Surface characterization of nanoparticles using near-field light scattering

The effect of nanoparticle surface coating characteristics on colloidal stability in solution is a critical parameter in understanding the potential applications of nanoparticles, especially in biomedicine. Here we explored the modification of the surface of poly(ethylene glycol)-coated superparamagnetic iron oxide nanoparticles (PEG-SPIOs) with the synthetic pseudotannin polygallol via interpolymer complexation (IPC). Changes in particle size and zeta potential were indirectly assessed via differences between PEG-SPIOs and IPC-SPIOs in particle velocity and scattering intensity using near-field light scattering. The local scattering intensity is correlated with the distance between the particle and waveguide, which is affected by the size of the particle (coating thickness) as well as the interactions between the particle and waveguide (related to the zeta potential of the coating). Therefore, we report here the use of near-field light scattering using nanophotonic force microscopy (using a NanoTweezerTM instrument, Halo Labs) to determine the changes that occurred in hydrated particle characteristics, which is accompanied by an analytical model. Furthermore, we found that altering the salt concentration of the suspension solution affected the velocity of particles due to the change of dielectric constant and viscosity of the solution. These findings suggest that this technique is suitable for studying particle surface changes and perhaps can be used to dynamically study reaction kinetics at the particle surface.

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Investigation of Adsorption Capacity of Magnetite Nanoparticles

WSEAS TRANSACTIONS ON APPLIED AND THEORETICAL MECHANICS ◽

10.37394/232011.2021.16.18 ◽

2021 ◽

Vol 16 ◽

pp. 165-171

Author(s):

V. V. Rodchenko ◽

Kyaw Ye Ko

Keyword(s):

Light Scattering ◽

Zeta Potential ◽

Colloidal Stability ◽

Particle Surface ◽

Decisive Role ◽

Component Composition ◽

Hydrodynamic Diameter ◽

Synthesis Of Nanoparticles ◽

Air Atmosphere ◽

Correct Determination

In this work, the preparation of Fe3O4 nanoparticles modified with 3-aminopropyltriethoxysilane (APTES) was carried out under various synthesis modes (in air or in argon). The zeta potential and hydrodynamic diameter of Fe3O4-APTES nanoparticles were determined by the method of dynamic and electrokinetic light scattering. The effect of humic acids on the zeta potential, hydrodynamic diameter and colloidal stability of Fe3O4-APTES at different pH values was established by the method of dynamic and electrophoretic light scattering. It has been shown that changes in the conditions of the synthesis of nanoparticles of one component composition Fe3O4-APTES (argon) and Fe3O4-APTES (air) (in an inert medium and in an air atmosphere, respectively) lead to a change in the charge of the particle surface and a subsequent change in the sorption properties with respect to HA. It was demonstrated that the decisive role in the study of surface properties is played by the purification from low-molecular-weight impurities that can screen the surface of nanoparticles or bind with an indifferent electrolyte. The stage of dispersive post-preparation of samples is also important for the correct determination of the sorption capacity and hydrodynamic diameter of particles.

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PEGylation of Superparamagnetic Iron Oxide Nanoparticles with Self-Organizing Polyacrylate-PEG Brushes for Contrast Enhancement in MRI Diagnosis

Nanomaterials ◽

10.3390/nano8100776 ◽

2018 ◽

Vol 8 (10) ◽

pp. 776 ◽

Cited By ~ 11

Author(s):

Erzsébet Illés ◽

Márta Szekeres ◽

Ildikó Tóth ◽

Katalin Farkas ◽

Imre Földesi ◽

...

Keyword(s):

Light Scattering ◽

Dynamic Light Scattering ◽

Colloidal Stability ◽

Serum Proteins ◽

Electrokinetic Potential ◽

Blood Compatibility ◽

Superparamagnetic Iron Oxide ◽

Protein Corona ◽

Superparamagnetic Nanoparticles ◽

Mri Diagnosis

For biomedical applications, superparamagnetic nanoparticles (MNPs) have to be coated with a stealth layer that provides colloidal stability in biological media, long enough persistence and circulation times for reaching the expected medical aims, and anchor sites for further attachment of bioactive agents. One of such stealth molecules designed and synthesized by us, poly(polyethylene glycol methacrylate-co-acrylic acid) referred to as P(PEGMA-AA), was demonstrated to make MNPs reasonably resistant to cell internalization, and be an excellent candidate for magnetic hyperthermia treatments in addition to possessing the necessary colloidal stability under physiological conditions (Illés et al. J. Magn. Magn. Mater. 2018, 451, 710–720). In the present work, we elaborated on the molecular background of the formation of the P(PEGMA-AA)-coated MNPs, and of their remarkable colloidal stability and salt tolerance by using potentiometric acid–base titration, adsorption isotherm determination, infrared spectroscopy (FT-IR ATR), dynamic light scattering, and electrokinetic potential determination methods. The P(PEGMA-AA)@MNPs have excellent blood compatibility as demonstrated in blood sedimentation, smears, and white blood cell viability experiments. In addition, blood serum proteins formed a protein corona, protecting the particles against aggregation (found in dynamic light scattering and electrokinetic potential measurements). Our novel particles also proved to be promising candidates for MRI diagnosis, exhibiting one of the highest values of r2 relaxivity (451 mM−1s−1) found in literature.

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Systematic Investigation of Functional Ligands for Colloidal Stable Upconversion Nanoparticles

10.26434/chemrxiv.5701156.v1 ◽

2017 ◽

Author(s):

Hien Duong ◽

Yinghui Chen ◽

Sherif Abdulkader Tawfik ◽

Shihui Wen ◽

Maryam Parviz ◽

...

Keyword(s):

Colloidal Stability ◽

Phosphate Buffer Solution ◽

Systematic Investigation ◽

Sulphonic Acid ◽

Upconversion Nanoparticles ◽

Buffer Solution ◽

Potential Applications ◽

Anchoring Groups ◽

Poly Ethylene ◽

Phosphate Ligands

<div> <p>Despite intense efforts on surface functionalization to generate hydrophilic upconversion nanoparticles (UCNPs), long-term colloidal stability in physiological buffers remains a major concern. Here we quantitatively investigate the competitive adsorption of phosphate, carboxylic acid and sulphonic acid onto the surface of UCNPs and study their binding strength to identify the best conjugation strategy. To achieve this, we designed and synthesized three di-block copolymers composed of poly(ethylene glycol) methyl ether acrylate and a polymer block bearing phosphate, carboxylic or sulphonic acid anchoring groups prepared by an advanced polymerization technique, Reversible Addition Fragmentation Chain Transfer (RAFT). Analytical tools provide the evidence that phosphate ligands completely replaced all the oleic acid capping molecules on the surface of the UCNPs compared with incomplete ligand exchange by carboxylic and sulphonic acid groups. In the meanwhile, simulated quantitative adsorption energy measurements confirmed that among three functional groups, calculated adsorption strength for phosphate anchoring ligands is higher which is in good agreement with experimental results regarding the best colloidal stability especially in phosphate buffer solution. The finding suggests that polymers with multiple anchoring negatively charged phosphate moieties provide excellent colloidal stability for lanthanide ion-doped luminescent nanoparticles for various potential applications.</p> </div> <br>

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Nanogels obtained by gamma radiation induced polymerization

Polimery ◽

10.14314/polimery.2021.9.1 ◽

2021 ◽

Vol 66 (9) ◽

pp. 451-458

Author(s):

Nur Fathin Amirah Shafie ◽

Mohd Yusof Hamzah ◽

Roshafima Rasit Ali

Keyword(s):

Light Scattering ◽

Dynamic Light Scattering ◽

Zeta Potential ◽

Ethylene Glycol ◽

Gamma Radiation ◽

Biomedical Applications ◽

Poly Ethylene Glycol ◽

Glycol Diacrylate ◽

Radiation Induced ◽

Poly Ethylene

The influence of 2-(dimethylamino)ethyl methacrylate (DMAEMA) concentration on the temperature sensitivity of nanogels based on N-isopropylacrylamide (NIPAAM), poly(vinylpyrrolidone) (PVP), poly(ethylene glycol) diacrylate (PEGDA) by gamma radiation induced polymerization was investigated. Dynamic light scattering (DLS) and zeta potential measurements were used to characterize the nanogels. Temperature has been found to cause the nanogel particles to swell and shirnkage, allowing controlled dosing of the drug contained in capsules. The developed nanogels are promising materials with great potential for biomedical applications.

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A Robust and General Approach to Quantitatively Conjugate Enzymes to Plasmonic Nanoparticles

10.26434/chemrxiv.8299301.v1 ◽

2019 ◽

Author(s):

Yuyang Wang ◽

Karsten van Asdonk ◽

Peter Zijlstra

Keyword(s):

Protein Function ◽

Colloidal Stability ◽

Near Field ◽

Particle Surface ◽

Field Enhancement ◽

Medical Diagnostics ◽

Enzyme Concentration ◽

Plasmonic Nanoparticles ◽

Protein Activity ◽

Refractive Index Sensitivity

<div>Bioconjugates of plasmonic nanoparticles have received considerable attention due to their potential biomedical applications. Succesfull bioconjugation requires control over the number and activity of the conjugated proteins, and the colloidal stability of the particles. In practice, this requires re-optimization of the conjugation protocol for each combination of protein and nanoparticle. Here we report a robust and general protocol that allows for the conjugation of a range of proteins to different types of nanoparticles using very short polyethylene-glycol(PEG) linkers, while simultaneously preserving protein activity and colloidal stability. The use of short linkers ensures that the protein is located close to the particle surface, where their refractive index sensitivity and near-field enhancement is maximal. We demonstrate that the use a Tween20 containing stabilizing buffer is critical in maintaining colloidal stability and protein function throughout the protocol. We obtain quantitative control over the average number of enzymes per particle by either varying the number of functional groups on the particle, or the enzyme concentration during incubation. This new route of preparing quantitative protein-nanoparticle bioconjugates paves the way to develop rational and quantitative strategies to functionalize nanoparticles for applications in sensing, medical diagnostics and drug delivery.</div>

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The effect of poly(ethylene glycol) coating on colloidal stability of superparamagnetic iron oxide nanoparticles as potential MRI contrast agent

International Journal of Pharmaceutics ◽

10.1016/j.ijpharm.2012.04.080 ◽

2012 ◽

Vol 433 (1-2) ◽

pp. 129-141 ◽

Cited By ~ 82

Author(s):

Afshin Masoudi ◽

Hamid Reza Madaah Hosseini ◽

Mohammad Ali Shokrgozar ◽

Reza Ahmadi ◽

Mohammad Ali Oghabian

Keyword(s):

Iron Oxide ◽

Ethylene Glycol ◽

Contrast Agent ◽

Colloidal Stability ◽

Superparamagnetic Iron Oxide ◽

Mri Contrast Agent ◽

Oxide Nanoparticles ◽

Poly Ethylene Glycol ◽

Mri Contrast ◽

Poly Ethylene

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Aqueous processing of SiC green sheets I: Dispersant

Journal of Materials Research ◽

10.1557/jmr.2002.0298 ◽

2002 ◽

Vol 17 (8) ◽

pp. 2012-2018 ◽

Cited By ~ 32

Author(s):

J. X. Zhang ◽

D. L. Jianga ◽

S. H. Tana ◽

L. H. Gui ◽

M. L. Ruan

Keyword(s):

Zeta Potential ◽

Aqueous Media ◽

Tape Casting ◽

Particle Surface ◽

Aqueous Processing ◽

Ethylene Imine ◽

Affinity Adsorption ◽

Rheological Measurements ◽

Poly Ethylene ◽

The Stability

Poly(ethylene imine) (PEI) has been used as a dispersant for tape casting of SiC powders in aqueous media. The stability of SiC suspensions was studied and characterized in terms of zeta potential, sedimentation, adsorption, and rheology measurements. Zeta potential studies showed that the particle surface was negatively charged in the absence of PEI in the pH 2.5–13 ranges. Adsorptions of PEI increased the zeta potential and led to the shift of isoelectric point from pH 2.4 to pH 10.5. Sedimentation study showed that, in the absence of PEI, SiC slurries were stable around pH 6, while, in the presence of PEI, stabilization could be achieved at a condition of saturated adsorption (1.07 mg/m2) and was related to the high-;affinity adsorption in the pH = 10.5–11.5 range. The rheological measurements showed that SiC slurries (50 vol%) were well stability with slight thixotropical behavior. Finally, the best conditions to obtain a homogeneous stable slurry with high powder loading suitable for tap casting were determined.

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