Colloid Size Characterization

Our Dimensional Characterization Platform

The particle size of a colloidal particle is one of its important defining properties. Alfa Chemistry can select suitable techniques for particle size determination with high precision for different materials.

Fig.1 Typical characterization schemes for core–shell nanoparticles.^[3]

We would love to challenge those complex colloidal systems with multiple components. Our technologies include but are not limited to:

• Centrifugal Liquid Sedimentation(CLS)

The method mainly measures the settling time of nanoparticles when the gravity is increased, and uses the sedimentation time to calculate the Stokes particle size.^[1]

• Particle Tracking Analysis(PTA)

TRPS is a relatively new particle size measurement technique. It measures the blocking signal as the particle passes through the membrane and compares it to the signal produced by a calibrated particle of known properties, allowing the particle size to be determined assuming spherical geometry. TRPS performs particle-by-particle measurements, providing a statistical distribution of the data rather than an average result.

Fig.2 Representative (A) size distribution and (B) ζ-potential measurements of calibration particles CPC100 in EMEM buffer by TRPS. ^[2]

• 2D Analytical Ultracentrifugation(2D AUC)
  2D AUC refers to an ultracentrifuge equipped with one or more optical detection systems. It is able to observe the fractionation process of substances dissolved in solution, and combine 2D mathematical and computational modeling to map the distribution of sedimentation and diffusion coefficients of substances in solution.^[3]
  Advantages: ①No calibration required; ②Small sample volume required; ③Simple operation; ④Wide range of applications, covering almost any particle soluble in the liquid phase.
• Wide-Angle X-ray Scattering(WAXS)
  The principle of WAXS is based on the fact that when the crystallite structure is small enough, the Bragg peaks in the diffraction pattern broaden, the amount of which is inversely proportional to the particle size. Therefore, the particle size can be estimated from the width of the diffraction peaks.^[4]

Our Services

The characterization of the shape and size of colloidal particles provided by Alfa Chemistry has important implications for the development and quality control of these materials.Our services include:

• Sample Pretreatment
• Experimental Characterization
• Data Evaluation
• Uncertainty Assessment
• Report Writing

References

1. Christian Gollwitzer, et al. A comparison of techniques for size measurement of nanoparticles in cell culture medium. Analytical Methods. 2016, 8.
2. Aneta, et al. Size and ζ-Potential Measurement of Silica Nanoparticles in Serum Using Tunable Resistive Pulse Sensing. Langmuir. 2016, 32(9):2216-2224.
3. Carney R P, et al. Determination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation. Nature Communications. 2011, 2(1):335.
4. Qazi S, et al. Use of wide-angle X-ray diffraction to measure shape and size of dispersed colloidal particles. Journal of Colloid & Interface Science. 2009, 338(1):105-110.

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