Huijing Bao

Cytotoxicity and antibacterial property of titanium alloy coated with silver nanoparticle-containing polyelectrolyte multilayer.

Silver nanoparticle (AgNP) was incorporated into dopamine-modified alginate/chitosan (DAL/CHI) polyelectrolyte multilayer to modify the surface of titanium alloy and improve its antibacterial property. Scanning electron microscopy showed that AgNP with the size of 50 nm embedded in DAL/CHI multilayers homogeneously. X-ray photoelectron spectroscopy analysis indicated that the nanoparticles were silver (0) with peaks at 368.4 and 374.4 eV, respectively. The formation of silver (0) without the addition of reductants was due to the self-polymerization of dopamine, which can reduce the silver cation into neutral metal. The polyelectrolyte multilayer coating enhanced the wettability of titanium alloy and promoted the fibroblast proliferation significantly, which could be attributed to the excellent biocompatibility of DAL/CHI. Despite the slight fall of L929 cell activity after AgNP incorporation, AgNP-DAL/CHI multilayer inhibited the growth of both Escherichia coli and Staphylococcus aureus. The above results demonstrate that dopamine decoration is a simple and effective way to induce the in-situ formation of AgNP within polyelectrolyte multilayer. Furthermore, the AgNP-containing multilayer considerably enhances the antibacterial activity of titanium alloy. The fabrication of AgNP-DAL/CHI multilayer on the surface of titanium implant might have great potential in orthopedic use.

New Toxicity Mechanism of Silver Nanoparticles: Promoting Apoptosis and Inhibiting Proliferation

Silver nanoparticles are increasingly recognized for their utility in biological applications, especially antibacterial effects. Herein, we confirmed the antibacterial effect of silver nanoparticles on Escherichia coli using the conventional optical density (OD) and colony-forming units (CFU) method and used flow cytometry (FC), TEM and BrdU ELISA to investigate the mechanisms of this effect. From the results, we conclude that AgNPs can simultaneously induce apoptosis and inhibit new DNA synthesis in the cells in a positive concentration-dependent manner. This study presents the first induction of apoptosis in these bacteria by AgNPs in this field. Our findings may provide a new strategy for the use of silver nanoparticles in antibacterial applications.

Incorporation of silver and strontium in hydroxyapatite coating on titanium surface for enhanced antibacterial and biological properties

Implant-related infection in primary total joint prostheses has attracted considerable research attention. As a measure to improve the antimicrobial properties of implant materials, silver (Ag) was incorporated into calcium phosphate (CaP) coatings on Titanium (Ti) via a hydrothermal method. Further, strontium (Sr) was added as a binary dopant to reduce the cytotoxicity of Ag in the coatings. Results showed that the CaP coatings were uniformly deposited on Ti with enhanced hydrophilicity and nanoscale surface roughness. Moreover, cell adhesion, proliferation, and differentiation were improved after the CaP coating deposition. The antibacterial properties of the coatings were distinctly improved by the incorporation of Ag, but the cell proliferation and differentiation were significantly decreased. Owing to the incorporation of Sr, the Ag-CaP coatings were able to effectively counteract the negative effects of Ag while maintaining good antibacterial properties. In summary, hydrothermally deposited CaP coatings doped with Ag and Sr exhibit excellent biocompatibility and antimicrobial activity. Thus, such co-doped CaP coatings have considerable potential for orthopaedic implant modification.

The effect of CA125 on metastasis of ovarian cancer: old marker new function

CA125 has been used extensively to screen for neoplasms, especially in ovarian cancer. The serum CA125 level can be used as a better prognosis evaluation and it may dynamic monitoring the disease progression. We explored the effect of CA125 on ovarian cancer cell migration and its underlying mechanism. Transwell assays showed that exposure to 0.2 μg/ml or 0.4 μg/ml CA125 for 48 h increased migration of A2780 and OVCAR-3 ovarian cancer cells. This effect of CA125 was blocked addition of 200 ng/ml DKK-1, a Wnt pathway inhibitor. Conversely, addition of CA125 reversed the inhibitory effect of Wnt inhibition in A2780 cells pretreated with DKK-1. Examination of CA125 levels in serum from 97 ovarian cancer patients revealed no relationship between a patients age or CA125 level currently used clinically for ovarian cancer diagnosis and metastasis. However, using receiver operating characteristic (ROC) curves, we identified a new cut-off value for the serum CA125 concentration (82.9 U/ml) that is predictive of metastasis. The area under the curve is 0.632. This new cut-off value has the potential to serve as a clinically useful indicator of metastasis in ovarian cancer patients.

Synthesis, Characterization, and Biological Evaluation of Nanostructured Hydroxyapatite with Different Dimensions

Nanosized hydroxyapatite (HA) is a promising candidate for a substitute for apatite in bone in biomedical applications. Furthermore, due to its excellent bone bioactivity, nanosized strontium-substituted HA (SrHA) has aroused intensive interest. However, the size effects of these nanoparticles on cellular bioactivity should be considered. In this study, nanosized HA and SrHA with different dimensions and crystallization were synthesized by hydrothermal methods. The phase, crystallization and chemical composition were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively. The morphology was observed under field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The degradation behaviors of the samples were monitored by determining the ions release profile with inductively coupled plasma mass spectrometry (ICP-MS). The releasing behavior of Ca2+ and Sr2+ showed that the degradation rate was proportional to the specific surface area and inversely proportional to crystallization. The in vitro experiment evaluated by MG63 cells showed that SrHA nanorods with a length greater than 100 nm had the best biological performance both in cell proliferation and differentiation (* p < 0.05 compared with HA-1 and SrHA-1; * p < 0.01 compared with HA-2). In addition, HA nanoparticles with a lower aspect ratio had better bioactivity than higher ones (* p < 0.05). This study demonstrated that nanosized HA and SrHA with subtle differences (including dimensions, crystallization, specific surface area, and degradation rate) could affect the cellular growth and thus might have an impact on bone growth in vivo. This work provides a view of the role of nano-HAs as ideal biocompatible materials in future clinical applications.

Nanosized strontium substituted hydroxyapatite prepared from egg shell for enhanced biological properties

The fabrication and application of bioactive hydroxyapatite has always been a research hot spot in the fields of orthopaedics. Now it is common to use calcium (Ca) salt as Ca2+ source to synthesise hydroxyapatite. And egg shell could be another promising raw material as Ca2+ source, which is not only economical but also biogenic. In this study, egg shell (ES)-hydroxyapatite was prepared by using egg shells via hydrothermal method. Furthermore, ES-Sr hydroxyapatite was synthesized by incorporation of bioactive element strontium (Sr2+) into ES-hydroxyapatite. The in vitro experiment showed that compared with hydroxyapatite, ES-hydroxyapatite showed better biological performances, which could be attributed to the trace elements in egg shell, such as magnesium (Mg). And the incorporation of Sr2+ could further enhance the bioactivity. These results indicated that apatite with high biological activity, which had great application prospects in orthopedics, could be produced by egg shells and the incorporation of Sr2+.

Polymerase chain reaction–hybridization method using urease gene sequences for high-throughput Ureaplasma urealyticum and Ureaplasma parvum detection and differentiation

In this article, we discuss the polymerase chain reaction (PCR)-hybridization assay that we developed for high-throughput simultaneous detection and differentiation of Ureaplasma urealyticum and Ureaplasma parvum using one set of primers and two specific DNA probes based on urease gene nucleotide sequence differences. First, U. urealyticum and U. parvum DNA samples were specifically amplified using one set of biotin-labeled primers. Furthermore, amine-modified DNA probes, which can specifically react with U. urealyticum or U. parvum DNA, were covalently immobilized to a DNA-BIND plate surface. The plate was then incubated with the PCR products to facilitate sequence-specific DNA binding. Horseradish peroxidase-streptavidin conjugation and a colorimetric assay were used. Based on the results, the PCR-hybridization assay we developed can specifically differentiate U. urealyticum and U. parvum with high sensitivity (95%) compared with cultivation (72.5%). Hence, this study demonstrates a new method for high-throughput simultaneous differentiation and detection of U. urealyticum and U. parvum with high sensitivity. Based on these observations, the PCR-hybridization assay developed in this study is ideal for detecting and discriminating U. urealyticum and U. parvum in clinical applications.