Surface modification of beta-tricalcium phosphate scaffolds with topological nanoapatite coatings

Enhanced Osteogenic Differentiation via Collagen and BMP-2 Mimetic Peptide Conjugation to β-TCP Scaffolds Using a Cold Atmospheric Plasma-Assisted Strategy

Bone defects arising from trauma, disease, or surgical intervention represent significant challenges. Developing effective bone tissue engineering strategies to address these issues and promote repair is crucial. β-Tricalcium phosphate (β-TCP) has emerged as a promising synthetic graft due to its porous, degradable structure and excellent biocompatibility. However, the lack of biological cues in β-TCP limits its functionality, requiring different surface modification strategies. Bone morphogenetic protein-2 mimetic peptide (BMP; NSVNSKIPKACCVPTELSAI) and collagen mimetic peptide (CMP; GTPGPQGIAGQRGVV) have a known significant therapeutic potential due to their ability to enhance cell attachment and osteogenic differentiation. Herein, a peptide functionalization strategy for β-TCP scaffolds was introduced. Briefly, β-TCP was treated with cold atmospheric plasma (CAP) to create functional hydroxyl groups on the surface of the β-TCP. Subsequently, peptides were conjugated by using a three-step method: (1) silanization with APTES, (2) EDC activation, and (3) peptide conjugation. The successful surface modification with CAP and peptide conjugation was confirmed via XRD, FTIR, and Raman analysis. Furthermore, the effects of BMP and CMP peptides on osteogenic differentiation after CAP treatment were investigated in human mesenchymal stem cells (hMSCs). Both β-TCP/BMP and β-TCP/CMP scaffolds demonstrated excellent biocompatibility with hMSCs, enhancing cell proliferation and promoting osteogenic differentiation. Remarkably, β-TCP/CMP showed better results in terms of proliferation and differentiation compared with β-TCP/BMP. These findings highlight the clinical potential of peptide-functionalized β-TCP scaffolds for bone tissue engineering while also providing a promising methodology for β-TCP functionalization.

Cytotoxicity Study of UV-Laser-Irradiated PLLA Surfaces Subjected to Bio-Ceramisation: A New Way towards Implant Surface Modification

In this research we subjected samples of poly(L-lactide) (PLLA) extruded film to ultraviolet (193 nm ArF excimer laser) radiation below the ablation threshold. The modified film was immersed in Simulated Body Fluid (SBF) at 37 °C for 1 day or 7 days to obtain a layer of apatite ceramic (CaP) coating on the modified PLLA surface. The samples were characterized by means of optical profilometry, which indicated an increase in average roughness (Ra) from 25 nm for the unmodified PLLA to over 580 nm for irradiated PLLA incubated in SBF for 1 day. At the same time, the water contact angle decreased from 78° for neat PLLA to 35° for irradiated PLLA incubated in SBF, which suggests its higher hydrophilicity. The obtained materials were investigated by means of cell response fibroblasts (3T3) and macrophage-like cells (RAW 264.7). Properties of the obtained composites were compared to the unmodified PLLA film as well as to the UV-laser irradiated PLLA. The activation of the PLLA surface by laser irradiation led to a distinct increase in cytotoxicity, while the treatment with SBF and the deposition of apatite ceramic had only a limited preventive effect on this harmful impact and depended on the cell type. Fibroblasts were found to have good tolerance for the irradiated and ceramic-covered PLLA, but macrophages seem to interact with the substrate leading to the release of cytotoxic products.

Recent Progress on Biodegradable Tissue Engineering Scaffolds Prepared by Thermally-Induced Phase Separation (TIPS)

Porous biodegradable scaffolds provide a physical substrate for cells allowing them to attach, proliferate and guide the formation of new tissues. A variety of techniques have been developed to fabricate tissue engineering (TE) scaffolds, among them the most relevant is the thermally-induced phase separation (TIPS). This technique has been widely used in recent years to fabricate three-dimensional (3D) TE scaffolds. Low production cost, simple experimental procedure and easy processability together with the capability to produce highly porous scaffolds with controllable architecture justify the popularity of TIPS. This paper provides a general overview of the TIPS methodology applied for the preparation of 3D porous TE scaffolds. The recent advances in the fabrication of porous scaffolds through this technique, in terms of technology and material selection, have been reviewed. In addition, how properties can be effectively modified to serve as ideal substrates for specific target cells has been specifically addressed. Additionally, examples are offered with respect to changes of TIPS procedure parameters, the combination of TIPS with other techniques and innovations in polymer or filler selection.

β-tricalcium phosphate for bone substitution: Synthesis and properties

β-tricalcium phosphate (β-TCP) is one the most used and potent synthetic bone graft substitute. It is not only osteoconductive, but also osteoinductive. These properties, combined with its cell-mediated resorption, allow full bone defects regeneration. Its clinical outcome is sometimes considered to be "unpredictable", possibly due to a poor understanding of β-TCP physico-chemical properties: β-TCP crystallographic structure is not fully uncovered; recent results suggest that sintered β-TCP is coated with a Ca-rich alkaline phase; β-TCP apatite-forming ability and osteoinductivity may be enhanced by a hydrothermal treatment; β-TCP grain size and porosity are strongly modified by the presence of minute amounts of β-calcium pyrophosphate or hydroxyapatite impurities. The aim of the present article is to provide a critical, but still rather comprehensive review of the current state of knowledge on β-TCP, with a strong focus on its synthesis and physico-chemical properties, and their link to the in vivo response. STATEMENT OF SIGNIFICANCE: The present review documents the richness, breadth, and interest of the research devoted to β-tricalcium phosphate (β-TCP). β-TCP is synthetic, osteoconductive, osteoinductive, and its resorption is cell-mediated, thus making it one of the most potent bone graft substitutes. This comprehensive review reveals that there are a number of aspects, such as surface chemistry, crystallography, or stoichiometry deviations, that are still poorly understood. As such, β-TCP is still an exciting scientific playground despite a 50 year long history and > 200 yearly publications.

3D-Printed Bioactive Ca3SiO5 Bone Cement Scaffolds with Nano Surface Structure for Bone Regeneration

Silicate bioactive materials have been widely studied for bone regeneration because of their eminent physicochemical properties and outstanding osteogenic bioactivity, and different methods have been developed to prepare porous silicate bioactive ceramics scaffolds for bone-tissue engineering applications. Among all of these methods, the 3D-printing technique is obviously the most efficient way to control the porous structure. However, 3D-printed bioceramic porous scaffolds need high-temperature sintering, which will cause volume shrinkage and reduce the controllability of the pore structure accuracy. Unlike silicate bioceramic, bioactive silicate cements such as tricalcium silicate (Ca₃SiO₅ and C₃S) can be self-set in water to obtain high mechanical strength under mild conditions. Another advantage of using C₃S to prepare 3D scaffolds is the possibility of simultaneous drug loading. Herein, we, for the first time, demonstrated successful preparation of uniform 3D-printed C₃S bone cement scaffolds with controllable 3D structure at room temperature. The scaffolds were loaded with two model drugs and showed a loading location controllable drug-release profile. In addition, we developed a surface modification process to create controllable nanotopography on the surface of pore wall of the scaffolds, which showed activity to enhance rat bone-marrow stem cells (rBMSCs) attachment, spreading, and ALP activities. The in vivo experiments revealed that the 3D-printed C₃S bone cement scaffolds with nanoneedle-structured surfaces significantly improved bone regeneration, as compared to pure C₃S bone cement scaffolds, suggesting that 3D-printed C₃S bone cement scaffolds with controllable nanotopography surface are bioactive implantable biomaterials for bone repair.

Biosilicate scaffolds for bone regeneration: influence of introducing SrO

Strontium (Sr), a bioactive element in natural bone, plays a crucial role in stimulating bone remodeling and inhibiting bone resorption.

Preparation and properties of g-TTCP/PBS nanocomposites and its in vitro biocompatibility assay

In an effort to decrease the aggregation of tetracalcium phosphate (TTCP, Ca4(PO4)2O) in composites and develop better bone substitute materials, a series of poly(l-lactic acid) (PLLA)-grafted TTCP (g-TTCP) particles were prepared by a ring-opening polymerization with l-lactide (the monomer for synthesizing PLLA) in the presence of catalyst stannous octoate [Sn(Oct)2]. The g-TTCP/poly(1,4-butylene succinate) (PBS) composites with the different g-TTCP contents were prepared via melting processing. The bonding between the PLLA and the TTCP particles was analyzed by FTIR, TG, (1)H NMR and XPS. The results confirmed that the PLLA was grafted on the surface of the TTCP particles. Time-dependent phase monitoring indicated that the g-TTCP had enhanced dispersion in the PBS solution. Water contact angle measurement and cell culture were also used to investigate the properties of the g-TTCP/PBS composites. The g-TTCP in composites provided more favorable environments for rat osteoblast to attach and grow on the surface of the g-TTCP/PBS composites. Cell proliferated well in the extracted solution of the g-TTCP/PBS composites with different g-TTCP content, and there was no necrotic or suspended cells appeared.