Real Time Testing Of Gel Photocrosslinking Using ElastoSens™ Bio

Applications / Photocrosslinking

In life sciences, photocrosslinkable hydrogels have been developed to overcome the low mechanical strength and processability of soft biomaterials including collagen, gelatin, hyaluronic acid, dextran, among others. These biomaterials contain photosensitive groups that are chemically introduced into their chains to allow their crosslinking under light exposure. These induced reactions make a liquid solution turn into a solid gel (gelation process) in a controlled manner.

The use of photocrosslinkable hydrogels offers many different strategies to control their final viscoelastic properties. The concentration of the biomaterial and photoinitiator, their degree of modification, the light intensity and exposure time can all be varied to fine tune the outcomes. With these many variables, it can be challenging to analyze the possible combinations in an effective way.

ElastoSens™ Bio can apply light at selected wavelengths (365 nm, 385 nm, and 405 nm – or others) during testing to obtain the crosslinking kinetics in real time of photosensitive biomaterials. These biomaterials can be poured directly into the sample holder and tested during crosslinking under controlled temperature, light exposure time and light intensity (in mW/cm2). The instrument measures, with no contact, real time changes in the sample height (or volume) and in the storage (G’) and loss (G’’) shear modulus which are immediately displayed on the tablet.

In this example, the evolution of the shear storage modulus (G’, Pa) as a function of time for a methacrylated gelatin (PhotoGel® 10%, Advanced BioMatrix, CA, USA) is shown under light exposure for 2, 4 and 6 minutes. The light was programmed to be switched on at 10 minutes of testing with the mentioned duration. Interestingly, the increase in G’ continued even after the light was switched off but at a lower rate. This means that the crosslinking reactions were still occurring for some minutes more (10-20 min).

ElastoSens™ Bio is able to capture the crosslinking kinetics under light exposure of photocrosslinkable hydrogels in real time. Scientists can now better understand the behavior of their biomaterials under different light intensities and exposure times. This also helps them to identify which light exposure time and intensity are needed to reach a target viscoelasticity.

Related Application Notes

All cells in the human body are exposed to mechanical forces which regulate cell function and tissue development, and each cell type is specifically adapted to the mechanical properties of the tissue it resides in. The matrix properties of human tissues can also change with disease and in turn facilitate its progression.

Gelatin and hyaluronic acid (HA) are biomaterials widely used in the biomedical research field. HA is the most abundant glycosaminoglycan in the body and is an important component of several tissues. HA contributes to tissue hydrodynamics, movement and proliferation of cells, and participates in a number of cell surface receptor interactions.

Hydrogels have been widely used in biomedical research for developing engineered tissues and novel treatments such as wound dressings and drug delivery systems. Photo-crosslinkable polymers are an interesting option in the field due to the possibility of tuning its microstructure by regulating the wavelength, intensity and duration of the applied light [1, 2, 3].

Related Scientific Articles

This study presents a novel 3D bioprinting strategy using a microfluidic printhead to fabricate hydrogel fibrous structures of gelatin methacryloyl (GelMA) with precise control over polymer concentration. The printhead utilizes a coaxial core-sheath flow and a photo-crosslinking system to enable in situ cross-linking of GelMA and the formation of hydrogel filaments. Computational modeling was employed to optimize process parameters and understand the diffusive and fluid dynamic behavior of the coaxial flow. The cytocompatibility of the system was demonstrated by bioprinting cell-laden bioinks containing U87-MG cells. This pipeline, integrating computational modeling with bioprinting, has the potential to be applied to various photo-cross-linkable bioinks for the generation of living tissues with customizable material and cellular characteristics.


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