Arburg Plastic Freeforming was used to produce biomimetic bone scaffolds made of polycaprolactone with channel structures for the ingrowth of blood vessels.

The targeted introduction of defined channel structures is very important to support the ingrowth of blood vessels, which greatly supports the regeneration of natural tissue.

The tibia model used was divided into the cortical bone and the cancellous bone in order to be able to compare the fulfillment of the different requirements of the two natural structures with the printed structures separately.

To check the requirements, the canals were exposed using a microtome and characterized with SEM. Compression tests were also carried out on a tensile testing machine. It was found that the channels in the tibial cortex led to a slightly higher stiffness compared to those without channels due to the frame outlines. Overall, however, the stiffness was significantly lower than that of natural bone. In the cancellous bone scaffolds, the stiffness with channels was below that without channels, but still within the physiological range, as was the model without channels. The porosity, examined using SEM images, was within the required range for both scaffold types.

Introduction

Gelatin methacryloyl (GelMA) is a photocrosslinkable biomaterial that has gained significant attention in biomedical applications, particularly within the field of tissue engineering and biofabrication. In recent years, numerous efforts have been directed towards meeting the specific requirements of diverse tissues and mimicking the physical and biochemical characteristics of native extracellular matrix (ECM) with the main goal of improving biocompatibility, promoting favorable cellular responses, facilitating functional tissue regeneration, and ultimately enabling generation of personalized printable scaffolds. To tailor hydrogel’s properties for specific applications, it is essential to investigate the key parameters and their combined interactions affecting photocrosslinking reactions. Understanding these dynamics is crucial for unraveling photocrosslinking kinetics and effectively controlling the mechanical characteristics of GelMA hydrogels.

Methods

This study employed a systematic approach to evaluate the mechanical characteristics and to shed light on the interplay between key parameters influencing photocrosslinking reactions. The mechanical properties of GelMA hydrogels were systematically examined using a Design of Experiment (DOE) methodology. Key parameters including GelMA concentration, degree of GelMA modification, photoinitiator concentration, and photocrosslinking time were tuned within a controlled range. Additionally, a sequential crosslinking strategy involving both physical and chemical crosslinking was implemented. Mechanical properties were subsequently determined through unconfined compression testing. Furthermore, the printability of the selected compositions was tested using an extrusion-based 3D printer.

Results

This comprehensive approach facilitated a thorough understanding of how photocrosslinking parameters collectively influence the mechanical characteristics of GelMA hydrogels. Considering the studied ranges of the parameters, GelMA concentration, degree of GelMA modification, and sequential crosslinking are found to be key parameters that improve certain mechanical properties through synergistic effects. Their combined effect leads to a more substantial enhancement in mechanical properties which enables e.g., the attainment of an elastic modulus spanning from a few kilopascals to megapascals. The assessment of printability demonstrated constructs with high shape fidelity, underlining the importance of fine-tuning printing temperature for the precision of biofabrication.

Conclusion

By gaining insights into the influence of key photocrosslinking parameters on GelMA hydrogel properties, this study paves the way for customized biomaterial design to meet specific biomedical needs. The synergistic effects observed highlight the potential of enhancing GelMA hydrogel mechanical properties through optimized crosslinking strategies. This understanding holds promise for advancing tissue engineering and biofabrication technologies towards improved clinical outcomes.

Introduction

Nose-to-brain drug delivery provides an alternative administration route for drugs to the central nervous system, bypassing the blood-brain barrier. Microparticle formulations based on chitosan have been explored in literature due to chitosan mucoadhesive properties, swelling behavior, and ability to open tight junctions. Thiolation of chitosan enhances its mucoadhesive properties, making it an attractive excipient for nose-to-brain drug delivery. A synthesis strategy for L-cysteine chitosan was developed and the resulting material served as a matrix for microparticles produced by the spray-drying.

Methods

Chitosan was chemically modified with L-cysteine through carbodiimide chemistry and the product was purified in an acidic medium and freeze-dried. The resulting material was physically-chemically characterized and used to prepare a 1% w/v solution in water or acetic acid. The solutions were spray-dried using a two-fluid nozzle and the resulting microparticles are characterized for size, morphology, swelling, and free thiols.

Results

Chitosan microparticles successfully encapsulated active biopharmaceuticals, allowing controlled release. To improve chitosan characteristics, the thiolation of chitosan was successfully achieved with a high amount of thiols per gram of polymer, which is connected to enhanced mucoadhesion. The resulting polymer showed high solubility in a wide range of pH, allowing for spray-drying in different conditions. The spray-drying yield was consistently above 60% in all conditions. The material proved suitable for spray drying and the free thiol content can be tuned easily by adjusting the pH of the feeding solution, resulting in a controlled crosslinking degree.

Conclusion

Chitosan microparticles proved a good platform for nose-to-brain drug delivery. Chitosan was successfully modified to achieve a water-soluble material with a high amount of free thiols per gram of polymer. The material proved suitable for spray drying and the free thiol content can be tuned easily by adjusting the pH of the feeding solution, resulting in a controlled crosslinking degree.

Introduction

According to official figures, about 200 million people worldwide are affected by incontinence. With increasing age, the probability of becoming incontinent increases. Elderly people are often admitted to care facilities because of existing incontinence. To improve continence performance, patients need to train their pelvic floor muscles. For patients it is difficult to train the pelvic floor because they do not know which muscles they have to activate during the training. The smart pants developed in the project “PelFit” can monitor the muscle activity during pelvic floor training.

Methods

For the development of the EMG pants a software was created for the biofeedback-based training. The EMG-pants is equipped with embroidered textile electrodes.

Results

The position of the electrodes was defined with a 3D model of the pelvic floor. After measuring the muscle activity us-ing EMG electrodes, the measured signals are interpreted to form a muscle model and this muscle model is compared with the anatomical model. EMG measurements were made for several movements of the body. The signal curves of the textile electrode pair as well as the signal curves of the signal curves of the respective synergists of the pelvic floor muscles were measured with adhesive electrodes in direct comparison. In all exercises, a simultaneous activation of the synergists of the pelvic floor muscles and the pelvic floor muscles themselves is recognizable.

Conclusion

The study demonstrated that underwear can be equipped with embroidered textile electrodes to measure the muscle activity in the pelvic floor. The measured data of the muscles can be sent via Bluetooth to an app. In the app the acti-vated muscle and the intensity of the muscle activity can be visualized for the patient or therapist.