Thermal Analyzers

What is a Thermal Analyzer?

Any instrument that uses the addition or subtraction of heat for monitoring the physical or chemical properties of a sample could be considered a Thermal Analyzer. In this category of scientific instrument, exposure of the sample to a change in temperature can change other physical properties including melting, unfolding, binding, mechanical strength, composition, crystallization or glass transition, rheological properties and much more. 

Some Thermal Analysis instruments can monitor the change in temperature of a sample down to 0.000001 °C or less. These subtle changes in temperature can be the difference between for example two folded states of a protein, or the formation of crystal structure and can result in significantly different physical properties including things like stability, toxicity, viscoelasticity, and conductivity.

View the Malvern Panalytical range of microcalorimeters for Thermal Analysis.

Types of Thermal Analyzers

Thermal Analyzer	Abbreviation	Heat Applied or monitored	Property Observed	Derived Properties
Differential Scanning Calorimeter	DSC	Applied & Monitored	Temperature	Melting Point (Tm) Onset of Unfolding (Tonset) Enthalpy (∆H) Heat capacity (ΔCp)
Isothermal Titration Calorimeter	ITC	Monitored	Temperature	Binding Constant (KD) Stoichiometry (n) Enthalpy (ΔH) Entropy (ΔS) Gibbs Free Energy (ΔG)
Differential Scanning Fluorescence	DSF	Applied	Intrinsic Fluorescence	Melting Point (Tm) Onset of Unfolding (Tonset) Number of Transitions (n) Enthalpy (ΔH) Gibbs Free Energy (ΔG)*
Thermogravimetric Analysis	TGA	Applied	Sample Mass	Phase Transition temperature Sample mass change
Dynamic Mechanical Analysis	DMA	Applied	Mechanical Properties	Shear storage and loss moduli (G’, G’’)
Thermal Conductivity Analyzer	TCA	Applied	Conductivity	Thermal Conductance

* When performing an Isothermal Chemical Denaturation experiment

Applications of Thermal Analyzers

Thermal analyzers have a wide range of applications across various industries, some of which include:

1. Biopharmaceutical Analysis: For biopharmaceuticals, the structural and colloidal stability of a protein in a given formulation is considered to be relative to thermal stability or melting point (T _m ) of a protein. A higher melting point indicates greater stability and shelf life.
2. Pharmaceutical Analysis: Thermal analyzers can be used in the development and analysis of drugs to determine their thermal stability, crystal structure , degradation, shelf-life, and compatibility with other components.
3. Reaction Kinetics: The heat released or absorbed during a chemical reaction can be used to monitor properties of the reaction including binding constant (K _D ), stoichiometry (n), enthalpy (ΔH), and entropy (ΔS).
4. Food Science: Thermal analyzers can be used to study the thermal properties of food, such as the glass transition temperature of sugars and fats, which is useful in the development of food products and storage conditions.
5. Chemical Manufacturing: Thermal analyzers can be used in the optimization and quality control of chemical processes, such as the determination of the melting and crystallization behaviour of chemical compounds.
6. Polymer Characterization: Thermal analyzers can provide critical information about the thermal and mechanical properties of polymers, which is important in the development and optimization of polymer-based products such as plastics, rubber, and composites.

MicroCal Differential Scanning Calorimeters (DSC)

Differential Scanning Calorimetry (DSC) is a microcalorimetric technique used to characterize the structural stability of a protein or other biomolecule. It does this by measuring the heat change associated with the molecule’s thermal denaturation when heated at a constant rate.

Theoretically, the higher the thermal transition midpoint (T_m), the more stable the molecule. DSC measures the enthalpy (∆H) of unfolding that results from heat-induced denaturation. It is also used to determine the change in heat capacity (ΔCp) of denaturation. DSC can elucidate the factors that contribute to the folding and stability of biomolecules. These include hydrophobic interactions, hydrogen bonding, conformational entropy and the physical environment.

View the Malvern Panalytical MicroCal DSC Range here

MicroCal Isothermal Titration Calorimetry (ITC)

Isothermal Titration Calorimetry (ITC) is a label-free quantification technique used in studies of biomolecular interactions. It works by measuring the heat released (exothermic reactions) or absorbed (endothermic reactions) during a binding event.

ITC is the only technique that can simultaneously determine all binding parameters in a single experiment. Requiring no modification of binding partners, either with fluorescent tags or through immobilization, measuring affinity of binding partners in their native state.

Measuring heat transfer during binding enables accurate determination of binding constants (K_D), reaction stoichiometry (n), enthalpy (∆H) and entropy (ΔS). This provides a complete thermodynamic profile of the molecular interaction.

View the Malvern Panalytical MicroCal ITC Range here

Differential Scanning Fluorescence (DSF) 

Differential Scanning Fluorimetry (DSF) is a fluorescence spectroscopy-based technique that monitors the intrinsic emission spectrum of a protein relative to the applied temperature. During a thermal denaturation process, amino acids that make up a protein are exposed to more hydrophilic environments, causing the maximum signal (λ_max) of the intrinsically fluorescent amino acids (Trp, Tyr) to shift from 330 nm to 350 nm. This easily observable signal can then be plotted against temperature, and the second derivative applied to the data to find the thermal transition temperatures (T_m). 

Multiple thermal transitions can often occur in a single protein, making this technique highly suitable for monitoring applications such as effect of mutations on protein structural stability, and the effect of buffer composition on protein stability. The technique can even be applied to study binding affinities of low molecular weight ligands, to rank binding affinities of potential drug candidates.