Ginger extract loaded Fe2O3/MgO-doped hydroxyapatite: Evaluation of biological properties for bone-tissue engineering.

Since antiquity, the medicinal properties of naturally sourced biomolecules such as ginger (Zingiber officinale) extract are documented in the traditional Indian and Chinese medical systems. However, limited work is performed to assess the potential of ginger extracts for bone-tissue engineering. Our work demonstrates the direct incorporation of ginger extract on iron oxide-magnesium oxide (Fe2O3 and MgO) co-doped hydroxyapatite (HA) for enhancement in the biological properties. The addition of Fe2O3 and MgO co-doping system and ginger extract with HA increases the osteoblast viability up to ~ 1.4 times at day 11. The presence of ginger extract leads to up to ~ 9 times MG-63 cell viability reduction. The co-doping does not adversely affect the release of ginger extract from the graft surface in the biological medium at pH 7.4 for up to 28 days. Assessment of antibacterial efficacy according to the modified ISO 22196: 2011 standard method indicates that the combined effects of Fe2O3, MgO, and ginger extract lead to ~ 82 % more bacterial cell reduction, compared to the control HA against S. aureus. These ginger extract-loaded artificial bone grafts with enhanced biological properties may be utilized as a localized site-specific delivery vehicle for various bone tissue engineering applications.

Multifunctional polydopamine - Zn2+-curcumin coated additively manufactured ceramic bone grafts with enhanced biological properties.

The lack of site-specific chemotherapeutic agents after osteosarcoma surgeries often induces severe side effects. We propose the utilization of curcumin as an alternative natural chemo-preventive drug for tumor-specific delivery systems with 3D printed tricalcium phosphate (TCP) based artificial bone grafts. The poor bioavailability and hydrophobic nature of curcumin restrict its clinical use. We have used polydopamine (PDA) coating with Zn2+ functionalization to enhance the curcumin release in the biological medium. The obtained PDA-Zn2+ complex is characterized by X-ray photoelectron spectroscopy (XPS). The presence of PDA-Zn2+ coating leads to ~2 times enhancement in curcumin release. We have computationally predicted and validated the optimized surface composition by a novel multi-objective optimization method. The experimental validation of the predicted compositions indicates that the PDA-Zn2+ coated curcumin immobilized delivery system leads to a ~12 folds decrease in osteosarcoma viability on day 11 as compared to only TCP. The osteoblast viability shows ~1.4 folds enhancement. The designed surface shows the highest ~90 % antibacterial efficacy against gram-positive and gram-negative bacteria. This unique strategy of curcumin delivery with PDA-Zn2+ coating is expected to find application in low-load bearing critical-sized tumor-resection sites.

In vivo and In vitro properties evaluation of curcumin loaded MgO doped 3D printed TCP scaffolds.

The lack of site-specific chemotherapeutic agents to treat bone malignancy throws a significant challenge in the design of a delivery vehicle. The major scientific question posed in this study is, can we utilize curcumin-loaded magnesium oxide (MgO) doped 3D printed tricalcium phosphate (TCP) bone grafts as a localized delivery system that improves early stage in vivo osseointegration and in vitro chemoprevention, antibacterial properties? We have utilized curcumin as an alternative natural chemopreventive agent for bone cancer-specific delivery after direct incorporation on the 3D printed tricalcium phosphate (TCP) bone grafts. The addition of MgO as a dopant to TCP leads to ∼1.3 times enhancement in compressive strength. The designed drug delivery system shows up to ∼22% curcumin release in a physiological pH of 7.4 after 30 days. The presence of curcumin leads to up to ∼8.5 times reduction in osteosarcoma viability. In vitro results indicate that these scaffolds significantly enhance bone-forming osteoblast cells while reducing the bone-resorbing osteoclast cells. The in vivo rat distal femur model surgery followed by histological assessment with H&E, vWF, and Movat pentachrome staining results show that the designed scaffolds lead to new bone formation (up to ∼2.5 times higher than the control) after successful implantation. The presence of MgO and curcumin results in up to ∼71% antibacterial efficacy against osteomyelitis causing S. aureus. These 3D printed osteogenic and chemopreventive scaffolds can be utilized in patient-specific low load-bearing defect sites.

Allicin-Loaded Hydroxyapatite: Enhanced Release, Cytocompatibility, and Antibacterial Properties for Bone Tissue Engineering Applications.

Allicin, the active compound of garlic extract, is a naturally sourced biomolecule, which promotes a vast range of health benefits. However, the limited stability of allicin restricts its applications in tissue engineering. Additionally, the detailed effects of allicin in bone health are yet to be explored. Our work reports on the fabrication of a novel allicin-loaded hydroxyapatite drug delivery system with enhanced biological properties. The fabricated system shows excellent antibacterial efficiency against S. aureus after 36 h of bacterial interaction with a sample. The allicin release kinetics are enhanced with polycaprolactone (PCL). The obtained results after 20 days of drug release study indicate that PCL coating leads to an increase in cumulative allicin release from ~ 35% to 70% at a physiological pH of 7.4. These scaffolds maintain stability during the whole period of drug release. Cytocompatibility of tested compositions with osteoblasts indicates enhanced cell viability and good filopodial attachment on the sample surface at day 7. These allicin-loaded antibacterial and cytocompatible scaffolds can find applications as localized delivery vehicles for bone tissue engineering.

Plasma sprayed fluoride and zinc doped hydroxyapatite coated titanium for load-bearing implants.

Titanium (Ti) alloys show excellent fatigue and corrosion resistance, high strength to weight ratio, and no toxicity; however, poor osseointegration ability of Ti may lead to implant loosening in vivo. Plasma spraying of hydroxyapatite [HA, Ca10 (PO4)6 (OH)2] coating on Ti surfaces is commercially used to enhance osseointegration and the long-term stability of these implants. The biological properties of HA can be improved with the addition of both cationic and anionic dopants, such as zinc ions (Zn2+) and fluoride (F-). However, the hygroscopic nature of fluoride restricts its utilization in the radiofrequency (RF) plasma spray process. In addition, the amount of doping needs to be optimized to ensure cytocompatibility. We have fabricated zinc and fluoride doped HA-coated Ti6Al4V (Ti64) to mitigate these challenges using compositional and parametric optimizations. The RF induction plasma spraying method is utilized to prepare the coatings. Multiple parametric optimizations with amplitude and frequency during the processing result in coating thicknesses between 80 and 145 µm. No adverse effects on the adhesion properties of the coating are noticed because of doping. The antibacterial efficacy of each composition is tested against S. aureus for 24, 48, and 72 h, and showed that the addition of zinc oxide and calcium fluoride to HA leads to nearly 70 % higher antibacterial efficacy than pure HA-coated samples. The addition of osteogenic Zn2+and F- leads to 1.5 times higher osteoblast viability for the doped samples than pure HA-coated samples after 7-days of cell culture. Zn2+ and F- doped HA-coated Ti64 with simultaneous improvements in anti-bacterial efficacy and in vitro biocompatibility can find application in load-bearing implants, particularly in revision surgeries and immune-compromised patients.

Zinc curcumin complex on fluoride doped hydroxyapatite with enhanced biological properties for dental and orthopedic applications.

Since antiquity, curcumin, from turmeric is utilized in traditional Indian medicine (Ayurveda) to treat bone disorders. However, the hydrophobic nature and poor absorption of curcumin limit its clinical applications. There is a need to develop a novel strategy that can significantly enhance curcumin's biological properties. The current work reports the utilization of Zn2+-curcumin complex from a fluoride doped hydroxyapatite matrix for osteosarcoma inhibition, osteoblast growth, and anti-bacterial properties. The interaction between Zn2+ and curcumin increases curcumin release by ~ 2.5 folds. The fabricated drug delivery system shows up to ~ 1.6 times enhancement in osteoblast cell viability. The presence of curcumin results in ~ 4 times more osteosarcoma inhibition compared to control. The antibacterial efficacy of this system is confirmed against Staphylococcus aureus, due to the presence of antibacterial fluoride, zinc, and curcumin. This multifunctional drug delivery system can be utilized for various bone-tissue engineering and dental applications.

3D printed hydroxyapatite - Zn2+ functionalized starch composite bone grafts for orthopedic and dental applications.

Hydroxyapatite (HA) - polymer composite based 3D printed bone grafts require extensive mechanical and biological property optimization for specific clinical needs. This fuels the need to develop innovative methods of optimization. Using an in-house extrusion-based 3D printer, we show the feasibility of fabricating hydroxyapatite- Zn2+ functionalized starch composites as artificial bone graft substitutes. The experimental procedure for this purpose is fortified with a univariate multi-objective optimization strategy to predict the best composition. The compressive strength of the grafts improves up to ~ 4 folds by parametric optimization and Zn2+ functionalization, without any post-processing. These grafts maintain mechanical integrity and strength during 6 weeks of dissolution study in simulated body fluid (SBF), while the non -functionalized starch-HA grafts fully degrade within a week. The Zn2+ functionalization results in up to ~ 79% antibacterial efficacy against S. aureus. Osteoblast cell viability increases ~ 1.6 folds on these graft surfaces on day 11. Our innovative methods of optimization are expected to reduce the experiment time, cost, and chance of human error in 3D printing. This study redefines the importance of understanding composition and process dependence for making a functionalized 3D printed bone graft for repairing low load-bearing defects such as craniomaxillofacial bone.

3D printed hydroxyapatite-nacre-starch based bone grafts: Evaluation of biological and mechanical properties.

The possibilities of utilizing nacre as a reinforcing material to manufacture 3D printed bone grafts are yet to be explored. This work reports the feasibility of fabricating 3D printed nacre-hydroxyapatitestarch composite bone graft substitutes, emphasizing the effects of nacre addition on biological and mechanical properties. Pressure-less extrusion-based 3D printing of ceramic-polymer viscous slurry is challenging due to the composition and process-parameter variations. To overcome these challenges, a dual extrusion solid freeform fabricator (SFF) has been designed. An increase in nacre loading improves the compressive strength from 9.5 ± 0.1 MPa to 11.7 ± 0.2 MPa, without any post-processing or sintering. Nacre's in vitro osteogenic properties lead to a slight increase in hFOB cellular attachment on the graft surface by day 11. The fabricated structures show good mechanical integrity during the dissolution study in simulated body fluid (SBF). These bone graft substitutes may be utilized to repair low load bearing skeletal defects.

Influence of random and designed porosities on 3D printed tricalcium phosphate-bioactive glass scaffolds.

Calcium phosphate (CaP)-based ceramics are a popular choice for bone-graft applications due to their compositional similarities with bone. Similarly, Bioactive glass (BG) is also common for bone tissue engineering applications due to its excellent biocompatibility and bone binding ability. We report tricalcium phosphate (TCP)-BG (45S5 BG) composite scaffolds using conventional processing and binder jetting-based 3D printing (3DP) technique. We hypothesize that BG's addition in TCP will enhance densification via liquid phase sintering and improve mechanical properties. Further, BG addition to TCP should modulate the dissolution kinetics in vitro. This work's scientific objective is to understand the influence of random vs. designed porosity in TCP-BG ceramics towards variations in compressive strength and in vitro biocompatibility. Our findings indicate that a 5 wt % BG in TCP composite shows a compressive strength of 26.7 ± 2.7 MPa for random porosity structures having a total porosity of ~47.9%. The same composition in a designed porosity structure shows a compressive strength of 21.3 ± 2.9 MPa, having a total porosity of ~54.1%. Scaffolds are also tested for their dissolution kinetics and in vitro bone cell materials interaction, where TCP-BG compositions show favorable bone cell materials interactions. The addition of BG enhances a flaky hydroxycarbonate apatite (HCA) layer in 8 weeks in vitro. Our research shows that the porous TCP- BG scaffolds, fabricated via binder jetting method with enhanced mechanical properties and dissolution properties can be utilized in bone graft applications.

Human Teeth-Derived Bioceramics for Improved Bone Regeneration.

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is one of the most promising candidates of the calcium phosphate family, suitable for bone tissue regeneration due to its structural similarities with human hard tissues. However, the requirements of high purity and the non-availability of adequate synthetic techniques limit the application of synthetic HAp in bone tissue engineering. Herein, we developed and evaluated the bone regeneration potential of human teeth-derived bioceramics in mice's defective skulls. The developed bioceramics were analyzed by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (FE-SEM). The developed bioceramics exhibited the characteristic peaks of HAp in FTIR and XRD patterns. The inductively coupled plasma mass spectrometry (ICP-MS) technique was applied to determine the Ca/P molar ratio in the developed bioceramics, and it was 1.67. Cytotoxicity of the simulated body fluid (SBF)-soaked bioceramics was evaluated by WST-1 assay in the presence of human alveolar bone marrow stem cells (hABMSCs). No adverse effects were observed in the presence of the developed bioceramics, indicating their biocompatibility. The cells adequately adhered to the bioceramics-treated media. Enhanced bone regeneration occurred in the presence of the developed bioceramics in the defected skulls of mice, and this potential was profoundly affected by the size of the developed bioceramics. The bioceramics-treated mice groups exhibited greater vascularization compared to control. Therefore, the developed bioceramics have the potential to be used as biomaterials for bone regeneration application.

Crystal Chemistry and Antibacterial Properties of Cupriferous Hydroxyapatite.

Copper-doped hydroxyapatite (HA) of nominal composition Ca10(PO4)6[Cux(OH)2-2xOx] (0.0 ≤ x ≤ 0.8) was prepared by solid-state and wet chemical processing to explore the impact of the synthesis route and mode of crystal chemical incorporation of copper on the antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) strains. Apatites prepared by solid-state reaction showed unit cell volume dilation from 527.17 Å3 for copper-free HA to 533.31 Å3 for material of the putative composition Ca10(PO4)6[Cu0.8(OH)0.4O0.8] consistent with Cu+ insertion into the [001] hydroxyapatite channel. This was less pronounced (528.30 Å3 to 529.3 Å3) in the corresponding wet chemical synthesised products, suggesting less complete Cu tunnel incorporation and partial tenancy of Cu in place of calcium. X-ray absorption spectroscopy suggests fast quenching is necessary to prevent oxidation of Cu+ to Cu2+. Raman spectroscopy revealed an absorption band at 630 cm-1 characteristic of symmetric O-Cu+-O units tenanted in the apatite channel while solid-state 31P magic-angle-spinning nuclear magnetic resonance (MAS NMR) supported a vacancy-Cu+ substitution model within the apatite channel. The copper doping strategy increases antibacterial efficiency by 25% to 55% compared to undoped HA, with the finer particle sizes and greater specific surface areas of the wet chemical material demonstrating superior efficacy.