Tissue Engineering Scaffolds and Fabrication Techniques

Vocabulary flashcards covering fundamental definitions, scaffold requirements, fabrication techniques, process limitations, and characterization methods from the tissue engineering lecture.

Tissue Engineering

An approach to repair, replace, and regenerate injured tissues by using a combination of biomaterials, cells, growth factors, and drugs.

Scaffold (Tissue Engineering)

A porous and degradable structure implanted in a region of injury, made of materials that facilitate cell regeneration while degrading over time as new cells grow.

Tissue Engineering Scaffold Requirements

Essential properties required of a scaffold, including biocompatibility, biodegradability, and interconnected macro-porous networks allowing cell migration, nutrient delivery, and vascularization.

3D Printing / Rapid Prototyping

The most advanced fabrication method used for developing tissue engineering scaffolds.

Freeze-Drying (Lyophilization)

The most common scaffold fabrication method, which involves freezing a scaffold material and sublimating the ice crystals under low pressure to remove water, resulting in a highly porous structure.

Limitations of Freeze Drying

Includes limited mechanical strength (unsuitable for load-bearing applications like bone or cartilage) and difficulty in controlling uniform pore size across the scaffold.

Freeze Casting (Ice Templating)

A fabrication method involving freezing a suspension or slurry and sublimating ice crystals, distinct for creating aligned, interconnected pore structures tailored by manipulating freezing conditions.

Blending-Pressing-Sintering Method

A scaffold fabrication technique consisting of blending materials, pressing the blend into a desired shape, and sintering to consolidate the material into a porous structure.

Limitations of Blending-Pressing-Sintering

Includes limited porosity and interconnectivity, material restrictions due to thermal degradation of natural polymers/bioactive molecules during sintering, and potential residual stress or defects like cracks.

Electrospinning

A scaffold fabrication technique used to produce 2D scaffolds that are particularly well-suited for skin or wound healing applications.

Material Characterizations

Analytical methods used to evaluate scaffold physical and chemical properties, including FTIR, XRD, NMR, Rheology, Mechanical analysis, and Thermal Analysis.

In Vitro Cellular and Molecular Characterizations

Biological evaluations of cell-scaffold interaction, including attachment, proliferation, PCR, Western Blot, Flow Cytometry, and DNA Analysis.

Blending Pressing sintering: Applications in Tissue Engineering

Bone tissue engineering, dental applications, metallic scaffolds for orthopedics(load-bearing Implants)

Dental applications of blending pressing sintering

The method is used to fabricate dental implants and filters, where strong, bioactive materials are required to support and regenerate dental tissue

Blending pressing sintering metallic scaffolds for orthopedics applications

The method is applied in the fabrication of metallic scaffolds (e.g. titanium, magnesium alloys) for orthopedics applications, providing strong, durable, and biocompatible support structures for bone healing and regeneration

Electrospinning

Creation of ultra-fine fibers from polymers using an electric field. Fibers can mimic extracellular matrix (ECM) of natural tissues, making it appropriate for fabricating scaffolds with nanoscale architecture that supports cell attachment, proliferation,and differentiation.

Basic setup components for elctrospinning

Polymer solution, syringe pump, high-voltage power supply, collector

Polymer solution (electrospinning)

A solution or melt of the desired polymer(or polymer blend) that will form the fibers

Syringe pump(electrospinning)

A string filled with the polymer solution is mounted on a syringe pump that controls the flow rate of the polymer solution

High-voltage power supply (electrospinning)

Creates an electric field between the needle of the string and a grounded collector plate

Collector (Electrospinning)

Can be flat , rotating, or have a specific geometry, collects the spun fibers and forms a non woven fibrous mat or scaffold

Limitations of electrospinning in scaffolds fabrication

Limited mechanical strength, poor cell infiltration, limited layer thickness, solvent use and residual solvents

Limited mechanical strength (electrospinning)

Especially when made from natural polymers or when highly porous

Poor cell infiltration(electrospinning)

The dense packing of fibers and small pore sizes in electrospinning mats can limit cell infiltration into the scaffold, especially for cells larger than the pore size

Limited layer thickness (electrospinning)

Limited to thin layers due to the challenges in building up thick, three-dimensional structures with uniform fiber distribution

Solvent use and residual solvents (electrospinning)

The use of solvents, can pose challenges in terms of toxicity and environmental safety. Proper solvent removal and scaffold cleaning are necessary to ensure biocompatibility, particularly for in vivo applications

Applications in Tissue Engineering (electrospinnning)

Skin tissue engineering, bone and cartilage regeneration, vascular grafts and nerve regeneration, drug delivery systems

Skin tissue engineering (electrospinning)