Melt Electrospinning Writing of Three-dimensional Poly(ε-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

Summary

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

Abstract

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

Introduction

The manufacture of three-dimensional (3D) biocompatible structures for cells is one of the key contributions of additive biomanufacturing to tissue engineering (TE), aiming to restore tissues by applying customized biomaterials, cells, biochemical factors, or a combination of them. Therefore, the main requirements of scaffolds for TE applications include: manufacturability from biocompatible materials, controllable morphological properties for targeted cell invasion and optimized surface properties for enhanced cell interaction¹.

MEW is a solvent-free manufacturing technique that combines the principles of additive m....

Protocol

1. Material Preparation

1. Fill 2 g of PCL in a 3 mL plastic syringe with a funnel and insert a piston into the open end.
2. Place the syringe in a preheated oven at 65 °C for 8 h. Point the tip upwards to allow the air bubbles to aggregate close to the opening.
3. Push the piston with a thin object to release the trapped air within the molten material.
4. Let it cool down to room temperature, which is achieved when the polymer is not transparent anymore after 10 minutes.
5. Store the PCL pre-loaded syringe at room temperature in a dry and dark environment until it is used.

2. Hardware and Soft....

Results

Two different methods of collection are commonly used in MEW, which are flat collection and mandrel collection. The resulting architectures depend on the programming of the G-Code (Table 2), which is executed by the software.

Flat collection
Applying flat collectors refers to the most common method and facilitates the direct deposition of material referring to the pre-programmed G-code. 0/90.......

Discussion

Integrating AM in order to find innovative solutions for the challenges in the medical field presents a new paradigm for the 21^st century. The so-called field of "Bio-fabrication" is on the rise and innovations in fabrication technologies enable the production of highly sophisticated architectures for TE applications. The electrospinning of polymer melts in a direct writing mode (here MEW) is seen as one of the most promising manufacturing candidates to comply with the needs of the TE community, where .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Plastic syringe	Nordson Australia Pty Ltd	7012072	EFD BARREL O 3mL Clear 50
Medical grade Poly (ε-caprolactone) (mPCL)	Corbion Purac, The Netherlands	PURASORB PC12
23 GA needle	Nordson Australia Pty Ltd	7018302	#23GP .013 X .25 ORANGE 50 PC
Plunger	Nordson Australia Pty Ltd	7012166	PISTON O 3mL WH WIPER 50
Pressure adapter	Nordson Australia Pty Ltd	7012059	ADAPTER ASM O 3mL BL 1.8M
Aluminium collector	Action Aluminium, Australia	SHP2	Sheet 5005 H34
Acrylic glass	Mulford Plastics Pty Ltd	ACC6-13094
Mach 3 software	Art Soft		Purchased online
Safety switch interlock	RS components Pty Ltd	12621330
High voltage generator	EMCO High Voltage Co.	DX250R
Temperature controller	WATLOW	PM9R1FJ
X and Y positioning slide	VELMEX Inc.	XN-10-0020-M011