Quantification of Subcellular Nanoparticle Size Distributions with Light Transmission Spectroscopy

We present measurements of the particle size distribution (PSD) of subcellular particles using Light Transmission Spectroscopy. In this work PSDs are established in two ways: (1) using our traditional approach of applying Mie theory to obtain PSDs from measured optical extinction spectra over a wavelength range of ~ 250 nm to 1000 nm and (2) with a new approach where the concentration of proteins is obtained directly from the magnitude of absorption peaks in the optical extinction spectra. In these ways we have successfully obtained PSDs for plant and animal cells over a wide size range: from ~ 2 nm to 3000 nm. These results reveal a power law dependence of particle concentration, N(D), with diameter, D, where N(D) ∝ D ^-α. We discuss values obtained for the power-law exponents, α, for cells (in the vicinity of 3) compared to other nanoparticle systems, and present primitive packing models.