title: How subvisible particles become invisible-relevance of the refractive index for protein particle analysis.
abstract: The aim of the present study was to quantitatively assess the relevance of transparency and refractive index (RI) on protein particle analysis by the light-based techniques light obscuration (LO) and Micro-Flow Imaging (MFI). A novel method for determining the RI of protein particles was developed and provided an RI of 1.41 for protein particles from two different proteins. An increased RI of the formulation by high protein concentration and/or sugars at pharmaceutically relevant levels was shown to lead to a significant underestimation of the subvisible particle concentration determined by LO and MFI. An RI match even caused particles to become "invisible" for the system, that is, not detectable anymore by LO and MFI. To determine the influence of formulation RI on particle measurements, we suggest the use of polytetrafluoroethylene (PTFE) particles to test a specific formulation for RI effects. In case of RI influences, we recommend also using a light-independent technique such as resonant mass measurement (RMM) (Archimedes) for subvisible particle analysis in protein formulations.
authors: Coriolis Pharma, 82152 Martinsried-Munich, Germany.
authors: Sarah
authors: S
authors: Zölls
authors: Manuel
authors: M
authors: Gregoritza
authors: Ruedeeporn
authors: R
authors: Tantipolphan
authors: Michael
authors: M
authors: Wiggenhorn
authors: Gerhard
authors: G
authors: Winter
authors: Wolfgang
authors: W
authors: Friess
authors: Andrea
authors: A
authors: Hawe
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry*; D058846:Antibodies, Monoclonal, Murine-Derived / Q000737:chemistry*; D000068800:Etanercept; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry*; D000069285:Infliximab; D008027:Light; D010316:Particle Size; D018124:Receptors, Tumor Necrosis Factor / Q000737:chemistry*; D012031:Refractometry; D000069283:Rituximab; D012542:Scattering, Radiation; D012709:Serum Albumin / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D012709:Serum Albumin; D000069283:Rituximab; D000069285:Infliximab; D000068800:Etanercept