Accelerated Osteogenic Response of Electrodynamically Stimulated Mg1-xCaxSi1-xZrxO3 (x = 0-0.4) Bioelectrets

MgSiO3-based biodegradable ceramics demonstrated remarkable potential for treating small-scale bone defects and temporary bone replacement. In addition, the dissolution behavior of MgSiO3 bioceramics can be tuned by doping of Ca and Zr elements at Mg and Si sites, respectively. The present study reported the influence of formation of Ca- and Zr-codoped Mg1-xCaxSi1-xZrxO3 (x = 0, 0.1, 0.2, 0.3, and 0.4) bioelectrets and electrodynamic stimulation toward improving their osteogenic response. Mg1-xCaxSi1-xZrxO3 electrets were successfully synthesized by a solid-state route. A detailed X-ray photoelectron spectroscopy (XPS) analyses revealed that the electrets produced oxygen-deficient active sites. The formation of Mg1-xCaxSi1-xZrxO3 electrets significantly increased the surface hydrophilicity. Inductively coupled plasma (ICP) analyses were used to examine the leaching behavior of Ca/Zr-codoped MgSiO3 bioceramics. In vitro cell culture analyses indicated that the osteogenesis of MG-63 cells was remarkably enhanced on the electrodynamic field-treated Mg1-xCaxSi1-xZrxO3 bioelectrets as compared to hydroxyapatite (HA). Moreover, a better osteogenic response was observed for higher concentrations of Ca (0.3 and 0.4) and Zr (0.3 and 0.4) doping in the MgSiO3 bioelectrets. Further, the mechanism of enhanced cellular functionality was revealed by the measurement of intracellular Ca2+.

Determination of Mechanical Properties of Epoxy Composite Materials Reinforced with Silicate Nanofillers Using Digital Image Correlation (DIC)

In this study, silicate nanofillers; dicalcium silicate, magnesium silicate, tricalcium silicate, and wollastonite; were synthesized using four different methods and incorporated into the epoxy resin to improve its mechanical properties. Characterization of the newly synthesized nanofillers was performed using Fourier-transformation infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The purpose of this study was to analyze newly developed composite materials reinforced with silicate nanoparticles utilizing tensile testing and a full-field non-contact 3D Digital Image Correlation (DIC) method. Analysis of deformation and displacement fields gives precise material behavior during testing. Testing results allowed a more reliable assessment of the structural integrity of epoxy composite materials reinforced using different silicate nanofillers. It was concluded that the addition of 3% of dicalcium silicate, magnesium silicate, tricalcium silicate, and wollastonite lead to the increasement of tensile strength up to 31.5%, 29.0%, 27.5%, and 23.5% in comparison with neat epoxy, respectively. In order to offer more trustworthy information about the viscoelastic behavior of neat epoxy and composites, a dynamic mechanical analysis (DMA) was also performed and rheological measurements of uncured epoxy matrix and epoxy suspensions were obtained.

Bioactive Ceramic Scaffolds for Bone Tissue Engineering by Powder Bed Selective Laser Processing: A Review

The implementation of a powder bed selective laser processing (PBSLP) technique for bioactive ceramics, including selective laser sintering and melting (SLM/SLS), a laser powder bed fusion (L-PBF) approach is far more challenging when compared to its metallic and polymeric counterparts for the fabrication of biomedical materials. Direct PBSLP can offer binder-free fabrication of bioactive scaffolds without involving postprocessing techniques. This review explicitly focuses on the PBSLP technique for bioactive ceramics and encompasses a detailed overview of the PBSLP process and the general requirements and properties of the bioactive scaffolds for bone tissue growth. The bioactive ceramics enclosing calcium phosphate (CaP) and calcium silicates (CS) and their respective composite scaffolds processed through PBSLP are also extensively discussed. This review paper also categorizes the bone regeneration strategies of the bioactive scaffolds processed through PBSLP with the various modes of functionalization through the incorporation of drugs, stem cells, and growth factors to ameliorate critical-sized bone defects based on the fracture site length for personalized medicine.

Structural and Biomedical Properties of Common Additively Manufactured Biomaterials: A Concise Review

Biomaterials are in high demand due to the increasing geriatric population and a high prevalence of cardiovascular and orthopedic disorders. The combination of additive manufacturing (AM) and biomaterials is promising, especially towards patient-specific applications. With AM, unique and complex structures can be manufactured. Furthermore, the direct link to computer-aided design and digital scans allows for a direct replicable product. However, the appropriate selection of biomaterials and corresponding AM methods can be challenging but is a key factor for success. This article provides a concise material selection guide for the AM biomedical field. After providing a general description of biomaterial classes—biotolerant, bioinert, bioactive, and biodegradable—we give an overview of common ceramic, polymeric, and metallic biomaterials that can be produced by AM and review their biomedical and mechanical properties. As the field of load-bearing metallic implants experiences rapid growth, we dedicate a large portion of this review to this field and portray interesting future research directions. This article provides a general overview of the field, but it also provides possibilities for deepening the knowledge in specific aspects as it comprises comprehensive tables including materials, applications, AM techniques, and references.

Advanced Biomaterials and Techniques for Oral Tissue Engineering and Regeneration-A Review

The reconstruction or repair of oral and maxillofacial functionalities and aesthetics is a priority for patients affected by tooth loss, congenital defects, trauma deformities, or various dental diseases. Therefore, in dental medicine, tissue reconstruction represents a major interest in oral and maxillofacial surgery, periodontics, orthodontics, endodontics, and even daily clinical practice. The current clinical approaches involve a vast array of techniques ranging from the traditional use of tissue grafts to the most innovative regenerative procedures, such as tissue engineering. In recent decades, a wide range of both artificial and natural biomaterials and scaffolds, genes, stem cells isolated from the mouth area (dental follicle, deciduous teeth, periodontal ligament, dental pulp, salivary glands, and adipose tissue), and various growth factors have been tested in tissue engineering approaches in dentistry, with many being proven successful. However, to fully eliminate the problems of traditional bone and tissue reconstruction in dentistry, continuous research is needed. Based on a recent literature review, this paper creates a picture of current innovative strategies applying dental stem cells for tissue regeneration in different dental fields and maxillofacial surgery, and offers detailed information regarding the available scientific data and practical applications.

Indirect selective laser sintering-printed microporous biphasic calcium phosphate scaffold promotes endogenous bone regeneration via activation of ERK1/2 signaling

The fabrication technique determines the physicochemical and biological properties of scaffolds, including the porosity, mechanical strength, osteoconductivity, and bone regenerative potential. Biphasic calcium phosphate (BCP)-based scaffolds are superior in bone tissue engineering due to their suitable physicochemical and biological properties. We developed an indirect selective laser sintering (SLS) printing strategy to fabricate 3D microporous BCP scaffolds for bone tissue engineering purposes. The green part of the BCP scaffold was fabricated by SLS at a relevant low temperature in the presence of epoxy resin (EP), and the remaining EP was decomposed and eliminated by a subsequent sintering process to obtain the microporous BCP scaffolds. Physicochemical properties, cell adhesion, biocompatibility, in vitro osteogenic potential, and rabbit critical-size cranial bone defect healing potential of the scaffolds were extensively evaluated. This indirect SLS printing eliminated the drawbacks of conventional direct SLS printing at high working temperatures, i.e. wavy deformation of the scaffold, hydroxyapatite decomposition, and conversion of β-tricalcium phosphate (TCP) to α-TCP. Among the scaffolds printed with various binder ratios (by weight) of BCP and EP, the scaffold with 50/50 binder ratio (S4) showed the highest mechanical strength and porosity with the smallest pore size. Scaffold S4 showed the highest effect on osteogenic differentiation of precursor cells in vitro, and this effect was ERK1/2 signaling-dependent. Scaffold S4 robustly promoted precursor cell homing, endogenous bone regeneration, and vascularization in rabbit critical-size cranial defects. In conclusion, BCP scaffolds fabricated by indirect SLS printing maintain the physicochemical properties of BCP and possess the capacity to recruit host precursor cells to the defect site and promote endogenous bone regeneration possibly via the activation of ERK1/2 signaling.

A Novel MgO-CaO-SiO₂ System for Fabricating Bone Scaffolds with Improved Overall Performance

Although forsterite (Mg₂SiO₄) possesses good biocompatibility and suitable mechanical properties, the insufficient bioactivity and degradability hinders its further application. In this study, a novel MgO-CaO-SiO₂ system was developed by adding wollastonite (CaSiO₃) into Mg₂SiO₄ to fabricate bone scaffolds via selective laser sintering (SLS). The apatite-forming ability and degradability of the scaffolds were enhanced because the degradation of CaSiO₃ could form silanol groups, which could offer nucleation sites for apatite. Meanwhile, the mechanical properties of the scaffolds grew with increasing CaSiO₃ to 20 wt %. It was explained that the liquid phase of CaSiO₃ promoted the densification during sintering due to its low melting point. With the further increase in CaSiO₃, the mechanical properties decreased due to the formation of the continuous filling phase. Furthermore, the scaffolds possessed a well-interconnected porous structure and exhibited an ability to support cell adhesion and proliferation.

Hierarchical Structure and Mechanical Improvement of an n-HA/GCO-PU Composite Scaffold for Bone Regeneration

To improve the mechanical properties of bone tissue and achieve the desired bone tissue regeneration for orthopedic surgery, newly designed hydroxyapatite/polyurethane (HA/PU) porous scaffolds were developed via in situ polymerization. The results showed that the molecular modification of PU soft segments by glyceride of castor oil (GCO) can increase the scaffold compressive strength by 48% and the elastic modulus by 96%. When nano-HA (n-HA) particles were incorporated into the GCO-PU matrix, the compressive strength and elastic modulus further increased by 49 and 74%, from 2.91 to 4.34 MPa and from 95 to 165.36 MPa, respectively. The n-HA particles with fine dispersity not only improved the interface bonding with the GCO-PU matrix but also provided effective bioactivity for bonding with bone tissue. The hierarchical structure and mechanical quality of the n-HA/GCO-PU composite scaffold were determined to be appropriate for the growth of cells and the regeneration of bony tissues, demonstrating promising prospects for bone repair and regeneration.

Alginate Microspheroid Encapsulation and Delivery of MG-63 Cells Into Polycaprolactone Scaffolds: A New Biofabrication Approach for Tissue Engineering Constructs

Scaffolds play an important role in tissue engineering by providing structural framework and a surface for cells to attach, proliferate, and secrete extracellular matrix (ECM). In order to enable efficient tissue formation, delivering sufficient cells into the scaffold three-dimensional (3D) matrix using traditional static and dynamic seeding methods continues to be a critical challenge. In this study, we investigate a new cell delivery approach utilizing deposition of hydrogel-cell encapsulated microspheroids into polycaprolactone (PCL) scaffolds to improve the seeding efficiency. Three-dimensional-bioplotted PCL constructs (0 deg/90 deg lay down, 284 ± 6 μm strand width, and 555 ± 8 μm strand separation) inoculated with MG-63 model bone cells encapsulated within electrostatically generated calcium-alginate microspheroids (Ø 405 ± 13 μm) were evaluated over seven days in static culture. The microspheroids were observed to be uniformly distributed throughout the PCL scaffold cross section. Encapsulated cells remained viable within the constructs over the test interval with the highest proliferation noted at day 4. This study demonstrates the feasibility of the new approach and highlights the role and critical challenges to be addressed to successfully utilize 3D-bioprinting for microencapsulated cell delivery.

A review on powder-based additive manufacturing for tissue engineering: selective laser sintering and inkjet 3D printing

Since most starting materials for tissue engineering are in powder form, using powder-based additive manufacturing methods is attractive and practical. The principal point of employing additive manufacturing (AM) systems is to fabricate parts with arbitrary geometrical complexity with relatively minimal tooling cost and time. Selective laser sintering (SLS) and inkjet 3D printing (3DP) are two powerful and versatile AM techniques which are applicable to powder-based material systems. Hence, the latest state of knowledge available on the use of AM powder-based techniques in tissue engineering and their effect on mechanical and biological properties of fabricated tissues and scaffolds must be updated. Determining the effective setup of parameters, developing improved biocompatible/bioactive materials, and improving the mechanical/biological properties of laser sintered and 3D printed tissues are the three main concerns which have been investigated in this article.