Differential scanning calorimetry (DSC) is an established biophysical tool for the characterization of protein stability . A protein's stability is a critical quality attribute (CQA) which is characterized throughout biopharmaceutical drug discovery and development, to help decide if it should be chosen to advance in the pipeline, and also to help guide selection of the process and formulation conditions needed to maintain its stability. In a DSC system, the protein in solution is placed in the DSC cell and heated at a constant rate, resulting in the protein unfolding due to thermal denaturation. The protein’s heat capacity (Cp) changes as the protein denatures. The peak of a DSC thermogram represents the protein's thermal transition midpoint (TM). For a protein which reversibly denatures, TM is the temperature where 50% of the protein is in its native (folded) conformation, and 50% is in its denatured (unfolded) conformation. TM is considered a good indication of thermal stability – the higher the TM, the more thermally stable the protein. Even if a protein is irreversibly denatured during a DSC experiment, the TM still provides important insights into its thermal stability. Multi-domain proteins (like antibodies) typically have more than one peak on a DSC thermogram, so more than one TM can be determined.
The first automated DSC system for biopharmaceutical applications, MicroCal VP-Capillary DSC, was launched in 2002. With automation, DSC quickly performs TM screening for biopharmaceutical preformulation and formulation development. Data from MicroCal VP-Capillary DSC systems are used to evaluate protein drug products for: candidate selection/protein engineering; process development; higher order structure (HOS) characterization during comparability studies and manufacturing support; HOS characterization for biosimilar development.
In 2017, Malvern Instruments launched the MicroCal PEAQ-DSC Automated system. Compared to the MicroCal VP-Capillary DSC, the MicroCal PEAQ-DSC Automated system has new features and improvements designed to improve productivity during biopharmaceutical discovery and development, generating high-quality, reproducible, and reliable DSC data which can be used for regulatory submissions. MicroCal PEAQ-DSC Automated systems are essential additions to the 'biophysical toolbox' in biopharma, CROs and CDMOs, and core facilities at academic and government research laboratories.