Investigation and optimization of In-Vitro behaviour of Perovskite barium titanate as a scaffold and protective coatings.

The piezoelectric effect is widely known to have a significant physiological function in bone development, remodeling, and fracture repair. As a well-known piezoelectric material, barium titanate is particularly appealing as a scaffold layer to improve bone tissue engineering applications. Currently, the chemical bath deposition method is used to prepare green synthesized barium titanate coatings to improve mechanical and biological characteristics. Molarity of the solutions, an essential parameter in chemical synthesis, is changed at room temperature (0.1-1.2 Molar) to prepare coatings. The XRD spectra for as deposited coatings indicate amorphous behavior, while polycrystalline nature of coatings is observed after annealing (300 °C). Coatings prepared with solutions of relatively low molarities, i.e. from 0.1 to 0.8 M, exhibit mixed tetragonal - cubic phases. However, the tetragonal phase of Perovskite barium titanate is observed using solution molarities of 1.0 M and 1.2 M. Relatively high value of transmission, i.e. ∼80%, is observed for the coatings prepared with high molarities. Band gap of annealed coatings varies between 3.47 and 3.70 eV. For 1.2 M sample, the maximum spontaneous polarization (Ps) is 0.327x10-3 (µC/cm2) and the residual polarization (Pr) is 0.072x10-3 (µC/cm2). For 1.2M solution, a high hardness value (1510 HV) is recorded, with a fracture toughness of 28.80 MPam-1/2. Low values of weight loss, after dipping the coatings in simulated body fluid, is observed. The antibacterial activity of BaTiO3 is tested against E. coli and Bacillus subtilis. Drug encapsulation capability is also tested for different time intervals. As a result, CBD-based coatings are a promising nominee for use as scaffold and protective coatings.

Improved osteointegration response using high strength perovskite BaTiO3 coatings prepared by chemical bath deposition.

A wide range of bioactive materials have been investigated for tissue engineering and regeneration. Barium titanate is a promising smart material to be used as scaffold for bone tissue engineering. Barium titanate coatings are prepared in the present study using chemical bath deposition technique. Coatings are prepared at room temperature with the variation in solution molarity from 0.1 to 1.2 M. Perovskite tetragonal phase is observed after annealing the samples at 300 °C using 1.0-1.2 M solutions. Normal-anomalous dielectric response is observed for annealed coatings. Maximum transmission of ∼55% and ∼82% is observed under as-prepared and annealed coatings, respectivly. Variation in direct band gap, i.e. 3.45-3.64 eV, is observed with varying molarity. High hardness of the coatings (∼1180 HV) is observed at 1.2M with fracture toughness of ∼22 MPam-1/2. Biodegradation studies show smaller values of weight loss even after immersion in simulated body fluid (SBF) after 26 weeks. Barium titanate coatings also show high antioxidant activity. BaTiO3's antibacterial reaction is evaluated against microorganisms such as Escherichia coli (E. coli) and Staphylococcus aureus. Antibacterial activity shows highest zone of inhibition (∼31 mm) against Staphylococcus aureus bacteria. Quantitative real-time PCR is used to assess the gene expression profile in cultivated cells. Thus, coatings produced without the use of hazardous solvents/reagents utilizing CBD technique are a potential material for biomedical applications.

Tangerine mediated synthesis of zirconia as potential protective dental coatings.

Demand of bioactive materials that may create a bacteria-free environment while healing and regenerating the defect area is increasing day by day. Zirconia is a very interesting material because of its biocompatibility and high fracture toughness. In this research work, zirconia nanoparticles (NPs) have been synthesized using sol-gel method. Molarity of sols is varied in the range of 25 to 125 mM. The effect of acidic and basic nature of sols is studied by maintaining acidic (2) and basic (9) pH. As-synthesized NPs are made soluble in deionized (DI) water using tangerine drops. Dissolved NPs are spin coated onto glass substrate prior to characterization. Pure tetragonal phase, observed under all conditions using basic medium (pH 9), is accompanied by smaller crystallite size and unit cell volume. Presence of stabilized zirconia phase leads to higher value of density and higher mechanical strength. Nanodendrites with distinct features are observed for the sample prepared with high molarity using basic medium. Whereas, soft agglomerated nanodendrites are observed using acidic medium. Optical properties show transmission of 60-80% in the visible and infrared regions for acidic based samples and ~84% for basic samples. Direct energy band gap is varied from 4.96 eV to 5.1 eV in acidic (pH 2) and 4.91 eV to 4.97 eV in basic (pH 9) media. FTIR spectra show the formation of fundamental tetragonal band at 490 cm-1 for basic samples. Antibacterial response of zirconia is tested against E. coli, Streptococcus and Bacillus bacteria. Human teeth, bare and zirconia coated, are tested for their possible weight loss after dipping in various beverages. Zirconia coated tooth shows negligible degradation in hardness and weight after 24 hr dipping period. Thus, coatings prepared using water soluble zirconia (WSZ) nanoparticles, without the use of toxic solvents/reagents, are promising material to be used as protective coatings in biomedical applications.

Antibacterial performance of glucose-fructose added MW based zirconia coatings - Possible treatment for bone infection.

Use of ceramic coatings has increased dramatically in orthopedics by improving their wear resistance and consequent long-term stability. Such stability involves not only the strength of material but also its resistance toward bacterial attacks. Amongst all ceramics, zirconia is selected in the present study due to its white color and high value of hardness making it a potential candidate to be used as implants and their coatings. In the present study effect of varying microwave powers (i.e. 100W, 200W, 300W, 400W, 500W, 600W, 700W, 800W, 900W and 1000W) on sol-gel synthesized glucose and fructose added zirconia coatings has been investigated. Formation of mixed tetragonal - monoclinic phases has been observed at relatively low microwave powers, i.e. 100-500W. However, at 600-1000W phase pure tetragonal zirconia is observed without any post heat treatment. FTIR analysis confirms formation of tetragonal phase of zirconia at 600-1000W microwave power. XPS results confirm the binding energies of Zr 3d and O 1s of microwave assisted zirconia coatings. High value of transmittance, i.e. ~90%, is observed at higher microwave powers. Variation in microwave powers is observed to tune the energy band gap of zirconia coatings in the range of 4.2-5.1 eV. Dielectric constant of 8-10 at log f = 4 is observed. High value of hardness and fracture toughness i.e. 1231 HV and 24.85 MPam-1/2, respectively, is observed for stabilized tetragonal zirconia coatings. Stabilized glucose fructose added zirconia shows strong antioxidant activity. Zirconia coatings are tested against Staphylococcus aureus bacteria for their potential application to treat bone infection. Results suggest that stabilized tetragonal zirconia can be successfully employed for orthopedic coatings.

Chloroform extract of turmeric inhibits biofilm formation, EPS production and motility in antibiotic resistant bacteria.

In the form of biofilms, bacteria exhibit more resistance to antibiotics. Biofilm formers can withstand severe conditions and the host's defense system. Therefore, it is necessary to search for effective biofilm inhibitors. In this study, we investigated the effect of a chloroform extract of turmeric on biofilm formation against antibiotic resistant bacteria. The extract exhibited its antibiofilm effect by altering adherence, motility, extracellular polymeric substance (EPS) production and cell surface hydrophobicity; important attributes of biofilm formation. Cell attachment assays indicated that a chloroform extract resulted in a 38.9-60.2% inhibition of cell adherence to a polystyrene surface, and a 44.5-58.3% inhibition to a glass surface. Static biofilm formation assays indicated that a chloroform extract resulted in a 23-74.5% reduction in biofilm formation. The chloroform extract inhibited flagella-directed swarming and swimming motility and pilus-directed twitching motility in a dose-dependent manner. In addition to repression of motility, a chloroform extract also significantly (p < 0.05) altered the hydrophobic behavior, and bacterial strains such as K. pneumoniae and E. cloacae exhibited hydrophilic behavior after the addition of the extract, as compared with control cells. The presence of the extract also significantly (p < 0.05) increased the detachment of biofilms by a surfactant as compared with controls. Fourier transformed infrared spectroscopy (FTIR) had indicated a loss of vital functional groups of polysaccharides and proteins from the EPS of cells treated with a chloroform extract. Gas chromatography mass spectrometry (GC-MS) analysis indicated the presence of many phytochemical constituents, mainly sesquiterpenes and fatty acid groups. These results clearly suggested that turmeric could affect multiple cellular activities in biofilm formers exhibiting antibiotic resistance by modulating adherence, EPS production, motility and surface hydrophobicity.

Screening, characterization and biofilm formation of nickel resistant bacteria isolated from indigenous environment.

Nickel resistant bacteria (ZB, ZC, ZD, ZL, ZK and S1X) were isolated from industrial effluents and corroded iron pieces from indigenous environment of Punjab, Pakistan. These six strains could tolerate nickel at different levels with ZB, ZC, ZD, ZL, ZK, and S1X having 233, 225, 267, 233, 228 and 296 mM minimum inhibitory concentration (MIC) of nickel ions, respectively. These bacteria were sensitive to Cu(+2), Cr(+3), Co(+2), and Al(+3) as they did not grow even in the presence of 1 mM concentration of all these ions in minimal medium, whereas all of them were resistant to Fe3 upto 1.3 mM in minimal medium. The best appropriate temperature for nickel resistant bacteria was 37 degrees C and all of them showed maximum growth at pH 8. These bacteria were characterized morphologically and biochemically. Biofilm forming ability of the bacteria was checked with and without nickel stress and it was found that strains ZK and S1X were able to form a compact biofilm even under nickel stress. The sequencing of 16S rRNA-encoding genes from these nickel resistant bacteria showed that they belonged to four different genera namely, Klebsiella, Pseudomonas, Bacillus and Cronobacter.