Direct measurements of aggregation forces in piconewton range between two red blood cells in pair rouleau are performed under physiological conditions using double trap optical tweezers. Aggregation and disaggregation properties of healthy and pathologic (system lupus erythematosis) blood samples are analyzed. Strong difference in aggregation speed and behavior is revealed using the offered method which is proposed to be a promising tool for SLE monitoring at single cell level.
Aggregation peculiarities of red blood cells (RBCs) in autologous plasma are studied using double trap optical
tweezers technique. The positions of RBCs are controlled with submicrometer accuracy by two optical traps
formed by strongly focused laser beams (λ=1064 nm). Quantitative measurements of interaction forces between
RBCs in pair aggregates are performed. Depending on the RBCs aggregation force, four different end-points of
disaggregation induced by optical trap movement are revealed. Analysis of experimental force dependence on
the distance between two RBCs during disaggregation is in a good agreement with the model of ring-shaped
interaction surfaces of RBCs in pair aggregate. Aggregation velocities measured are shown to be strongly different
for healthy and pathologic (System Lupus Erythematosis - SLE) blood samples.
Optical tweezers technique combined with local confocal luminescence spectroscopy is suggested as a tool for
investigation of local optical fields. Utilizing this method plasmon-enhanced optical fields inside a pair of dielectric
2 μm spheres partially covered by 70 nm silver nanoparticles are visualized via field enhanced luminescence of
rhodamine dye solution. Positions of the particles are controlled with submicrometer accuracy by two optical
traps formed by strongly focused laser beams with λ=980nm. A supplementary beam from CW laser with
λ=532nm provided for luminescence excitation is also focused into the sample cavity just to the trapping area.
In order to obtain spatial filtering of the signal and separate luminescence signal from an area near the spheres
pin-hole based confocal system is designed. The focal volume available for luminescence signal collection turns
out to be approximately 3μm x 3 μm x 5 μm. Since optical field is enhanced in the region near plasmon-active 2
μm spheres the enhancement of luminescence intensity is observed. Collective plasmonic effects in two-particle
measurements are also considered.
The results of experimental observation of magneto-optical Kerr effect (MOKE) enhancement caused by surface
plasmon-polaritons (SPP) excitation in 1D and 2D magnetoplasmonic crystals are presented. One-dimensional
nickel magnetoplasmonic crystals have periodic structure formed by periodic nickel grooves made on nickel
surface. The period of the structure is 320 nm and the depth of the grooves is 50 nm. The second group of the
samples represents itself a 2D self-assembled hexagonally ordered monolayer of polystyrene (PS) microspheres
with diameters from 500 to 760 nm and covered by 100- nm - thick nickel film. MOKE measurements performed
in transversal configuration demonstrate that SPP excitation lead to transversal Kerr effect (TKE) enhancement
resulting as a sharp peak in TKE spectrum.
One-dimensional photonic microstructures with optical thicknesses chosen according to the fractal sequence of
the Cantor's ladder are considered. Experimental samples made by electrochemical etching of porous silicon are
studied. Both numerical calculations and experimental results demonstrate self-similarity in reflection spectrum.
Numerical calculations demonstrate self-similarity in space distribution and time-resolved response caused by
self-similarity in morphology.
Wood's anomaly is experimentally observed in 2D plasmon-assisted nickel magnetophotonic crystals. It is shown
to be accompanied by ≃ 2 times enhancement of longitudinal Kerr effect. Wood's anomaly appears only for
p-polarization of incident light at any angle of incidence in the range between 10° and 70°. It vividly indicates
surface plasmon-polariton inducing on nickel surface. The experimental results are proved by numerical
calculations.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.