Tissue engineering in Turkey: focus shifts to melt electrospinning and hybrid manufacturing

Researchers at Sabanci University in Turkey are further adopting new technologies to manufacture scaffolds to promote the development of tissue engineering, and have recently published “Bionics in Biological Manufacturing: Melt Electrospinning Writing Technology for Hybrid Biological Manufacturing” Outlines their work.

Electrospinning methods are often used (especially by researchers) and provide advantages such as simple design, moderate price, flexible combination of polymers and improved mechanical properties. Melt electrospinning (SE) is a popular method that uses syringes and nozzles, syringe pumps, high-voltage power supplies, and current collectors. However, historically, SE has faced challenges, and researchers have had to overcome problems such as solvent toxicity and evaporation rates. Other obstacles include problems such as solubility and flow instability.

The researchers said: “In addition, due to the accumulation of residual charges in the deposited filaments, the manufacture of large-scale alignment 3D structures is still a challenge.”
Melt Electrospinning (ME) is environmentally friendly and does not require solvents, which means that no effort or preparation is required to create proper ventilation or final removal. This saves time, money, and eliminates toxicity-centric safety hazards.

In addition, some polymers that cannot be dissolved in any solvent can be processed by ME. The researchers said: “This also provides an opportunity to use multiple materials at once. It may not be possible to find a common solvent, otherwise it will make electrospinning ribbon difficult. Similar to SE, the polymer jet is exposed to the tip of the spinneret. Tensile force (electrostatic coulomb and gravity) and resistance (surface tension and viscoelasticity). However, polymer melts with higher viscosity and lower conductivity will produce a more stable jet during the deposition process, which will make it easier to obtain a shape Controlled filament.”

Melt Electrospinning Writing (MEW) provides hope for building supports, and has flexibility in adjusting the size, shape, and porosity of the print. Of course, MEW still has challenges and complexities, including temperature and conductivity issues, as well as the correct placement of insulating shielding layers to prevent electrical interference. Other areas that need to be overcome include manufacturing structures that deal with the increased distance from the tip of the needle to the collector, as well as dealing with the temperature and charge issues associated with the injector and nozzle, resulting in viscosity levels and electricity.

You can choose to use a variety of biocompatible and biodegradable materials, and you can create a scaffold for the project:

• skin
• Intima
• nerve
• Heart tissue

Many polymers have been used in ME tissue engineering, including:

• Polycaprolactone (PCL)
• Polylactic acid (PLA)
• Poly-L-lactic acid (PLLA)
• Polyethylene Glycol (PEG)
• Polyurethane (PU)
• Polymethyl methacrylate (PMMA)
• Polypropylene (PP)

The challenges faced by MEW continue to focus on balancing the problem, creating materials with appropriate mechanical properties and ensuring biocompatibility. The researchers pointed out that MEW can also provide hope when combined with “other existing manufacturing technologies” that can go beyond current limitations and expand its use.

“With the help of hybrid methods, people can create hierarchical structures to meet cellular and mechanical requirements and meet the requirements of tissue engineering construction, while other application standards (such as mechanical durability and/or processing challenges for specific materials) can be solved.” Personnel said.

Hydrogels are also promising because they can mimic the extracellular matrix in human tissues. To prepare hydrogel-MEW composites, the fibers must be prepared by the method of hydrogel penetration.

Different hybrid manufacturing methods using melt electrospinning (MEW).

The research team also tried to use PCL fibers and hydroxyapatite nanoparticles (nHA) to create “simulated calcification zones.” MEW is also expected to be used to create heart tissue with appropriate mechanical strength, as well as engineered nerve, skin and bone tissue, and help wound healing applications.

General modeling overview of continuous models and miniature finite element (FE) models. (A) Uniaxial compression test, used to study the reinforcement mechanism of composite materials. (B) Continuous finite element model on a quarter of the ideal composite structure (C) μ-CT schematic diagram of the miniature finite element model of the actual composite structure under different deformation levels.

(A) Survival rate and (B) morphology of cardiac precursor cells (CPC) permeated by collagen hydrogel in square and rectangular bare PCL and mixed PCL scaffolds.

The researchers said: “Through the further development of materials and structures, we foresee a wide range of advances in the use of a variety of polymers and hydrogels, as well as a variety of biomolecules, cells and nanoparticles in hybrid systems.”

“More comprehensive experiments and numerical modeling studies are needed to better understand the mechanical properties and optimize the performance of the hybrid MEW structure. Although the elastic modulus and Poisson’s ratio of the various components of the hybrid structure are regarded as the main modeling research Parameters, but other biomechanical characteristics of these components and the interaction between the components should be considered to improve the accuracy of modeling.”

Tissue engineering has become a huge science, and the uses of hydrogels are also expanding. From the use of chitosan-gelatin hydrogel for bioprinting, to testing the electrical conductivity of granular hydrogels, to experimenting with graphene oxide, etc.

(Editor in charge: admin)