Products

Product Literature

VP-DSC Differential Scanning Calorimeter

The VP-DSC is the most sensitive, easy to use differential scanning calorimeter to study samples in solution.  Providing fast, accurate transition midpoint (T_m) determination, the VP-DSC has revolutionized the study of liquid biopharmaceutical formulations by reducing the time and cost of stability testing.  In addition, a complete thermodynamic profile is generated to understand the factors that affect conformation and stability.

The VP-DSC is controlled by an intelligent user interface (VPViewer™ software) and data analysis is performed with Origin®, a market-leading data analysis package.

Applications include:

• Protein stability and folding.
• Liquid biopharmaceutical formulations.
• Process development.
• Protein engineering.
• Antibody domain studies.
• Characterization of membranes, lipids, nucleic acids and micellar systems.
• Assessment of the effects of structural change on a molecule’s stability.
• Measurement of ultra-tight molecular interactions (up to 10²⁰ M^-1).
• Assessment of biocomparability during manufacturing.

Why VP-DSC?

• Save time and money in stability testing.
• Study molecules in their native state without labeling.  Can be used with solutions that interfere with optical methods including turbid or colored solutions or particulate suspensions.
• Provides insights into mechanisms of unfolding and refolding.
• Determine ultra-tight binding constants that cannot be measured by other techniques (up to 10²⁰ M^-1).
• Easy to use: Unattended operation after sample loading.
• Complete system: No additional accessories to purchase and no reagents or consumables are required.

VP-DSC features:

• Active cell volume ~ 0.5 ml.
• Non-reactive Tantalum 61™ cells for excellent chemical resistance.
• Fixed-in-place cells for reproducible ultrasensitive performance with low maintenance.
• Operating temperature range of –10ºC to +130ºC.
• Peltier element for precise temperature control.
• User selectable temperature scan rates (0ºC to 90ºC per hour upscans) and range for application versatility.
• Unparalleled sensitivity and reproducibility (Figure 1).
• Three user selectable response times (US Patent #5,967,659) for maximum performance.
• Allows studies of fast or slow transition processes.
• Self-contained pressurizing system (0-45 psi) for studying solutions above their boiling point.
• Includes ThermoVac^® sample preparation and cleaning device.
• Pressure Perturbation Calorimetry accessory available for the determination of partial specific volumes.

The VP-DSC was the first calorimeter to feature user-selectable modes of operation: high gain, low gain, and passive. Passive mode is the most sensitive and is used to scan broad transitions (e.g. proteins), while the high gain mode is recommended for sharp transitions (e.g. lipids) (Figure 2). This patented feature is available exclusively on MicroCal instruments.

FIGURE 1. Data obtained from four repeat experiments using only 48 micrograms of lysozyme. Repeatability of the scans was excellent and the data for all four scans fell within a differential power band of 2 µcal/min (+/-0.15 µW) at all temperatures. The upper frame shows the standard deviations for these four experiments, which average only 0.35 µcal/min (0.025 µW). These deviations are 20-fold smaller than standard deviations obtained with other DSC instruments. The data shown in the lower frame noise demonstrates the excellent reproducibility of the VP-DSC.

FIGURE 2. The study of two systems where different response times are required. Data in the upper frame shows two separate experiments at a scan rate of 45˚C per hour using 86 micrograms of chymotrypsinogen. This transition is broad and requires high sensitivity to resolve the small signal changes. Highest sensitivity is obtained using slow response times. The opposite is often required for studies of very sharp gel-to-liquid crystal transitions of lipids such as 1,2 diipalmitoyl-sn-glycerol-3-phosphocholine (DPPC) at moderate scan rates. This is illustrated in the lower frame with a scan rate of 20˚C per hour.  Using a fast response time, a sharp peak with a width at half-height of only 0.13˚C is observed while a much broader transition is observed using slower response times.

Need more information? Contact us.