Metal oxides with nanostructures such as zinc oxide (ZnO), titanium dioxide (TiO2) have been used in biomedical fields for their multifunctional properties. In this study, ZnO/TiO2 nanoarray (nZnO/TiO2) coatings were prepared via hydrothermal synthesis followed by low temperature liquid phase method. The particle size of the composites were no more than 100 nm in diameter, assembled into nanoarray on the Ti substrate. In vitro antibacterial experiments showed that the maximum bacteriostatic rate could reach 99% against Staphylococcus aureus and 90% against Escherichia coli, respectively. Moreover, the nZnO/TiO2 coatings were of cytocompatibility and biocompatibility, promoting the proliferation of MC3T3-E1 and the expression of alkaline phosphatase (ALP). The piezoelectric properties of nZnO/TiO2 coatings were preliminarily investigated. The smaller the size of the composite particle was, the better the antibacterial property, biocompatibility and piezoelectric properties were. Under the stimulation of the periodic loading, the growth of MC3T3-E1 was promoted, so the secretion of ALP was. The nZnO/TiO2 composite coating with antibacterial activity, osteogenesis and intellectual stimulation would be a promising smart coating for orthopedic implants. 相似文献
The recovery of poly(3-hydroxybutyrate) [PHB] fromAlcaligenes eutrophus and a recombinantEscherichia coli strain harboring theA. eutrophus poly(3-hydroxyalkanoates) biosynthesis genes was studied. When PHB was recovered using sodium hypochlorite or sodium dodecyl
sulfate (SDS), non-PHB cell materials (NPCM) of the recombinantE. coli seemed to be more easily digested than those ofA. eutrophus. Furthermore, viscosity increase caused by cell lysis during SDS treatment was negligible for the recombinantE. coli, whereas a very viscous suspension was formed forA. eutrophus. These results, together with our previous finding that PHB in the recombinantE. coli is far less susceptible to molecular degradation by sodium hypochlorite, suggested that the recombinantE. coli was more beneficial than A.eutrophus in terms of PHB recovery. In order to develop an easy and efficient recovery process, we adopted and optimized the SDS treatment
since, with the hypochlorite treatment, we could not handle high biomass concentrations effectively. We could obtain a PHB
of 95 % purity with 96 % recovery under the optimal condition of a biomass concentration of 5 %, a ratio of SDS to biomass
of 0.6, a treatment time of 60 minutes, and a treatment temperature of 30°C. 相似文献
Optically transparent, crack-free, mesoporous anatase TiO2 thin films were fabricated. The Ag/TiO2 composite films were prepared by incorporating Ag in the pores of TiO2 films with an impregnation method via photoreduction. The as-prepared composite films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectronic spectra (XPS) and N2 adsorption. The release behavior of silver ions in the mesoporous composite film was also studied. Moreover, the antimicrobial behaviors of the mesoporous film were also investigated by confocal laser scanning microscopy. The antibacterial activities of the composite films were studied by a fluorescence label method using Escherichia coli (E. coli) as a model. The as-prepared mesoporous TiO2 films showed much higher antimicrobial efficiency than that of glass and commercial P25 TiO2 spinning film. The facts would result from the high surface area, small crystal size and more active sites for the mesoporous catalysis. After the doping of Ag, a significant improvement for the antimicrobial ability was obtained. To elucidate the roles of the membrane photocatalyst and the doped silver in the antimicrobial activity, cells from a silver-resistant E. coli were used. These results indicated that Ag nanoparticles in the mesoporous were not only an antimicrobial but also an intensifier for photocatalysis. The as-prepared mesoporous composite film is promising in application of photocatalysis, antimicrobial and self-clean technologies. 相似文献
In the present contribution, electrospinning was used to fabricate ultrafine fiber mats from poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-2-hydroxyvalerate) (PHBV), and their 50/50 w/w blend for potential use as bone scaffolds. Cytotoxicity evaluation of these as-spun fiber mats with human osteoblasts (SaOS-2) and mouse fibroblasts (L929) indicated biocompatibility of these materials to both types of cells. The potential for use of these fiber mats as bone scaffolds was further assessed in vitro in terms of the attachment, the proliferation, and the alkaline phosphatase (ALP) activity of SaOS-2 that were seeded or cultured at different times. The cells appeared to adhere well on all types of the fibrous scaffolds after 16 h of cell seeding. During the early stage of the proliferation period (i.e., from ∼24 to 72 h in culture), the viability of the cells increased considerably and appeared to be unchanged with further increase in the time in culture. In comparison with the corresponding solution-cast film scaffolds, all of the fibrous scaffolds exhibited much better support for cell attachment and proliferation. Lastly, among the various fibrous scaffolds investigated, the electrospun fiber mat of the 50/50 w/w PHB/PHBV blend showed the highest ALP activity. These results implied a high potential for use of these electrospun fiber mats as bone scaffolds. 相似文献
Polycaprolactone (PCL) blend with poly(hydroxybutyrate) (PHB) or poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) dual‐leached scaffolds are prepared by using the solvent casting and salt–polymer‐leaching technique. The blending of the PHB and PHBV in PCL scaffolds results in decreased porosities of the scaffolds, and the water absorption capacities of the scaffolds also decrease. The compressive modulus of the PCL–PHB and PCL–PHBV dual‐leached scaffolds is greatly increased by the blending of PHB or PHBV matrix. An indirect cytotoxicity evaluation of all scaffolds with mouse fibroblastic cells (L929) and mouse calvaria‐derived preosteoblastic cell (MC3T3‐E1) indicates that all dual‐leached scaffolds are posed as nontoxic to cells. Both PCL–PHB and PCL–PHBV dual‐leached scaffolds are supported by the attachment of MC3T3‐E1 at significantly higher levels to tissue culture polystyrene plate (TCPS) and are able to support the proliferation of MC3T3‐E1 at higher levels to that cells on TCPS and PCL scaffolds. For mineralization, cells cultured on surfaces of PCL–PHB and PCL–PHBV dual‐leached scaffolds show higher mineral deposition than on TCPS and PCL scaffold.
In this paper, TiO2 and Ag-doped TiO2 photocatalysts were coated on the cylindrical cordierite honeycomb monolith (CHM) to evaluate their photocatalytic disinfection against Escherichia coli (E. coli) bacteria under artificial sunlight irradiation. The X-ray diffraction (XRD) patterns showed a single-phase anatase structure for TiO2 samples calcined at 500 °C for 2 h. With the presence of Ag, the bandgap of TiO2 becomes narrower, and the absorption edge shifts toward the visible region. 6 mol% Ag-doped TiO2 (6Ag-T) showed a reduction of bandgap energy to 2.2 eV. TiO2 and Ag-doped TiO2 solutions were prepared and coated on the channels’ surface of CHM for antibacterial applications. Although monolithic TiO2 caused a slight decrease in the number of alive E. coli, Ag dopant showed significant improvement in antibacterial properties. 6 mol% Ag-doped TiO2 coated on CHM (6Ag-T/S10/M) showed strong antibacterial effectiveness against E. coli that the bacterial cell concentration dropped to zero after 1 h of exposure. Impressively, reusability tests with these materials showed superior performance, where the antibacterial remains unchanged after five or seven successive operation cycles.
A fibrous scaffold of curdlan/poly(vinyl alcohol) (PVA) blend is prepared by electrospinning technique and antimicrobial property is imparted to it by the addition of silver nitrate (1, 3, and 5 wt%). All the scaffolds except the PVA/curdlan with 5 wt% AgNO3 show good viability of Swiss 3T3 fibroblast cells. Significant reductions in the growth of Staphylococcus aureus and Escherichia coli are also observed in all the scaffolds. In vitro scratch assay and cell adhesion studies indicate that the scaffold containing 1% AgNO3 shows significant wound healing and better cell spreading. The in vivo results also show faster healing of excision wounds in diabetic rats treated with the same material when compared to the control and the commercial sample. Furthermore, downregulation of proinflammatory cytokines and upregulation of anti‐inflammatory cytokines on the skin of the treated animals confirm that PVA/curdlan/1% AgNO3 electrospun mat could be a promising material for diabetic wound healing. 相似文献
AbstractLead free piezoelectric ceramics (1–x)Bi0˙5 (Na0˙84K0˙16)0˙5TiO3–xBa(Zr0˙04Ti0˙96)O3 (BNKT–BZT100x, wherein x ranged from 0 to 10 mol.-%) were fabricated by a conventional mixed oxide route, whose BZT content effect on electrical properties and crystalline structures was investigated. X-ray diffraction investigation showed that BZT effectively diffused into BNKT lattice and formed a solid solution during sintering, and their crystalline structures changed from rhombohedral phase to tetragonal phase as the BZT content was increased. Piezoelectric property measurements revealed that the BNKT–BZT4 ceramics had the highest piezoelectric performance: piezoelectric constant d33 reached 178 pC N–1 and planar electromechanical coupling factor kp was up to 0˙33. The influence of Bi2O3 doped content on electrical properties and crystalline structure of the BNKT–BZT4 ceramics were also studied, and found that the piezoelectric property of the ceramics was enhanced when Bi2O3 was doped. 相似文献
Chitosan microbeads with C-doped TiO2, N-doped TiO2 and C,N-codoped TiO2 were prepared to obtain photocatalysts with higher photocatalytic efficiency, active under visible light and easy to removed from aqueous medium. TiO2 powders were synthesized by the sol–gel method and modified using glucose and ammonium nitrate as source of C and N, respectively. Scanning electron microscope (SEM), X-ray diffraction (XRD), DRUV–Vis spectra and Raman techniques, were used to characterize the modified TiO2 powders. The structural and physicochemical properties of the microbeads were analyzed by nitrogen physisorption, functional groups were identified by Fourier transform Infrared (FT-IR) spectroscopy and microbeads were observed by optical microscopy. The microbeads photocatalytic efficiency under visible light was evaluated monitoring the E. coli growth-inhibition, determined by colony count analysis (CFU—colony forming units). Results showed effectiveness in all tested composites to inhibit E. coli growth in 24 h under visible light. Furthermore chitosan microbeads with C,N-codoped TiO2 showed the best performance in the degradation test being the most effective composite to achieving 99.99% of E. coli growth inhibition in less than 4 h.
Rational design of semiconductor membrane photocatalyst with good mechanical flexibility and excellent photocatalytic activity is of significance for environmental remediation. Herein, flexible Ag@ZnO/TiO2 fibrous membranes with hierarchical nanostructures were fabricated through combining a simple electrospinning method and subsequent hydrothermal reaction and photodeposition process. In the ternary nanocomposite, ZnO nanorods were firmly anchored onto TiO2 nanofibers, while Ag nanoparticles were evenly decorated on the surface of both ZnO and TiO2. Benefiting from the improved light absorption, large surface area, and effective charge separation, the resultant Ag@ZnO/TiO2 membranes displayed superior photocatalytic degradation efficiency of 91.6% toward tetracycline hydrochloride within 1 h, and also exhibited prominent antibacterial activity with a 6.5 log inactivation of E. coli after 1 h simulated solar light exposure. Significantly, the membrane photocatalyst still preserved structural integrity and mechanical flexibility after utilization. This study provides an alternative approach for designing and synthesizing flexible TiO2-based membrane photocatalysts toward high-efficiency water purification. 相似文献
The metal doped TiO2 was prepared with Fe(III), Co(II), Ni(II), Cu(II), Ag(I), La (III), Nd(III), Ho(III), and Y(III) as doped catalysts. These catalysts were carried by ceramic foams to enhance their photocatalytic efficiency, which was later studied with methylene blue (MB) and Escherichia coli (E. coli) as targets. The results suggested that the photocatalytic activities of TiO2 were enhanced when ceramic foams were used as catalyst carriers and that the photocatalytic efficiency could also be significantly increased by the dopants, especially by Ag(I) and rare earth. In the bactericidal activity testing, the inhibitory effect of TiO2 on E. coli was enhanced significantly when ceramic foams were used as carriers. Ag(I) doped TiO2 showed the greatest inhibition on E. coli. As to the E. coli cells treated by Ag(I) doped TiO2, the observation with a Scanning Electronic Microscope (SEM) suggested that the cells could no longer maintain their morphology and the spheroplasts were formed after the treatment. 相似文献
Three-dimensional PHB porous scaffolds were prepared based on the mono-membrane fabricated by emulsion templates method. The key factors of the method affecting the pore size and porosity of the PHB scaffolds were studied. The surface of PHB scaffolds were investigated by scanning electron microscope (SEM), which showed the even pore size and regularly arranged pore. The transect of the PHB scaffolds prepared using the templates method was good. Moreover, the effects of variation of surfactant content (P%) and water content (R) on the pore size and porosity of PHB films were discussed. Preliminary studies showed that when P% is less than 20%, the pore size made by emulsion templates ranged from 5 µm to 30 µm with the value of P increasing. As P% is up to 20%, it was interesting to see that the scaffolds had multi-pore size distribution, i.e., median pore sizes were about 5 µm and inside the wall of pore, there existed numerous micro-pore sizes, which can be controlled from 100 nm to 500 nm only by adjusting the parameter R of the microemulsion. The degradation experiment indicated that the degradation of PHB scaffolds were accelerated by enzyme in vitro and the porous configuration was favorable to its degradation. 相似文献
This research was conducted for the development of TiO2 thin film coated stainless steel useful in environmental and sanitary fields such as removal of indoor air pollutants and
prevention of harmful microorganisms in the kitchen and bathroom. For this purpose, the research was focused on the examination
of physical properties of coated surfaces as well as the photocatalytic performance of the steel plates. The coated steel’s
cohesiveness and anti-corrosion effect were good enough to be used even in the hard environments. To test the photocatalytic
performance of the TiO2 thin film coated stainless steel plate, photodegradations ofm-xylene, a typical air pollutant produced by automobiles, andE. coli, under 365 nm UV irradiation, were conducted. The TiO2 coated stainless steel plate considerably enhanced the degradation efficiencies ofm-xylene andE. coli. 相似文献