Zinc-doped Hydroxyapatite Nanoparticles Research Articles

Novel Antimicrobial Agents Based on Zinc-Doped Hydroxyapatite Loaded with Tetracycline

In this paper, we present for the first time the development of zinc-doped hydroxyapatite enriched with tetracycline (ZnHApTe) powders and provide a comprehensive evaluation of their physico-chemical and biological properties. Various techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were used for the sample’s complex evaluation. Moreover, the biocompatibility of zinc-doped hydroxyapatite (ZnHAp) and ZnHApTe nanoparticles was evaluated with the aid of human fetal osteoblastic cells (hFOB 1.19 cell line). The results of the biological assays suggested that these nanoparticles hold great promise as potential candidates for the future development of novel biocompatible and antimicrobial agents for biomedical applications. The antimicrobial properties of the ZnHAp and ZnHApTe nanoparticles were assessed using the standard reference microbial strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Candida albicans ATCC 10231. The results of the in vitro antimicrobial assay demonstrated that both tested materials exhibited good antimicrobial activity. Additionally, these data also indicated that the antimicrobial effects of the ZnHAp nanoparticles were intensified by the presence of tetracycline (Te). Furthermore, the results also suggested that the antimicrobial activity of the samples increased with the incubation time.

The effect of zinc doping on the cytocompatibility and antibacterial efficacy of hydroxyapatite nanoparticles for treatment of bone infection

In the face of antibiotic resistance, new antibacterial methods are urgently needed for bone infections. Local delivery of therapeutic metal ions via osteogenic nanoparticles (NPs) is a viable alternative, but high concentrations risk toxicity to mammalian cells. In this study first four ions (Mg2+, Sr2+, Cu2+, Zn2+) were assessed for cytocompatibility and antibacterial properties. Only zinc ions showed antibacterial effects at non-toxic levels. Subsequently, zinc-doped hydroxyapatite nanoparticles (ZnHA NPs) were synthesized with varying zinc content (0–20 mol%). ZnHA NPs were characterized on size, morphology, composition, and antibacterial activity, with 15 mol% ZnHA NPs exhibiting the optimal balance between cytocompatibility and antibacterial efficacy. These NPs show promise as deliverable biomaterials for bone infection treatment.

Evaluation of Antibacterial Activity of Zinc-Doped Hydroxyapatite Colloids and Dispersion Stability Using Ultrasounds.

This study proves that the new developed zinc-doped hydroxyapatite (ZnHAp) colloids by an adapted sol-gel method can be widely used in the pharmaceutical, medical, and environmental industries. ZnHAp nanoparticles were stabilized in an aqueous solution, and their colloidal dispersions have been characterized by different techniques. Scanning Electron Microscopy (SEM) was used to get information on the morphology and composition of the investigated samples. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the elemental compositions of ZnHAp colloidal dispersions. The homogeneous and uniform distribution of constituent elements (zinc, calcium, phosphorus, oxygen) was highlighted by the obtained elemental mapping results. The X-ray diffraction (XRD) results of the obtained samples showed a single phase corresponding to the hexagonal hydroxyapatite. The characteristic bands of the hydroxyapatite structure were also evidenced by Fourier-transform infrared spectroscopy (FTIR) analysis. For a stability assessment of the colloidal system, ζ-potential for the ZnHAp dispersions was estimated. Dynamic light scattering (DLS) was used to determine particles dispersion and hydrodynamic diameter (DHYD). The goal of this study was to provide for the first time information on the stability of ZnHAp particles in solutions evaluated by non–destructive ultrasound-based technique. In this work, the influence of the ZnHAp colloidal solutions stability on the development of bacteria, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), was also established for the first time. The antimicrobial activity of ZnHAp solutions was strongly influenced by both the stability of the solutions and the amount of Zn.

Multiscale connections between morphology and chemistry in crystalline, zinc-substituted hydroxyapatite nanofilms designed for biomedical applications

Hydroxyapatite (HA), Ca10(PO4)6(OH)2, is a key material used to manufacture thin, bioactive coatings on metal implants for hard tissue regeneration. Technical challenges in their fabrication include control of the coating structure and chemical composition, as well as managing surface activation via ionic substitution. In this study, 15 – 216 nm-thick zinc-doped HA (ZnHA) thin films were grown via magnetron sputtering at room temperature. The effect of substituting Zn2+ for Ca2+ on the ultrastructures of the HA films was analyzed during several stages of film growth. Infrared vibrational scattering scanning near-field optical microscopy (s-SNOM) using the ultra-broad-band IR beam from synchrotron radiation was compared with Fourier transform infrared spectroscopy in attenuated total reflectance (FTIR/ATR) to reveal the close relationships between local topography and the chemical compositions of the film surface and the bulk of the film. The energy delivered via ionic bombardment induced the formation of complex structures: island-shaped nanoparticles of amorphous zinc-doped calcium phosphate, coalescent islands, disordered non-stoichiometric ZnHA nanoparticles, and long-range structures of nearly stoichiometric and crystalline ZnHA. Grazing incidence X-ray diffraction (GIXRD) from synchrotron radiation, X-ray photoelectron spectroscopy (XPS), focusing ion beam (FIB), and high-resolution transmission electron microscopy (HRTEM) confirmed Zn substitution into the HA lattice. Zinc was distributed homogeneously within the film structure (1.6 at%) but its concentration increased slightly on the film surface. The bulk of the film consisted of crystalline, columnar ZnHA domains oriented perpendicular to the substrate surface while the regions near the film/substrate interface were preferentially disordered and non-stoichiometric.

Preparation of strontium- and/or zinc-doped hydroxyapatite nanoparticles and their polycaprolactone composite fibrous scaffolds

In this work, hydroxyapatite (HA) and hydroxyapatite doped with Sr (HA-Sr), Zn (HA-Zn) and both Sr-Zn (HA-SrZn) were synthesized by a sol-gel method and combined with polycaprolactone (PCL) to make HA/PCL composites using an electrospinning technique. The synthesized nanoparticles and their composite fibers were investigated using various techniques. The X-Ray Diffraction (XRD) result showed the characteristic peaks of the hydroxyapatite structure; whereas the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results revealed that the synthesized nanoparticles were successfully incorporated into the randomly interconnected and highly porous PCL matrix.

Structural and Biological Assessment of Zinc Doped Hydroxyapatite Nanoparticles

The aim of the current research work was to study the physicochemical and biological properties of synthesized zinc doped hydroxyapatite (ZnHAp) nanoparticles with Zn concentrationsxZn=0(HAp),xZn=0.07(7ZnHAp), andxZn=0.1(10ZnHAp) for potential use in biological applications. The morphology, size, compositions, and incorporation of zinc into hydroxyapatite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman scattering, and X-Ray Photoelectron Spectroscopy (XPS). In addition, the cytotoxicity of ZnHAp nanoparticles was tested on bothE. colibacteria and human hepatocarcinoma cell line HepG2. The results showed that ZnHAp nanoparticles (HAp, 7ZnHAp, and 10ZnHAp) have slightly elongated morphologies with average diameters between 25 nm and 18 nm. On the other hand, a uniform and homogeneous distribution of the constituent elements (calcium, phosphorus, zinc, and oxygen) in the ZnHAp powder was noticed. Besides, FTIR and Raman analyses confirmed the proper hydroxyapatite structure of the synthesized ZnHAp nanoparticles with the signature of phosphate, carbonate, and hydroxyl groups. Moreover, it can be concluded that Zn doping at the tested concentrations is not inducing a specific prokaryote or eukaryote toxicity in HAp compounds.

PCL/chitosan/Zn-doped nHA electrospun nanocomposite scaffold promotes adipose derived stem cells adhesion and proliferation

Chitosan (Ch), and poly(ɛ-caprolactone) (PCL), widely used as biomaterials with desirable properties for tissue engineering applications, were both blended with zinc-doped hydroxyapatite nanoparticles(nZnHA) and electrospun into nanofibrous scaffolds using formic acid/acetic acid. The rationale behind this study was to demonstrate that presence of small quantities of Zn(2+) ions doped in HA nanoparticles can improve biocompatibility of PCL/Ch blends. SEM observation revealed that average fiber diameter was increased from about 136 nm for a PCL/Ch blend, to around 210 nm for PCL/Ch/nZnHA nanocomposite. PCL/Ch/nZnHA scaffolds offered higher elastic modulus (about 3-fold) and tensile strength (nearly 1.5-fold) than the corresponding PCL/Ch scaffolds. In-vitro biocompatibility studies using human adipose derived stem cells (hAD-MSCs), demonstrated that the presence of only 5 wt% nZnHA in PCL/Ch/nZnHA nanocomposites enhanced hAD-MSCs' attachment compared to PCL/Ch and PCL/Ch/nHA. Finally, hAD-MSCs proliferation occurred at significantly higher rates of 1.5, 1.3 and 1.2 times on PCL/Ch/nZnHA scaffold compared to PCL, PCL/Ch and PCL/Ch/nHA, respectively.

Pure and zinc doped nano-hydroxyapatite: Synthesis, characterization, antimicrobial and hemolytic studies

The structural, antimicrobial, and hemolytic properties and bioactivity have been studied of pure hydroxyapatite (HAP) and zinc doped hydroxyapatite (Zn-HAP) nano-particles for their medical applications. Pure HAP and Zn-HAP nano-particles were synthesized by the surfactant mediated approach. The doping of zinc was estimated by EDAX. The average particle size was determined by applying Scherrer׳s formula to powdered XRD patterns. The nano-particle morphology was studied by TEM and the presence of various functional groups was identified by FTIR spectroscopy. Good antimicrobial activity of nano-HAP and nano-Zn-HAP was found against five organisms, viz., Pseudomonas aeruginosa and Shigella flexneri as Gram negative as well as Micrococcus luteus, Staphylococcous aureus and Bacillus cereus as Gram positive. The ability of new apatite formation on the surface of pure and doped HAP samples was studied by using Simulated Body Fluid (SBF) in vitro. Hemolytic study indicated that all samples were non-hemolytic and suggesting potential application as bone implant material.

Size-mediated cytotoxicity of nanocrystalline titanium dioxide, pure and zinc-doped hydroxyapatite nanoparticles in human hepatoma cells

Nanoparticles are highly used in biological applications including nanomedicine. In this present study, the interaction of HepG2 hepatocellular carcinoma cells (HCC) with hydroxyapatite (HAp), zinc-doped hydroxyapatite, and titanium dioxide (TiO2) nanoparticles were investigated. Hydroxyapatite, zinc-doped hydroxyapatite and titanium dioxide nanoparticles were prepared by wet precipitation method. They were subjected to isochronal annealing at different temperatures. Particle morphology and size distribution were characterized by X-ray diffraction and transmission electron microscope. The nanoparticles were co-cultured with HepG2 cells. MTT assay was employed to evaluate the proliferation of tumor cells. The DNA damaging effect of HAp, Zn-doped HAp, and TiO2 nanoparticles in human hepatoma cells (HepG2) were evaluated using DNA fragmentation studies. The results showed that in HepG2 cells, the anti-tumor activity strongly depend on the size of nanoparticles in HCC cells. Cell cycle arrest analysis for HAp, zinc-doped HAp, and TiO2 nanoparticles revealed the influence of HAp, zinc-doped HAp, and titanium dioxide nanoparticles on the apoptosis of HepG2 cells. The results imply that the novel nano nature effect plays an important role in the biomedicinal application of nanoparticles.

Nanocrystalline hydroxyapatite and zinc-doped hydroxyapatite as carrier material for controlled delivery of ciprofloxacin

In bone disorders infections are common. The concentration of majority of antibiotics is very low in the bone tissue. A high local dose can be obtained from the ciprofloxacin-loaded hydroxyapatite nanoparticles. The present study is aimed at developing the use of hydroxyapatite and zinc-doped hydroxyapatite nanoparticles as a carrier for ciprofloxacin drug delivery system. The ciprofloxacin-loaded hydroxyapatite and zinc-doped hydroxyapatite have a good antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus. Hydroxyapatite and zinc-doped hydroxyapatite were prepared and characterized using X-ray diffraction, Transmission electron microscopy and inductively coupled plasma optical emission spectrometry. They were loaded with ciprofloxacin using optimized drug loading parameters. Drug loading, in vitro drug release and antimicrobial activity were analyzed. The influence of zinc on the controlled release of ciprofloxacin was analyzed. The results show that the presence of zinc increases the drug release percentage and that the drug was released in a controlled manner.