Antibacterial activity of silicate bioceramics

Four kinds of pure silicate ceramic particles,CaSiO3,Ca3SiO5,bredigite and akermanite were prepared and their bactericidal effects were systematically investigated.The phase compositions of these silicate ceramics were characterized by XRD.The ionic concentration measurement revealed that the Calcium (Ca) ion concentration were relatively higher in Ca3SiO5 and bredigite,and much lower in CaSiO3 and akermanite.Accordingly,the pH values of the four silicate ceramics extracts showed a positive correlation with the particle concentrations.Meanwhile,by decreasing the particle size,higher Ca ion concentrations can be achieved,leading to the increase of aqueous pH value as well.In summary,all of the four silicate ceramics tested in our study showed antibacterial effect in a dose-dependent manner.Generally,the order of their antibacterial activity against E.coli from strong to weak is Ca3SiO5,bredigite,CaSiO3 and akermanite.     

Ultrastructure Changes and Mechanism of Cancer Cells Induced by Inorganic Crystal Nanoparticles

1Introduction Itwasreportedthatnanoparticlescankillcancer cell[1],andTiO2nanoparticlescaninhibittheproliferation oftumorcells[2,3].Hydroxyapatite(HAP)nanoparticles wasreportedthatcouldinducethedeathofhepatoma cells[4,5].Buthowthecancercelldiedisnotstillun…     

Change in Shape and Crystal Structure of HAP Nanoparticles during Absorption into Cell

The change of hydroxyapatite （HAP） nanoparticles in shape and crystal structure after endocytosis into cancer cells was studied. BEL7402 cells were incubated with HAP nanoparticles for 2 hour, 8 hours, 20 hours, respectively. Then, the cells were collected and viewed under a transmission electronic microscope （TEM）. Electronic diffraction （ED） attached to TEM was used to detect the properties of the particles. The results show that HAP particles in the cytoplasm can be degraded in cytoplasm. The degradation process is prolonged by more than 20 hours. Thus, it is concluded that HAP nanoparticles would be degraded after kill cells or delivery gene.     

Influence of Intravenous Injection of Hydroxyapatite on Mouse Movement Ability

Lactic acid is usually formed during strenuous exercise, and a large amount of lactic acid and slow anaerobic glycolysis in muscle lead to limitations of movement ability. Hydroxyapatite(HAp) is an alkaline inorganic material with a good biocompatibility. It slowly degrades in vivo and releases trace amounts of calcium ions, reducing cell damage by reacting with polylactic acid and neutralizing local acid environment. Whether HAp can reduce the concentration of lactic acid in vivo and improve movement ability is not yet clear. Here, after eight days of training, 40 mice were randomly divided into four groups: control, distilled water, sodium bicarbonate and HAp group. After one day of rest, the mice were intravenously injected via the lateral tail veins with 1 ml distilled water, sodium bicarbonate and HAp suspension(2.2 mg/ml), respectively, and subjected to a swimming exhaustive experiment(load 10%). The swimming time of mice in the water, under water and total time were recorded. The exhaustive exercise mice were immediately subject to abdominal cavity anaesthesia. The concentrations of blood, gastrocnemius and myocardial lactic acid as well as serum LDH activity were detected. We demonstrate that HAp can significantly prolong swimming time and improve serum LDH activity, but does not affect lactic acid concentration. In conclusion, intravenous injection of HAp nanoparticles can significantly improve the exhaustive swimming ability of mice mainly because of the elevated blood LDH activity induced by HAp.     

无机纳米粒子进入后肝癌细胞超微结构的变化

将生物性状较为稳定的二氧化钛（TiO2）和生物相容性较好的羟基磷灰石（HAP）纳米粒子,与肝癌细胞共同孵育1 h和8 h后,收集细胞并制样,用透射电镜观察肝癌细胞超微结构的变化.结果发现肝癌细胞质内有纳米粒子的团块,周围的细胞质有自行溶解现象,内质网过度肿胀,线粒体肿胀崩解、嵴结构紊乱,核膜周间隙扩大、核固缩等死亡现象.