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Here we report silver incorporated anatase TiO 2 developed on Ti metal by H 2 O 2 -AgNO 3 and heat treatment to have faster biomineralisation or apatite-forming ability in simulated body fluid (SBF). Apatite-forming ability has been investigated concerning heat treatment temperatures ranges, 400-800 °C and duration of soaking period in SBF. The apatite formation showed an increasing trend with increase in the heat treatment temperatures up to 600 °C and beyond that the Ti metal lost this ability. XRD as wells as Raman results of such chemical and heat-treated Ti metal at different temperatures further correlates the apatite nucleation directly in relation with that of anatase to rutile TiO 2 formation. Further, a time dependent apatite mineralisation study by XPS revealed simultaneous calcium and phosphate deposition at the early stage of soaking in SBF. Therefore, the apatite nucleation in the present chemically treated Ti metal depends on the crystalline phase of TiO 2 formed by H 2 O 2 and heat treatment along with Ag + ion release., Competing Interests: Declaration of competing interest Authors declare no conflict of interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A nano-structured titanate layer encapsulated with Ca 2+ and Ag + ions was successfully grown over commercially pure (CP) Ti metal by chemical treatment with H 2 O 2 and subsequent treatment with Ca (NO 3 ) 2 /AgNO 3 solutions. Heat treatment at 600 °C, further transformed this nano-structured titanate layer into titania containing Ca 2+ and Ag + ions. Thus modified Ti metal showed significant enhancement in apatite-forming ability when soaked in simulated body fluid (SBF). Presence of Ag + ions showed good antimicrobial activity against pathogenic Staphylococcus aureus, and, Ca 2+ ions being a major component of bone mineral accelerated the apatite-forming ability over Ti metal in SBF. Further, Ca 2+ and Ag + ions proportion over Ti metal surface could be optimised in order to have minimum Ag concentration that can have not only antibacterial activity and also cell compatibility against MG 63 osteoblast-like cells. Therefore, the proposed surface modification approach presented here is expected to be useful in orthopaedic implants that necessitate enhanced bioactivity, antibacterial activity and cell compatibility., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Here, effect of solution pH on precipitation of silver decorated hydroxyapatite (Ag-HAp) nano powder during its wet-synthesis was systematically studied. XRD pattern of Ag-HAp nano powder synthesised at pH ranging from 5 to 10 shows that calcium hydrogen phosphate was formed as dominating phase when the solution pH was between 5 and 9 and this phase was gradually transformed into a stable HAp above pH 9. A quantitative analysis of silver amount in Ag-HAp nano powder synthesised at different pH showed that silver can be precipitated to its maximum amount at pH 8 and the further addition of ammonia leads to the formation of a silver-ammonium complex, thereby remaining in the solution. HR-TEM and XPS analysis further confirmed the presence of silver in HAp nanocrystals, synthesised at an optimum pH 9. This trace amount of silver in HAp nano powder showed effective antibacterial activity against Staphylococcus aureus and Escherichia coli. In addition, the cytocompatibility studies carried out on MG63 cells further confirmed the present optimised silver concentration of the Ag-HAp nano powder is well within the toxic limit to be useful in various biomedical applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

[Display omitted] • A solvent-free method was used to synthesize a Zeolitic Tetrazole Framework. • The synthesized ZTF-8 showed a good affinity towards Ag+ ions. • A simple and low-cost Ag+ ions sensor was prepared, characterized and optimized. • The fabricated sensor showed good repeatability and reproducibility. • The prepared sensor exhibited high sensitivity and satisfactory recoveries. Human silver poisoning through water consumption constitutes a real public health concern nowadays. Thus, the development of sensitive, accurate and low-cost tools for silver ions (Ag+) determination in drinking water would significantly help in facing this great challenge. Herein, a cost effective and eco-friendly material namely Zeolitic Tetrazole Framework (ZTF-8) was synthesized and used as electrode material for Ag+ ions electroanalysis. XRD, FT-IR, TGA, XPS and FE-SEM were utilized to evidence the successful synthesis of the electrode material. Electrochemical characterization of the associated sensor revealed its good affinity towards Ag+ ions as well as the satisfactory repeatability and reproducibility of the obtained results. The sensor optimization showed that to achieve its best performance, 3 μL of ZTF-8 suspension, 1 mg/mL should be utilized for its fabrication. Given that the sensing mechanism was based on the deposition of Ag0 on the sensor surface followed by their redissolution, the sensor optimization also revealed that the optimal deposition potential and time are −0.1 V vs. SCE and 200 s, respectively. Calibrated in concentration range of 0.2 to 1.6 µM, the prepared sensor exhibited a linear relationship (0.997) with a sensitivity of (0.56 ± 0.01) µA/µM; the statistic limit of detection was found to be 0.9 nM. Moreover, the fabricated sensor showed great potential for real samples analysis and satisfactory recoveries in mineral water, tap water, water obtained from a reverse osmosis plant and in an AAS standard solution. Furthermore, obtained results were validated using FAAS and ICP-OES. [ABSTRACT FROM AUTHOR]

In the present study, the pH dependence hydroxyapatite (HAp) ceramics synthesis, and, their phase stabilities with respect to calcination temperatures were examined. Subsequently, HAp ceramics mixed with different silver amounts (HAp–Ag composites) were prepared in the temperature range 800–1200°C to evaluate the phase stability of HAp in presence of silver. XRD results showed that as-synthesized HAp powder to be partially crystalline and are independent of pH of solution in the range of 9–11. These HAp phases remained stable even upto 1200°C although crystallinity increased in all cases. Additional Ag peaks were appeared in HAp–Ag composites when the mixed powders were heated in the temperature range 800–1200°C. FTIR result further confirmed the presence of Ca2+ and PO4 3− ions. TEM observation showed the precipitation of needle like HAp nanocrystals of 20–40nm in length which agglomerated into particulate morphology above 800°C. Antibacterial study of HAp–Ag composites on Staphylococcus aureus for 1, 3 and 5wt% silver concentration showed that 3wt% silver is sufficient to kill the surrounding bacteria. Further studies on NIH3T3 cells for HAp–Ag composites at 10wt% silver of different concentrations showed good cytocompatibility compared to HAp indicates the prospective applications in therapeutic interventions. [ABSTRACT FROM AUTHOR]