Introduction Using the innovative method of resonant mass measurement (RMM), we present data showing how mass, density and concentration from particle count–for particles ranging from nanometers up to micrometers can be... [ view full abstract ]
Introduction
Using the innovative method of resonant mass measurement (RMM), we present data showing how mass, density and concentration from particle count–for particles ranging from nanometers up to micrometers can be determined. The technology utilizes a suspended MEMS microchannel resonator, through which individual particles transit across the resonator altering the resonant frequency, which is then detected using an optical-based method. Changes in frequency observed when a particle enters the microchannel resonator are proportional to the buoyant mass of the particle, and can be translated into mass, size or surface area[1]. RMM therefore allows particle concentration to be determined as well as particle mass in a single measurement.
Furthermore, RMM enables differentiation of mixtures of particles types based on density differences. For example, silicone oil droplets found in therapeutic pre-filled syringes can be discriminated from protein aggregates, thus enabling accurate quantification of both silicon oil content and protein aggregate concentration[2]. Folzer et al have also shown differences in aggregate densities for protein particles stemming from different proteins such as BSA and IgG[3]. RMM also has the capability of resolving mass differences between uncoated and coated nano-scale particles, as shown by the binding of proteins to latex beads[4].
Methods & Results
Exemplifying the technique, we show how size and concentration of among other gold nanoparticles in suspension can be determined, as well as particle density determination of a range of materials including polystyrene latex, mesoporous silica and metal nanoparticles.
Discussion
Mass is an inherent attribute of all particles, and exploiting this as a detection technique offers a more universal method for characterizing nano-scale particles in a wide variety of dispersants. The ability to measure the particle density is critical for characterization of nano particles, to understand and optimize the production of nano particles for applications such as for example drug delivery, diagnostics or imaging.
REFERENCES
[1] T.P. Burg,M. Godin,S.M. Knudsen,W. Shen,G. Carlson,J.S. Foster,K. Babcock and S. Manalis,Nature 446,1066-1069,2007.
[2] A.R. Patel,D. Lau,and J. Liu, Anal. Chem,84,6833-6840,2012.
[3] E. Folzer,T. Khan,R. Schmidt,C. Finkler,J. Huwyler,H-C. Mahler,and A.V. Koulov,J.Pharm.Sci.,1-7,2015.
[4] M.R. Nejadnik and Wim Jiskoot,J.Pharm.Sci,1-7,2014.
Targeted drug delivery and Nanocarriers , Toxicology and risk assessment of nanomedicine systems
