Hydroxylapatite Nanoparticles Research Articles

HA/PLA Composite Nanoparticles for Enhanced Oral Bioavailability of Capsaicin: Fabrication, Characterization and in vitro‐in vivo Evaluation

AbstractIn this paper, hydroxylapatite (HA) nanoparticles were constructed through the ultrasound‐assisted dispersion method. Using scanning electron microscopy (SEM), we studied the preparation methods of HA nanoparticles, and spherical HA nanoparticles with a size of about 50 nm were prepared. Besides, we constructed the HA/PLA composite nanoparticles with polylactic acid (PLA) as the material. The effects of different composite proportions on the HA/PLA composite nanoparticles were investigated before Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), Transmission electron microscope (TEM), and SEM, were applied to preliminary evaluate the effects of the above‐mentioned nanoparticles on capsaicin release. Through an in vitro study, we found that the release rate of the drug could be influenced by various release media and different compounding ratios (of HA and PLA). Furthermore, the pharmacokinetics study of capsaicin powder and capsaicin‐loaded HA/PLA composite nanoparticles demonstrated marked increased Cmax, prolongation of Tmax to 8 h, increased T1/2 and mean retention time (MRT) by 6.7 and 5.6 times respectively, coupled with 9240.2 % increase in relative bioavailability. Of note, HA/PLA composite nanoparticles showed good biocompatibility and exhibited good long‐term controlled release carriers, coupled with the ability to improve the solubility and bioavailability of a lipophilic drug.

Programmed biomolecule delivery orchestrate bone tissue regeneration via MSC recruitment and epigenetic modulation

An on-demand delivery of chemotactic and osteogenic biomolecules to induce the recruitment and osteogenic differentiation of endogenous stem cells for in situ bone regeneration is appealing but challenging. To meet the changing demands at different periods of bone regeneration, a programmed delivery system was successfully fabricated by incorporating the near-infrared (NIR) light-responsive polydopamine-coated hydroxylapatite nanoparticles (nHA@PDA) into the thermo-responsive hydroxybutyl chitosan (HBC) hydrogel to regulate the therapeutic concentrations and time points of chemotactic simvastatin (SIM) and osteogenic pargyline (PGL). This smart hydrogel composite could perform an initial rapid release of SIM to meet the need of endogenous stem cell recruitment at the beginning of bone healing. Meanwhile, a flexible and NIR light-triggered increased release of PGL could promote osteogenic differentiation of migrated cells via a safe and stable epigenetic mechanism. Taken together, a well-orchestrated therapeutic timeline of two drugs was obtained in our programmed delivery system, thus enhancing bone regeneration in a highly effective method. In addition, the small molecular drugs utilized in this study were stable, safe, and easy for translation and clinical applications in bone tissue engineering.

Effect of Foliar Nano Fertilizers and Irrigation Intervals on Soybean Productivity and Quality

During summer seasons of 2015 and 2017, a field experiment was conducted at the Research and Experimental Station (30°19′ N, 31°16′ E), Faculty of Agriculture, Ain Shams University at Shalakan, Kalubia Governorate, Egypt, to investigate the effects of combinations between hydroxyl apatite nanoparticles (0, 3, and 6 kg/fad) and calcium carbonate nanoparticles (0, 500g/fad) as nano-fertilizers under irrigation intervals, (irrigation every 2 or 3 weeks whereas irrigation every 2 weeks as a recommended practice) on yield components and quality of soybean plants. Plants irrigated every two weeks produced higher seed and biological yield in the two resulted seasons; and its combined. Interaction between 6 kg/fad hydroxyl apatite nanoparticles (A3)and 500 g/fad calcium carbonate nanoparticles (C2) under irrigation every 2 week (IR 1) recorded the maximum values of 100-seed weight, pod yield, seed and biological yield . On the other hand the lowest means values were recorded at combination between zero kg/fed hydroxyl apatite nanoparticles (A1)and zero g/fed calcium carbonate nanoparticles (C1) under irrigation every 3 week (IR 2). Regarding to chemical composition interactions of irrigation intervals x apatite concentrations x nano calcium carbonate scored the highest and significant oil% and protein %.  Interaction between 6 kg/fed hydroxyl apatite nanoparticles (A3)and 500 g/fed calcium carbonate nanoparticles (C2) under irrigation every 2 week (IR 1) recorded the maximum values of yield and quality studied traits of soybean plants.

Shear Bond Strength of a Multi-Mode Universal Adhesive Containing Hydroxy-Apatite Nanoparticles to Dentin (In vitro study)

Aim: To evaluate the effect of addition of Hydroxyl-Apatite nanoparticles to a commercial universal adhesive on sheer-bond-strength to dentin using two application modes, immediately and after thermocycling. Methods: A-commercial UA was used for bonding composite-resin to dentin and considered as control. 10% of HAp were prepared and added to the commercial UA and considered as experimental. 88-freshly extracted sound human premolar teeth were sectioned to expose mid-coronal-dentin. Samples were y divided into: control and experimental group. Each group was further divided based on the application protocol. Half of the samples were stored in distilled water for 24h at 37°C for immediate SBS testing whereas the other half was subjected to thermocycling for 20,000 cycles. SBS was measured one-day post polymerization and after thermocycling using universal testing machine. SBS values and failure modes were recorded and statistically analyzed. Results: the experimental group presented significantly lower resin-dentin SBS than the control group. Thermocycling significantly lowered SBS values for both groups. When using SE mode, the experimental group reported lower resin-dentin SBS than the control group before and after thermocyclying. When using ER mode before thermocycling, no significant difference was found between the two groups, while after thermocycling, the experimental group reported significantly higher resin-dentin SBS than the control group. For both adhesive groups, mixed failure dominated with ER mode while adhesive failure dominated with SE mode. Conclusions:Addition of HA may provide resistance to degradation and offer a potential to improve resin-dentin bond stability against thermal changes when ER protocol is applied.

RESPONSE OF SOYBEAN GROWTH TO NANO-MINERAL FERTILIZERS UNDER TWO IRRIGATION INTERVALS

During summer seasons of 2015 and 2017, a field experiment was conducted at the Research and Experimental Station (30°19′ N, 31°16′ E), Faculty of Agriculture, Ain Shams University at Shalakan, Kalubia Governorate, Egypt, to investi-gate the effects of combinations between hydroxyl apatite nanoparticles (0, 3, and 6 kg/fad) and cal-cium carbonate nanoparticles (0, 500g/fad) as nano-fertilizers under irrigaton intervals, (irrigation every 2 or 3 weeks whereas irrigation every 2 weeks as a recommended practice) on growth of soybean plants. Irrigation intervals had statistically significant effect on plant height (cm), number of branches per plant, number of leaves per plant, leaf area index, number of pods per plant, number of root nodules per plant, root dry weight per plant, stem dry weight per plant, leaves dry weight per plant and pods dry weight per plant. These results were fairly true in the two studied seasons 2015, 2017 and combined result. plant height, numbers of branches per plant, numbers of leaves per plant, leaf area index, number of nodules per plant and number of pods per plant of soybean plants which treated with 500 g/fed surpassed untreated plants in the two studied seasons 2015, 2017 and com-bined. Soybean plants treated with 6 kg hydroxyl apatite nanoparticles per feddan out-numbered other plants in its numbers of leaves per plant, leaf area index, number of root nodules per plant and number of pods per plant in the two growing sea-sons 2015, 2017 and combined data. Results showed that normal irrigation x 500g/fed calcium carbonate nanoparticles x 6kg/fed hydroxyl apatite nanoparticles was the effective combination for producing the highest values of plant height (cm), number of branches per plant, number of leaves per plant, leaf area index, number of pods per plant, number of root nodules per plant, root dry weight per plant (g), stem dry weight per plant (g), leaves dry weight per plant (g) and pods dry weight per plant (g). There weren’t significant results be-tween plants treated with nano-mineral fertilizers under irrigation every 3 week and plants untreated but irrigated every 2 week in all growth traits, which reflect appositive result of this chemical substance in mitigation harmful effect of water shortage in season 2015, 2017 and combined data.

Effects of phosphate-solubilizing bacteria on phosphorous release and sorption on montmorillonite

Most of P is fixed in pedosphere and lithosphere, i.e., not directly available to ecosystem. Interactions between phosphate-solubilizing bacteria and clay minerals contribute heavily to P biogeochemistry. In this study, hydroxylapatite (HAp), montmorillonite (Mt.) and Enterobacter sp. were applied to investigate their influences on P release, sorption, and transformation. Enterobacter sp. promoted the dissolution of HAp via secreting formic acid (pH declined from neutral to ~5.0). However, respiration of the bacteria with addition of Mt. was decreased by ~15.0% after their logarithm growth. SEM analysis also indicated that the number of Enterobacter sp. cells was significantly reduced on Mt. surface. Mt. was hence able to inhibit the activity of the adsorbed bacteria on its surface. Meanwhile, the mobile bacteria helped to transform HAp mineral to nanoparticles via partial dissolution. Despite the low sorption of mobile P anions (< 0.2 mg L−1), Mt. was able to adsorb plenty of HAp nanoparticles. The subsequently enhanced adsorption of P nanoparticles by Mt. protects the environment from P losses. Therefore, interaction of mobile bacteria and clay minerals have a positive feedback in regulating P transportation in long-term. This study elucidated the different roles of mobile and fixed bacterial cells in P biogeochemistry influenced by Mt.

Towards osteogenic bioengineering of dental pulp stem induced by sodium fluoride on hydroxyapatite based biodegradable polymeric scaffold

Hydroxylapatite (HA) and sodium fluoride (NaF) are expected to have enhanced osteoblast proliferation and differentiation ability and as a result gained much attention in tissue-engineering applications. The aim of this study is to investigate the effect of NaFand/or HA addition to three-dimensional (3D) nanofibrous poly(e-caprolactone) (PCL)/poly lactic acide (PLA) scaffolds on Human dental pulp stem cells (DPSCs) proliferation, osteoblast differentiation and mineralization. For this purpose, PCL and PLA homopolymers and HA nanoparticles were synthesized. Then a 3D nanofibrous composite scaffold of PCL/PLA/HA was prepared by electrospinning method with fiber diameter in the range of around 120-300 nm. NaF was added to media during DPSCs culturing step. Cell proliferation was assessed over a 14 days period. Reverse transcription polymerase chain reaction (RT-PCR) was used to evaluate the osteogenic induction. The in vitro biocompatibility tests performed with DPSCs showed excellent cell attachment (SEM), proliferation (MTT assay), and mineralization (Alizarin Red). QRT-PCR results, demonstrated significantly superior osteogenesis markers in group of DPSCs bioengineered in PCL/PLA/HA and PCL/PLA/HA/NaF. Simultaneous application of HA in nanofibrous PCL/PLA scaffolds and NaF in the media showed synergistic effects on the growth and differentiation of DPSCs, and consequently seems to be a promising scaffold for tissue regeneration in the oral cavity.

Effect of inflammatory conditions on bare and coated Ti-6Al-4V surfaces

Event Abstract Back to Event Effect of inflammatory conditions on bare and coated Ti-6Al-4V surfaces Sarah Höhn1 and Sannakaisa Virtanen1 1 University of Erlangen-Nürnberg, Materials Science, Germany Introduction: The calcium-phosphate (Ca-P) formation during long-term immersion in biological environment play an important role for the biocompatibility of the implant. Hence, Ti-6Al-4V was coated with different nano sized structures to evaluate corrosion resistance and Ca-P formation in DMEM under physiological (pH7) and inflammatory con-ditions (pH5 + H2O2). Methods: The samples were pretreated and afterwards coated with TiO2 and incorporated hydroxylapatite nanoparticles, according to Höhn et al[1]. The influence of the coatings on Ca-P formation was investigated with XPS and SEM after immersion in DMEM at pH7 and in comparison under simulated inflammatory conditions at pH5 and in presence of H2O2. The long-term immersion tests at pH5 were performed for 14 days followed by a pH change to pH7 indicating the end of the inflammatory reactions. The effect on corrosion resistance was investigated by electrochemical impedance measurements (EIS). Results: Fig. 1. SEM images of TiO2-NP (~ 30nm; (A)) and HA incorporated TiO2 (~ 700nm (B)) samples and after three months immersion in DMEM at pH5 + H2O2 (C) and (D). Fig. 2. EIS of TiO2-NP (A) and HA incorporated TiO2 coating (B) at pH5 + H2O2 after long-term immersion tests in DMEM. Discussion and Conclusion: The SEM images (Fig. 1) showed that the formation of Ca-P is possible on the different coatings on Ti-6Al-4V in general. However for the pH5 the formation is time-delayed (Fig. 1D). EIS measurements at pH5 showed no effect of the additional Ca-P layer after 14 days immersion. Already after 28d (Fig. 2) and the end of the inflammatory conditions both coatings showed two time constants according to the barrier layer and outer porous layer and thus the Ca-P formation[2]. Compared to the measurements at pH7 the formation is also time-delayed.

Lentivirus Immobilization to Nanoparticles for Enhanced and Localized Delivery From Hydrogels

Hydrogels can provide a controllable cell microenvironment for numerous applications in regenerative medicine, and delivery of gene therapy vectors can be employed to enhance their bioactivity. We investigated the delivery of lentiviral vectors from hydrogels, and employed the immobilization of lentivirus to hydroxylapatite (HA) nanoparticles as a means to retain and stabilize vectors within hydrogels, and thereby increase delivery efficiency. Entrapment of the vector alone within the hydrogel maintained the activity of the virus more effectively compared to the absence of a hydrogel, and release was slowed with an increasing solid content of the hydrogel. Association of the lentivirus with HA increased the activity of the complexes, with HA increasing the virus activity for 72 hours. Cells seeded onto lentivirus-HA-loaded hydrogels had a decreased number of infected cells outside of the hydrogel relative to the absence of HA. In vivo studies with collagen hydrogels loaded with lentivirus and HA-lentivirus demonstrated sustained and localized transgene expression for at least 4 weeks, with increased expression using the lentivirus-HA complex. This strategy of nanoparticle immobilization to stabilize and retain vectors is broadly applicable to hydrogels, and may provide a versatile tool to combine gene therapy and biomaterials for applications in regenerative medicine.

Natural enamel wear – A physiological source of hydroxylapatite nanoparticles for biofilm management and tooth repair?

Dental caries is a widespread chronic disease caused by glucolytic biofilms. Despite considerable success in prophylaxis, there is still a strong demand for biomimetic biofilm management. Reflections on the abraded, but mostly caries-free teeth observed in prehistoric sculls or omnivorous primates, respectively, offer perspectives for developing new approaches in preventive dentistry. It is hypothesized that nano-sized hydroxylapatite crystallites occur in the oral cavity during extensive physiological wear of the hierarchical structured enamel surface due to dental abrasion and attrition. These nano-scaled apatite enamel crystallites might promote re-mineralization and physiological biofilm management at the tooth surface. Indeed, modern bioinspired nanomaterials in preventive dentistry containing nano-sized hydroxylapatite particles have shown efficacy in reducing oral biofilm formation and yield re-mineralizing effects. Accordingly, they seem to mimic extensive abrasions which do not occur with modern diet.

Integrated Multifunctional Nanosystems for Medical Diagnosis and Treatment

AbstractThis article provides an overview on the development of integrated multifunctional nanosystems for medical diagnosis and treatment. In particular, a novel system is developed specifically for achieving simultaneous diagnosis and treatment of cancer. Critical issues are addressed on the architecture and assembly of nanocomponents based on medical requirements: targeted in vivo imaging, controlled drug release, localized hyperthermia, and toxicity. Nanotube‐based carriers are summarized with surface functionalized properties. Other types of nanocarriers are also included such as super paramagnetic composite nanospheres and biodegradable hydroxylapatite nanoparticles. In addition, polymeric‐based nanosystems are introduced with several novel features: they can be bio‐dissolved due to environmental pH and temperature fluctuations. The nanocarriers are surface tailored with key functionalities: surface antibodies for cell targeting, anti‐cancer drug loading, and magnetic nanoparticles for both hyperthermia and MRI. Future requirements, aims, and trends in the development of multifunctional nanosystems, particularly with intelligent functionalities for fundamental studies, are also provided.

Hydroxylapatite nanoparticles obtained by fiber laser-induced fracture

This work presents the results of laser-induced fragmentation of hydroxylapatite microparticles in water dissolution. Calcined fish bones in form of powder, which were previously milled to achieve microsized particles, were used as precursor material. Two different laser sources were employed to reduce the size of the suspended particles: a pulsed Nd:YAG laser and a Ytterbium doped fiber laser working in continuous wave mode. The morphology as well as the composition of the obtained particles was characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and conventional and high resolution transmission electron microscopy (TEM, HRTEM). The results show that nanometric particles of hydroxylapatite and β-tricalcium phosphate as small as 10 nm diameter can be obtained.

Quantum dot conjugated hydroxylapatite nanoparticles for in vivo imaging

Hydroxylapatite (HA) nanoparticles were conjugated with quantum dots (QDs) for in vivoimaging. The surface structures of HA nanoparticles with conjugated quantum dots(HA-QD) were studied by transmission electron microscopy (TEM) and laserfluorescent spectroscopy. The TEM data showed that the quantum dots were wellconjugated on the HA nanoparticle surfaces. The laser fluorescent spectroscopyresults indicated that the HA-QD exhibited promising luminescent emission invitro. The initial in vivo experiments revealed clear images of HA-QD from thehypodermic injected area at the emission of 600 nm. Furthermore, the optimized in vivoimages of HA-QD with near-infrared emission at 800 nm were visualized afterintravenous injection. These luminescent HA-QD nanoparticles may find importantapplications as biodegradable substrates for biomarkers and in drug delivery.

Formation of zinc sulfide and hydroxylapatite nanoparticles in polyelectrolyte-modified microemulsions

The paper is focused on the formation of nanoparticles, i.e., zinc sulfide (ZnS) and hydroxylapatite, in a microemulsion template phase consisting of heptanol, water, and a surfactant with a sulfobetaine head group in the absence and presence of an added polyelectrolyte. In the absence of a polyelectrolyte, beside larger particles, spherical ZnS nanoparticles with a diameter below 10 nm can be redispersed after solvent evaporation. In the presence of the synthetic cationic polyelectrolyte poly(diallyldimethylammonium chloride), a reloading of the particle surface is observed, and cationic charged ZnS nanoparticles, of about 5 nm in size, can be redispersed as a main fraction. When hydroxylapatite is formed in the presence of the more stiff biopolymer chitosan hydroxylapatite, hybrid structures were formed. Transmission electron micrographs show fiber-like aggregate structures, consisting of individual small nanoparticles ordered along the polymer chain.

Fabrication and characterization of PLGA/HAp composite scaffolds for delivery of BMP-2 plasmid DNA

The objective of this study is to construct complex of DNA and PLGA/HAp composite scaffold for bone tissue engineering. Naked DNA has low transfection efficiency so DNA loaded chitosan particles are used nowadays in gene delivery due to their high transfection efficiency, but unfortunately this is accompanied by strong immunological reaction of cells. In order to preserve the advantage of polymeric particles and reduce immunological effect at the same time, a new DNA release system is developed which makes possible sustained DNA release with negligible immunological effects. Poly (lactide-co-glycolide) (PLGA)/Hydroxylapatite (HAp) composite scaffolds with different HAp contents (0%, 5% and 10%) are fabricated by an electrospinning method and DNA is incorporated into the scaffolds in 3 ways (i.e. naked DNA, encapsulation of DNA/chitosan nanoparticles into scaffolds after fiber fabrication by dripping, and encapsulation of DNA/chitosan nanoparticles into scaffold by mixing with PLGA/HAp solution before fiber fabrication). All the scaffolds are characterized by SEM, XRD, DSC and GC-MS and the results show that the scaffolds are non-woven, nano- to micro-fibered membrane structures composed predominantly of PLGA with amorphous dispersion of HAp nanoparticles inside polymeric matrix. In vitro release tests were carried out on 9 different scaffolds to check the effects of HAp contents and the encapsulation ways of DNA on the release properties. These effects are also tested by human marrow stem cells (hMSCs) by comparing their cell attachment ability, cell viability and DNA transfection efficiency. It is demonstrated that the addition of HAp nanoparticles increased the release rate of DNA for both naked and encapsulated DNA. Cell culture experiments show that the scaffolds with encapsulated DNA/chitosan nanoparticles have higher cell attachment, higher cell viablility and desirable transfection efficiency of DNA. The observations show that DNA/chitosan nanoparticles encapsulated PLGA/HAp composite scaffold is promising for use in bone regeneration.

Luminescent hydroxylapatite nanoparticles by surface functionalization

Hydroxylapatite (HA) nanoparticles were functionalized by depositing rare-earth-doped Y2O3 nanoparticles on the surface, and the structural evolutions of both HA and Y2O3 phases at different annealing temperatures were investigated by x-ray diffraction and transmission electron microscopy. Laser spectroscopy indicated that the surface functionalized HA nanoparticles exhibited strong visible emissions. No visible emissions were observed from rare-earth-doped Y2O3 without any substrate, suggesting a doping-induced environmental change of optically active rare-earth elements in the functionalized HA nanoparticles. The luminescent hydroxylapatite nanoparticles may find important applications as a biodegradable substrate for biomarking and drug delivery.