February 23, 2023
Guidance to the optimal point for freeze-drying a hydrogel
Freeze-drying is a common method to produce porous scaffolds from a hydrogel composed of natural or synthetic polymers. In a number of cases, the polymeric solution is crosslinked (bonds or interactions are established among the polymeric chains) and the hydrogel is then freeze-dried to obtain the porous and dried scaffold (1-3).
July 28, 2022
How microgels are used in regenerative medicine?
Microgels are hydrogel particles that can be used in tissue engineering due to their unique properties, such as high water content and the ability to encapsulate bioactive factors. These microparticles provide a high surface area that facilitates better cell growth, nutrient transfer, and improved cell interactions. They can be used independently or incorporated into a larger "carrier" hydrogel system. Due to their injectability, they're useful in non-invasive surgical procedures. Microgels can also serve as inks in 3D and 4D bioprinting, creating scaffolds for cells either before or after printing.
July 21, 2022
A magnetically orientable microgel for tissue regenerationlife
Researchers at the DWI – Leibniz-Institute for Interactive Materials, Aachen, Germany have developed injectable microgels that can be magnetically oriented within a larger hydrogel to regenerate various types of tissue. The team began by functionalizing a material called six-arm poly(ethylene oxide-stat-propylene oxide) with acrylate groups, which can be broken down and removed by the kidney. Superparamagnetic iron oxide nanoparticles, which can align to an applied magnetic field, were mixed into the functionalized material. The team then crosslinked this mixture with UV-light to form microgels. To increase the contact surface with cells, a peptide containing the RGD sequence, a focal adhesion point for cells, was grafted onto the microgels. This innovative strategy provides a promising tool for tissue regeneration.
June 29, 2022
Machine learning for gel time prediction of living hydrogels
The development of tissue engineering products faces challenges due to the variety of biomaterials available and their dynamic properties once implanted. A recent study used artificial intelligence (AI) to help address this problem. The researchers created a system that automates the prediction of gelation time (when a liquid solution becomes a hydrogel) for different formulations. The hydrogels were composed of silk, horseradish peroxidase (HRP), hydrogen peroxide, and bacterial cells. They utilized differential dynamic microscopy (DDM) to identify gelation time and machine learning (ML) to predict the gelation time of different hydrogel compositions. This allowed them to streamline the process of finding hydrogel formulations with specific properties.
June 16, 2022
AI-based prediction of hydrogel gelation kinetics and their mechanical properties
Hydrogels are biomaterials that are widely studied in the biomedical field. They are used, for example, to produce contact lenses and wound dressings, for drug release systems, or as scaffolds for tissue engineering. The design of such hydrogels is often multidimensional since multiple parameters related to their chemical composition and physical properties affect how they are going to behave in vivo.
May 31, 2022
Why is 4D bioprinting important in life sciences?
4D bioprinting introduces "time" as the fourth dimension, enabling printed objects to change over time. Physical stimuli like light, temperature, or magnetism can induce transformations. The bioprinting process can also allow targeted drug release through changes in temperature or pH. Nano-hydrogels can serve as drug carriers, directed by magnetic fields, and can be quickly degraded by enzymes. Furthermore, hydrogels can react to biological signals, aiding in tumor treatment by releasing drugs then biodegrading over time.
May 19, 2022
A 4D bioink for dynamic 4D engineered tissues
4D-bioprinting introduces "time" into the printing process, allowing printed structures to evolve. Researchers from the University of Illinois Chicago used oxidized and methacrylated alginate (OMA) to develop a bioink for 4D bioprinting. They made OMA into precursor beads, then transformed them into a "microgel" that could be easily printed into stable 3D constructs. Mixed with cells, the microgel became a bioink, which was printed into complex structures. The printed constructs could be further crosslinked to create 3D scaffolds that could change shape due to differential swelling, adding the 4th dimension, "time," to the printing process.
March 31, 2022
Controlling the molecular structure in 3D printed biomaterials
Recent advancements in 3D-bioprinting have opened the possibility of creating engineered tissues mimicking human native tissues. However, reproducing the extracellular matrix (ECM) composition and microscopic architecture within the biomaterial ink remains challenging. To tackle this, a research group from the AO Research Institute Davos developed a bioink containing both collagen type 1 and tyramine derivative hyaluronan for tissue engineering. They used optimal concentrations of these two components, along with human bone marrow-derived mesenchymal stromal cells. Two crosslinking pathways were used to induce gelation and create a 3D scaffold that was then printed using the bioink's shear-thinning properties. They successfully printed an anisotropic hydrogel, achieving control over the microscopic organization of the matrix. This breakthrough could pave the way for better mimicry of native human tissues, especially anisotropic ones, in tissue engineering applications.
January 26, 2022
Methods to 3D print alginate-based scaffolds
In January 2022, we studied alginate hydrogels in tissue engineering and drug delivery. Alginate, often used as a bioink in 3D bioprinting, forms hydrogels with tunable properties. We examined the effects of varying CaCl2 concentration on alginate crosslinking, crucial for 3D printing. Due to alginate's low viscosity, printing methods include pre-crosslinking with CaCl2, using a coaxial needle for immediate crosslinking, or mixing alginate with other biomaterials to improve printability.