Currently I am working on preparing alginate based hydrogel (in the form of beads) to use it as a carrier for controlled drug release. I want to use them in their pristine form i.e. the wet state itself without applying drying steps like lyophilization, supercritical drying etc. However, from most of the literature I have come across, I have found that the prepared hydrogels have been dried before carrying out any characterization technique.
So I would like to know what are the characterization techniques that can be employed to effectively determine and compare the properties of wet hydrogel samples? Also, if I resort to techniques like cryo-SEM, cryo-TEM etc. to determine the morphology of my wet hydrogel samples, would the results bring out a correct picture of my sample's property (i.e. the property of the samples in their pristine form)?
I am working with PVA hydrogels. To determine mechanical properties of the hydrogels nanoindentation technique is the best technique. Hysitron triboindenter can test hydrogel samples and also samples immersed in liquid. However, you need to use fluid tip rather than the normal tip. For more details about indentation fundamentals, go through below links.
http://onlinelibrary.wiley.com/doi/10.1002/app.43532/full
http://www.sciencedirect.com/science/article/pii/S0032386116301227
Dear Mallikarjunachari,
Thanks for you input. Actually I am more interested in determining the surface morphology and texture of my hydrogel samples. So can you please suggest me in what form to use my samples (beads) if I am looking forward to do FTIR, SEM etc.
Also I would like to know whether the PVA hydrogels you are working on, do you dry them before carrying out indentation test or do you use it in the wet form as it is?
Nanoindentation gives the surface morphology, texture and RMS roughness of the wet samples. I have done surface morphology analysis of PVA hydrogels when they are in the wet state. It is doable.
I do not have much idea about other techniques. But, I worked with ATR-FTIR. I have characterized the cement curing during the hydration process. ATR-FTIR is a useful method to characterize the surface properties of the wet material. ATR-FTIR does not provide any information about surface texture and morphology. However, it contains a wealth of information about intermolecular forces.
For more details go through below links.
http://onlinelibrary.wiley.com/doi/10.1002/app.43532/full
http://www.sciencedirect.com/science/article/pii/S0032386116301227
You can also study the wetting behaviour if you have plane film by spectroscopic ellipsometry or if you even produce microstrcutures you can use imaging ellipsometry.
Schmaljohann, Dirk, et al. "In situ study of the thermoresponsive behavior of micropatterned hydrogel films by imaging ellipsometry." Langmuir 21.6 (2005): 2317-2322.
Best regards
Christian
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