Near-infrared spectroscopy for in-line monitoring of protein unfolding and its interactions with lyoprotectants during freeze-drying

Sigrid Pieters, Thomas De Beer, Julia Christina Kasper, Dorien Boulpaep, Oliwia Waszkiewicz, Mohammad Goodarzi, Christophe Tistaert, Wolfgang Friess, Jean Paul Remon, Chris Vervaet, Yvan Vander Heyden

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


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 proteins 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.

Original languageEnglish (US)
Pages (from-to)947-955
Number of pages9
JournalAnalytical Chemistry
Issue number2
StatePublished - Jan 17 2012

ASJC Scopus subject areas

  • Analytical Chemistry


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