Osteoinductive superparamagnetic Fe nanocrystal/calcium phosphate heterostructured microspheres

A magnetic calcium phosphate for selective capture of multi-phosphopeptides

The specific enrichment of multi-phosphopeptides in the presence of non-phosphopeptides and mono-phosphopeptides was still a challenge for phosphoproteomics research. Most of these enrichment materials relied on Zn, Ti, Sn, and other rare precious metals as the bonding center to enrich multi-phosphopeptides while ignoring the use of common metal elements. The addition of rare metals increased the cost of the experiment, which was not conducive to their large-scale application in biomedical proteomics laboratories. In addition, multiple high-speed centrifugation steps also resulted in the loss of low-abundance multi-phosphopeptides in the treatment procedure of biological samples. This study proposed the use of calcium, a common element, as the central bonding agent for synthesizing magnetic calcium phosphate materials (designated as CaP-Fe3O4). These materials aim to capture multi-phosphopeptides and identifying phosphorylation sites. The current results demonstrate that CaP-Fe3O4 exhibited excellent selection specificity, high sensitivity, and stability in the enrichment of multi-phosphopeptides and the identification of phosphorylation sites. Additionally, the introduction of magnetic separation not only reduced the time required for multi-phosphopeptides enrichment but also prevented the loss of these peptides during high-speed centrifugation. These findings contribute to the widespread application and advancement of phosphoproteomics research.

Development of Biomaterials Based on Biomimetic Trace Elements Co-Doped Hydroxyapatite: Physical, In Vitro Osteoblast-like Cell Growth and In Vivo Cytotoxicity in Zebrafish Studies

Synthesized hydroxyapatite (sHA)-calcium phosphate (CaP) based biomaterials play a vital role and have been widely used in the process of bone regeneration for bone defect repair, due to their similarities to the inorganic components of human bones. However, for bone tissue engineering purpose, the composite components, physical and biological properties, efficacy and safety of sHA still need further improvements. In this work, we synthesized inhomogeneous hydroxyapatite based on biomimetic trace elements (Mg, Fe, Zn, Mn, Cu, Ni, Mo, Sr, Co, BO₃^3-, and CO₃^2-) co-doped into HA (THA) (Ca_10-δM_δ(PO₄)_5.5(CO₃)_0.5(OH)₂, M = trace elements) via co-precipitation from an ionic solution. The physical properties, their bioactivities using in vitro osteoblast cells, and in vivo cytotoxicity using zebrafish were studied. By introducing biomimetic trace elements, the as-prepared THA samples showed nanorod (needle-like) structures, having a positively charged surface (6.49 meV), and showing paramagnetic behavior. The bioactivity studies demonstrated that the THA substrate can induce apatite particles to cover its surface and be in contact with surrounding simulated body fluid (SBF). In vitro biological assays revealed that the osteoblast-like UMR-106 cells were well-attached with growth and proliferation on the substrate's surface. Upon differentiation, enhanced ALP (alkaline phosphatase) activity was observed for bone cells on the surface of the THA compared with that on the control substrates (sHA). The in vivo performance in embryonic zebrafish studies showed that the synthesized THA particles are nontoxic based on the measurements of essential parameters such as survivability, hatching rate, and the morphology of the embryo. The mechanism of the ions release profile using digital conductivity measurement revealed that sustained controlled release was successfully achieved. These preliminary results indicated that the synthesized THA could be a promising material for potential practical applications in bone tissue engineering.

Tumor Diagnosis and Therapy Mediated by Metal Phosphorus-Based Nanomaterials

Metal phosphorus-based nanomaterials (Metal-P NMs) including metal phosphate nanomaterials, metal phosphide nanomaterials, and metal-black phosphorus (Metal-BP) nanocomposite are widely used in the field of biomedicine owing to their excellent physical and chemical properties, biocompatibility, and biodegradability. In recent years, metal phosphate nanomaterials and Metal-BP nanocomposite acted as medicine delivery system have made breakthroughs in tumor diagnosis including magnetic resonance imaging, fluorescence imaging, photoacoustic imaging, nuclear imaging, and therapies including chemotherapy, gene therapy, photothermal therapy, photodynamic therapy, and radiation therapy. Metal phosphate nanomaterials have good biodegradability, especially calcium-based metal phosphate nanomaterials can be dissolved into nontoxic ions and participate in the metabolisms of normal organs. Compared with metal phosphate nanomaterials, metal phosphide nanomaterials have excellent optical, magnetic, and catalytic properties, which can be used as multifunctional diagnostic nanoplatforms and therapeutic agents for chemodynamic therapy, photothermal therapy, or immunotherapy. The latest developments in Metal-P NMs, covering the range of preparation methods and biological applications, such as serving as drug carriers, tumor diagnosis, and therapy, are focused. All in all, the current trends, key issues, future prospects and challenges of Metal-P NMs are concluded and discussed, which are important for the development of this research field and shining more lights on this direction.

Bio-inspired polymeric iron-doped hydroxyapatite microspheres as a tunable carrier of rhBMP-2

Hybrid superparamagnetic microspheres with bone-like composition, previously developed by a bio-inspired assembling/mineralization process, are evaluated for their ability to uptake and deliver recombinant human bone morphogenetic protein-2 (rhBMP-2) in therapeutically-relevant doses along with prolonged release profiles. The comparison with hybrid non-magnetic and with non-mineralized microspheres highlights the role of nanocrystalline, nanosize mineral phases when they exhibit surface charged groups enabling the chemical linking with the growth factor and thus moderating the release kinetics. All the microspheres show excellent osteogenic ability with human mesenchymal stem cells whereas the hybrid mineralized ones show a slow and sustained release of rhBMP-2 along 14 days of soaking into cell culture medium with substantially bioactive effect, as reported by assay with C2C12 BRE-Luc cell line. It is also shown that the release extent can be modulated by the application of pulsed electromagnetic field, thus showing the potential of remote controlling the bioactivity of the new micro-devices which is promising for future application of hybrid biomimetic microspheres in precisely designed and personalized therapies.

Fe and Zn co-substituted beta-tricalcium phosphate (β-TCP): Synthesis, structural, magnetic, mechanical and biological properties

In the present work, Fe³⁺ and Zn²⁺ co-substituted β-tricalcium phosphate (β-TCP) has been synthesized by wet co-precipitation method. Co-substitution level in the range from 1 to 5 mol% has been studied. Thermal decomposition of as-prepared precipitates was shown to be affected by introducing of foreign ions, decreasing the decomposition temperature of precursor. It was determined that partial substitution of Ca²⁺ by Fe³⁺ and Zn²⁺ ions leads to the change in lattice parameters, which gradually decrease as doping level increases. Lattice distortion was also confirmed by means of Raman spectroscopy, which showed gradual change of the peaks shape in the Raman spectra. Rietveld refinement and electron paramagnetic resonance study confirmed that Fe³⁺ ions occupy only one Ca crystallographic site until Fe³⁺ and Zn²⁺ substitution level reaches 5 mol%. All co-substituted samples revealed paramagnetic behavior, magnetization of powders was determined to be linearly dependent on concentration of Fe³⁺ ions. Cytotoxicity of the synthesized species was estimated by in vivo assay using zebrafish (Danio rerio) and revealed non-toxic nature of the samples. Preparation of ceramic bodies from the powders was performed, however the results obtained on Vickers hardness of the ceramics did not show improvement in mechanical properties induced by co-substitution.

Preparation and Application of Magnetic Responsive Materials in Bone Tissue Engineering

At present, many kinds of materials are used for bone tissue engineering, such as polymer materials, metals, etc., which in general have good biocompatibility and mechanical properties. However, these materials cannot be controlled artificially after implantation, which may result in poor repair performance. The appearance of the magnetic response material enables the scaffolds to have the corresponding ability to the external magnetic field. Within the magnetic field, the magnetic response material can achieve the targeted release of the drug, improve the performance of the scaffold, and further have a positive impact on bone formation. This paper first reviewed the preparation methods of magnetic responsive materials such as magnetic nanoparticles, magnetic polymers, magnetic bioceramic materials and magnetic alloys in recent years, and then introduced its main applications in the field of bone tissue engineering, including promoting osteogenic differentiation, targets release, bioimaging, cell patterning, etc. Finally, the mechanism of magnetic response materials to promote bone regeneration was introduced. The combination of magnetic field treatment methods will bring significant progress to regenerative medicine and help to improve the treatment of bone defects and promote bone tissue repair.

Surface Morphologies and Mechanical Properties of Mg-Zn-Ca Amorphous Alloys under Chemistry-Mechanics Interactive Environments

Mg-Zn-Ca amorphous alloys are considered as potential bone implants. A large number of works have focused on the alloys under free corrosion environment. However, the real service environment of bone implants is a kind of chemistry-mechanics interactive environment in which the materials not only suffer corrosion by body fluids but also bear applied force induced by body movement. In order to imitate the real service environment, surface morphologies and mechanical properties of Mg-Zn-Ca amorphous alloys were studied under different chemistry-mechanics interactive environments in this paper. It was found that cracks and Ca/Mg phosphates formed on the surface of amorphous alloys. The compressive strength of the alloys decreased seriously but could still reach an acceptable value to avoid material failure. Fan-shaped patterns found on all the samples implied that brittle fracture was the main fracture form. Moreover, vein-like patterns could still be found in some areas, showing a locally plastic deformation. This was the reason why the alloy could maintain a high compressive strength after severe and interactive treatments. The study could guide related works in the establishment of experimental environments in the future, which will facilitate a more accurate biomedical evaluation of bone implants.

Intracellular Interaction of Hydroxyapatite-Based Nanocrystals with Uniform Shape and Traceable Fluorescence

The intracellular interaction between osteoblasts and hydroxyapatite (HA) is of great importance for future applications of HA nanocrystals in tracing cell differentiation and bone regeneration. This research attempts to provide insight into the intracellular interaction between osteoblasts and synthetic HA nanocrystals by employing the uniform shape and fluorescence of terbium-doped HA nanocrystals jointly for the first time. When cultured for 7 days, the abundant cytoplasm of the osteoblasts could be clearly and homogeneously visualized via the green fluorescence of the internalized HA nanocrystals, which kept a uniform morphology but showed a slight size decrease and degradation; the gene expression of the osteoblasts was not obviously affected. However, on day 14, the uniform HA nanocrystals had degraded into smaller and irregular nanoparticles, and agglomeration had occurred. Meanwhile, multilayer membrane structures and vacuolization around the degraded HA particles appeared in the osteoblasts; the expression of genes largely decreased, or the genes could not be normally expressed. The results indicate that the morphology and composition change of the internalized HA nanocrystals and the microstructure change of the osteoblasts are closely related and correspond to each other. The feasible new method and insightful details will aid in future investigations of the interaction of synthetic HA nanocrystals with various cells. The results from the intracellular interaction also remind us to pay more attention to the in-depth study of HA nanoparticles used for bone repair and reconstruction.