Use cases for 3D Bioprinting
Tissue engineering and regenerative medicine
Transplantation and clinics
Drug screening and high throughput assays
In vitro disease models
•E.g. for cancer research
What process occurs when calcium chloride is added to the alginate? Please include a sketch and explanation behind the process, in terms of its chemistry.
•Crosslinking
•Interaction of negatively charged alginate with Ca2+
Viscosity depends on??
•Molecular weight
•Concentration
•Interaction between polymers
•Polymer length
What does Higher alginate concentration mean??
Higher interaction with Ca2+ cations
Higher initial viscosity
What are the major advantages using hydrogels over solid polymeric structures for bio applications?
Biocompatibility, mimicking the extracellular matrix
High water content, flexible
Ability to absorb molecules similar to physiological molecules
What is the role of Methylcellulose in generating a bio-ink?
Methylcellulose reinforcing hydrogen bonds, stabilization
Methoxy groups disturb building of hard crystals which would prohibit entry of water molecules
Why is calibration so important and what effect can it have on downstream processes and tissue engineering purposes?
•Experiments should be reproducible
•XYZ calibration and pressure calibration are performed
•Depending on cell type different timeframes for printing
•Pressure and shear stress endured by cells is varying
How can the viscosity of bio-inks affect the pressure required to extrude the material?
•Applied pressure is directly connected to flow rate of bio-ink
•Higher viscosity —> higher pressure needed, otherwise lower flow rate
•Lower viscosity —> lower pressure needed, otherwise unprecise printing
Name three types of bioprinting methods
extrusion-based bioprinting, inkjet-based bioprinting and laser-based bioprinting.
Which formula is used to calculate the rheological moduli of the inks?
How come PD06 had the best shape retention and highest resolution?
The PD06, which contained gelatin methyl acrylate, was found to have the best shape retention and highest resolution due to its ability to undergo photopolymerisation with the introduction of a photoinitiator and UV light. This process creates covalent cross-links to form, which can be manipulated to control the density and stiffness of the bioprint
Extrusion-based bioprinting - how does it work?
whereas extrusion-based bioprinting is the most common one. Here a pneumatic pressure system containing a syringe and a nozzle is used. The syringe is filled with bio-ink which is pressured through the nozzle.
inkjet-based bioprinting works - how does it work?
In inkjet-based bioprinting a piezoelectric actuator or heater is used to create mechanical or air-pressure pulses producing dropleads at the print head.
Laser assisted bioprinting - how does it work?
For laser-assisted bioprinting a laser creates a pulse on an energy-absorbing layer causing drops to fall down from a donor slide at the position of the pulse.
natural vs. synthethis bio inks
Natural polymers-based bio-inks form a favourable microenvironment for cells, with alginates, collagen and gelatine being the most popular (Yu et al., 2020). Gelatine is known for its low mechanical strength and viscosity at room temperature but can be modified with methacrylates to increase strength and form a crosslinked hydrogel network after UV irradiation with a photo initiator
VS.
Synthetic bio-inks, on the other hand, consist of synthetic polymers such as Polyvinyl alcohol (PVA), polyethylene glycol (PEG) or polycaprolactone (PCL)
How much alginate was used in generating a 2 % and a $ % w/v solution in mg?
Last changeda year ago
