Transglutaminase-mediated crosslinking of gelatine and silk hydrogels : Use of microbial transglutaminase for enzymatic crosslinking of gelatine and silk in the formation of hydrogels with tuneable and improved properties

Abstract

Hydrogels are polymeric networks capable of retaining large amounts of water. They have high biocompatibility and have thus received great attention for various biomedical applications, including as wound dressing and drug delivery agents. They can be fabricated using several methods and from various polymers. In this project, we explored the enzymatic crosslinking of gelatine hydrogels using microbial transglutaminase. We utilised a factorial design layout, varying the gelatine type, concentration, and crosslinking temperature to model the properties of the hydrogel. Using the model, we found the optimal conditions for high diffusion: gelatine type A at 30 mg/ml, crosslinked at 25°C. We further investigated the potential of silk fibroin and high molecular weight gelatine to improve the mechanical strength of the diffusion-optimised gel without limiting its diffusional properties. We believe silk and high molecular weight gelatine have excellent potential for this purpose. However, further investigations are needed to determine the effect of this supplementation on the diffusion rate through the gels.

Popular Abstract

Hydrogels are fascinating materials composed of polymer networks capable of absorbing and retaining large amounts of water—sometimes up to a thousand times their dry weight. Because of their high water content, they can closely resemble human tissues, making them valuable for various medical applications. Most hydrogels can be inserted into the body or applied to tissues without causing significant irritation or disturbing the surrounding tissues and cells, offering a wide range of potential uses. Due to their diverse properties, hydrogels have been explored for numerous medical applications. For instance, they can cover open wounds, acting as a barrier to infection while keeping the area moist for better healing. They can also be loaded with pharmaceuticals and inserted into the body, slowly releasing the drug for sustained therapeutic effects. Additionally, hydrogels serve as scaffolds for cell growth in tissue engineering, facilitating the generation of new tissues. To make gels that have suitable properties for a particular application, such as being very strong or allowing different molecules to diffuse quickly through the gel, it is essential to have good control over the gel properties and know which factors affect them. One outstanding challenge is that hydrogel strength and transport properties are mutually exclusive. For example, finding a hydrogel with high strength and diffusion rate is almost impossible.

Hydrogels can be made from various materials, including plant-based substances like cellulose or animal-derived materials like gelatine. They can also be synthesized from entirely synthetic materials, designed to meet specific needs, or be created using a combination of different polymers. In biomedical applications, natural polymers are often preferred because they are usually more similar to substances found in the human body and are, therefore, less irritating to surrounding tissues and cells. The method used to bind the polymers into a network is also essential. Traditional methods involve adding specific molecules that form bonds between polymers through chemical reactions. However, these methods can sometimes involve toxic or irritating conditions, or the linker molecules can be harmful. In this project, we used microbial transglutaminase (mTG) enzyme to crosslink the polymers. This enzyme-catalysed reaction requires no additives besides the enzyme itself, and it is performed under mild conditions, such as neutral pH and temperatures close to those of the human body.

Our project focused on developing gelatine hydrogels with tuneable properties by investigating various factors that affect their characteristics. We also explored incorporating silk fibroin, a natural polymer known for its exceptional mechanical strength, to enhance the strength of the hydrogels without compromising their diffusional properties.

We experimented with different gelatine types, varying gelatine concentrations, and different temperatures for the enzymatic reaction. We analysed the gels' ability to swell in water and retain their shape at temperatures that usually melt gelatine. We also measured the diffusional properties, the amount of gelatine released from the gels, and their mechanical properties. Based on these results, we selected the gel with the best diffusional properties and modified it by adding silk fibroin or higher molecular weight gelatine in various ratios. Both additions improved the mechanical strength of the hydrogels. Although measuring diffusion through the gels was challenging, our findings suggest that the new gels maintained good diffusional properties. In conclusion, we believe that silk fibroin and gelatine can enhance the properties of mTG crosslinked hydrogels. However, further research is needed to fully understand and optimize the diffusional properties of these improved gels.

• author: Gustafsson, Edith
• supervisor: Cedric Dicko
• organization: Pure and Applied Biochemistry; Computational Chemistry
• course: KBKM05 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: hydrogel, gelatine, silk, applied biochemistry
• language: English
• id: 9165941
• date added to LUP: 2025-01-27 17:01:35
• date last changed: 2025-01-27 17:01:35