Table 1.

Summary of particle properties and mAb-particle adsorption footprint values. Particle area was measured by nitrogen adsorption of dry particles. Particle size of microparticles was measured by dilution of a suspension of particles in buffer into pure water in the LS230 laser diffraction particle analyzer. Particle ζ-potential was measured in buffer using the ZetaSizer Nano-ZS®. Adsorption footprints were determined by depletion of protein from solution by addition of particles as described in the methods.

	Particle area (m2/g ± SD)	Particle size: 90% < size (μm) ; mean size (μm)	Particle ζ-potential (mV ± SD)	mAb adsorption footprint (m2/mg ± SD)
ground glass vials	5.37 ± 0.03	3.0 ± 0.2 ; 1.0 ± 0.1	−55 ± 2	0.51 ± 0.01
ground glass syringes	5.20 ± 0.03	3.3 ± 0.1 ; 1.1 ± 0.1	−41 ± 1	0.61 ± 0.01
ground glass vials (after sulfate-wash)	7.56 ± 0.01	3.4 ± 0.1 ; 1.3 ± 0.1	−62 ± 2	0.80 ± 0.01
cellulose microparticles	1.91 ± 0.07	23.3 ± 0.4 ; 6.2 ± 0.1	−13 ± 1	0.27 ± 0.03
Fe2O3 microparticles	5.0	2 ± 1; 0.7 ± 0.2	−2 ± 15	0.99 ± 0.03
stainless steel microparticles	0.15 ± 0.01	42 ± 1 ; 14 ± 1	−11 ± 1	0.94 ± 0.01
stainless steel microparticles (after passivation)	0.12 ± 0.01	43 ± 1 ; 15 ± 1	−8 ± 2	0.84 ± 0.02
silica microparticles	6.4 ± 0.2	1.4 ± 0.1 ; 0.63 ± 0.02	−42 ± 2	0.69 ± 0.02
silica nanoparticles a	73.8 ± 0.1	0.7 a (0.015) a	−42 ± 1	0.68 ± 0.03
alumina microparticles	0.41 ± 0.01	12.8 ± 0.3 ; 7.6 ± 0.2	+45 ± 1	0.75 ± 0.01
alumina nanoparticles a	33.9 ± 0.2	0.5a (0.04) a	+43 ± 2	NA
titania microparticles	1.9	8.6 ± 0.3 ; 5.0 ± 0.2	−3 ± 1	0.64 ± 0.01

^aApparent average size for nanoparticles agglomerates in buffer was measured by dynamic light scattering using the ZetaSizer Nano-ZS® and the manufacturer supplied information for primary nanoparticle size is given in parentheses. Standard deviations represent results from three separate experiments or readings from the same batch/lot of microparticulate material.