title: Near-infrared spectroscopy for in-line monitoring of protein unfolding and its interactions with lyoprotectants during freeze-drying.
abstract: This work presents near-infrared spectroscopy (NIRS) as an in-line process analyzer for monitoring protein unfolding and protein-lyoprotectant hydrogen bond interactions during freeze-drying. By implementing a noncontact NIR probe in the freeze-drying chamber, spectra of formulations containing a model protein immunoglobulin G (IgG) were collected each process minute. When sublimation was completed in the cake region illuminated by the NIR probe, the frequency of the amide A/II band (near 4850 cm(-1)) was monitored as a function of water elimination. These two features were well correlated during protein dehydration in the absence of protein unfolding (desired process course), whereas consistent deviations from this trend to higher amide A/II frequencies were shown to be related to protein unfolding. In formulations with increased sucrose concentrations, the markedly decreased amide A/II frequencies seen immediately after sublimation indicated an increased extent of hydrogen bond interaction between the protein's backbone and surrounding molecules. At the end of drying, there was evidence of nearly complete water substitution for formulations with 1%, 5%, and 10% sucrose. The presented approach shows promising perspectives for early fault detection of protein unfolding and for obtaining mechanistic process information on actions of lyoprotectants.
authors: Department of Analytical Chemistry and Pharmaceutical Technology, Center for Pharmaceutical Research, Free University of Brussels (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
authors: Sigrid
authors: S
authors: Pieters
authors: Thomas
authors: T
authors: De Beer
authors: Julia Christina
authors: JC
authors: Kasper
authors: Dorien
authors: D
authors: Boulpaep
authors: Oliwia
authors: O
authors: Waszkiewicz
authors: Mohammad
authors: M
authors: Goodarzi
authors: Christophe
authors: C
authors: Tistaert
authors: Wolfgang
authors: W
authors: Friess
authors: Jean-Paul
authors: JP
authors: Remon
authors: Chris
authors: C
authors: Vervaet
authors: Yvan
authors: Y
authors: Vander Heyden
mesh_terms: D000577:Amides / Q000737:chemistry*; D005079:Excipients / Q000737:chemistry*; D005612:Freeze Drying; D006801:Humans; D006860:Hydrogen Bonding; D007074:Immunoglobulin G / Q000737:chemistry*; D011489:Protein Denaturation; D058767:Protein Unfolding; D019265:Spectroscopy, Near-Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D000577:Amides; D005079:Excipients; D007074:Immunoglobulin G; D014867:Water