Use of Micro-Computed Tomography to Nondestructively Characterize Biomineral Coatings on Solid Freeform Fabricated Poly (L-Lactic Acid) and Poly (ɛ-Caprolactone) Scaffolds In Vitro and In Vivo

Abstract

Biomineral coatings have been extensively used to enhance the osteoconductivity of polymeric scaffolds. Numerous porous scaffolds have previously been coated with a bone-like apatite mineral through incubation in simulated body fluid (SBF). However, characterization of the mineral layer formed on scaffolds, including the amount of mineral within the scaffolds, often requires destructive methods. We have developed a method using micro-computed tomography (m-CT) scanning to nondestructively quantify the amount of mineral in vitro and in vivo on biodegradable scaffolds made of poly (L-lactic acid) (PLLA) and poly (e-caprolactone) (PCL). PLLA and PCL scaffolds were fabricated using an indirect solid freeform fabrication (SFF) technique to achieve orthogonally interconnected pore architectures. Biomineral coatings were formed on the fabricated PLLA and PCL scaffolds after incubation in modified SBF (mSBF). Scanning electron microscopy and X-ray diffraction confirmed the formation of an apatite-like mineral. The scaffolds were implanted into mouse ectopic sites for 3 and 10 weeks. The presence of a biomineral coating within the porous scaffolds was confirmed through plastic embedding and m-CT techniques. Tissue mineral content (TMC) and volume of mineral on the scaffold surfaces detected by m-CT had a strong correlation with the amount of calcium measured by the orthocresolphthalein complex-one (OCPC) method before and after implantation. There was a strong correlation between OCPC preand postimplantation and m-CT measured TMC (R 2 = 0.96 preimplant; R 2 = 0.90 postimplant) and mineral volume (R 2 = 0.96 preimplant; R 2 = 0.89 postimplant). The m-CT technique showed increases in mineral following implantation, suggesting that m-CT can be used to nondestructively determine the amount of calcium on coated scaffolds.

Biomineral Coating Increases Bone Formation by Ex Vivo BMP‐7 Gene Therapy in Rapid Prototyped Poly(l‐lactic acid) (PLLA) and Poly(ε‐caprolactone) (PCL) Porous Scaffolds

“…A smoother surface was observed on the uncoated PLLA and PCL scaffolds (Figure j,l,n,p), while the coated PLLA and PCL scaffolds had a rougher surface (Figure i,k,m,o). Nanoscale plate‐like crystalline structures were observed in the mineral coating on both coated PLLA and PCL scaffolds ( Figure a,b) provided from our previous publication with permission . Analysis of the biomineral composition by X‐ray energy‐dispersive spectroscopy (XEDS) showed that the mineral was composed primarily of calcium and phosphorous with a Ca/P ratio of 1.58 for the coated PLLA scaffold (Figure c) and 1.56 for the coated PCL scaffold (Figure d), which are both in the range of biological apatites.…”

“…The gross images of the fabricated scaffolds are shown in Figure a–d provided from our previous publication with permission . The uncoated PLLA and PCL scaffolds had similar 3D architecture and surface morphology, which became less transparent after mineral coating.…”

“…To address these needs, we combined SFF scaffolds with biomineral coating using two types of biodegradable polymers, PLLA and PCL. We previously characterized this coating on design 3D printed scaffolds with interconnected pore structures . In the present study, bone tissue was regenerated in ectopic site utilizing bone morphogenetic protein 7 (BMP‐7)‐transduced human gingival fibroblasts (HGFs) delivered from the scaffolds, a commonly used model for bone tissue engineering .…”

Design, construction and mechanical testing of digital 3D anatomical data-based PCL–HA bone tissue engineering scaffold

“…[29][30][31]. The 3D anatomical data are often limited by the software packages of CT machine workstation instead of by the digitalization of human anatomic structure, therefore it could not be connected to the CAD post-processing, processing and computer-aided manufacturing (CAM) of reverse engineering, thus the RP modeling of reverse engineering could not be completed [11,[32][33][34]. In this paper, the digital reconstruction performed the CT data post-processing in Mimics, forming the digitized anatomical data that CAD software could recognize, then looked for the solutions comprehensively based on the integrated deformation conditions, which was finally connected CAD/ CAM for the design and manufacturing of ABTES.…”

Design Control for Clinical Translation of 3D Printed Modular Scaffolds

“…To build these complex designs, we utilize 3D printing, specifically laser sintering as the fundamental modular fabrication process. 26,30,33 Additional modular processes include fluid or gas based functionalization, in which gas or fluid is forced through the pores to modify the scaffold surface, for example creating osteoconductive nanocoatings 27 or chemical vapor deposition (CVD) coatings to which viruses may be attached for gene therapy. 16 …”