Synthesis, characterization, in vitro biocompatibility and antibacterial properties study of nanocomposite materials based on hydroxyapatite-biphasic ZnO micro- and nanoparticles embedded in Alginate matrix

ZnO Nanoparticle-Infused Vaterite Coatings: A Novel Approach for Antimicrobial Titanium Implant Surfaces

Loss of implant function is a common complication in orthopaedic and dental surgery. Among the primary causes of implant failure are peri-implant infections which often result in implant removal. This study demonstrates the development of a new antimicrobial titanium coating with ZnO nanoparticles of various sizes and morphologies immobilised in poly(allylamine hydrochloride) and alginate multilayers, combined with epitaxially grown vaterite crystals. The coated samples were characterised with various methods (FTIR, XRD, SEM) and surface properties were evaluated via water contact angle and surface charge measurements. Zinc ion release was quantified using ICP-MS. The antimicrobial efficacy of the coatings was tested against Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans while the biocompatibility was tested with preosteoblast cells (MC3T3-E1). Results demonstrated the successful preparation of a calcium carbonate/ZnO composite coating with epitaxially grown vaterite on titanium surfaces. The Zn ions released from ZnO nanoparticles dramatically influenced the morphology of vaterite where a new flower-like morphology was observed. The coated titanium surfaces exhibited robust antimicrobial activity, achieving over 90% microbial viability reduction for Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans. Importantly, the released Zn2+ concentrations remained below the cytotoxicity limit for MC3T3-E1 cells, showing potential for safe and effective implant applications.

Polarised hydroxyapatite- sodium alginate composite as an antibacterial filler matrix

Bone-substituted composite material based on bioceramics and polymer has enhanced their biological performance with dynamic properties such as bioactivity, biocompatibility, osseointegration, and mechanical stability, which can be used in a controlled drug delivery system for avoiding infections as well as pain. Here in this study, we developed a new approach for inducing antibacterial and osteogenic responses on biomaterial substrates via surface polarisation. The hydroxyapatite- sodium alginate composite was negatively polarised using a corona poling setup and characterised using X-ray diffraction analysis. The thermally stimulated depolarization current study showed a maximum current of 4.74 nA/cm2, observed at a temperature of 480 °C. The wettability of the specimen was measured using contact angle measurements, which demonstrated that the polarised composite specimen exhibited higher water retention ability. The bacterial cell viability test was measured using the 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay, which revealed poor bacterial growth on polarised specimens as compared to their unpolarised counterparts. In addition, the osteogenic MG63 cell proliferation showed increased gene expression on polarised specimens. These findings showed that polarising hydroxyapatite- sodium alginate composite could be an excellent option to be used as an antibacterial bone filler matrix for faster healing as it showed both antibacterial and osteogenic activity.

Antibacterial activity of carbonate hydroxyapatite-based honeycomb scaffolds doped with zinc for medical implants

BackgroundThe utilization of bioceramics for medical implants necessitates the incorporation of antibacterial properties to mitigate post-surgical inflammation of bone tissue.ObjectiveIn this research, Zn2+ ions were introduced as an antibacterial agent into carbonate-hydroxyapatite-based honeycomb Scaffold bioceramics (CHA/HCB), with varying doping concentrations, to investigate the impact of Zn2+ on the antibacterial activity of CHA/HCB against Staphylococcus aureus and Pseudomonas aeruginosa.MethodsCHA was synthesized from abalone shells through the co-precipitation method, followed by the fabrication of a CHA-based scaffold with HCB using the porogen leaching technique. Subsequently, the Zn ion doping process was executed through the ion exchange method, using concentrations of 0.05 M, 0.1 M, 0.15 M, and 0.2 M. The samples were characterized using XRF and antibacterial test.ResultsThe XRF results revealed that the Ca/P ratio of CHA/HCB was within the range of 1.48-1.85, indicating a declining trend with the introduction of Zn2+ as a dopant. Nevertheless, these results remained within acceptable ranges, ensuring compatibility with bone tissue. In terms of antibacterial activity, the measured inhibition zone diameters increased alongside the increase of Zn concentration. The zone diameters ranged from 14.3 to 22.0 mm against Staphylococcus aureus and 13.7 to 21.4 mm against Pseudomonas aeruginosa.ConclusionThe findings suggest that Zn doping in CHA/HCB bioceramics has a potential an antibacterial agent in CHA scaffolds as well as potential for practical applications, particularly in reducing the risk of postoperative infection in bone tissue implantation.

Structural and optical properties of alginate-based antibacterial dressing with calcium phosphate and zinc oxide for biodegradable wound painting applications

The skin is the outermost part of the body. Although susceptible to damage, the skin is in direct contact with the external environment. Wound dressing is a clinical method that plays a vital role in wound healing. Herein, we developed an antibacterial wound dressing using alginate as the basic material. The dressing was prepared using the solvent casting method, which was used to analyze the effects of adding CaP and ZnO on its structural, optical, and antibacterial properties. Adding CaP exhibited strong but stiff mechanical properties, unlike the CaP/ZnO, which possessed high strength and elasticity. The optical properties of sample S2 did not have a considerable impact. By contrast, the addition of ZnO to sample S3 notably increases the wavelength and absorption value. The diameter of the inhibition zone for S. aureus bacteria exhibited a successive increase in its antibacterial properties, and sample S3 exhibited the highest value. Thus, sample S3 is the most promising wound dressing concerning speeding up the wound healing process because it possesses the most optimal mechanical, optical, and antibacterial properties. The main limitation to be addressed is that sample S3 cannot be easily digested in the environment.

Functionalization of Alginate Hydrogels with a Multifunctional Peptide Supports Mesenchymal Stem Cell Adhesion and Reduces Bacterial Colonization

Hydrogels with cell adhesive moieties stand out as promising materials to enhance tissue healing and regeneration. Nonetheless, bacterial infections of the implants represent an unmet major concern. In the present work, we developed an alginate hydrogel modified with a multifunctional peptide containing the RGD cell adhesive motif in combination with an antibacterial peptide derived from the 1-11 region of lactoferrin (LF). The RGD-LF branched peptide was successfully anchored to the alginate backbone by carbodiimide chemistry, as demonstrated by 1H NMR and fluorescence measurements. The functionalized hydrogel presented desirable physicochemical properties (porosity, swelling and rheological behavior) to develop biomaterials for tissue engineering. The viability of mesenchymal stem cells (MSCs) on the peptide-functionalized hydrogels was excellent, with values higher than 85 % at day 1, and higher than 95 % after 14 days in culture. Moreover, the biological characterization demonstrated the ability of the hydrogels to significantly enhance ALP activity of MSCs as well as to decrease bacterial colonization of both Gram-positive and Gram-negative models. Such results prove the potential of the functionalized hydrogels as novel biomaterials for tissue engineering, simultaneously displaying cell adhesive activity and the capacity to prevent bacterial contamination, a dual bioactivity commonly not found for these types of hydrogels.

Reducing Water Absorption and Improving Flexural Strength of Aluminosilicate Ceramics by MnO2 Doping

As key performance indicators, the water absorption and mechanical strength of ceramics are highly associated with sintering temperature. Lower sintering temperatures, although favorable for energy saving in ceramics production, normally render the densification degree and water absorption of as-prepared ceramics to largely decline and increase, respectively. In the present work, 0.5 wt.% MnO2, serving as an additive, was mixed with aluminosilicate ceramics using mechanical stirring at room temperature, achieving a flexural strength of 58.36 MPa and water absorption of 0.05% and lowering the sintering temperature by 50 °C concurrently. On the basis of the results of TG-DSC, XRD, MIP, and XPS, etc., we speculate that the MnO2 additive promoted the elimination of water vapor in the ceramic bodies, effectively suppressing the generation of pores in the sintering process and facilitating the densification of ceramics at a lower temperature. This is probably because the MnO2 transformed into a liquid phase in the sintering process flows into the gap between grains, which removed the gas inside pores and filled the pores, suppressing the generation of pores and the abnormal growth of grains. This study demonstrated a facile and economical method to reduce the porosity and enhance the densification degree in the practical production of aluminosilicate ceramics.

Effect of zinc oxide micro- and nanoparticles on cytotoxicity, antimicrobial activity and mechanical properties of apatite-polymer osteoplastic material

This work is devoted to the comparison of the physical and biological properties of synthesized osteoplastic composites with an experimentally determined content (375 μg/g) of the micro (ZnOMPs) and nano (ZnONPs) particles, immobilized in Hydroxyapatite-Alginate-Chitosan matrix (HA-Alg-CS). ZnONPs show pronounced antimicrobial activity against E.coli ATCC 25922 and S. aureus ATCC 25923, while ZnOMPs only in the CS presence. Composites containing ZnONPs/MPs do not have a toxic effect on bone-forming cells - osteoblasts, preserving their ability to biomineralization. ZnOMPs and ZnONPs to varying degrees, but significantly affect composites' swelling, porosity, shape stability, and prolong vitamin D3 release for 120h, compared to Control. Composites do not demonstrate unwanted "burst release." ZnONPs/MPs increase Youngs' modulus of the HA-Alg matrix, namely 348 → 419 MPa (ZnOMPs), 348 → 646 MPa (ZnONPs), and weaken the plastic (irreversible) deformations. The compressive strength of HA-Alg and HA-Alg/CS matrixes containing ZnONPs (178 MPa and 251 MPa, respectively) is in the range of values for native cortical bone (170-193 MPa). Biocompatibility and lack of toxic effect give both composites a perspective for osteoplastic application, but composites doped with ZnONPs are more attractive.

3D-Printed Multifunctional Ag/CeO2/ZnO Reinforced Hydroxyapatite-Based Scaffolds with Effective Antibacterial and Mechanical Properties

Conventional three-dimensional (3D)-printed hydroxyapatite (HA)-based constructs have limited utility in bone tissue engineering due to their poor mechanical properties, elevated risk of microbial infection, and limited pore interconnectivity. 3D printing of complex multiple components to fabricate fully interconnected scaffolds is a challenging task; here, in this work, we have developed a procedure for fabrication of printable ink for complex systems containing multinanomaterials, i.e., HAACZ (containing 1 wt % Ag, 4 wt % CeO2, and 6 wt % ZnO) with better shear thinning and shape retention properties. Moreover, 3D-printed HAACZ scaffolds showed a modulus of 143.8 GPa, a hardness of 10.8 GPa, a porosity of 59.6%, effective antibacterial properties, and a fully interconnected pore network to be an ideal construct for bone healing. Macropores with an average size of ∼469 and ∼433 μm within the scaffolds of HA and HAACZ and micropores with an average size of ∼0.6 and ∼0.5 μm within the strut of HA and HAACZ were developed. The distribution of fully interconnected micropores was confirmed using computerized tomography, whereas the distribution of micropores within the strut was visualized using Voronoi tessellation. The water contact angle studies revealed the most suitable hydrophilic range of water contact angles of ∼71.7 and ∼76.6° for HA and HAACZ, respectively. HAACZ scaffolds showed comparable apatite formation and cytocompatibility as that of HA. Antibacterial studies revealed effective antibacterial properties for the HAACZ scaffold as compared to HA. There was a decrease in bacterial cell density for HAACZ from 1 × 105 to 1.2 × 103 cells/mm2 against Gram-negative (Escherichia coli) and from 1.9 × 105 to 5.6 × 103 bacterial cells/mm2 against Gram-positive (Staphylococcus aureus). Overall, the 3D-printed HAACZ scaffold resulted in mechanical properties, comparable to those of the cancellous bone, interconnected macro- and microporosities, and excellent antibacterial properties, which could be utilized for bone healing.

Synthesis, Properties, and Applications of Nanocomposite Materials Based on Bacterial Cellulose and MXene

MXene exhibits impressive characteristics, including flexibility, mechanical robustness, the capacity to cleanse liquids like water through MXene membranes, water-attracting nature, and effectiveness against bacteria. Additionally, bacterial cellulose (BC) exhibits remarkable qualities, including mechanical strength, water absorption, porosity, and biodegradability. The central hypothesis posits that the incorporation of both MXene and bacterial cellulose into the material will result in a remarkable synthesis of the attributes inherent to MXene and BC. In layered MXene/BC coatings, the presence of BC serves to separate the MXene layers and enhance the material's integrity through hydrogen bond interactions. This interaction contributes to achieving a high mechanical strength of this film. Introducing cellulose into one layer of multilayer MXene can increase the interlayer space and more efficient use of MXene. Composite materials utilizing MXene and BC have gained significant traction in sensor electronics due to the heightened sensitivity exhibited by these sensors compared to usual ones. Hydrogel wound healing bandages are also fabricated using composite materials based on MXene/BC. It is worth mentioning that MXene/BC composites are used to store energy in supercapacitors. And finally, MXene/BC-based composites have demonstrated high electromagnetic interference (EMI) shielding efficiency.

Enhancement of Antibacterial Properties, Surface Morphology and In Vitro Bioactivity of Hydroxyapatite-Zinc Oxide Nanocomposite Coating by Electrophoretic Deposition Technique

To develop medical-grade stainless-steel 316L implants that are biocompatible, non-toxic and antibacterial, such implants need to be coated with biomaterials to meet the current demanding properties of biomedical materials. Hydroxyapatite (HA) is commonly used as a bone implant coating due to its excellent biocompatible properties. Zinc oxide (ZnO) nanoparticles are added to HA to increase its antibacterial and cohesion properties. The specimens were made of a stainless-steel grade 316 substrate coated with HA-ZnO using the electrophoretic deposition technique (EPD), and were subsequently characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), stylus profilometry, electrochemical corrosion testing and Fourier transform infrared (FTIR) spectroscopy. Additionally, cross-hatch tests, cell viability assays, antibacterial assessment and in vitro activity tests in simulated body fluid (SBF) were performed. The results showed that the HA-ZnO coating was uniform and resistant to corrosion in an acceptable range. FTIR confirmed the presence of HA-ZnO compositions, and the in vitro response and adhesion were in accordance with standard requirements for biomedical materials. Cell viability confirmed the viability of cells in an acceptable range (>70%). In addition, the antibacterial activity of ZnO was confirmed on Staphylococcus aureus. Thus, the HA-ZnO samples are recommended for biomedical applications.

Hydroxyapatite-based carriers for tumor targeting therapy

At present, targeted drug delivery is regarded as the most effective means of tumor treatment, overcoming the lack of conventional chemotherapeutics that are difficult to reach or enter into cancer cells. Hydroxyapatite (HAP) is the main component of biological hard tissue, which can be regarded as a suitable drug carrier due to its biocompatibility, nontoxicity, biodegradation, and absorbability. This review focuses on the cutting edge of HAP as a drug carrier in targeted drug delivery systems. HAP-based carriers can be obtained by doping, modification, and combination, which benefit to improve the loading efficiency of drugs and the response sensitivity of the microenvironment in the synthesis process. The drug adsorbed or in situ loaded on HAP-based carriers can achieve targeted drug delivery and precise treatment through the guidance of the in vivo microenvironment and the stimulation of the in vitro response. In addition, HAP-based drug carriers can improve the cellular uptake rate of drugs to achieve a higher treatment effect. These advantages revealed the promising potential of HAP-based carriers from the perspective of targeted drug delivery for tumor treatment.

Copper(II) and Cobalt(II) Complexes Based on Abietate Ligands from Pinus Resin: Synthesis, Characterization and Their Antibacterial and Antiviral Activity against SARS-CoV-2

Co-abietate and Cu-abietate complexes were obtained by a low-cost and eco-friendly route. The synthesis process used Pinus elliottii resin and an aqueous solution of CuSO₄/CoSO₄ at a mild temperature (80 °C) without organic solvents. The obtained complexes are functional pigments for commercial architectural paints with antipathogenic activity. The pigments were characterized by Fourier-transform infrared spectroscopy (FTIR), mass spectrometry (MS), thermogravimetry (TG), near-edge X-ray absorption fine structure (NEXAFS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and colorimetric analysis. In addition, the antibacterial efficiency was evaluated using the minimum inhibitory concentration (MIC) test, and the antiviral tests followed an adaptation of the ISO 21702:2019 guideline. Finally, virus inactivation was measured using the RT-PCR protocol using 10% (w/w) of abietate complex in commercial white paint. The Co-abietate and Cu-abietate showed inactivation of >4 log against SARS-CoV-2 and a MIC value of 4.50 µg·mL^-1 against both bacteria Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The results suggest that the obtained Co-abietate and Cu-abietate complexes could be applied as pigments in architectural paints for healthcare centers, homes, and public places.

One-Pot Hydrothermal Preparation of Hydroxyapatite/Zinc Oxide Nanorod Nanocomposites and Their Cytotoxicity Evaluation against MG-63 Osteoblast-like Cells

In the present study, HAp-ZnO nanorod nanocomposites were successfully prepared using a customized hydrothermal reactor and studied for their compatibility against MG-63 osteoblast-like cells. The crystallinity, morphology, presence of chemical elements, and surface area properties were studied by XRD (X-ray diffraction), FE-SEM (field emission scanning electron microscopy), TEM (transmission electron microscopy), EDS (energy dispersive spectrum) and N₂ adsorption/desorption isotherm techniques, respectively. Further, the mechanical strength and thermal analysis were carried out using the nanoindentation method and thermogravimetric/differential scanning calorimeter (TG/DSC) methods, respectively. Moreover, in vitro biocompatibility studies for the prepared samples were carried out against human osteosarcoma cell lines (MG-63). The crystalline nature of the samples without any impurity phases was notified from XRD results. The formation of composites with the morphology of nanorods and the presence of desired elements in the intended ratio were verified using FE-SEM and EDS spectra, respectively. The TG/DSC results revealed the improved thermal stability of the HAp matrix, promoted by the reinforcement of the ZnO nanorods. The nanoindentation study ensured a significant enhancement in the mechanical stability of the prepared composite material. Finally, it demonstrated that the HAp matrix's mechanical strength and thermal stability were improved by the reinforcement of ZnO, and the cytotoxicity evaluation affirmed the biocompatible nature of the biomimetic hydroxyapatite in the composite.

Manufacturing hydroxyapatite scaffold from snapper scales with green phenolic granules as the space holder material

Hydroxyapatite (HA) scaffold was made using the powder metallurgy with an use of a space holder method with a pore-forming agent from green phenolic (GP) granules. The novelty of this study was the use of GP granules as an agent that does not melt at high temperatures to avoid damaging the tangential contact between the HA powder during the sintering process. HA from snapper scales was added and mixed with polyvinyl alcohol (PVA) and ethanol to form a slurry. The ethanol content was then removed by drying at room temperature. The HA, which contained PVA, was added with GP granules as a pore-forming agent in various amounts to get the desired porosity. The green body was made using a stainless steel mold with the uniaxial pressing process under a pressure of 100 MPa. To make a scaffold sintered body, a sintering process ran at 1200 °C with a holding time of 2 h while maintaining the heating and cooling rates at 5 °C/min. The physical properties of the scaffold sintered body were characterized through linear shrinkage test, pore measurement, porosity test, phase observation by X-ray diffraction (XRD), and microstructure observation by scanning electron microscopy (SEM) and digital microscopy (DM). So were the mechanical ones through a compressive strength test. The results showed that the sintered body had a compressive strength value of 1.6 MPa at a porosity of 60.7% with a pore size of 129-394 μm. The scaffold contained interconnections between pores at a HA:GP ratio of 55:45 wt%, which matched the condition required for cell tissue growth. The conclusion is that GP granules are good enough to be used as a pore-making agent on scaffolds using the space holder method because they do not damage the tangential contact between the HA powder during the sintering process. However, efforts are needed to remove the remaining GP ash on the scaffold.

Sorption analysis of composites based on zinc oxide for catalysis and medical materials science

Modified structures based on zinc oxide are of special interest in catalysis and medicine. The work discusses the composite structures based on zinc oxide and hydroxyapatite, as well as silver-modified zinc oxide nanostructures obtained by chemical deposition. The obtained materials were studied using a Rigaku SmartLab diffractometric complex and a Sorbi MS sorption analyzer. The specific surface area was studied and the average size of nanoparticles in the samples is determined. The application scope of the considered materials was catalysis and medicine, including the use in bone engineering as bioactive coatings deposited on the surface of a metal bioimplant.

Synthesis of hydroxyapatite nanoparticles using Acacia falcata leaf extract and study of their anti-cancerous activity against cancerous mammalian cell lines

This study deals with the synthesis of hydroxyapatite nanoparticles (HAPnps) mediated by Acacia falcata leaf extract. Aggregates of needle-shaped crystalline nanostructures were confirmed by FE-SEM and TEM analysis. Well-defined rings in the SAED patterns corroborated the polycrystalline nature of the HAPnps. Individual elements present in the HAPnps were attested by the specific signals for Ca, P, and O in the EDS and XPS analyses. The distinct peaks observed in the XRD spectrum matched well with the HAP hexagonal patterns with a mean crystallite size of 55.04 nm. The FTIR study unveiled the coating of the nanoparticles with the biomolecules from Acacia falcata leaves. The suspension HAPnps exhibited polydispersity (0.446) and remarkable stability (zeta potential: - 31.9 mV) as evident from DLS studies. The pore diameter was 25.7 nm as obtained from BET analysis, suggesting their mesoporous nature. The HAPnps showed the cytotoxic effect on A549 lung and MDA-MB231 breast carcinoma cell lines, with an IC₅₀ value of 55 μg/mL. The distortion of the cell membrane and cell morphology, along with the chromatin condensation and cell necrosis on treatment with HAPnps were detected under fluorescence microscopy post acridine orange/ethidium bromide dye staining. This study reports the anti-cancerous potential of non-drug-loaded plant-mediated HAPnps. Therefore, the HAPnps obtained in this investigation could play a vital role in the biomedical field of cancer therapy.

Zn-containing Wollastonite with Well-defined Microstructural and Good Antifungal Activity.. [DOI: 10.21203/rs.3.rs-2184143/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Antimicrobial and antifungal materials we prepared from Zn-containing wollastonite set by wet precipitation method. Wollastonite, hardystonite, willemite and very little quartz were developed after sintering at 1100°C/2h, however, the Raman spectroscopy approved the later phases by their characteristic Raman shift bands. The microstructure exhibited accumulated rounded to irregular clusters containing nano-size particles (< 500nm) developed in all sintered samples. Zeta potential; exposed negative values for all powdered samples from − 2.64 to -17.6 mV (i.e., for Zn-free to highest Zn-containing samples). It can be easily noticed that the lowest ZnO-content exhibits a varied range of antibacterial activities in contrast to Gram-negative (E. coli) and Gram-positive (S. aureus & B. subtilis). Correspondingly, the CZS5 exhibits good inhibitory effect against the filamentous pathogenic fungus (A. niger).

Enhanced ectopic bone formation by strontium-substituted calcium phosphate ceramics through regulation of osteoclastogenesis and osteoblastogenesis

To explore how strontium influences osteoclastogenesis and osteoblastogenesis during material-induced ectopic bone formation, porous strontium-substituted biphasic calcium phosphate (Sr-BCP) and BCP ceramics with equivalent pore structures and comparable grain size and porosity were prepared. In vitro results showed that compared with BCP, Sr-BCP inhibited the osteoclastic differentiation of osteoclast precursors by delaying cell fusion, down-regulating the expression of osteoclast marker genes, and reducing the activity of osteoclast specific proteins, possibly due to the activated ERK signaling pathway but the suppressed p38, JNK and AKT signaling pathways. Meanwhile, Sr-BCP promoted the osteogenic differentiation of mesenchymal stem cells (MSCs) by up-regulating the osteogenic gene expression. Sr-BCP also mediated the expression of important osteoblast-osteoclast coupling factors, as evidenced by the increased Opg/Rankl ratio in mMSCs, and the reduced Rank expression and enhanced EphrinB2 expression in osteoclast precursors. Similar results were observed in an in vivo study based on a murine intramuscular implantation model. The sign of ectopic bone formation was only seen in Sr-BCP at 8 weeks. Compared to BCP, Sr-BCP obviously hindered the formation of TRAP- and CTSK-positive multinucleated osteoclast-like cells during the early implantation time up to 6 weeks, which is consistent with the in vivo PCR results. This suggested that Sr-BCP could clearly accelerate the ectopic bone formation by promoting osteogenesis but suppressing osteoclastogenesis, which might be closely related to the expression of osteoblast-osteoclast coupling factors regulated by Sr²⁺. These findings may help in the design and fabrication of smart bone substitutes with the desired potential for bone regeneration through modulating both osteoclastic resorption and osteoblastic synthesis.

Tailoring of TiAl6V4 Surface Nanostructure for Enhanced In Vitro Osteoblast Response via Gas/Solid (Non-Line-of-Sight) Oxidation/Reduction Reactions

An aging global population is accelerating the need for better, longer-lasting orthopaedic and dental implants. Additive manufacturing can provide patient-specific, titanium-alloy-based implants with tailored, three-dimensional, bone-like architecture. Studies using two-dimensional substrates have demonstrated that osteoblastic differentiation of bone marrow stromal cells (MSCs) is enhanced on surfaces possessing hierarchical macro/micro/nano-scale roughness that mimics the topography of osteoclast resorption pits on the bone surface. Conventional machined implants with these surfaces exhibit successful osseointegration, but the complex architectures produced by 3D printing make consistent nanoscale surface texturing difficult to achieve, and current line-of-sight methods used to roughen titanium alloy surfaces cannot reach all internal surfaces. Here, we demonstrate a new, non-line-of-sight, gas/solid-reaction-based process capable of generating well-controlled nanotopographies on all open (gas-exposed) surfaces of titanium alloy implants. Dense 3D-printed titanium-aluminum-vanadium (TiAl6V4) substrates were used to evaluate the evolution of surface nanostructure for development of this process. Substrates were either polished to be smooth (for easier evaluation of surface nanostructure evolution) or grit-blasted and acid-etched to present a microrough biomimetic topography. An ultrathin (90 ± 16 nm) conformal, titania-based surface layer was first formed by thermal oxidation (600 °C, 6 h, air). A calciothermic reduction (CaR) reaction (700 °C, 1 h) was then used to convert the surface titania (TiO₂) into thin layers of calcia (CaO, 77 ± 16 nm) and titanium (Ti, 51 ± 20 nm). Selective dissolution of the CaO layer (3 M acetic acid, 40 min) then yielded a thin nanoporous/nanorough Ti-based surface layer. The changes in surface nanostructure/chemistry after each step were confirmed by scanning and transmission electron microscopies with energy-dispersive X-ray analysis, X-ray diffraction, selected area electron diffraction, atomic force microscopy, and mass change analyses. In vitro studies indicated that human MSCs on CaR-modified microrough surfaces exhibited increased protein expression associated with osteoblast differentiation and promoted osteogenesis compared to unmodified microrough surfaces (increases of 387% in osteopontin, 210% in osteocalcin, 282% in bone morphogenic protein 2, 150% in bone morphogenic protein 4, 265% in osteoprotegerin, and 191% in vascular endothelial growth factor). This work suggests that this CaR-based technique can provide biomimetic topography on all biologically facing surfaces of complex, porous, additively manufactured TiAl6V4 implants.

A Review of Biomimetic Topographies and Their Role in Promoting Bone Formation and Osseointegration: Implications for Clinical Use

The use of metallic and polymeric materials for implants has been increasing over the past decade. This trend can be attributed to a variety of factors including a significant increase in basic science research focused on implant material characteristics and how various surface modifications may stimulate osseointegration and, ultimately, fusion. There are many interbody fusion devices and dental implants commercially available; however, detailed information about their surface properties, and the effects that various materials and surface modifications may have on osteogenesis, is lacking in the literature. While the concept of bone-implant osseointegration is a relatively recent addition to the spine fusion literature, there is a comparatively large body of literature related to dental implants. The purpose of this article is to summarize the science of surface modified bone-facing implants, focusing on biomimetic material chemistry and topography of titanium implants, to promote a better understanding of how these characteristics may impact bone formation and osseointegration. This manuscript has the following aspects: highlights the role of titanium and its alloys as potent osteoconductive bioactive materials; explores the importance of biomimetic surface topography at the macro-, micro- and nano-scale; summarizes how material surface design can influence osteogenesis and immune responses in vitro; focuses on the kinds of surface modifications that play a role in the process. Biomimetic surface modifications can be varied across many clinically available biomaterials, and the literature supports the hypothesis that those biomaterial surfaces that exhibit physical properties of bone resorption pits, such as roughness and complex hierarchical structures at the submicron and nanoscale, are more effective in supporting osteoblast differentiation in vitro and osteogenesis in vivo.

Eggshells biowaste for hydroxyapatite green synthesis using extract piper betel leaf - Evaluation of antibacterial and antibiofilm activity

The present research work reports the biosynthesis of hydroxyapatite (HAp) from eggshells and green synthesis of HAp from eggshells with incorporation of Piper betel leaf extract (PBL-HAp) using microwave conversion method. Although there are several works on synthesis of HAp from eggshells and other calcium and phosphorus rich substrates, the incorporation of herbal extract with HAp to promote antimicrobial and antibiofilm activity is less explored and reported. This research work highlights a simple and cost-effective method for development of antimicrobial biomaterials by combining the concepts of waste management, biomaterial science, and herbal medicine. In the present study, characterization of synthesized HAp was applied by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Proton Nuclear Magnetic Resonance (¹H NMR) spectroscopy, and morphological analysis using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The characterization results indicated that the prepared HAp and PBL-HAp were pure b-type carbonated HAp. The PBL-HAp was checked for its antibacterial activity using the well diffusion method and biofilm inhibitory activity by crystal violet assay against some common pathogens. The antibacterial activities against Staphylococcus aureus and biofilm inhibitory activities against Escherichia coli, Vibrio harveyi, Pseudomonas aeruginosa, and Staphylococcus aureus of Piper betel leaf extract coated HAp (PBL-HAp) were showed to be significant and offered a promising role for the development of potent dental biomaterials.

Investigation into the trophic transfer and acute toxicity of phosphorus-based nano-agromaterials in Caenorhabditis elegans

Biogenic phosphorus (P) based - nanomaterials (NMs) are currently being explored as nanofertilizers. In this study, the acute toxic effects and trophic transfer of multiple types of P-based NMs were examined on soil-dwelling nematode, Caenorhabditis elegans. The study involved four variants of nanohydroxyapatites (nHAPs) synthesized either via a biogenic or a chemical route and another NM, nanophosphorus (nP), biosynthesized from bulk rock phosphate (RP). The pristine NMs differed in their physicochemical properties with each possessing different shapes (biogenic nHAP: platelet-shaped, ˜35 nm; biogenic nP, ˜5-10 nm: dots; chemically synthesized nHAPs: spherical, ˜33 nm, rod, ˜80 nm and needle-shaped, ˜64 nm). The toxic effects of NMs' in C. elegans were assessed using survival, hatching and reproductive cycle as the key endpoints in comparison to bulk controls, calcium phosphate and RP. The interactions and potential uptake of fluorescent-tagged nHAP to E. coli OP50 and C. elegans were investigated using confocal microscopy. The transformation of NMs within the nematode gut was also explored using dynamic light scattering and electron microscopy. C. elegans exposed to all of the variants of nHAP and the nP had 88-100% survival and 82-100% hatch rates and insignificant effects on brood size as observed at the tested environmentally relevant concentrations ranging from 5 to 100 μg.mL^-1. Confocal microscopy confirmed the interaction and binding of fluorescent-tagged nHAP with the surface of E. coli OP50 and their trophic transfer and internalization into C. elegans. Interestingly, there was only a small reduction in the hydrodynamic diameter of the nHAP after their uptake into C. elegans and the transformed NMs did not induce any additional toxicity as evident by healthy brood sizes after 72 h. This study provides key information about the environmental safety of agriculturally relevant P-based NMs on non-target species.

Metal-modified sludge-based biochar enhance catalytic capacity: Characteristics and mechanism

The improvement of the catalytic performance of sludge-based biochar plays an important role in the catalytic application of biochar. This work aimed to use transition metals and rare earth elements (Fe, Ce, La, Al, Ti) to modify sludge and prepare modified biochar with better catalytic performance through pyrolysis. Through the Fourier transform infrared spectrometer, Raman spectrometer, and X-ray photoelectron spectroscopy, the effects of different metal modifications on the surface morphology, molecular structure, element compositions, and valence of elements of biochar were comprehensively investigated. The results showed that metal elements were successfully modified onto the surface of biochar as metal oxides. Although the highest intensity of persistent free radicals was detected in blank-biochar by electron spin resonance, the intensities of hydroxyl radicals catalyzed by modified biochars in H₂O₂ system were higher than that catalyzed by blank-biochar, indicating that the catalytic performance of modified biochar was mainly related to the metal oxide loaded and the defect structure on the surface of metal-modified biochar. Furthermore, in the H₂O₂ system, the degradation efficiencies of tetracycline catalyzed by the biochars within 4 h were 51.7% (blank-biochar), 90.7% (Fe-biochar), 69.0% (Ce-biochar), 59.9% (La-biochar), 58.0% (Al-biochar), 58.0% (Ti-biochar), respectively, suggesting that Fe-biochar not only possessed the best catalytic performance but also shortened the reaction time. This research not only provided the possibility for recycling the waste activated sludge, but also proposed a modification method to improve the catalytic performance of biochar.

Biological response, antibacterial properties of ZrO2/hydroxyapatite/graphene oxide encapsulated into nanofibrous scaffolds of polylactic acid for wound healing applications

Designing proper nanofibrous scaffolds for wound healing applications is a necessity for improving the health care system. Hydroxyapatite (HAP), zirconia (ZrO₂), and graphene oxide (GO) nanosheets have been encapsulated in mono, di, or tri phases into nanofibrous scaffolds of polylactic acid (PLA). The structure of nanofibrous scaffolds is confirmed using XRD, XPS, while FESEM inspected the surface morphology. The surface morphology detection exhibited that the scaffolds have been formed in networked nanofibers with diameters from 1.19 to 2.38 to 0.59-1.42 µm, while the maximum height of the roughness increased from 610.4 to 809 nm for HAP@PLA and HAP/ZrO₂/GO@PLA, respectively. The contact angle was measured and showed a decreasing trend from 101.2 ± 4.1° and 89.1 ± 5.4° for HAP@PLA and HAP/ZrO₂/GO@PLA nanofibrous scaffolds. Moreover, the mechanical properties were examined and revealed that ZrO₂ dopant induced a significant enhancement into the tensile strength, which increased from 3.49 ± 0.3 to 8.45 ± 1.1 MPa for the nanofibrous scaffolds of HAP@PLA and HAP/ZrO₂/GO@PLA, respectively. The incorporation of ternary phases into PLA nanofibers promoted the cell viability to be around 98.2 ± 5%. The antibacterial potency has been investigated and showed that the activity increased to 69.2 ± 3.6 and 78.1 ± 4.5% against E. coli and S. aureus, respectively. Additionally, human fibroblasts proliferated on the surface and pores of nanofibrous scaffolds and significantly grown upon the compositional variation.

Antimicrobial Activity of Zinc Oxide Nano/Microparticles and Their Combinations against Pathogenic Microorganisms for Biomedical Applications: From Physicochemical Characteristics to Pharmacological Aspects

Zinc oxide (ZnO) nano/microparticles (NPs/MPs) have been studied as antibiotics to enhance antimicrobial activity against pathogenic bacteria and viruses with or without antibiotic resistance. They have unique physicochemical characteristics that can affect biological and toxicological responses in microorganisms. Metal ion release, particle adsorption, and reactive oxygen species generation are the main mechanisms underlying their antimicrobial action. In this review, we describe the physicochemical characteristics of ZnO NPs/MPs related to biological and toxicological effects and discuss the recent findings of the antimicrobial activity of ZnO NPs/MPs and their combinations with other materials against pathogenic microorganisms. Current biomedical applications of ZnO NPs/MPs and combinations with other materials are also presented. This review will provide the better understanding of ZnO NPs/MPs as antibiotic alternatives and aid in further development of antibiotic agents for industrial and clinical applications.

In vitro evaluation of electrochemically bioactivated Ti6Al4V 3D porous scaffolds

Triply periodic minimal surfaces (TPMS) are known for their advanced mechanical properties and are wrinkle-free with a smooth local topology. These surfaces provide suitable conditions for cell attachment and proliferation. In this study, the in vitro osteoinductive and antibacterial properties of scaffolds with different minimal pore diameters and architectures were investigated. For the first time, scaffolds with TPMS architecture were treated electrochemically by plasma electrolytic oxidation (PEO) with and without silver nanoparticles (AgNPs) to enhance the surface bioactivity. It was found that the scaffold architecture had a greater impact on the osteoblast cell activity than the pore size. Through control of the architecture type, the collagen production by osteoblast cells increased by 18.9% and by 43.0% in the case of additional surface PEO bioactivation. The manufactured scaffolds demonstrated an extremely low quasi-elastic modulus (comparable with trabecular and cortical bone), which was 5-10 times lower than that of bulk titanium (6.4-11.4 GPa vs 100-105 GPa). The AgNPs provided antibacterial properties against both gram-positive and gram-negative bacteria and had no significant impact on the osteoblast cell growth. Complex experimental results show the in vitro effectiveness of the PEO-modified TPMS architecture, which could positively impact the clinical applications of porous bioactive implants.

Immobilization of Dextranase on Nano-Hydroxyapatite as a Recyclable Catalyst

The immobilization technology provides a potential pathway for enzyme recycling. Here, we evaluated the potential of using dextranase immobilized onto hydroxyapatite nanoparticles as a promising inorganic material. The optimal immobilization temperature, reaction time, and pH were determined to be 25 °C, 120 min, and pH 5, respectively. Dextranase could be loaded at 359.7 U/g. The immobilized dextranase was characterized by field emission gun-scanning electron microscope (FEG-SEM), X-ray diffraction (XRD), and Fourier-transformed infrared spectroscopy (FT-IR). The hydrolysis capacity of the immobilized enzyme was maintained at 71% at the 30th time of use. According to the constant temperature acceleration experiment, it was estimated that the immobilized dextranase could be stored for 99 days at 20 °C, indicating that the immobilized enzyme had good storage properties. Sodium chloride and sodium acetic did not desorb the immobilized dextranase. In contrast, dextranase was desorbed by sodium fluoride and sodium citrate. The hydrolysates were 79% oligosaccharides. The immobilized dextranase could significantly and thoroughly remove the dental plaque biofilm. Thus, immobilized dextranase has broad potential application in diverse fields in the future.

Enhanced corrosion resistance, antibacterial properties, and biocompatibility by hierarchical hydroxyapatite/ciprofloxacin-calcium phosphate coating on nitrided NiTi alloy

Multi-functional hierarchical coatings are deposited on the nitrided NiTi alloy. The nitrided layer is first deposited by nitrogen plasma immersion ion implantation and a middle layer containing porous hydroxyapatite and ciprofloxacin (Cip) is produced before the top calcium phosphate coating is deposited by the sol-gel method. The thicknesses of the coating and nitrided intermediate layer are about 1.54 μm and 160 nm, respectively and Cip penetrates to a depth of about 530 nm. Calcium phosphate reduces surface defects resulting in a surface roughness of 17 ± 2 nm compared to 34 ± 5 nm of the porous hydroxyapatite coating. The corrosion resistance is improved due to reduced defects and localized corrosion as manifested by the decrease in the Ni²⁺ release rate by 11.6% from 0.0198 to 0.0175 mg L^-1 cm^-2. The bacterial resistance against E. coli is also improved by about 88 times on account of Cip release and good biocompatibility is confirmed by proliferation of MC3T3 cells. This multi-functional hierarchical coating has large potential in orthopedic and dental applications.

Biochar derived from pyrolysis of oily sludge waste: Structural characteristics and electrochemical properties

Oily sludge is the main hazardous waste produced by the petroleum industry, and its harmless disposal and recycling have become urgent problems. In this study, the pyrolysis technique was used to prepare oily sludge biochar at different temperatures (400 °C, 500 °C, 600 °C, and 700 °C). The characteristics of the biochar, including weight reduction, elemental composition, and molecular structure, were comprehensively investigated. From the perspective of the electrochemical properties of biochar, the relationship between the structure of the biochar and the redox capacity was discussed, and the feasibility of biochar as a battery cathode material was explored. The results suggested that the improper pyrolysis temperature could reduce the content of the quinone structure which was related to the redox capacity, the biochar prepared at 600 °C should have the strongest electron transfer capability. Moreover, the highest degree of condensation and aromaticity of pyrolysis products could be obtained at a higher pyrolysis temperature (700 °C), which might result in the relatively high discharge-charge capacity and good cycle performance of biochar which was used as an electrode material of a battery. This study explored the feasibility of pyrolysis as a disposal route for oily sludge waste and provided a reference for the electrochemical application of biochar prepared from oil sludge waste.

High Nanodiamond Content-PCL Composite for Tissue Engineering Scaffolds

Multifunctional scaffolds are becoming increasingly important in the field of tissue engineering. In this research, a composite material is developed using polycaprolactone (PCL) and detonation nanodiamond (ND) to take advantage of the unique properties of ND and the biodegradability of PCL polymer. Different ND loading concentrations are investigated, and the physicochemical properties of the composites are characterized. ND-PCL composite films show a higher surface roughness and hydrophilicity than PCL alone, with a slight decrease in tensile strength and a significant increase in degradation. Higher loading of ND also shows a higher osteoblast adhesion than the PCL alone sample. Finally, we show that the ND-PCL composites are successfully extruded to create a 3D scaffold demonstrating their potential as a composite material for tissue regeneration.

Potential Natural Fiber Polymeric Nanobiocomposites: A Review

Composite materials reinforced with biofibers and nanomaterials are becoming considerably popular, especially for their light weight, strength, exceptional stiffness, flexural rigidity, damping property, longevity, corrosion, biodegradability, antibacterial, and fire-resistant properties. Beside the traditional thermoplastic and thermosetting polymers, nanoparticles are also receiving attention in terms of their potential to improve the functionality and mechanical performances of biocomposites. These remarkable characteristics have made nanobiocomposite materials convenient to apply in aerospace, mechanical, construction, automotive, marine, medical, packaging, and furniture industries, through providing environmental sustainability. Nanoparticles (TiO2, carbon nanotube, rGO, ZnO, and SiO2) are easily compatible with other ingredients (matrix polymer and biofibers) and can thus form nanobiocomposites. Nanobiocomposites are exhibiting a higher market volume with the expansion of new technology and green approaches for utilizing biofibers. The performances of nanobiocomposites depend on the manufacturing processes, types of biofibers used, and the matrix polymer (resin). An overview of different natural fibers (vegetable/plants), nanomaterials, biocomposites, nanobiocomposites, and manufacturing methods are discussed in the context of potential application in this review.

Fe and Zn co-substituted beta-tricalcium phosphate (β-TCP): Synthesis, structural, magnetic, mechanical and biological properties

In the present work, Fe³⁺ and Zn²⁺ co-substituted β-tricalcium phosphate (β-TCP) has been synthesized by wet co-precipitation method. Co-substitution level in the range from 1 to 5 mol% has been studied. Thermal decomposition of as-prepared precipitates was shown to be affected by introducing of foreign ions, decreasing the decomposition temperature of precursor. It was determined that partial substitution of Ca²⁺ by Fe³⁺ and Zn²⁺ ions leads to the change in lattice parameters, which gradually decrease as doping level increases. Lattice distortion was also confirmed by means of Raman spectroscopy, which showed gradual change of the peaks shape in the Raman spectra. Rietveld refinement and electron paramagnetic resonance study confirmed that Fe³⁺ ions occupy only one Ca crystallographic site until Fe³⁺ and Zn²⁺ substitution level reaches 5 mol%. All co-substituted samples revealed paramagnetic behavior, magnetization of powders was determined to be linearly dependent on concentration of Fe³⁺ ions. Cytotoxicity of the synthesized species was estimated by in vivo assay using zebrafish (Danio rerio) and revealed non-toxic nature of the samples. Preparation of ceramic bodies from the powders was performed, however the results obtained on Vickers hardness of the ceramics did not show improvement in mechanical properties induced by co-substitution.