Direct-write assembly of 3D scaffolds using colloidal calcium phosphates inks

Abstract

Additive manufacture techniques using concentrated colloidal inks are a promising approach for creating three-dimensional (3D) calcium phosphates scaffolds for bone repair and regeneration. Among those, the direct-write assembly allows building scaffolds with precise size and geometry. In the present work, commercial β-TCP and HA were used to produce two types of colloidal ink. According to the ink composition used to build the scaffolds, two different groups were obtained. Group I: scaffolds produced with β-TCP-based ink; and Group II: scaffolds produced with biphasic CaP-based ink (BCP). The 3D scaffolds were assembled in a cylindrical shape (Φ = 8mm x H= 16 mm) with interconnected pore channels of approximately 500μm by robotic deposition of 64 layers using a robocasting machine. The mechanical compression property of the scaffolds was determined using universal testing machine. To assure the controlled geometry of the scaffolds, digital images were obtained by reconstructing each individual scan obtained with a micro-computed tomography. An optical contact angle measurement system was used to evaluate the wettability of the materials. After analyzing the results it was concluded that: the robocasting system is suitable for building 3D periodic calcium phosphates scaffolds; the direct-write assembly didn't change the hydrophilic characteristic of CaPs; and presented mean compressive strength around 11 MPa (β-TCP group) and 15 MPa (BCP group), which is compatible with trabecular bone.

Simple additive manufacturing of an osteoconductive ceramic using suspension melt extrusion

“…In the compressive test, the implants had an average Young's modulus of 247 MPa and compressive strength of 11.6 MPa, both values lie within the range of normal human skull bone, Young's modulus and compressive strength ranging from 72 MPa to 3654 MPa (average: 1393MPa) and from 5.3 MPa to 108.2 MPa (average: 36.5MPa), respectively [36]. The values are comparable with those achieved with aqueous TCP formulations [37]. A high activity of alkaline phosphatase on day 2+7 in cell culture was observed, alkaline phosphatase releases phosphate for calcium phosphate mineralization, and an increase in mineralization was observed on day 2+25 using µCT.…”

Robocasting of ceramic glass scaffolds: Sol–gel glass, new horizons

“…A scaffold with high macro-sized interconnectivity is a crucial element for the cells to be able to migrate into to the centre of the scaffold, and to allow a sufficient supply of nutrient for the cells to grow [9]. Many techniques have been used to build scaffolds, such as replica templating [10], foaming [11], starch consolidation [12], freeze casting [13], and robocasting [14][15][16][17]. Among these methods, robocasting offers a better control on the macro-pores´shape and size, as well as the possibility to produce tailored, shaped implants for an individual patient.…”

A biocompatible thermoset polymer binder for Direct Ink Writing of porous titanium scaffolds for bone tissue engineering

“…Meanwhile, the strength of the samples is significantly greater than that of human cortical bone [14]. Both the 0.2% yield strength (0.2) and compressive strength at 30% compression (30) are superior to those of porous titanium scaffolds manufactured through standard powder metallurgy techniques employing a space holder approach [13,34] and ceramic scaffolds produced using DIW techniques [31][32][33]. These promising results show the suitability of the porous titanium samples manufactured by the DIW for implant applications.…”

“…colloidal calcium phosphates inks [33] 15 ± 6.9 (BCP) 36 (BCP) printing are also shown in Figure 2(B). Compared to porous scaffold manufactured by metallic 3d printing such as Selective Laser Melting [30] and Electron Beam Melting [19], the effective Young's modulus of the porous DIW processed titanium samples is relatively low and within the range of that of human cortical bone, curtailing any potential "stress shielding" effects [14].…”