Nanopore-based Detection versus Dynamic Light Scattering
The qNano is a unique non-opitcal nanopore-based system that enables accurate particle size distribution determination with individual particle detail. This is in contast to intensity-weighted averaging effects inherent in other size analysis technologies, such as dynamic light scattering (DLS).
Light scattering approaches allow particle characterization in a wide range of solvents and over a particle size range from a few nanometers to several microns. However, these ensemble measurement techniques often give rise to erroneous results, as they can be biased by small populations within polydisperse samples. For example - these techniques are inherently skewed towards larger particles in a suspension due to the proportional relationship between light scattering intensity and particle size (i.e. I∝d6) .
Resistive Pulse Sensing with Size-Tunable Nanopores is a method of ensuring
(D. Kozak, et al., 2011).
In the example above, the same mixture of 220nm and 380nm polymer particle standards with measured on DLS and a qNano.
Dynamic Light Scattering
DLS showed only one population with a Z-average of 260.4nm for the 220nm + 380nm mixture (Fig 1). The inherent limitation of an ensemble technique and intensity-weighted skewing resulted in inaccurate and misleading information, particularly if this were a mixture of particles produced for vaccines or as drug delivery carriers.
Resistive Pulse Sensing: qNano
The qNano, in contrast, measures individual particles. Particle-by-Particle measurement means that accurate size distribution of particles is obtained. Distinct particle populations are resolved with high precision (Fig 2).
Additional details about individual particles are simultaneously determined, e.g. the number of particles (concentration in particles per mL) and relative surface charge distribution.
Comparison with Other Particle Characterization Techniques
qNano enables accurate analysis of 50nm-10μm size particles with single-particle resolution - providing an attractive alternative or complement to existing characterization techniques.
References:
D. Kozak, et al.,"Advances in resistive pulse sensors: Devices bridging the void between molecular and microscopic detection" Nano Today (2011).
E. van der Pol, et al. "Optical and non-optical methods for detection and characterization of microparticles and exosomes" Journal of Thrombosis and Haemostasis (2010), 8: 2596–2607.
R. Vogel, et al. ""Quantitative Sizing of Nano/Microparticles with a Tunable Elastomeric Pore Sensor" Journal of Analytical Chemistry 83 (9), pp 3499–3506 (2011).
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