Nonlinear spectroscopy signals detected by fluorescence from dilute samples of N non-interacting molecules are usually adequately described by simply multiplying the single molecule response by N. We show that signals that scale with higher powers of N are generated by the joint detection of several particles. This can be accomplished by phase sensitive detection such as phase cycling, photo-ac...

We performed efficient optical trapping combined with sensitive optical detection of individual silver nanoparticles. The particles ranging in size from 20 to 275 nm in diameter were trapped in three dimensions using low laser power by minimizing spherical aberrations at the focus. The optical forces were quantified, and we found that the larger the particle, the stronger the optical force. The...

We have observed Cherenkov rings from minimum-ionizing particles using a low-pressure, parallel-plate pad-chamber with a cesium-iodide solid photocathode . This detector is blind to minimum-ionizing particles, and sensitive to Cherenkov photons of wavelengths 170-210 rim. An average of 5 photoelectrons per Cherenkov ring were detected using a 2-cm-thick radiator of liquid C6F14 . This paper rep...

Superparamagnetic iron oxide nanoparticles have been established as sensitive probes for magnetic resonance imaging (MRI). While the majority of specific nanosensors are based on sterically stabilized iron oxide particles, the focus of this review is on the use of very small iron oxide particles (VSOPs) that are electrostatically stabilized by an anionic citrate acid shell. We used VSOPs to dev...

Nephelometry has become a very reliable and convenient method for immunoassays. Recent innovations in polymer chemistry have led to the design of highly sensitive and reproducible immunoassays. Key advances include the preparation and use of particles with polystyrene cores covered by thin shells with chemically reactive groups. The shells allow a covalent binding of the immunochemicals of inte...

We use sensitive dynamic cantilever magnetometry to measure the magnetic hysteresis of individual Janus particles. These particles consist hemispherical caps material deposited on micrometer-scale silica spheres. The measurements, combined with corresponding micromagnetic simulations, reveal configurations present in these curved magnets. In remanence, ferromagnetic are found host a global vort...

[1] We present a highly sensitive and accurate method for quantitative detection and characterization of noninteracting or weakly interacting uniaxial single domain particles (UNISD) in rocks and sediments. The method is based on high-resolution measurements of first-order reversal curves (FORCs). UNISD particles have a unique FORC signature that can be used to isolate their contribution among ...

Cytoplasmic extracts of HeLa cells made 1 to 2 h after infection with radioactive poliovirus contained 150-s virus particles and 130-s, perhaps partially disrupted, particles. The latter were resistant to RNase but sensitive to dodecylsulphate. Both particles were associated with fast sedimenting material from which they could be released by deoxycholate, but not by EDTA. In isopyenic gradients...

objective:at the present study, relationship between phagocytosis of plga particles and combined effects of particle size and surface pegylation was investigated.  materials and methods:microspheres and nanospheres (3500 nm and 700 nm) were prepared from three types of plga polymers (non-pegylated and pegylation percents of 9% and 15%). these particles were prepared by solvent evaporation metho...

Nanoparticle assemblies can be investigated in 3 dimensions using electron tomography. However, it is not straightforward to obtain quantitative information such as the number of particles or their relative position. This becomes particularly difficult when the number of particles increases. We propose a novel approach in which prior information on the shape of the individual particles is explo...