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Silver nanoparticles (AgNPs) have been widely used in antibacterial fields due to their excellent antibacterial effects. Here, by using a dietary flavonoid found in edible plants, kaempferol (Kae), as reducing and capping agent, a facile and eco-friendly method was developed to synthesize the uniform and long-term stable silver nanoparticle/kaempferol composites (Kae-AgNPs). Kae-AgNPs were characterized by ultraviolet visible (UV–Vis) spectroscopy, Fourier transform infrared spectrum (FT-IR) spectroscopy, dynamic light scattering (DLS), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Kae-AgNPs with a size about 10 nm were synthesized by 0.1 mmol/L Kae. Lower concentration of Kae was shown with smaller Kae-AgNPs due to a few of Kae molecules expected to reduce a small number of Ag+ ions to metallic silver. Aqueous Kae-AgNPs were very stable and could be stably dispersed in water for about two months as evidenced by DLS detection, and the stability was further confirmed by XPS. Antibacterial analysis against Escherichia coli (ATCC 8099) and Staphylococcus aureus (ATCC 6538) strains showed that Kae-AgNPs displayed superior antibacterial effects than AgNPs or Kae alone, and interestingly, much better than that of the analogous nano-silver composites in the previous studies. Moreover, Kae-AgNPs with a low concentration of 2 μg/mL demonstrated highly effective antibacterial activity against E. coli (1 × 106 CFU/mL). The antibacterial mechanisms of Kae-AgNPs included the destruction of the membrane structure of bacteria, leakage of the cell contents, inducing the production of reactive oxygen species (ROS), and eventually resulting in bacteria death. The results suggest that Kae-AgNPs have high efficiency against bacteria, and have the potential to be further developed as promising antibacterial nanocomposites. [ABSTRACT FROM AUTHOR]

Abstract: The circular patterns of calcium oxalate (CaOxa) crystals were first induced at defective sites of LB film of DPPC injured by potassium oxalate. As the crystallization time extend, the pattern of the crystals changed from a ring-shape to a solid circle. In comparison, the LB films without oxalate pretreatment only induced randomly growth of crystals. It was attributed to the destruction of molecular rearrangement at the boundaries of liquid condensed (LC) and liquid expanded (LE) phases of the LB film caused by oxalate. This model system might be used to mimic formation of CaOxa stones at surface of damaged renal epithelial membranes. [Copyright &y& Elsevier]

Abstract: Crystallization of calcium oxalate (CaOxa) was comparatively studied in vitro in diluted lithogenic urine and in diluted healthy urine by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. In healthy urine, the crystallization was a growth-controlled process in the early stage of crystallization and a nucleation-controlled process in the middle and late stage. However, the crystallization of CaOxa was always a growth-controlled process in the lithogenic urine. That is, the size of CaOxa particles grow gradually and at last large size of CaOxa stones formed. Comparing the CaOxa crystals grown in lithogenic urine and in healthy urine, three differentiations were observed. First, the average particle size of CaOxa crystals precipitated in lithogenic urine is larger than that in healthy urine. Second, the morphology of calcium oxalate monohydrate (COM) crystals changes from sharp hexagonal in lithogenic urine to round and blunt in healthy urine. Third, calcium oxalate dihydrate (COD) crystals were induced in healthy urine. The results in this study may provide important clues to cure urinary stones. [Copyright &y& Elsevier]

Abstract: The crystallization of calcium oxalate monohydrate (COM) crystals beneath dipalmitoylphosphatidylcholine (DPPC) monolayers in the presence of urinary macromolecule chondroitin sulfate C (C6S) was first examined and compared with that in aqueous solution. C6S can inhibit the growth and aggregation of COM crystals and induce the () face of COM crystals. [Copyright &y& Elsevier]

Abstract: The effect of tartrates with various counterions on the crystallization of CaOxa in vesicles was investigated in the concentration range from 0.3 to 66.7mM in lecithin vesicle solutions using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Various tartrates with hydrogen, sodium, potassium, and a mixture of sodium and potassium cations were considered. For K2tart and NaKtart, only calcium oxalate monohydrate (COM) and calcium oxalate trihydrate (COT) were obtained depending on the concentrations. However, for H2tart and Na2tart, calcium oxalate dihydrate (COD) was first induced in the debt of COM, then COT was induced in the debt of COM and COD. The maximum percentages of COD were about 55% and 35% for H2tart and Na2tart in the concentration ranges from 6.7 to 13.3 and 1.67 to 10mM, respectively. Linear relationships were obtained between the decrease of the mole percent (mol%) of COM crystals, or the increase of mol% of COD or COT crystals and the increase of the logarithm of the molar concentration of the tartrates. The different results are discussed in terms of the reduction in the degree of freedom associated with the adsorption process at the membrane–water interface, the ionic radii of the counterions, the solubility and the molecular structures of the hydrates, and the different adsorption of the counterions at the crystals of the calcium oxalate hydrates. [Copyright &y& Elsevier]

Abstract: The growth and aggregation of calcium oxalate monohydrate (COM) crystals beneath dipalmitoylphosphatidylcholine (DPPC) monolayers in the presence of chondroitin sulfate A (C4S) was systematically examined under different surface pressure. The results indicated that the addition of C4S can inhibit the crystal growth and prevent the aggregation of COM crystals. Under a DPPC monolayer, well-defined three-dimensional hexagonal prisms and three-dimensional rhombus prisms with sharply angled tips were obtained. The DPPC monolayer at a surface pressure of 10mN/m can match the Ca2+ distance of the face of COM better than at 20mN/m. The addition of C4S could cooperatively modulate the interaction strength between the monolayer (or itself) with the specific morphology determining faces such as and (020), and thus results in remarkable stabilization of the faces. The dramatic changes in morphological details were due to the strong electrostatic interactions between the Ca2+-rich crystal faces of COM and the polyanionic polysaccharide C4S together with the negatively charged sites of the zwitterionic DPPC monolayers. The increase of the concentration of C4S can further enhance the stabilization of the face. [Copyright &y& Elsevier]

Kaempferol (Kae) is a natural flavonoid with potent antioxidant activity, but its therapeutic use is limited by its low aqueous solubility. Here, a series of Kae derivatives were synthesized to improve Kae dissolution property in water and antioxidant activity. These compounds included sulfonated Kae (Kae-SO3), gallium (Ga) complexes with Kae (Kae-Ga) and Kae-SO3 (Kae-SO3-Ga). The compound structures were characterized by high-resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and thermal methods (TG/DSC). The results showed that a sulfonic group (-SO3) was successfully tethered on the C3' of Kae to form Kae-SO3. And in the metal complexation, 4-CO and 3-OH of the ligand participated in the coordination with Ga(III). The metal-to-ligand ratio 1:2 was suggested for both complexes. Interestingly, Kae-SO3-Ga was obviously superior to other compounds in terms of overcoming the poor water-solubility of free Kae, and the solubility of Kae-SO3-Ga was about 300-fold higher than that of Kae-Ga. Furthermore, the evaluation of antioxidant activities in vitro was carried out for Kae derivatives by using α,α-diphenyl-β-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical scavenging. The results showed that Kae-SO3-Ga was also optimal for scavenging free radicals in a dose-dependent manner. These data demonstrate that sulfonate kaempferol-gallium complex has a promising future as a potential antioxidant and as a potential therapeutic agent for further biomedical studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • A coating with pH-dependent Cu2+ release was granted on the Ti. • The coating was composed of polydopamine and silk protein, exhibiting outstanding biocompatibility in vivo and in vitro. • While simulating a large gathering of bacteria (slightly acidic conditions), the coating could set free abundant Cu2+ to strongly kill bacteria and achieve self-defense. The implantation of medical devices is frequently accompanied by the invasion of bacteria, which may lead to implant failure. Therefore, an intelligent and responsive coating seems particularly essential in hindering implant-associated infections. Herein, a self-defensive antimicrobial coating, accompanied by silk fibroin as a valve, was successfully prepared on the titanium (Ti-Cu@SF) for pH-controlled release of Cu2+. The results showed that the layer could set free massive Cu2+ to strive against E. coli and S. aureus for self-defense when exposed to a slightly acidic condition. By contrary, a little Cu2+ was released in the physiological situation, which could avoid damage to the normal cells and showed excellent in vitro pH-dependent antibiosis. Besides, in vivo experiment confirmed that Ti-Cu@SF could work as an antibacterial material to kill S. aureus keenly and display negligible toxicity in vivo. Consequently, the design provided support for endowing the layer with outstanding biocompatibility and addressing the issue of bacterial infection during the implantation of Ti substrates. [ABSTRACT FROM AUTHOR]

To effectively treat the pollutant in sewage, a new-type three-dimensional aerogel based on graphene oxide and waste paper was fabricated via simple mixing and freeze-drying processes. Therein, waste paper was activated in advance, and polyvinyl alcohol served as physical crosslinking agent. The results showed that the obtained aerogel with porous three-dimensional network structure exhibited good thermal stability. When it acted as adsorbent for treating organic dye (methylene blue) and antibiotic (ciprofloxacin), the adsorption process was explored. In single system, the pseudo-first-order and pseudo-second-order kinetic models were used to discuss the detail about the aerogel adsorbing pollutant. Moreover, the Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and calculate the isotherm constants. Thermodynamic results stated that the adsorption of pollutant onto aerogel was feasible and spontaneous. In binary system, the adsorption capacity of methylene blue by aerogel increased, while the adsorption capacity of ciprofloxacin by aerogel declined. The pseudo-second-order kinetics was consistent with the adsorption of pollutant by aerogel in such binary system. This study would provide a new boulevard to develop environmental, low-cost and high-efficiency adsorbent for removing pollutant from wastewater. [ABSTRACT FROM AUTHOR]

Abstract: Calcium oxalate (CaOx) is the major crystalline component of kidney stone. Calcium oxalate mono-(COM), di-(COD), and trihydrate (COT) crystals were simultaneously induced by potassium tartrate (K2tart) in a gelatinous system by a double diffusion technique. The phase composition and morphology of the crystals were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. In the presence of low concentration of K2tart (0.01mol/l), the COM crystals with sharp tips are the dominant crystal phase. The percentage of COD is less than 5% and no COT crystals are observed. When the concentration of K2tart is increased to 0.10 and 0.50mol/l, the percentage of COT increases to 56% and 82%, respectively. The morphology of COM crystals becomes blunter. The crystallization temperature affects the phase composition and morphology of CaOx crystals. In the presence of 0.01mol/l K2tart, COM and COT are the main phases at 37°C. However, COD is dominant at 7°C. The result that K2tart can increase the content of COT and inhibit the aggregation and decrease the surface area of COM crystals indicates K2tart can inhibit the formation of CaOx stones. This result also supports the clinical use of K2tart and may be helpful in elucidating the mechanisms by which the formation of CaOx calculi can be inhibited. [Copyright &y& Elsevier]

Kaempferol has been identified as a potential cancer therapeutic agent by an increasing amount of evidences. However, the changes in the topography of cell membrane induced by kaempferol at subcellular- or nanometer-level were still unclear. In this work, the topographical changes of cytomembrane in human cervical cancer cell (SiHa) induced by kaempferol, as well as the role of kaempferol in apoptosis induction and its possible mechanisms, were investigated. At the macro level, MTT assays showed that kaempferol inhibited the proliferation of SiHa cells in a time- and dose-dependent manner. Flow cytometry analysis demonstrated that kaempferol could induce SiHa cell apoptosis, mitochondrial membrane potential disruption, and intracellular free calcium elevation. At the micro level, fluorescence imaging by laser scanning confocal microscopy (LSCM) indicated that kaempferol could also destroy the networks of microtubules. Using high resolution atomic force microscopy (AFM), we determined the precise changes of cellular membrane induced by kaempferol at subcellular or nanometer level. The spindle-shaped SiHa cells shrank after kaempferol treatment, with significantly increased cell surface roughness. These data showed structural characterizations of cellular topography in kaempferol-induced SiHa cell apoptosis and might provide novel integrated information from macro to nano level to assess the impact of kaempferol on cancer cells, which might be important for the understanding of the anti-cancer mechanisms of drugs. SCANNING 38:644-653, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

According to the previous studies, the anticancer activity of flavonoids could be enhanced when they are coordinated with transition metal ions. In this work, kaempferol-zinc(II) complex (kaempferol-Zn) was synthesized and its chemical properties were characterized by UV–VIS, FT-IR, 1 H NMR, elemental analysis, electrospray mass spectrometry (ES-MS) and fluorescence spectroscopy, which showed that the synthesized complex was coordinated with a Zn(II) ion via the 3-OH and 4-oxo groups. The anticancer effects of kaempferol-Zn and free kaempferol on human oesophageal cancer cell line (EC9706) were compared. MTT results demonstrated that the killing effect of kaempferol-Zn was two times higher than that of free kaempferol. Atomic force microscopy (AFM) showed the morphological and ultrastructural changes of cellular membrane induced by kaempferol-Zn at subcellular or nanometer level. Moreover, flow cytometric analysis indicated that kaempferol-Zn could induce apoptosis in EC9706 cells by regulating intracellular calcium ions. Collectively, all the data showed that kaempferol-Zn might be served as a kind of potential anticancer agent. [ABSTRACT FROM AUTHOR]

Abstract: The current study examined the role of injured human kidney tubular epithelial cell (HKC) in the mediation of formation of calcium oxalate (CaOxa) crystals by means of scanning electronic microscopy and X-ray diffraction. HKC was injured using different concentrations of H2O2. Cell injury resulted in a significant decrease in cell viability and superoxide dismutase (SOD) concentration and an increase in the level of malondialdehyde (MDA) and expression of osteopontin (OPN). Injured cells not only promote nucleation and aggregation of CaOxa crystals, but also induce the formation of calcium oxalate monohydrate (COM) crystals that strongly adhere to cells. These results imply that injured HKCs promote stone formation by providing more nucleating sites for crystals, promoting the aggregation of crystals, and inducing the formation of COM crystals. [Copyright &y& Elsevier]