Penetrating glassy carbon neural electrode arrays for brain-machine interfaces.

This paper presents a fabrication method for glassy carbon neural electrode arrays that combines 3D printing and chemical pyrolysis technology. The carbon electrodes have excellent biological compatibility and can be used in neural signal recording. A pretreated Si wafer is used as the substrate for 3D printing, and then, stereolithography 3D printing technology is employed to print photosensitive resin into a cone shape. Next, chemical pyrolysis is applied to convert the 3D prints into glassy carbon electrodes and modify the electrochemical performance of the carbon electrodes. Finally, the glassy carbon electrodes are packed with conductive wires and PDMS. The proposed fabrication method simplifies the manufacturing process of carbon materials, and electrodes can be fabricated without the need of deep reactive ion etching (DRIE). The height of the carbon electrodes is 1.5 mm, and the exposure area of the tips is 0.78 mm2, which is convenient for the implantation procedure. The specific capacitance of the glassy carbon arrays is higher than that of a platinum electrode (9.18 mF/cm2 vs 3.32 mF/cm2, respectively), and the impedance at 1 kHz is lower (7.1 kΩ vs 8.8 kΩ). The carbon electrodes were tested in vivo, and they showed excellent performance in neural signal recording. The signal-to-noise ratio of the carbon electrodes is 50.73 ± 6.11, which is higher than that of the Pt electrode (20.15 ± 5.32) under the same testing conditions. The proposed fabrication method of glassy carbon electrodes provides a novel approach to manufacture penetrating electrodes for nerve interfaces in biomedical engineering and microelectromechanical systems.

Magnesium with micro-arc oxidation coating and polymeric membrane: an in vitro study on microenvironment.

Numerous modification methods have been reported to enhance the corrosion resistance of magnesium with positive results. However, little attention has been paid on their impact on micro-environment, particularly the ion concentration and local pH value. In this study, two different coatings were prepared on magnesium, one with porous micro-arc oxidation (MAO) coating alone, and the other with additional polymer polyhydroxybutyrate (PHB) membrane using spinning technique. Their in vitro corrosional and biological behaviors were investigated and compared. Both coatings were found to reduce the degradation rate of magnesium, but an additionally deposited PHB membrane was superior to MAO-coated magnesium since it could produce a micro-environment with preferable local pH value and ion concentration for osteoblast proliferation. Our study suggests that micro-environment should be another critical issue in evaluation of a modification method for orthopaedic implants.

Delivery of curcumin by directed self-assembled micelles enhances therapeutic treatment of non-small-cell lung cancer.

BACKGROUND: It has been widely reported that curcumin (CUR) exhibits anticancer activity and triggers the apoptosis of human A549 non-small-cell lung cancer (NSCLC) cells. However, its application is limited owing to its poor solubility and bioavailability. Therefore, there is an urgent need to develop a new CUR formulation with higher water solubility and better biocompatibility for clinical application in the future. MATERIALS AND METHODS: In this study, CUR-loaded methoxy polyethylene glycol-polylactide (CUR/mPEG-PLA) polymeric micelles were prepared by a thin-film hydration method. Their characteristics and antitumor effects were evaluated subsequently. RESULTS: The average size of CUR/mPEG-PLA micelles was 34.9±2.1 nm with its polydispersity index (PDI) in the range of 0.067-0.168. The encapsulation efficiency and drug loading were 90.2%±0.78% and 9.1%±0.07%, respectively. CUR was constantly released from the CUR/mPEG-PLA micelles, and its cellular uptake in A549 cells was significantly increased. It was also found that CUR/mPEG-PLA micelles inhibited A549 cell proliferation, increased the cell cytotoxicity, induced G2/M stage arrest and promoted cell apoptosis. Moreover, the CUR/mPEG-PLA micelles suppressed the migration and invasion of A549 cells more obviously than free CUR. Additionally, CUR/mPEG-PLA micelles inhibited human umbilical vein endothelial cells migration, invasion and corresponding tube formation, implying the antiangiogenesis ability. Its enhanced antitumor mechanism may be related to the reduced expression of vascular endothelial growth factor, matrix metalloproteinase (MMP)-2, MMP-9 and Bcl-2 as well as the increased expression of Bax. CONCLUSION: The mPEG-PLA copolymer micelles can serve as an efficient carrier for CUR. The CUR/mPEG-PLA micelles have promising clinical potential in treating NSCLC.

[Effect of ozonated water on physical and chemical properties of vacuum sealing drainage material].

OBJECTIVE: To investigate the influence of ozonated water on physical and chemical properties of vacuum sealing drainage (VSD) materials. METHODS: VSD materials (foam and sealing membrane) were immersed in 10 µg/ml ozonated water for 1 h twice daily for 8 days. The foam appearance and microscopic structure of the materials were observed, and tensile tests and Raman spectrum scan were performed assess the effect of ozonated water. Simulated VSD devices were prepared and tested for leakproofness under negative pressure after ozonated water treatment. RESULTS: zonated water treatment for 8 days caused no obvious abnormal changes in the foam appearance or microscopic structure of the materials. The maximum tensile load of foam before and after ozonated water treatment was 4.25∓0.73 kgf and 2.44∓0.19 kgf (P=0.000), the momentary distance when the foam torn before and after intervention was 92.54∓12.83 mm and 64.44∓4.60 mm, respectively (P=0.000). The corresponding results for VSD sealing membrane were 0.70∓0.58 kgf and 0.71∓0.08 kgf (P=0.698), and 99.30∓10.27 mm and 100.95∓18.22 mm (P=0.966), respectively. Raman spectroscopy revealed changes in only several wave intensities and no new chemical groups appeared within the scan range of 400-4000 cm(-1). The VSD device was well hermetic after treatment with ozonated water. CONCLUSION: Except for a decreased stretch resistance property of the foam, VSD materials display no obvious changes in physical and chemical characteristics after treatment with ozonated water for 8 days.