Enhancement of optical force acting on vesicles via the binding of gold nanoparticles

Here we found that gold nanoparticles (AuNPs) enhance the optical force acting on vesicles prepared from phospholipids via hydrophobic and electrostatic interactions. A laser beam was introduced into a cuvette filled with a suspension of vesicles and it accelerated them in its propagation direction via a scattering force. The addition of the AuNPs exponentially increased the velocity of the vesicles as their concentration increased, but polystyrene particles had no significant impact on velocity in the presence of AuNPs. To elucidate the mechanism of the increased velocity, the surface charges in the vesicles and the AuNPs were controlled; the surface charges of the vesicles were varied via the use of anionic, cationic and neutral phospholipids, whereas AuNPs with positive and negative charges were synthesized by coating with citrate ion and 4-dimethylaminopyridine, respectively. All vesicles increased the velocity at different degrees depending on the surface charge. The vesicles were accelerated more efficiently when their charges were opposite those of the AuNPs. These results suggested that hydrophobic and electrostatic interactions between the vesicles and the AuNPs enhanced the optical force. By accounting for the binding constant between the vesicles and the AuNPs, we proposed a model for the relationship between the concentration of the AuNPs and the velocity of the vesicles. Consequently, the increased velocity of the vesicles was attributed to the light scattering that was enhanced when AuNPs were adsorbed onto the vesicles.

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Plasmonic linear nanomotor using lateral optical forces

Science Advances ◽

10.1126/sciadv.abc3726 ◽

2020 ◽

Vol 6 (45) ◽

pp. eabc3726

Author(s):

Yoshito Y. Tanaka ◽

Pablo Albella ◽

Mohsen Rahmani ◽

Vincenzo Giannini ◽

Stefan A. Maier ◽

...

Keyword(s):

Laser Beam ◽

Incident Light ◽

Lateral Force ◽

Diffraction Limit ◽

Propagation Direction ◽

Optical Force ◽

Optical Forces ◽

Incident Laser ◽

New Class ◽

Force Direction

Optical force is a powerful tool to actuate micromachines. Conventional approaches often require focusing and steering an incident laser beam, resulting in a bottleneck for the integration of the optically actuated machines. Here, we propose a linear nanomotor based on a plasmonic particle that generates, even when illuminated with a plane wave, a lateral optical force due to its directional side scattering. This force direction is determined by the orientation of the nanoparticle rather than a field gradient or propagation direction of the incident light. We demonstrate the arrangements of the particles allow controlling the lateral force distributions with the resolution beyond the diffraction limit, which can produce movements, as designed, of microobjects in which they are embedded without shaping and steering the laser beam. Our nanomotor to engineer the experienced force can open the door to a new class of micro/nanomechanical devices that can be entirely operated by light.

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Bone Morphogenetic Protein 2 (BMP-2) Aggregates Can be Solubilized by Albumin—Investigation of BMP-2 Aggregation by Light Scattering and Electrophoresis

Pharmaceutics ◽

10.3390/pharmaceutics12121143 ◽

2020 ◽

Vol 12 (12) ◽

pp. 1143

Author(s):

Julius Sundermann ◽

Holger Zagst ◽

Judith Kuntsche ◽

Hermann Wätzig ◽

Heike Bunjes

Keyword(s):

Light Scattering ◽

Bone Morphogenetic Protein ◽

Electrostatic Interactions ◽

Hydrophobic Interactions ◽

Pharmaceutical Research ◽

Bone Morphogenetic Protein 2 ◽

Growth Factor Delivery ◽

Surface Charges ◽

High Tendency ◽

Morphogenetic Protein

Bone morphogenetic protein 2 (BMP-2) has a high tendency to aggregate at physiological pH and physiological ionic strength, which can complicate the development of growth factor delivery systems. The aggregation behavior in differently concentrated BMP-2 solutions was investigated using dynamic and static light scattering. It was found that at higher concentrations larger aggregates are formed, whose size decreases again with increasing dilution. A solubilizing effect and therefore less aggregation was observed upon the addition of albumin. Imaged capillary isoelectric focusing and the simulation of the surface charges of BMP-2 were used to find a possible explanation for the unusually low solubility of BMP-2 at physiological pH. In addition to hydrophobic interactions, attractive electrostatic interactions might be decisive in the aggregation of BMP-2 due to the particular distribution of surface charges. These results help to better understand the solubility behavior of BMP-2 and thus support future pharmaceutical research and the development of new strategies for the augmentation of bone healing.

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Analysis of Ultrasonic Fields by Light Diffraction

Canadian Journal of Physics ◽

10.1139/p73-178 ◽

1973 ◽

Vol 51 (12) ◽

pp. 1341-1349 ◽

Cited By ~ 4

Author(s):

J. Vrba ◽

R. R. Haering

Keyword(s):

Light Scattering ◽

Ultrasonic Wave ◽

Propagation Direction ◽

Index Of Refraction ◽

Light Diffraction ◽

Strain Fields ◽

Wave Fields ◽

Ultrasonic Fields ◽

The Relationship ◽

Hexagonal Crystals

It is shown how the frequency, wavelength, intensity, and propagation direction of waves present in ultrasonic wave fields may be determined by light scattering experiments. The relationship between index of refraction variations and arbitrary strain fields is developed for hexagonal crystals and explicit results valid for CdS crystals are presented.

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Particle Migration by Optical Scattering Force in Microfluidic System With Light-Absorbing Liquid

Journal of Heat Transfer ◽

10.1115/1.4005714 ◽

2012 ◽

Vol 134 (5) ◽

Cited By ~ 5

Author(s):

Masahiro Motosuke ◽

Jun Shimakawa ◽

Dai Akutsu ◽

Shinji Honami

Keyword(s):

Laser Beam ◽

Light Absorption ◽

Laser Power ◽

Microfluidic System ◽

Particle Migration ◽

Optical Scattering ◽

Optical Force ◽

Control Technique ◽

Temperature Sensitive ◽

Scattering Force

Optical force offers a promise of being applied as a noninvasive manipulation tool for microscopic objects without physical contact. Particle control in a microfluidic system is achieved by optics showing advantages over electric or the other methods. With optics, the fluid need not to be contamination free and there is no need for electrode fabrication. Particles can experience different forces depending on the optical configuration. The scattering force is predominant under parallel or gently focused irradiation, while the gradient force is predominant in tightly focused irradiation. This paper reports the experimental and theoretical investigations of the potential of optical scattering force for particle control technique in a microfluidic system with a light-absorbing liquid. The light-absorption of the incident laser beam in the liquid causes a temperature rise and induces the corresponding property changes of liquid and particles. The experiments were presented for particle migration using the scattering force exerted by a compact diode laser with a wavelength of 635 nm. The absorption of the light in the liquid was controlled by the concentration of dye substance added in a buffer solution. The velocities of polystyrene particles with a diameter of 1.9 μm and the temperature distributions of the liquid under laser irradiation were measured by tracking their movement and by temperature-sensitive fluorophore, respectively. When there is no light absorption in the liquid, the migration velocity of particles under the laser beam is linearly increased with the increase of the laser power, in agreement with the calculations based on ray optics theory. In the case of light-absorbing liquid, the migration speed of particles experiencing the optical force indicates a nonlinear increase as the laser power increases. This enhancement mainly attributes to the temperature-sensitive change of liquid viscosity resulting in a reduction of viscous drag for migrating particles. An appropriate arrangement of light absorption leads to an enhancement in the photophoretic velocity of particles, and eventual performance promotion of particle separation and/or sorting using the optical force.

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Faculty Opinions recommendation of Colorimetric detection of DNA sequences based on electrostatic interactions with unmodified gold nanoparticles.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1021421.243581 ◽

2004 ◽

Author(s):

Vincent Rotello

Keyword(s):

Gold Nanoparticles ◽

Dna Sequences ◽

Electrostatic Interactions ◽

Colorimetric Detection

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Varying the Surface Charges of Gold Nanoparticles in Span 80, AOT, and Span 80 + AOT Micellar Systems in n-Decane

Russian Journal of Physical Chemistry A ◽

10.1134/s0036024420110278 ◽

2020 ◽

Vol 94 (11) ◽

pp. 2291-2298

Author(s):

E. V. Poleeva ◽

A. T. Arymbaeva ◽

A. I. Bulavchenko

Keyword(s):

Gold Nanoparticles ◽

Surface Charges ◽

Micellar Systems ◽

Span 80

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Laboratory Measurements of Light Scattering by Dust Particles

International Astronomical Union Colloquium ◽

10.1017/s0252921100501948 ◽

1996 ◽

Vol 150 ◽

pp. 409-413

Author(s):

Patrick P. Combet ◽

Philippe L. Lamy

Keyword(s):

Light Scattering ◽

Laser Beam ◽

Mie Theory ◽

Spherical Particles ◽

Dust Particles ◽

Laboratory Measurements ◽

Scattering Function ◽

Hene Laser ◽

Set Up ◽

Good Agreement

AbstractWe have set up an experimental device to optically study the scattering properties of dust particles. Measurements over the 8 — 174° interval of scattering angles are performed on a continuously flowing dust loaded jet illuminated by a polarized red HeNe laser beam. The scattering is averaged over the population of the dust particles in the jet, which can be determined independently, and give the “volume scattering function” for the two directions of polarization directly. While results for spherical particles are in good agreement with Mie theory, those for arbitrary particles show conspicuous deviations.

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