Page 548 - IJB-9-6

International Journal of Bioprinting 3D printing of PCL-ceramic composite scaffolds

defect, trauma, or aging. TE aims to create functional The fundamental concepts that lead to the
organs from patients’ cells. The process of TE starts with establishment of bone tissue-engineered scaffolds are
biomaterials, followed by the fabrication of scaffolds, typically based on the selected biomaterial and production
combining them with cells and biochemical signals, such technique. Generally, for bone TE, pore sizes between
as growth factors, cytokines, mechanical stimulants, 100 and 350 micrometers and porosities more than 90%
to generate new tissue structures [1,2] . Microfabrication are preferred. PCL is a biodegradable polymer like other
techniques used in TE include photolithography, rapid degradable hydroxy polyesters such as PGA, poly-l-
prototyping (stereolithography, extrusion deposition lactic acid (PLLA), and their copolymers. PCL is one
printing), and soft lithography (microcontact printing, of the widely studied synthetic polymers in different
micro-molding, and microfluidics) . “A biomaterial is a formulations for TE due to its elastomeric mechanical
[2]
substance that has been engineered to take a form which, properties and biological properties. PCL is a rigid,
alone or as part of a complex system, is used to direct, by flexible polymer with a semi-crystalline structure having
control of interactions with components of living systems, high thermal stability, low glass transition (−60°C), and
the course of any therapeutic or diagnostic procedure, in melting temperatures (56–65°C). The slower degradation
human or veterinary medicine” [3-6] . Biomaterials are derived rate and mechanical properties limit the use of PCL
from several sources such as natural materials, synthetic compared to other polyester family members. However,
polymers, metals, ceramics, and composites [7,8] . Naturally the degradation kinetics and mechanical strength of the
derived biomaterials include protein-based biomaterials PCL can be tailored by copolymerization or blending with
(silk fibroin, keratin, collagen, gelatin, fibrin, and eggshell other polyesters or ceramic materials. PCL can be used
membrane) and polysaccharide-based biomaterials for scaffold fabrication for bone, liver, cartilage, skin, and
(chondroitin, glucose, cellulose, alginate, hyaluronan, protein delivery vehicles [24-28] .
and chitin and its derivative chitosan), and decellularized Numerous studies have been done on the blending of
tissue biomaterials. Synthetic polymers for tissue PCL with several bioceramics (e.g., calcium phosphate,
regeneration include polylactic acid (PLA), polyglycolic magnesium phosphate, biphasic calcium phosphate,
acid (PGA), poly (lactic-co-glycolic acid) (PLGA), and hydroxyapatite, and bioactive glass), natural polymers
polyurethanes. Metals include titanium alloys, nitinol, (chitosan, elastin, collagen, gelatin, and silk), and synthetic
magnesium alloys, stainless steel, and cobalt-chromium polymers (PLGA, PGA, PLLA, and carbon nanotubes) to
alloys. Composites include metal-ceramic, metal-polymer, enhance the mechanical endurance and biocompatibility
and polymer-ceramic [9-11] . Each of the above-mentioned of the scaffolds . Magnesium phosphate/PCL (MP/PCL)
[29]
individual biomaterial groups has specific advantages and composite scaffold enhances the polymer’s degradation
disadvantages. Biomaterials have played a crucial role rate by improving the PCL hydrophilicity [30,31] . Moreover,
in supporting and fostering regenerative cell growth in the surface wettability of the MP/PCL can be tailored by
the tissue engineering design paradigm and biomedical adjusting the amount of MP particles incorporated .
[32]
devices for numerous clinical regenerative therapies [12-18] . Blending nano-hydroxyapatite (nHA) with PCL improves
Scaffolds are temporary structures that mimic physical composite polymer scaffold strength (mechanical
[33]
microstructures of a natural extracellular matrix (ECM) property) and bioactivity . Biocomposite scaffolds made
to provide desired cellular interactions and guide cells to from polycaprolactone (PCL) and forsterite bioceramics
grow, synthesize, and other biological molecules to form can enhance and modulate mechanical and physical
new functional tissues . To engineer functional tissues and properties [34,35] . Incorporating aluminum oxide whiskers
[2]
organs successfully, scaffolds should possess the minimum within PCL significantly improves the composite scaffold’s
requirements, such as high porosity, proper degradation mechanical and hydrophilic surface properties with
[36]
rate, biocompatible, high surface area, mechanical good biocompatibility for TE and dental applications .
integrity, enhanced cell adhesion, growth, differentiated Composite scaffolds prepared with calcium alginate
function, and migration . Cell proliferation, attachment, threads and PCL demonstrate ideal porosity grade with
[19]
and differentiation are affected strongly by the scaffold suitable microstructure for enhanced bone cell growth
[25]
microenvironment, including the size, density of the pores, and differentiation . The presence of β-tricalcium
geometry, surface properties, and windows connecting phosphate (TCP) in PCL improves the cell proliferation
the pores . Techniques include porogen leaching, and compressive mechanical properties of the composite
[20]
[31,37-41]
phase separation, uniaxial freezing, micro-molding, gas scaffold for bone regeneration .
foaming, fiber meshes/fiber bonding, electrospinning, and Magnesium phosphate and calcium phosphate-based
additive manufacturing (laser-based, nozzle-based, and bioceramics are well-known in the biomaterials field and
printer-based) are used for the fabrication of scaffolds [21-23] . have been used separately with PCL scaffolds. However,

Volume 9 Issue 6 (2023) 540 https://doi.org/10.36922/ijb.0196