Strontium Hydroxyapatite Nanorods Research Articles

Differentiation Capacity of Monocyte-Derived Multipotential Cells on Nanocomposite Poly(e-caprolactone)-Based Thin Films.

Μonocyte-derived multipotential cells (MOMCs) include progenitors capable of differentiation into multiple cell lineages and thus represent an ideal autologous transplantable cell source for regenerative medicine. In this study, we cultured MOMCs, generated from mononuclear cells of peripheral blood, on the surface of nanocomposite thin films. For this purpose, nanocomposite Poly(e-caprolactone) (PCL)-based thin films containing either 2.5wt% silica nanotubes (SiO2ntbs) or strontium hydroxyapatite nanorods (SrHAnrds), were prepared using the spin-coating method. The induced differentiation capacity of MOMCs, towards bone and endothelium, was estimated using flow cytometry, real-time polymerase chain reaction, scanning electron microscopy and fluorescence microscopy after cells' genetic modification using the Sleeping Beauty Transposon System aiming their observation onto the scaffolds. Moreover, Wharton's Jelly Mesenchymal Stromal Cells were cultivated as a control cell line, while Human Umbilical Vein Endothelial Cells were used to strengthen and accelerate the differentiation procedure in semi-permeable culture systems. Finally, the cytotoxicity of the studied materials was checked with MTT assay. The highest differentiation capacity of MOMCs was observed on PCL/SiO2ntbs 2.5wt% nanocomposite film, as they progressively lost their native markers and gained endothelial lineage, in both protein and transcriptional level. In addition, the presence of SrHAnrds in the PCL matrix triggered processes related to osteoblast bone formation. To conclude, the differentiation of MOMCs was selectively guided by incorporating SiO2ntbs or SrHAnrds into a polymeric matrix, for the first time.

Newly emerging mesoporous strontium hydroxyapatite nanorods: microwave synthesis and relevance as doxorubicin nanocarrier

A new synthesis method is developed for preparation of mesoporous strontium hydroxyapatite (SrHAp) nanorods using CEM Discover microwave synthesizer. Nanorods preparation with surfactants SrHAp(+) and without surfactants SrHAp(−) were successfully achieved at 160 °C temperature and 15 min of hold time. Particle sizes with standard deviation were found to be 67 ± 18 and 69 ± 24 nm respectively. Mesoporous nanorods were thoroughly characterized using different methods, such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission gun transmission electron microscopy (FEG-TEM), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area and porosity measurement. It was observed that use of trisodium citrate and CTAB resulted in quite agglomerated particles, whereas nanorods synthesized without citrate and CTAB were well dispersed. Cell toxicity of both these materials synthesized was tested in MCF-7 and Zr-75 cell lines using MTT assay. SrHAp nanorods concentration up to 0.25 mg/ml was non-toxic at 48 hours (h) time point in both the cell lines. As SrHAp(−) were found to serve better in terms of cytotoxicity, they were chosen for doxorubicin (Dox) loading, pH depended release and cell uptake study. The successful loading of Dox was ascertained by UV-Visible and FTIR spectroscopy. Entrapment efficiency of Dox in SrHAp nanoparticles was found to be 83.71%, and loading capacity was 0.017 μg Dox per μg SrHAp nanoparticles. Rapid release was observed in the initial hours followed by slow release. Even until 31 days, only 27 and 32% drug was released at pH 7.4 and pH 4.5 respectively, which shows controlled release behavior. Further, cellular uptake of Dox-loaded nanoparticles at different time points was studied in the two breast cancer cell lines by fluorescence imaging. These nanoparticles were found to internalize within both these cells after 3 h of incubation and continued further until 24 h. Overall, high Dox loading efficacy, sustained release behavior, and cell uptake potential render SrHAp nanoparticles to give promising results when applied in vivo and emerge as a robust drug carrier towards solving purpose of slow and prolonged drug release.

Surfactant free novel one-minute microwave synthesis, characterization and cell toxicity study of mesoporous strontium hydroxyapatite nanorods

Synthesis of mesoporous strontium hydroxyapatite (SrHAp) nanorods was carried out in microwave without using any capping agent or surfactant.

Novel poly(butylene succinate) nanocomposites containing strontium hydroxyapatite nanorods with enhanced osteoconductivity for tissue engineering applications

Three series of poly(butylene succinate) (PBSu) nanocomposites containing 0.5, 1 and 2.5 wt% strontium hydroxyapatite (Sr5(PO4)3OH) nanorods (SrHAp nrds) were prepared by in situ polymerisation. The structural effects of Sr5(PO4)3OH nanorods, for the different concentrations, inside the polymeric matrix (PBSu), were studied through high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). HAADF-STEM measurements revealed that the SrHAp nanorods at low concentrations are dispersed inside the polymeric PBSu matrix while in 1 wt% some aggregates are formed. These aggregations affect the mechanical properties giving an enhancement for the concentration of 0.5 wt% SrHAp nrds in tensile strength, while a reduction is recorded for higher loadings of the nanofiller. Studies on enzymatic hydrolysis revealed that all nanocomposites present higher hydrolysis rates than neat PBSu, indicating that nanorods accel- erate the hydrolysis degradation process. In vitro bioactivity tests prove that SrHAp nrds promote the formation of hydrox- yapatite on the PBSu surface. All nanocomposites were tested also in relevant cell culture using osteoblast-like cells (MG-63) to demonstrate their biocompatibility showing SrHAp nanorods support cell attachment.

Modified chitosan coated mesoporous strontium hydroxyapatite nanorods as drug carriers.

Mesoporous strontium hydroxyapatite (SrHAp) nanorods (NRs) have been successfully synthesized using a simple and efficient chemical route, i.e. the hydrothermal method. Structural and morphological characterization of the as-synthesized SrHAp NRs have been performed by transmission electron microscopy (TEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). TEM and HAADF-STEM measurements of the NRs reveal the coexistence of longer and shorter particles with the length ranging from 50 nm to 400 nm and a diameter of about 20-40 nm. Electron tomography measurements of the NRs allow us to better visualize the mesopores and their facets. Two model drugs, hydrophobic risperidone and hydrophilic pramipexole, were loaded into the SrHAp NRs. These nanorods were coated using a modified chitosan (CS) with poly(2-hydroxyethyl methacrylate) (PHEMA), in order to encapsulate the drug-loaded SrHAp nanoparticles and reduce the cytotoxicity of the loaded materials. The drug release from neat and encapsulated SrHAp NRs mainly depends on the drug hydrophilicity. Importantly, although neat SrHAp nanorods exhibit some cytotoxicity against Caco-2 cells, the Cs-g-PHEMA-SrHAp drug-loaded nanorods show an acceptable cytocompatibility.

Thermal degradation kinetics and decomposition mechanism of PBSu nanocomposites with silica-nanotubes and strontium hydroxyapatite nanorods

Novel poly(butylene succinate) (PBSu) nanocomposites containing 5 and 20 wt% mesoporous strontium hydroxyapatite nanorods (SrHNRs) and silica nanotubes (SiNTs) were prepared by melt-mixing. A systematic investigation of the thermal stability and decomposition kinetics of PBSu was performed using pyrolysis-gas chromatography-mass spectroscopy (Py-GC-MS) and thermogravimetry (TG). Thorough studies of evolving decomposition compounds along with the isoconversional and model-fitting analysis of mass loss data led to the proposal of a decomposition mechanism for PBSu. Moreover, the effects of SrHNRs and SiNTs on the thermal stability and decomposition kinetics of PBSu were also examined in detail. The complementary use of these techniques revealed that the incorporation of SiNTs in PBSu does not induce significant effects neither on its thermal stability nor on its decomposition mechanism. In contrast, the addition of SrHNRs resulted in the catalysis of the initial decomposition steps of PBSu and also in modified decomposition mechanisms and activation energies. The evolving gaseous products of PBSu and their evolution pattern in the SiNT nanocomposites were the same as in neat PBSu, while they were slightly modified for the SrHNR nanocomposites, confirming the findings from thermogravimetric analysis.

Evaluation of silica-nanotubes and strontium hydroxyapatite nanorods as appropriate nanoadditives for poly(butylene succinate) biodegradable polyester for biomedical applications

In the present study two series of poly(butylene succinate) (PBSu) nanocomposites containing 5 and 20wt% of silica-nanotubes or strontium hydroxyapatite [Sr5(PO4)3OH] nanorods were prepared by melt mixing at 130°C. From SEM images it was found that SiO2 nanotubes are well dispersed inside the PBSu matrix while Sr5(PO4)3OH nanorods formed some aggregates. In both cases the mechanical properties of nanocomposites were slightly affected by the amount of nanoadditives. Enzymatic hydrolysis of PBSu and its nanocomposites was studied in aqueous solutions containing a mixture of R. delemar and Pseudomonas Cepacia lipases, at 50°C and pH=7.2. It was found that all nanocomposites have higher hydrolysis rates than neat PBSu indicating that nanoparticles accelerate the hydrolysis degradation process. The hydrophilicity of nanofillers, the presence of hydroxyl groups and the effect of a ‘‘gap” at the interface due to low adhesion of PBSu matrix and inorganic nanofillers, could increase the enzymatic hydrolysis rate of the polyester matrix. All prepared samples were tested in relevant cell culture using osteoblast-like cells (MG-63) to demonstrate their biocompatibility. It was found that SiO2 nanotubes support cell attachment, while Sr5(PO4)3OH nanorods decrease cell activity.

Crystallization and Melting Behavior of Poly(Butylene Succinate) Nanocomposites Containing Silica-Nanotubes and Strontium Hydroxyapatite Nanorods

The multiple melting behavior of poly(butylene succinate) (PBSu) nanocomposites containing silica nanotubes (SiNTs) and strontium hydroxyapatite nanorods (SrHNRs) was studied with Step Scan DSC. In the reversing signal curves, recrystallization proved to be significant for samples crystallized at low temperature, which lead to large supercooling, favoring fast crystallization and formation of poor crystals that suffer recrystallization on subsequent heating scans. The crystallization study, under both isothermal and nonisothermal conditions, evidenced that only SiNTs act effectively as nucleating agents. Consequently, crystallization of the nanocomposite samples filled with 5 and mainly with 20 wt % SiNTs occurred faster than that of the neat polymeric matrix. The insertion of SrHNRs slightly lowered the crystallization rate of PBSu due to the formation of larger aggregates inside the PBSu matrix, which may inhibit crystallization. The size of crystals was smaller for PBSu/SiNTs samples, as it was proved by wide angle X-ray diffracrion (WAXD), whereas the addition of SrHNRs did not significantly affect the crystalline size of nanocomposites.

Aptamer-Capped Multifunctional Mesoporous Strontium Hydroxyapatite Nanovehicle for Cancer-Cell-Responsive Drug Delivery and Imaging

A novel cancer-cells-triggered controlled-release gadolinium-doped luminescent and mesoporous strontium hydroxyapatite nanorods (designated as Gd:SrHap nanorods) system using cell-type-specific aptamers as caps has been constructed. Aptamers behave as a dual-functional molecule that acts as not only a lid but also a targeted molecular that can be used in an effective way for therapeutically special cancer cells. After incubated with cancer cells, for example, MCF-7 cells, the doxorubicin-loaded and aptamer-capped Gd:SrHap nanorods (designated as Gd:SrHap-Dox-aptamer) can be internalized into MCF-7 cells, resulting in the pore opening and drug releasing. Furthermore, the high biocompatibility and biodegradability Gd:SrHap nanorods with blue autofluorescence and paramagnetism could serve as a good contrast agent of targeting fluorescence and magnetic resonance imaging. We envision that this Gd:SrHap system could play a significant role in developing new generations of site-selective, controlled-release delivery and interactive sensory nanodevices.

Efficient and selective immobilization of Pb2+ in highly acidic wastewater using strontium hydroxyapatite nanorods

In this paper, strontium hydroxyapatite (Sr5(PO4)3(OH), SrHAp) nanorods were synthesized by a hydrothermal method and utilized for immobilization of Pb2+ from acidic aqueous solutions. The SrHAp nanorods exhibited a high immobilization capacity of 1482±137mgg−1 for Pb2+ in acidic solutions (pH=2.5) within 15min. The SrHAp nanorods could selectively immobilize Pb2+ with little immobilization effect on other co-existing metal ions when they were used to treat highly acidic nonferrous metallurgy wastewater (pH=1.1). The XRD, SEM, EDX and XPS results revealed that the immobilization of Pb2+ by the SrHAp nanorods was mainly due to ion exchange and Pb2+ precipitation.

Self-activated luminescent and mesoporous strontium hydroxyapatite nanorods for drug delivery

Multifunctional strontium hydroxyapatite (SrHAp) nanorods with luminescent and mesoporous properties have been successfully synthesized by a hydrothermal method. SEM and TEM images indicate that the mesoporous SrHAp samples consist of monodiperse nanorods with lengths of 120–150 nm, diameters of around 20 nm, and the mesopore size of 3–5 nm. The as-obtained SrHAp nanorods show an intense bright blue emission (centered at 432 nm, lifetime 11.6 ns, quantum efficiency: 22%), which might arise from CO 2· − radical impurities in the crystal lattice under long-wavelength UV-light irradiation. Furthermore, the amount of trisodium citrate has an obvious impact on the particle size and the luminescence properties of the products, respectively. The drug storage/release test indicates that the luminescent SrHAp nanorods show a drug loading and controlled release properties for ibuprofen (IBU). Additionally, the emission intensity of SrHAp in the drug carrier system increases with the cumulative released amount of IBU, making the drug release might be easily tracked and monitored by the change of the luminescence intensity. This luminescent material may be potentially applied in the drug delivery and disease therapy fields.