Simultaneous Identification of Spectral Properties and Sizes of Multiple Particles in Solution with
Subnanometer Resolution
Challenge
The need for a comprehensive and precise
method to characterize essential properties of polydisperse nanoparticles directly in
solution has remained unmet. Many nanoparticles have size-dependent optical properties that
can be optimized for various applications. However, past techniques were limited in quality
and resolution due to the significant variability in spectral properties of slightly
different quantum dot (QD) species.
Solution
A novel technique based on analytical
ultracentrifugation equipped with a multi-wavelength (MWL) detector has been introduced.
This method allows for simultaneous measurement of UV/Vis spectra while hydrodynamically
separating individual components in a mixture. By leveraging the two-dimensional spectrum
analysis (2DSA), it enhances the data evaluation by simultaneously capturing the spectral
properties of each species and providing high-resolution hydrodynamic analysis. The method
was applied on a mixture of CdTe quantum dots, revealing detailed size, anisotropy, molar
mass, and concentration of distinct species.
Conclusion
The innovative combination of analytical
ultracentrifugation with MWL detection and 2DSA provides an unparalleled solution for
characterizing nanoparticles in solution. This method, tested on CdTe QDs, displayed its
capability to determine multiple properties of nanoparticles with exceptional resolution and
accuracy, making it invaluable for a wide array of applications, including those involving
quantum dots, metal nanoparticles, and carbon nanotubes.
