Characteristics of functionalized nano-hydroxyapatite and internalization by human epithelial cell

Clinical and Radiographic Evaluation of Third-Generation Pericardium Membrane for the Treatment of Grade II Furcation Defect in Stage III Periodontitis Patients

Background and Objectives: Guided tissue regeneration, with or without a bone graft, is a modality for the treatment of furcation involvement. Because the direct application of a bone graft into the periodontal defect has drawbacks, such as the risk of microbial contamination and/or graft containment, a new modality of directly loading bone graft particles over the barrier membrane is now used. This study aimed to evaluate clinically and radiographically the effects of a two-layered membrane consisting of a layer of nanohydroxyapatite particles on a pericardium membrane in the treatment of stage III periodontitis, compared with direct application of a nanohydroxyapatite bone graft. Materials and Methods: Forty individuals with grade II furcation involvement were divided into two groups. Group I was treated with a two-layered membrane consisting of a pericardium membrane with nanohydroxy particles loaded onto its surface; group II was treated with direct application of a nano bone graft covered with pericardium membrane. Clinical and cone beam computed tomography (CBCT) radiographic assessments of the two groups were carried out after a 6-month follow-up period. Results: Clinically, the results showed a significant reduction in furcation involvement (F). The CBCT assessment also revealed reductions in depth (D), height (H), width (W), and 3D radiographic volume of furcation involvement in all study groups at baseline and at 6 months postoperative (p < 0.05) with no significant differences between groups. Conclusions: According to the results of the current study, a two-layer membrane formed by direct loading of bone graft particles onto a pericardium membrane can be used as an effective, reliable, and easy-to-use substitute for direct bone graft application into periodontal defects.

Lanthanides-Substituted Hydroxyapatite for Biomedical Applications

Lately, there has been an increasing demand for materials that could improve tissue regenerative therapies and provide antimicrobial effects. Similarly, there is a growing need to develop or modify biomaterials for the diagnosis and treatment of different pathologies. In this scenario, hydroxyapatite (HAp) appears as a bioceramic with extended functionalities. Nevertheless, there are certain disadvantages related to the mechanical properties and lack of antimicrobial capacity. To circumvent them, the doping of HAp with a variety of cationic ions is emerging as a good alterative due to the different biological roles of each ion. Among many elements, lanthanides are understudied despite their great potential in the biomedical field. For this reason, the present review focuses on the biological benefits of lanthanides and how their incorporation into HAp can alter its morphology and physical properties. A comprehensive section of the applications of lanthanides-substituted HAp nanoparticles (HAp NPs) is presented to unveil the potential biomedical uses of these systems. Finally, the need to study the tolerable and non-toxic percentages of substitution with these elements is highlighted.

Nanohydroxyapatite as a Biomaterial for Peripheral Nerve Regeneration after Mechanical Damage-In Vitro Study

Hydroxyapatite has been used in medicine for many years as a biomaterial or a cover for other biomaterials in orthopedics and dentistry. This study characterized the physicochemical properties (structure, particle size and morphology, surface properties) of Li⁺- and Li⁺/Eu³⁺-doped nanohydroxyapatite obtained using the wet chemistry method. The potential regenerative properties against neurite damage in cultures of neuron-like cells (SH-SY5Y and PC12 after differentiation) were also studied. The effect of nanohydroxyapatite (nHAp) on the induction of repair processes in cell cultures was assessed in tests of metabolic activity, the level of free oxygen radicals and nitric oxide, and the average length of neurites. The study showed that nanohydroxyapatite influences the increase in mitochondrial activity, which is correlated with the increase in the length of neurites. It has been shown that the doping of nanohydroxyapatite with Eu³⁺ ions enhances the antioxidant properties of the tested nanohydroxyapatite. These basic studies indicate its potential application in the treatment of neurite damage. These studies should be continued in primary neuronal cultures and then with in vivo models.

Response surface methodology optimized electrochemical DNA biosensor based on HAPNPTs/PPY/MWCNTs nanocomposite for detecting Mycobacterium tuberculosis

An important issue in the prognosis of tuberculosis (TB) is a short period between correct diagnosis and start the suitable antibiotic therapy. So, a rapid and valid method for detection of Mycobacterium tuberculosis (M. tb) complex is considered as a necessity. Herein, a rapid, low-cost, and PCR-free DNA biosensor was developed based on multi-walled carbon nanotubes (MWCNTs), polypyrrole (PPy), and hydroxyapatite nanoparticles (HAPNPs) for highly sensitive and specific recognition of M.tb. The biosensor consisted of M.tb ssDNA probe covalently attached to the HANPs/PPy/MWCNTs/GCE surface that hybridized to a complementary target sequence to form a duplex DNA. The M.tb target recognition was based on the oxidation signal of the electroactive Methylene Blue (MB) on the surface of the modified GCE using differential pulse voltammetry (DPV) method. It is worth to mention that for the first time Plackett-Burman (PB) screening design and response surface method (RSM) based on central composite design (CCD) was applied as a powerful and an efficient approach to find optimal conditions for maximum M.tb biosensor performance leading to simplicity and rapidity of operation. The proposed DNA biosensor exhibits a wide detection range from 0.25 to 200.0 nM with a low detection limit of 0.141 nM. The performance of designed biosensor for clinical diagnosis and practical applications was revealed through hybridization between DNA probe-modified GCE and extracted DNA from sputum clinical samples.

Interplay between surface chemistry and osteogenic behaviour of sulphate substituted nano-hydroxyapatite

Surface potential and chemical compositions of the bioceramics are the core of therapeutic effect and are key factors to trigger the interfacial interactions with surrounding hard and soft tissues to repair and regeneration. Ionic substitution in hydroxyapatite (Hap) lattice significantly influences the zeta potential from -16.46 ± 0.66 mV to -6.01 ± 0.68 mV as well as an average nano-rod length from ~40 nm to ~26 nm with respect to SO₄^2- ion content. Moreover, the surface chemistry of Hap is mainly inter-related to SO₄^2- substitution rate at PO₄^2- site. Specifically, nano-sized feature with lowered negative surface potential influences the protein adsorption via their weak repulsive or attractive forces. Bovine serum albumin (BSA) and lysozyme (LSZ) adsorption studies confirmed the increased affinity to active binding sites of Hap's surface. Further, SO₄^2- ion substituted Hap (SNHA) showed improved in vitro biomineralization activity and alkaline phosphatase activity. Expression of osteogenic biomarkers such as collagen I, V, osteopontin and osteocalcin were evaluated in Saos-2 and MC3T3-E1 cells. Gene expression of these markers was influenced by SO₄^2- ion content in Hap (maximum with 10SNHA). Altogether, these data emphasizes that chemical composition and surface properties are dominant aspect in bioceramic development towards bone regeneration.

A novel method for genetic transformation of C. albicans using modified-hydroxyapatite nanoparticles as a plasmid DNA vehicle

In modern biological research, genetic transformation is an important molecular biology technique with extensive applications. In this work, we describe a new method for the delivery of plasmid DNA (pDNA) into a yeast species, Candida albicans. This method is based on the use of novel arginine-glucose-PEG functionalized hydroxyapatite nanoparticles (M-HAp NPs) as a vehicle which delivers pDNA into Candida albicans with a high transformation efficiency of 10⁶ cfu μg^-1 of pDNA, without the need for preparation of competent cells. A four-fold higher transformation efficiency as compared to that of the electroporation method was obtained. This new method could provide exciting opportunities for the advancement of the applications of yeasts in the field of biotechnology.

Adsorption/desorption study of antibiotic and anti-inflammatory drugs onto bioactive hydroxyapatite nano-rods

The use of high doses of antibacterial and anti-inflammatory drugs for patients with bone diseases, associated to implants or bone filling, can develop adverse effects; and consequently, it promotes to think new strategies to avoid this problem. In this work, it has been described the adsorption/release (or desorption) behavior of two drugs, ciprofloxacin (CIP) and ibuprofen (IBU), onto hydroxyapatite (nano-HA) at 37 °C. Through Ultraviolet-Visible (UV-Vis) spectroscopy, the concentrations of both drugs in adsorption, kinetic and desorption processes were obtained. The Fourier Transformed-Infrared (FT-IR) spectroscopy, Zeta-potential (ζ-potential), High-Resolution Transmission Electron Microscopy (H-TEM) and x-Ray Diffraction (xRD) were also used to characterize bared nanoparticles and those with adsorbed drugs. Five adsorption models (Langmuir, Freundlich, Sips, Temkin and Dubinin-Radushkevich) were used for describing the behavior of both active compounds. The adsorption processes (CIP/nano-HA and IBU/nano-HA) were better predicted by the Sips model than by the others. The kinetic adsorption data were processed, for both active agents, by application of Avrami's model. Desorption/release process (of both drugs) was evaluated though Korsmeyer-Peppas (K-P) model. Owing to the predictability of these systems, we propose the use of these active ceramics as potential bone filler for improving the treatment against bacterial bone infections and to avoid its associated inflammatory process.

Halloysite nanotubes in analytical sciences and in drug delivery: A review

Halloysite (HNT) is a natural inorganic mineral that has many applications in manufacturing. This review (with 192 references) covers (a) the chemical properties of halloysites, (b) the effects of alkali and acid etching on the loading capacity and the release behavior of halloysites, (c) the use of halloysite nanotubes in analytical sciences and drug delivery, and (d) recent trends in the preparation of magnetic HNTs. Synthetic methods such as co-precipitation, thermal decomposition, and solvothermal method are discussed, with emphasis on optimal magnetization. In the analytical field, recent advancements are summarized in terms of applications of HNT-nanocomposites for extraction and detection of heavy metal ions, dyes, organic pollutants, and biomolecules. The review also covers methods for synthesizing molecularly imprinted polymer-modified HNTs and magnetic HNTs. With respect to drug delivery, the toxicity, techniques for drug loading and the various classes of drug-halloysite nanocomposites are discussed. This review gives a general insight on the utilization of HNT in analytical determination and drug delivery systems which may be useful for researchers to generate new ideas. Graphical abstract Schematic presentation of the structure of halloysite nanotubes, selected examples of modifications and functionalization, and represetative field of applications.

Inhibition of prostate cancer RM1 cell growth in vitro by hydroxyapatite nanoparticle‑delivered short hairpin RNAs against Stat3

The present study investigated the effect of signal transducer and activator of transcription 3 (Stat3) interference on RM1 prostate cancer cell viability in vitro, using plasmid‑based Stat3 specific short hairpin RNA (sh‑Stat3) delivered by hydroxyapatite nanoparticles (HAP). HAP carrying sh‑Stat3 plasmids were transfected into tumor cells. MTT assays were used to measure RM1 cell viability 24 and 48 h following transfection, and the apoptosis rate and cell cycle phase distribution were determined by flow cytometry. Stat3 mRNA expression levels were measured by reverse transcription‑quantitative polymerase chain reaction and Stat3, Cyclin D1, B cell lymphoma 2 apoptosis regulator (Bcl‑2), vascular endothelial growth factor (VEGF), Bcl‑2 associated X apoptosis regulator (Bax) and cleaved‑caspase‑3 protein expression levels were detected using western blot analysis. The results demonstrated that HAP‑delivered sh‑Stat3 significantly decreased RM1 cell viability through the promotion of cell cycle arrest and apoptosis. Stat3 mRNA and protein expression levels were significantly downregulated in RM1 cells. Bcl‑2, VEGF and Cyclin D1 were also significantly downregulated, but cleaved‑caspase‑3 and Bax mRNA and protein expression levels were significantly upregulated. HAP‑delivered sh‑Stat3 decreased RM1 cell viability in vitro, and HAP assisted plasmid‑based delivery of shRNA into tumor cells. The present results suggest that HAP may be a useful method for successful shRNA delivery into tumors.

Repair of rabbit cartilage defect based on the fusion of rabbit bone marrow stromal cells and Nano-HA/PLLA composite material

Objective To assess the effect of the fusion of rabbit bone marrow stromal cells (rBMSCs) and Nano-hydroxyapatite/poly (l-lactic acid) (Nano-HA/PLLA) in repairing the rabbit knee joint with full-thickness cartilage defect. Method The rBMSCs were isolated and cultured in vitro, and the third generation of rBMSCs was co-cultured with the Nano-HA/PLLA to construct the tissue-engineered cartilage (TEC). Eighteen New Zealand white rabbits were selected and randomly divided into three groups, namely, TEC group, Nano-HA/PLLA group, and control group. A cartilage defect model with the diameter of 4.5 mm and depth of 5 mm was constructed on the articular surface of medial malleolus of rabbit femur. General observation, histological observation, and Wakitani's histological scoring were conducted in the 12th and 24th week postoperatively. Results The results of TEC group indicated that new cartilage tissue was formed on the defect site and subchondral bone achieved physiological integration basically. Histological and immunohistochemical analyses indicated the generation of massive extracellular matrix. In contrast, limited regeneration and reconstruction of cartilage was achieved in the Nano-HA/PLLA group and control group, with a significant difference from the TEC group (p < 0.05). Moreover, the effect of cartilage repair was positively correlated with time. Conclusion The porous Nano-HA/PLLA combined with BMSCs promoted the repair of weight-bearing bone of adult rabbit's knee joint with cartilage defect.

Nickel doped nanohydroxyapatite: vascular endothelial growth factor inducing biomaterial for bone tissue engineering

Biomaterial induced activation of vascular endothelial growth factor (VEGF) pathway for angiogenesis is now gaining recognition as an effective option for tissue engineering.

Calcium Orthophosphate-Based Bioceramics

Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.

Delivery system for DNAzymes using arginine-modified hydroxyapatite nanoparticles for therapeutic application in a nasopharyngeal carcinoma model

DNAzymes are synthetic, single-stranded, catalytic nucleic acids that bind and cleave target mRNA in a sequence-specific manner, and have been explored for genotherapeutics. One bottleneck restricting their application is the lack of an efficient delivery system. As an inorganic nanomaterial with potentially wide application, nano-hydroxyapatite particles (nHAP) have attracted increasing attention as new candidates for nonviral vectors. In this study, we developed an nHAP-based delivery system and explored its cellular uptake mechanisms, intracellular localization, and biological effects. Absorption of arginine-modified nanohydroxyapatite particles (Arg-nHAP) and DZ1 (latent membrane protein 1 [LMP1]-targeted) reached nearly 100% efficiency under in vitro conditions. Using specific inhibitors, cellular uptake of the Arg-nHAP/DZ1 complex was shown to be mediated by the energy-dependent endocytosis pathway. Further, effective intracellular delivery and nuclear localization of the complex was confirmed by confocal microscopy. Biologically, the complex successfully downregulated the expression of LMP1 in nasopharyngeal carcinoma cells. In a mouse tumor xenograft model, the complex was shown to be delivered efficiently to tumor tissue, downregulating expression of LMP1 and suppressing tumor growth. These results suggest that Arg-nHAP may be an efficient vector for nucleic acid-based drugs with potential clinical application.