Rod-like Hydroxyapatite Nanoparticles Research Articles

A Selective Reduction of Osteosarcoma by Mitochondrial Apoptosis Using Hydroxyapatite Nanoparticles.

BackgroundIn recent years, using hydroxyapatite nanoparticles (HANPs) for tumor therapy attracted increasing attention because HANPs were found to selectively suppress the growth of tumor cells but exhibit ignorable toxicity to normal cells.PurposeThis study aimed to investigate the capacities of HANPs with different morphologies and particle sizes against two kinds of osteosarcoma (OS) cells, human OS 143B cells and rat OS UMR106 cells.MethodsSix kinds of HANPs with different morphologies and particle sizes were prepared by wet chemical method. Then, the antitumor effect of these nanoparticles was characterized by means of in vitro cell experiments and in vivo tumor-bearing mice model. The underlying antitumor mechanism involving mitochondrial apoptosis was also investigated by analysis of intracellular calcium, expression of apoptosis-related genes, reactive oxygen species (ROS), and the endocytosis efficiency of the particles in tumor cells.ResultsBoth in vitro cell experiments and in vivo mice model evaluation revealed the anti-OS performance of HANPs depended on the concentration, morphology, and particle size of the nanoparticles, as well as the OS cell lines. Among the six HANPs, rod-like HANPs (R-HANPs) showed the best inhibitory activity on 143B cells, while needle-like HANPs (N-HANPs) inhibited the growth of UMR106 cells most efficiently. We further demonstrated that HANPs induced mitochondrial apoptosis by selectively raising intracellular Ca2+ and the gene expression levels of mitochondrial apoptosis-related molecules, and depolarizing mitochondrial membrane potential in tumor cells but not in MC3T3-E1, a mouse pre-osteoblast line. Additionally, the anti-OS activity of HANPs also linked with the endocytosis efficiency of the particles in the tumor cells, and their ability to drive oxidative damage and immunogenic cell death (ICD).ConclusionThe current study provides an effective strategy for OS therapy where the effectiveness was associated with the particle morphology and cell line.

One-pot ultrasonic-assisted synthesis of magnetic hydroxyapatite nanoparticles using mussel shell biowaste with the aid of trisodium citrate

The studies on hydroxyapatite (HAp) nanoparticles have prompted prospects for superior biomaterials in orthopedics and dentistry. In this work, one-pot ultrasonic-assisted synthesis of magnetic HAp nanoparticles was carried out using a mussel shell calcium source by incorporating Fe2+/Fe3+ ions during Ca-citrate complex formation. Characterization of prepared specimens revealed that Fe2+/Fe3+ ions integration at low concentrations (0.01:0.02 ratio) does not affect the phase purity of HAp nanoparticles while at high concentrations (0.1:0.2 ratio) produced HAp/Fe3O4 nanocomposite. The developed HAp/Fe3O4 nanocomposite was composed of spherical Fe3O4 nanoparticles (10 nm size) and rod-like HAp nanoparticles (5–10 nm width and 20–30 nm length), and it revealed soft ferromagnetic properties with coercivity (Hc) and saturation magnetization (Ms) values of 750 G and 7.05 emu/g, respectively. Furthermore, the developed HAp/Fe3O4 nanocomposite exhibited good bone-forming ability in SBF and accomplished hyperthermia temperature within 8 min at 400 A applied current. Hence, it can be a potential bone repair material with magnetic induction heating ability. Also, this study utilized mussel shell calcium precursor which is a cost-effective and ecologically friendly method.

Nanostructural control of transparent hydroxyapatite nanoparticle films using a citric acid coordination technique.

Hydroxyapatite (HA), as the main mineral component in hard tissues, has good biocompatibility. In particular, HA films are widely used as bioactive coatings for artificial bones and dental implants in biomedical fields. However, it is currently difficult to prepare a nanostructure-controlled HA film by a wet process for further applications. Herein, we report the synthesis of HA nanoparticles coordinated by citric acid (Cit/HA) based on the interactions between carboxylate and calcium ions to control the sizes and shapes of the hybrid nanoparticles, to improve their dispersibility in water and to eventually form uniform transparent films with nanospaces, and investigated the film formation mechanism. As compared with the well-known rod-like HA nanoparticles (size: 48 × 15 nm2), we successfully synthesized spherical and negatively charged Cit/HA nanoparticles (size: 25 × 23 nm2) to achieve highly transparent Cit/HA films using the spin-coating technique. The Cit/HA films had uniform and crack-free appearance. About the nanostructures, we found that the Cit/HA film surfaces had meso-scaled nanospaces with a diameter of 4.2 nm based on the regular arrangement of spherical nanoparticles, instead of the HA film with a nanospace diameter of 24.5 nm formed by non-uniform accumulation. Therefore, we successfully achieved the control of the nanospace sizes of the films with the nanoparticle arrangement and realized transparent nanoparticle film formation in a very simple way, which will provide more convenient bioceramic films for biomedical applications.

Assessment of Collagen-Based Nanostructured Biomimetic Systems with a Co-Culture of Human Bone-Derived Cells.

Osteoporosis is a worldwide disease resulting in the increase of bone fragility and enhanced fracture risk in adults. In the context of osteoporotic fractures, bone tissue engineering (BTE), i.e., the use of bone substitutes combining biomaterials, cells, and other factors, is considered a potential alternative to conventional treatments. Innovative scaffolds need to be tested in in vitro systems where the simultaneous presence of osteoblasts (OBs) and osteoclasts (OCs), the two main players of bone remodeling, is required to mimic their crosstalk and molecular cooperation. To this aim, two composite materials were developed, based on type I collagen, and containing either strontium-enriched mesoporous bioactive glasses or rod-like hydroxyapatite nanoparticles. The developed nanostructured systems underwent genipin chemical crosslinking and were then tested with an indirect co-culture of human trabecular bone-derived OBs and buffy coat-derived OC precursors, for 2–3 weeks. The favorable structural and biological properties of the materials proved to successfully support the viability, adhesion, and differentiation of cells, encouraging a further investigation of the developed bioactive systems as biomaterial inks for the 3D printing of more complex scaffolds for BTE.

Synthesis of Hydroxyapatite Nanoparticles by Controlled Precipitation in the Presence of Sodium Dodecyl Sulfate

Hydroxyapatite nanoparticles (NPs) have been synthesized by controlled precipitation in the presence of a surfactant, sodium dodecyl sulfate. The sizes, shapes, and structures of the NPs depend on the sequence of mixing the reagents . When the addition of sodium phosphate to a surfactant solution is followed by the addition of calcium nitrate, rodlike hydroxyapatite NPs are formed, the length of which decreases with a rise in surfactant concentration. As the sodium dodecyl sulfate concentration increases, the ζ-potential of the NPs decreases to zero; then, its absolute value grows to –55 mV. This suggests that a surfactant bilayer is formed on the NP surface, with the bilayer shielding the surface of the growing crystals. The shielding leads to the formation of smaller NPs at high surfactant concentrations. When the addition of calcium nitrate to the surfactant solution is followed by the addition of sodium phosphate, the synthesis most likely occurs on the surface of micelles, which partially consist of calcium dodecyl sulfate. Therefore, the sulfate phase remains preserved in the synthesized particles, which is confirmed by X-ray diffraction analysis. At higher surfactant concentrations in the reaction medium, the presence of flexible cylindrical micelles is possible. The precipitation of hydroxyapatite on the surface of such micelles results in the formation of wavy threadlike particles.

Characterization of Nano-Scale Hydroxyapatite Coating Synthesized from Eggshells Through Hydrothermal Reaction on Commercially Pure Titanium

Commercially pure titanium (c.p. Ti) is often used in biomedical implants, but its surface cannot usually combine with the living bone. A coating of hydroxyapatite (HA) on the surface of titanium implants provides excellent mechanical properties and has good biological activity and biocompatibility. For optimal osteocompatibility, the structure, size, and composition of HA crystals should be closer to those of biological apatite. Our results show that the surface of c.p. Ti was entirely covered by rod-like HA nanoparticles after alkali treatment and subsequent hydrothermal treatment at 150 °C for 48 h. Nano-sized apatite aggregates began to nucleate on HA-coated c.p. Ti surfaces after immersion in simulated body fluid (SBF) for 6 h, while no obvious precipitation was found on the uncoated sample. Higher apatite-forming ability (bioactivity) could be acquired by the samples after HA coating. The HA coating featured bone-like nanostructure, high crystallinity, and carbonate substitution. It can be expected that HA coatings synthesized from eggshells on c.p. Ti through a hydrothermal reaction could be used in dental implant applications in the future.

Ultrasonic assisted functionalization of MWCNT and synergistic electrocatalytic effect of nano-hydroxyapatite incorporated MWCNT-chitosan scaffolds for sensing of nitrofurantoin.

In the present work, we report the fabrication of stable composite of chitosan hydrogels (CHI) on multiwalled carbon nanotubes (MWCNT) using a simple ultrasonic-assisted method. Also, rod-like hydroxyapatite nanoparticles (HA NPs) were synthesised using a hydrothermal route and were incorporated into the highly conductive MWCNT-CHI scaffolds using an ultrasonication method. The functionalization of MWCNT and preparation of HA NPs on MWCNT-CHI nanocomposite were done using the sonication over the frequency of 37 kHz with the ultrasonic power capable of 150 W (Elmasonic Easy 60H bath sonicator). The resulting hybrid HA NPs/MWCNT-CHI nanocomposites have an excellent surface area and high surface to volume ratio, which leads to the sensitive detection of nitrofurantoin than pristine MWCNT and HA NPs. The complete elemental and morphological analyses of the HA NPs/MWCNT-CHI nanocomposites were characterised by XRD, FTIR, RAMAN, FESEM, TEM, EDX, and elemental mapping techniques. Electrochemical analysis of the HA NPs/MWCNT-CHI nanocomposites was carried out by cyclic voltammetry, electrochemical impedance spectroscopy and amperometry methods. The modified glassy carbon electrode (GCE) of HA NPs/MWCNT-CHI nanocomposites exhibit the nitrofurantoin detection activity at the linear range of 0.005-982.1 µM with the detection limit of 1.3 nM. The synergistic electrocatalytic activity of HA NPs/MWCNT-CHI nanocomposites modified GCE is correlated to the sensitivity of 0.16 µAµM-1 cm-2 with excellent precision and accuracy towards the sensing of nitrofurantoin.

Preparation of bioactive hydroxyapatite@halloysite and its effect on MC3T3-E1 osteogenic differentiation of chitosan film.

Halloysite nanotubes (HNTs) are widely used in biomedical field due to their special tubular structure and high reinforcing ability, while hydroxyapatite (HAP) is generally used in tissue engineering owing to its excellent biocompatibility and biological activity. In this work, hydroxyapatite@halloysite nanotubes(HAP@HNTs) hybrid was synthesized via a facial hydrothermal reaction process. The morphology, particle size, specific surface area, and chemical composition of the hybrid were thoroughly characterized by different techniques. Rod-like HAP nanoparticles can be anchored on the outer surface of the clay tubes, which lead to a maximum increase of 4.7 m2/g in the specific surface area of HAP@HNTs over that of HNTs. HAP nanoparticles have little effect on the pores of HNTs, but diffraction peak strength of HNTs is covered by the HAP crystals. HAP@HNTs exhibit improved cytocompatibility and possess osteogenic differentiation ability towards MC3T3-E1 preosteoblasts. Chitosan/HAP@HNTs composite films were then prepared by doping of HAP@HNTs into chitosan by solution mixing. HAP@HNTs can serve as a functional phase which enhances mechanical properties of chitosan films and osteogenic differentiation of MC3T3-E1 cells. This work provides a facial synthesis routine of bioactive HAP@HNTs, which combines the osteogenic activity of HAP and the good mechanical properties of HNTs. HAP@HNTs can be used a novel bone regeneration biomaterial as local delivery systems with improved osteoinductive properties.

Bone-like nano-hydroxyapatite coating on low-modulus Ti–5Nb–5Mo alloy using hydrothermal and post-heat treatments

Titanium and its alloys are widely used as biomaterials for orthopedic and dental implants because of their excellent biocompatibility and mechanical properties. However, they are considered to be bioinert; when they are inserted into the human body these implants cannot bond directly to the surrounding living bone. Through hydrothermal reaction and heat treatment, this study aimed to improve the bioactivity of a low-modulus Ti–5Nb–5Mo alloy with a hydroxyapatite (HA) surface coating that used eggshells as a Ca source. The results showed that after hydrothermal reaction at 200 °C for 48 h, the entire alkali-treated alloy surface was covered with amorphous calcium phosphate nanoparticles. When later heat-treated at various temperatures (400, 500 or 600 °C) for 48 h, the surface coating of Ti–5Nb–5Mo alloy was transformed into crystalline, rod-like HA nanoparticles. Additionally, FTIR analysis confirmed the production of HA with mixed AB-type carbonate substitutions. The HA coating exhibited a carbonate-containing composition, rod-like morphology, and nano-sized particles, all of which indicate a bone-like structure. To evaluate the bioactivity of the bone-like HA-coated Ti–5Nb–5Mo alloy, the capability of apatite formation on the alloy surface was assessed by immersion in a simulated body fluid (SBF). A dune-like apatite layer was densely deposited on the surface of the HA-coated Ti alloy after 6 h of immersion in the SBF. Notably, the ability of a Ti–5Nb–5Mo alloy subjected to sequential processing with alkali, hydrothermal, and heat treatments to form a bone-like HA nanoparticle coating was close to double that of its counterpart without an HA coating.

The anti-tumor effect of p53 gene-loaded hydroxyapatite nanoparticles in vitro and in vivo

This research focused on anti-tumor effect of pEGFP-C1-p53 (p53) gene-loaded hydroxyapatite (HAp) nanoparticles in vitro and in vivo. Four kinds of HAp nanoparticles, spherical HAp nanoparticles (S-HAp, diameter: 50 nm), needle-like HAp nanoparticles (N-HAp, average length: 110 nm and width: 30 nm), rod-like HAp nanoparticles (R-HAp, average length: 100 nm and width: 30 nm), and short-rod-like HAp nanoparticles (SR-HAp, average length: 40 nm and width: 30 nm), were prepared initially. The HAp nanoparticles with or without being modified by PEI (named HAp and HAp-PEI, respectively) have excellent biocompatibility as shown by MTT assay and crystal violet staining tests. Then, the subsequent MTT, Hocehst staining tests, and Western blot showed that the killing effect of p53-loaded HAp-PEI (HAp-PEI-p53) was effective with fair selectivity toward Hep-3B and HuH-7 cells’ cell lines. Moreover, HAp-PEI-p53 could inhibit the tumor growth in vivo, and the mechanism of tumor growth inhibition was verified by the hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, P53 protein immunohistochemistry, and transmission electron microscope of the tumor cell in vivo. We found that HAp-PEI-p53 has good anti-cancer effect in vitro and in vivo, especially for the S-HAp-PEI-p53. Tumor metastasis could be suppressed significantly by the S-HAp-PEI-p53 and N-HAp-PEI-p53 treatments by the in vivo imaging system. All these results lead to the conclusion that the particle sizes of HAp ranging from 100 to 200 nm are appropriate for cancer gene therapy and may be widely used in anti-cancer investigation.

Synthesis and Electrochemical Capacitive Performances of Novel Hierarchically Micro-Meso-Structured Porous Carbons Fabricated Using Microporous Rod-Like Hydroxyapatites as a Template

Electrochemical capacitors (ECs) are attractive energy storage systems for applications with high power requirements. Porous carbons are the materials that are most frequently used for the electrodes in ECs, because of their large surface area, high conductivity, chemical inertness, low cost, and tunable pore structure. Here, novel hierarchically micro-meso-structured porous carbons were synthesized, using microporous rod-like hydroxyapatite nanoparticles as a template and sucrose as a carbon source. The morphology and surface properties of the as-prepared porous carbons were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller surface analysis. The electrochemical capacitive performances were evaluated in an aqueous solution of 1 mol·L-1 H2SO4 using cyclic voltammetry, electrochemical impedance spectroscopy, and constant current charge/discharge tests. The resultant carbons showed a high surface area of more than 719.7 m2·g-1, large pore volumes of more than 1.32 cm3·g-1, and a disordered pore structure composed of randomly distributed micropores, collapsed mesopores, and interweaving rod-like mesopores that took the shape of the template. As the carbonization temperature was increased, the density of micropores and rod-like mesopores decreased, and a tri-modal pore size distribution appeared for the carbon sample carbonized at 900 ° C. Because of these unique characteristics, the electrode material originated from the porous carbon carbonized at 900 °C exhibited good electrochemical capacitive performances.

Hydrothermal synthesis and characterisation of glutamine-modified rod-like hydroxyapatite nanoparticles

In this study, an amino acid, glutamine, has been employed as the modifier in the hydrothermal synthesis of rod-like hydroxyapatite (HAp) nanoparticles. X-ray diffractometer results confirm the formation of a typical HAp phase without impurities and microscopic results indicate that the morphology and size of the as-prepared products could be controlled by adjusting the pH value of the hydrothermal system. Owing to a variety of amino acids and characteristics of as-synthesised nano-sized HAp, the findings may have implications in the large-scale controllable synthesis of well-defined HAp nanomaterials; it may also provide a general facile and low-cost method for the preparation of uniform nanostructured HAp by utilising biomolecules as modifiers.

Surfactant-Assisted Hydrothermal Synthesis of Hydroxyapatite Nanopowders

Rod-like hydroxyapatite nanoparticles (n-HAp) with a highly ordered nanostructure were prepared by hydrothermal synthesis from calcium chloride, and phosphoric acid, as calcium and phosphorus sources, respectively. Various surfactant families such as cationic (CTAB), anionic (SDS) and nonionic (Triton X-100) were used as regulators of the nucleation and crystal growth. The synthesized nanopowders were characterized using X-ray diffraction (XRD), Fourier transform infrared spectrograph (FTIR) and transmission electron microscopy (TEM). The rod-like morphology was obtained regardless of the surfactant used during the hydrothermal treatment, but the aspect ratio of the crystals was found to be surfactant dependent. The mechanism of crystal growth as well-oriented nanostructure is discussed.

High Throughput Methodology for Continuous Preparation of Hydroxyapatite Nanoparticles in a Microporous Tube-in-Tube Microchannel Reactor

A microporous tube-in-tube microchannel reactor (MTMCR) was successfully adopted to prepare hydroxyapatite (HAP) nanoparticles. The rodlike HAP nanoparticles with a mean size of 58 nm, a specific surface area of 49.32 m2/g, and a narrow size distribution were obtained in an MTMCR under a high throughput of 3 L/min. The mean particle size sharply decreased with increasing the continuous phase flow rate, while first decreased and subsequently increased with increasing the dispersed phase flow rate and the reactant concentration. The extension of the mixing distance led to the initial rapid and following slight decrease of the mean particle size. The size of HAP nanoparticles was also strongly dependent on the micropore size on the surface of inner tube. Small micropore size was beneficial for producing small particles. For comparison, HAP nanoparticles were also prepared in a stirred tank reactor (STR) and a T-junction microchannel reactor (TMCR), clearly exhibiting the advantages of the MTMCR over the STR ...

Electrospun PVA/HAp nanocomposite nanofibers: biomimetics of mineralized hard tissues at a lower level of complexity

Based on the biomimetic approaches the present work describes a straightforward technique to mimic not only the architecture (the morphology) but also the chemistry (the composition) of the lowest level of the hierarchical organization of bone. This technique uses an electrospinning (ES) process with polyvinyl alcohol (PVA) and hydroxyapatite (HAp) nanoparticles. To determine morphology, crystalline structures and thermal properties of the resulting electrospun fibers with the pure PVA and PVA/HAp nanocomposite (NC) before electrospinning various techniques were employed, including transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, FT-IR spectroscopy was carried out to analyze the complex structural changes upon undergoing electrospinning as well as interactions between HAp and PVA. The morphological and crystallographic investigations revealed that the rod-like HAp nanoparticles exhibit a nanoporous morphology and are embedded within the electrospun fibers. A large number of HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA fibers, which closely resemble the naturally mineralized hard tissues of bones. Due to abundant OH groups present in PVA and HAp nanorods, they strongly interact via hydrogen bonding within the electrospun PVA/HAp NC fibers, which results in improved thermal properties. The unique physiochemical features of the electrospun PVA/HAp NC nanofibers prepared by the ES process will open up a wide variety of future applications related to hard tissue replacement and regeneration (bone and dentin), not limited to coating implants.

Histological reaction of sintered nanohydroxyapatite‐coated cuff and its fibroblast‐like cell hybrid for an indwelling catheter

Rapid tissue-ingrowth of a sintered hydroxyapatite(HAp)-coated and cell-hybrid subcutaneous cuff equipped with an indwelling catheter was developed. The rod-like HAp nanoparticles were coated by covalent bonding on the surface of the silk fibroin (SF) fibers for about 100 microm of the length. The fibers were transplanted three-dimensionally on a cuff substrate made of silicone elastomer with an adhesive. The fibroblast-like cells, explanted and proliferated from skin tissue containing the epidermis, dermis, and subcutaneous tissue of Japanese white rabbits, were incubated on the three-dimensional cuff for three days. Three types of cuff--polyester, HAp-coated, and cell-hybrid cuffs--were percutaneously implanted into the backs of the same animals for 3 and 7 days. The subcutaneous tissues around the cuffs were stained with hematoxylin-eosin. Immunohistochemical staining to identify macrophages and alpha-smooth muscle actin (alpha-SMA) was also done and examined by light microscopy. The alpha-SMA-positive area was very limited in the polyester cuff group even after 7 days, although many macrophages infiltrated into the fibers. In the cell-hybrid cuff group, on the other hand, an alpha-SMA-positive area was formed extensively after 3 and 7 days, causing severe inflammation. In the HAp-coated cuff group, an alpha-SMA-positive area was formed among the fibers with little inflammation. The extent order of the alpha-SMA-positive area was cell-hybrid cuff >> HAp-coated cuff >> polyester cuff, while the degree of inflammatory cells order was cell-hybrid cuff >> polyester cuff >> HAp-coated cuff.

Formation of uniform hydroxyapatite nanocoating triggered by nucleation at carboxylic groups embedded in ethylene/acrylic acid copolymer microspheres

A uniform thin layer of hydroxyapatite (HAp) was formed by promoting its nucleation at carboxylic groups on the surface of the substrate. In the present work, we chose ethylene (82wt%)/acrylic acid (18wt%) copolymer microsphere as the substrate. The HAp moiety was directly derived from calcium hydrogenphosphate with excess calcium ion in an aqueous phase at a basic condition adjusted with ammonia aqueous solution (pH∼11). The TEM observation revealed that a dense coating layer with the thickness below 100nm was formed on the surface of the copolymer microsphere. The coating layer was formed from rod-like HAp nanoparticles, which were densely stacked with each other. The carboxylic groups of the copolymerised acrylic acid promoted the nucleation and formation of the primary precursory layer of HAp on the surface of the copolymer microsphere.