Page 378 - IJB-9-2

International Journal of Bioprinting 3D gel-printed β-TCP/TiO2 porous scaffolds for cancellous bone tissue engineering

tumors [1-3] . An increasing demand for bone transplantation cannot provide a controllable design of the complex shape
and regeneration approaches is now a critical issue in as well as a microporous structure with precise parameters.
orthopedics. Autologous bone and allografts are considered Nowadays, 3D printing technology, combining computer-
a convenient strategy for bone repair operation, but each aided design (CAD) with computer-aided manufacturing
has some drawbacks [3,4] . For instance, variable quality, (CAM), has been developed to manufacture porous
limited availability, chronic donor site pain, and second structures with desirable porosity, precise shape, and
surgery requirement restrict their extensive applications, adjustable pore size [26-28] . Furthermore, 3D printing
rendering it vital to seek alternatives. Consequently, is a promising technique for fabricating orthopedic
synthetic bone-graft scaffolds were developed to overcome implants for tissue engineering by virtue of customizable
the inherent limitations of autografts and allografts, thus manufacturing and controlled hierarchical structures [29,30] .
attracting great interest in the orthopedic field [5,6] . Here, considering the advantages of β-TCP ceramic

The aim of bone tissue engineering is to regenerate and 3D printing technology, we designed and fabricated
damaged osseous tissue to its original state using bionic a novel β-TCP/titanium dioxide (TiO ) ceramic porous
2
scaffolds , relying on scaffolds that act as a platform to scaffold using a 3D gel-printing sintering for the first time.
[7]
motivate cells to adhere and spread with the ultimate goal Since TCP is brittle and has low tenacity , the TiO ,
[31]
2
of bone regeneration [8,9] . The bionic bone scaffolds must be which is also supposed to act as a base for nucleation, was
porous, characterized by the interconnected penetrating incorporated to improve the mechanical properties of
structure and pore with different sizes to sustain the growth scaffolds. Meanwhile, TiO can promote the adhesion of
2
of osteoblasts and provide a venue for vascularization [7,10,11] . bone cells with good biocompatibility [32,33] . The objective
Three-dimensional (3D) printing technology opens up new of this work was to explore the manufacturing process
opportunities for fabricating bone scaffolds with different of β-TCP/TiO ceramic porous scaffold with a systematic
2
extremely complex architectures and arbitrary shapes , characterization. Additionally, we demonstrated the
[12]
which is quite challenging for irregular bone defects adhesion, proliferation, and metabolic activity of the
by customization. Other than synthetic bone grafting MC3T3-E1cells on scaffolds to evaluate its potential in
granulation used in the therapy of small bone defects , the bone tissue engineering.
[10]
3D-printed porous scaffolds provide interconnected pores
and mechanical integrity, which are promising attributes in 2. Materials and methods
the treatment of large segmental defects .
[13]
2.1. Materials
Various biomaterials including bio-ceramics , β-TCP and TiO powder were obtained commercially
[14]
2
polymers and metal alloys, have been used to fabricate (Kunshan Technology, China). All the chemicals used
porous bone scaffolds . Among the different, calcium in this work, including gelatin, polyvinyl alcohol,
[15]
phosphate, typically the β-tricalcium phosphate (β-TCP) and biological reagent, were purchased from Aladdin
and hydroxyapatite (HA) [16,17] , is the most popular due Biochemical Technology Co., Ltd (Shanghai, China).
to its excellent bioactivity and biocompatibility . Since Other organic solvents and reagents were analytically pure
[18]
β-TCP and HA are the components of human bones, and purchased from Kelong Chemical Reagent Co., Ltd
their osteoconduction and osteointegration are similar to (Chengdu, China).
the natural bone , and they have been applied in bone
[19]
repair and reconstruction [20,21] . Several conventional routes 2.2. Preparation of β-TCP/TiO slurry and
2
have been adopted to fabricate porous β-TCP scaffolds. β-TCP/TiO ceramic
2
Tunable pore sizes and porosity can be attained using A stable slurry with the proper ratio of additives is
a space holder-assisted powder processing to fabricate fundamental to scaffold fabrication . In this study, β-TCP
[34]
β-TCP scaffolds, but uncontrolled shrinkage during ceramics containing different weight TiO (1–5 wt%)
2
sintering gives rise to the insufficient mechanical strength were produced via a molding-sintering method. First, 4 g
of scaffolds . Gel casting, summarized as a stable gel β-TCP powder, 1.8 mL gelatin solution (20 wt%), 0.2 mL
[22]
network in a casting mold which is sintered to decompose, PVA solution (20 wt%) and TiO powder were added into
2
is able to prepare ceramic scaffolds with high porosity a 5-mL beaker and stirred thoroughly to obtain a ceramic
but low interconnectivity . Another conventional pore- slurry. The ceramic slurry was then injected into a prepared
[23]
forming method, freeze casting, has been utilized to cylindrical mold with a diameter of 8 mm and a height of
manufacture porous ceramic scaffolds since the 2000s . 4 mm. Second, the ceramic billet was taken out quickly
[24]
The main shortcomings of freeze casting are the complexity from the mold after solidification. For the purpose of
of controllability and commonly low porosity with small preventing the deformation or collapse in the subsequent
pore size . Nevertheless, the aforementioned strategies degrease sintering process, the ceramic billet was put into a
[25]
Volume 9 Issue 2 (2023) 370 https://doi.org/10.18063/ijb.v9i2.673