Release date:2021/5/25 9:36:06

In the past few decades, the fields of tissue engineering and regenerative medicine dedicated to creating functional tissue constructs mimicking native tissues to repair and/or replace damaged tissues or entire organs have developed rapidly. Three-dimensional (3D) bioprinting is one of the most advanced technologies in this field. 3D bioprinting involves building tissues or organs layer by layer using a bottom-up approach. The purpose of 3D bioprinting is to imitate the natural cellular architecture in a certain way by depositing materials and cells in a specific way that can restore the normal structure and functionality of complex tissues. In 3D bioprinting, cells or biomolecules are directly printed on a substrate in a specific pattern so that the cells can be fixed together to form the desired 3D construct.

3D Bioprinting of tissue and organs. 

The most commonly used polymers in 3D printing technology are as follows: poly(ε-caprolactone) (PCL), poly(lactic acid) (PLA), poly(lactic-glycolic acid) (PLGA), hydrogel-based polymers as Alginate, gelatin and polyethylene glycol (PEG)-based materials. Here, we will discuss the details of PEG hydrogel-based 3D bioprinting.

Hydrogels, a 3D network of molecules composed of hydrophilic polymer chains, play a vital role in cell-filled 3D bioprinting, and those hydrogels mimic the physical and biochemical characteristics of natural extracellular matrix (ECM). It can be designed in any shape, size or form, and can absorb a thousand times its dry weight in a water-rich environment. Hydrogels that exhibit orthogonal control of multiple properties in cellular microenvironment should meet some of the physical and biological requirements to apply in 3D bioprinting. The main requirement is the biocompatibility of the material. Similarly, the hydrogel should have immunocompatibility and will not facilitate obvious inflammation at in vivo microenvironment. Most naturally-derived polymers (including alginate, chitosan, gelatin, hyaluronic acid and cellulose) always show good biocompatibility, and few synthetic polymers (such as PEG and its derivatives) show good biocompatibility under both in vitro and in vivo conditions. In addition to biocompatibility, several other factors must be considered, including mass transfer, biodegradability, target microenvironment, mechanical properties, and the impact of cross-linking reactions on cell viability.

PEG is one of the most widely studied hydrogels for cell research and drug delivery in tissue engineering scaffolds. PEG is a synthetic material formed by polymerization of ethylene oxide, highly valuable for its hydrophilicity that facilitates exchange of cell's nutrients and waste due to its inherent molecular structure. There are two hydroxyl end groups around the PEG diol, which can be converted into other functional groups, such as carboxyl, methoxy , thiol, amines, vinyl sulfanes, azides, acetylenes and acrylates. Photopolymerization is the most common strategy for preparing PEG hydrogels, which can provide more spatial and temporal control for in-situ manufacturing of scaffolds. PEG diacrylate (PEGDMA), PEG dimethacrylate (PEGDMA) and and multi-arm PEG acrylate (n-PEG-Acr) are the main types of PEG macromers used in photopolymerization to PEG hydrogels, which are not naturally biodegradable. It is important to note that PEG-derived materials allow hydrogel to be photo-crosslinked, which provides better mechanical stability after bioprinting. 

Hydrogel type Advantages Disadvantages Applications
PEG-based derivatives · Properties of the PEG-based derivatives can be easily manipulated using chemical modification techniques
· Good mechanical stability can be achieved
· Shows relatively good mechanical stability
· ​Mostly light polymerizable material within a short time
· Synthetic material
· Does not provide biological cues for cell proliferation
· Cell viability depends on the photocrosslinking time, the intensity of the light, and photoinitiator
Vascular tissue
Bone tissue
Cartilage tissue
The advantages and disadvantages of PEG-based hydrogel with its respective application in the biomedical field.

Biochempeg specializes exclusively in the development and manufacturing of high-quality polyethylene glycol (PEG) products and derivatives, and related custom synthesis and PEGylation services. Biochempeg caters to the PEGylation needs of the pharmaceutical, biotechnology, medical device and diagnostics, and emerging chemical specialty markets, from laboratory scale through large commercial scale. And we can provide PEG derivatives for 3D bioprinting. Suggested Biochempeg PEG derivative for 3D bioprinting:

Catalog No. Name
HO009009 AC-PEG-AC

Hydrogel-based 3D bioprinting: A comprehensive review on cell-laden hydrogels, bioink formulations, and future perspectives, doi: 10.1016/j.apmt.2019.100479
​ Current Developments in 3D Bioprinting for Tissue and Organ Regeneration–A Review, doi: 10.3389/fmech.2020.589171

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