsorbed on National Heart Lung and Blood Institute (NHLBI) reference materials polydimethylsiloxane and low-density polyethylene in situ using phase imaging AFM. Fibrinogen, a plasma protein important for blood coagulation and platelet aggregation, was adsorbed from dilute solution onto reference biomaterial surfaces at sub-monolayer coverage. Tapping mode AFM was used to image the samples. For polydimethylsiloxane, the lateral size of the surface features is much greater than the dimensions of proteins. This allowed adsorbed proteins to be observed in topographic images. The phase imaging signal of tapping mode AFM provides information on differences in material properties of the surface, and was used to distinguish individual protein molecules from the underlying polymer surface. On the low-density polyethylene surface, characteristic topographical features are of the same magnitude as the protein molecules, so that protein cannot be distinguished from the surface using topographic images. However, phase images were used to successfully locate and characterize the distribution of the protein. Phase imaging was not able to distinguish fibrinogen adsorbed onto expanded polytetrafluoroethylene. The utility and limitations of the phase imaging technique for characterizing protein adsorption to rough surfaces is discussed.

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“…If absolute surface concentrations are required, interfacial fluorescence measurements need to be calibrated and/or supplemented by another more quantitative technique. Several TIRF calibration schemes have been proposed for this purpose based on the use of either radiolabeled proteins (Hlady et aI., 1986) or a strong photobleaching laser pulse (Zimmermann et al, 1990).…”

Section: Interfacial Protein Studiesmentioning

confidence: 99%