Single nano particle analysis instrument
NanoTweezer from Optofluidics
An optical waveguide conducts laser light into a flow cell. Single nanoparticles in close proximity to the waveguide are trapped in the evanescent field around the waveguide. Light is scattered from the trapped nanoparticles while the intensity of the light depends on the size and in a smaller portion on the refractive index of the particle. With this method, different kinds of nanoparticles can be characterized in terms of shape, chemical composition and size.
|Single nanoparticle analysis in an evanescent field|
|Particle size: 20 nm - 3 µm|
|Light source: laser @1064 nm, 0-500 mW|
|Integrated design including pump for samples|
Chemical characterization of single nanoparticles
An improved method to analyze nanoparticle surfaces and learn about interfacial forces has been revolutionized by the NanoTweezer.
The main concept is simple, and the system answers one question: how much energy does it take to push a nanoparticle down onto a surface? Well stabilized particles will repel each other (otherwise they’d aggregate). They’ll also repel from any surface that mimics their own. These particles will be difficult to push down onto such a surface. Poorly stabilized particles, on the other hand, will be easier to push. The same concept holds true for any particle surface interaction: hydrophilic, steric, electrostatic, etc.
Spectroscopy on single nanoparticle
Unlike other Raman microscopes, which can only provide information about microparticles or larger, the NanoTweezer can trap, visualize, and obtain Raman spectra from true nanoparticles. Rather than an external laser focused onto a substrate, it uses near field light leaking out of a waveguide to optically excite and trap the particles in their native environments. This is the key breakthrough that enables the performance increase. The intense light in the form of an evanescent field leads to heightened signal and less background than traditional illumination systems. Additionally, because the particles are temporarily trapped during the analysis, an arbitrarily long exposure time can be acquired.
Protein aggregate analysis
Particle behavior and the shape of the scattered light observed with BSA protein was dramatically different than with spherical particle standards. Indeed, protein aggregates behave quite differently than any solid particle. Solid spherical particles, such as polystyrene, silica, PMMA, etc. traverse the waveguide and exhibit constant circular scatter patterns. As they moved along, their tumbling behavior was observed as widely different scattering patterns and dramatic intensity fluctuations.