Oscillatory Testing of Thermosensitive Polymer Hydrogels

If you need to demonstrate a temperature sensitive gelation, or identify whether changes in your formulation affect specificity of stimuli which cause gelling behaviour, we can provide data for these endeavours. Our lab provides oscillatory testing of thermally sensitive polymer hydrogels for demonstrating thermo-reversible gelling behaviour and temperature dependent sol-gel transitions. We are equipped with a variety of specialist equipment including rheometers capable of generating objective, repeatable and highly accurate data. The rheology lab provides comprehensive testing of multiple samples within a short time frame, and provide additional support from results discussion, data interpretation and regulatory support.

If you would like to discuss how we can help characterise the thermoreversible gelling behaviour of your formulation, then please feel welcome to contact us.

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Thermosensitive Injectable Polymer Hydrogels

Stimuli responsive polymers, polyamines and poloxamers are an exciting development within the pharmaceutical industry for their potential in creating high specificity therapies or sustained/modified drug release therapies. Many thermosensitive polymers such as poly(N-isopropylacrylamide) (PNIPAM) or poloxamer 407 possess a lower critical solution temperature (LCST) below physiological temperature i.e. they behave as liquids at low temperatures, but will gel at body temperature. The need for improved biocompatibility, reduced toxicity and precise control at the molecular level has driven the investigation into development of new polymers based off these structures, and whether salts, excipients or other polymers can help modulate response to gelation stimuli. These modifications may have the unintended effect of impairing the temperature specificity of the hydrogel, or other performance characteristics such as the viscosity below the LCST or stability over time or temperature fluctuations.

Oscillatory Testing – Showing a change in structure as a result of temperature

Viscosity profiling is not the best method for looking at structural changes in polymer hydrogels since the shear applied during a viscosity test may damage or even destroy the very structure that is being formed. In oscillatory testing, the sample is ‘wobbled’ very gently back and forth and the gel’s response to either stress or strain is measured. The test itself is minimally disruptive and provides more relevant information for structural changes. For gelled materials, it is more relevant to describe its physical properties in terms of structural strength, rigidity, and deformation in response to increasing stress/strain.

For illustrative purposes only. Temperature Sensitive Polymer Hydrogels
An example data set: An oscillatory temperature sweep showing differences in behaviour of temperature sensitive polymer hyrdrogels.

In an oscillation temperature sweep we can plot structural changes as a function of increasing or decreasing temperature, and quantify differences between benchmark formulations, helping formulators get a simple and informative overview of how their decisions have affected gelation behaviour and gel structural properties.

Expert characterisation – Demonstrating thermosensitivity of polymer hydrogels

Whether you are looking for characterisation of mixed polymer solutions, novel polymers or simply generating claims support data for regulatory submission, we have a variety of tools and methods to reliably describe rheological behaviour in a repeatable, objective and accessible manner. All our testing reports include ongoing support to ensure that the data generated can be exploited fully for any number of use cases, from formulation, processing or quality.

Contact us now to discuss our full characterisation capabilities and how we can support.

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