Polyethylene Glycol Adsorption on Silica:  From Bulk Phase Behavior to Surface Phase Diagram

Derkaoui, Nawal; Said, S.; Grohens, Yves; Olier, R.; Privat, Mireille

doi:10.1021/la070199u

Cited by 28 publications

(25 citation statements)

References 32 publications

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“…In addition, the adsorption of PEG is known to be driven by the formation of hydrogen bonds in the presence of polar groups such as silanol groups on surfaces. [25][26][27] Formation of hydrogen bond between PEG chains and silanol groups is expected in our case since our silica nanoparticles were only partially fluorinated (see XPS characterization in our previous paper 16 ). Subsequent enzyme adsorption on particle surface is prevented due to steric repulsions between the PEG chains and enzymes.…”

Section: Peg Adsorption Onto Particle Surfacementioning

confidence: 62%

Fluorinated Pickering Emulsions with Nonadsorbing Interfaces for Droplet-based Enzymatic Assays

2015

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This work describes the use of fluorinated Pickering emulsions with nonadsorbing interfaces in droplet-based enzymatic assays. State-of-the-art droplet assays have relied on one type of surfactants consisting of perfluorinated polyether and polyethylene glycol (PFPE-PEG). These surfactants are known to have limitations including the tedious synthesis and interdrop molecular transport which leads to the cross-contamination of droplet contents. Previously we have shown that replacing surfactants with nanoparticles as droplet stabilizers mitigate interdrop transport of small molecules. The nonspecific adsorption of enzymes on nanoparticle surface, however, could cause structural changes in enzymes and consequently the loss of enzymatic activity. To overcome such challenge, we render nanoparticle surface nonadsorbing to enzymes by in situ adsorption of polyethylene glycol (PEG) on particle surfaces. We show that enzyme activities are preserved in droplets stabilized by PEG-adsorbed nanoparticles, and are comparable with those in drops stabilized by PFPE-PEG surfactants. In addition, our nonadsorbing Pickering emulsions successfully prevent interdrop molecular transport, thereby maintaining the accuracy of droplet assays. The particles are also simple and economical to synthesize. The PEG-adsorbed nanoparticles described in this work are thus a competitive alternative to the current surfactant system, and can potentially enable new droplet-based biochemical assays.

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Section: Peg Adsorption Onto Particle Surfacementioning

confidence: 62%

Fluorinated Pickering Emulsions with Nonadsorbing Interfaces for Droplet-based Enzymatic Assays

2015

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“…It is well-known that PEG readily adsorbs to a variety of materials with high affinity and with no significant energy barriers [9, 64, 65]. Therefore, the adsorption of PEG is determined by the mass transfer rate from the bulk solution, making it reasonable to assume β = 1 [1].…”

Section: Resultsmentioning

confidence: 99%

Determination of a setup correction function to obtain adsorption kinetic data at stagnation point flow conditions

Mora

Nejadnik

Baylon-Cardiel

et al. 2010

Journal of Colloid and Interface Science

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This paper is the first report on the characterization of the hydrodynamic conditions in a flow cell designed to study adsorption processes by spectroscopic ellipsometry. The resulting cell enables combining the advantages of in-situ spectroscopic ellipsometry with stagnation point flow conditions. An additional advantage is that the proposed cell features a fixed position of the "inlet tube" with respect to the substrate, thus facilitating the alignment of multiple substrates. Theoretical calculations were performed by computational fluid dynamics and compared with experimental data (adsorption kinetics) obtained for the adsorption of polyethylene glycol to silica under a variety of experimental conditions. Additionally, a simple methodology to correct experimental data for errors associated with the size of the measured spot and for variations of mass transfer in the vicinity of the stagnation point is herein introduced. The proposed correction method would allow researchers to reasonably estimate the adsorption kinetics at the stagnation point and quantitatively compare their results, even when using different experimental setups. The applicability of the proposed correction function was verified by evaluating the kinetics of protein adsorption under different experimental conditions.

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“…A good explanation is the strong attractive interaction between the pendant ethylene oxide units and the silica surface. 46 Whereas hydroxypropyl methacrylate (HPMA) is too hydrophobic, surprisingly the more hydrophilic 2-hydroxyethyl methacrylate (HEMA) was not effective. In the case of acrylamide, the reason why this comonomer led to poor results may originate from unfavourable reactivity ratios.…”

Section: On the Adsorption Of The Pickering Stabilizer Onto Monomer Dmentioning

confidence: 99%

A mechanistic investigation of Pickering emulsion polymerization

Lotierzo

Bon

2017

Polym. Chem.

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A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription. Pickering emulsion polymerization offers a versatile way of synthetising hybrid core-shell latexes where a polymer core is surrounded by an armour of inorganic nanoparticles. A mechanistic understanding of the polymerization process is limited which restricts the use of the technique in the fabrication of more complex, multilayered colloids. In this paper clarity is provided through an in-depth investigation into the Pickering emulsion polymerization of methyl methacrylate (MMA) in the presence of nano-sized colloidal silica (Ludox TM-40). Mechanistic insights are discussed by studying both the adsorption of the stabiliser to the surface of the latex particles and polymerization kinetics. The adhesion of the Pickering nanoparticles was found not to be spontaneous, as confirmed by cryo-TEM analysis of MMA droplets in water and monomer-swollen PMMA latexes. This supports the theory that the inorganic particles are driven towards the interface as a result of a heterocoagulation event in the water phase with a growing oligoradical. The emulsion polymerizations were monitored by reaction calorimetry in order to establish accurate values for monomer conversion and the overall rate of polymerizations (Rp). Rp increased for higher initial silica concentrations and the polymerizations were found to follow pseudo-bulk kinetics.

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Polyethylene Glycol Adsorption on Silica: From Bulk Phase Behavior to Surface Phase Diagram

Cited by 28 publications

References 32 publications

Fluorinated Pickering Emulsions with Nonadsorbing Interfaces for Droplet-based Enzymatic Assays

Fluorinated Pickering Emulsions with Nonadsorbing Interfaces for Droplet-based Enzymatic Assays

Determination of a setup correction function to obtain adsorption kinetic data at stagnation point flow conditions

A mechanistic investigation of Pickering emulsion polymerization

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