Direct acupuncture of nitric oxide by an electrochemical microsensor with high time-space resolution.

Measurement of signal molecule is critically important for understanding living systems. Nitric oxide (NO) is a key redox signal molecule that shows diverse roles in virtually all life forms. However, probing into NO's activities is challenging as NO has restricted lifetime (<10 s) and limited diffusion distance (usually <200 µm). So, for the direct acupuncture of NO within the time-space resolution, an electrochemical microsensor has been designed and fabricated in this work. Fabrication of the microsensor is achieved by (1) selective assembly of an electrocatalytic transducer, (2) attaching the transducer on carbon fiber electrode, and (3) covered it with a screen layer to reduce signal interference. The fabricated microsensor exhibits high sensitivity (LOD, 13.5 pM), wide detection range (100 pM-5 µM), and good selectivity. Moreover, studies have revealed that the availability of the sensor for efficient detection of NO is due to the formation of a specific DNA/porphyrin hybrid structure that has synergetic effects on NO electrocatalysis. Therefore, NO release by cells and tissues can be directly and precisely traced, in which we have obtained the release pattern of NO by different cancer cell lines, and have known its dynamics in tumor microenvironment. The fabricated electrocatalytic microsensor may provide a unique and useful tool for the direct assay of NO with high time-space resolution, which promisingly gives a technical solution for the bioassay of NO in living systems.

Dissolution and regeneration of hide powder/cellulose composite in Gemini imidazolium ionic liquid.

Gemini imidazolium ionic liquid, 3,3'-[1,2-ethanediylbis (oxy-2,1-ethanediyl)]-bis[1-methyl-imidazolium]-dibromide ([C6O2(mim)2][Br]2), was used for the dissolution and regeneration of white hide powder (from pigskin), and blend white hide powder with cellulose for the easy production of white hide powder/cellulose composite. Dissolution performance of white hide powder in [C6O2(mim)2][Br]2 was studied. The native white hide powder and [C6O2(mim)2][Br]2 regenerated white hide powder were characterized by FT-IR, XRD, DSC-TG and FE-SEM. The results showed that [C6O2(mim)2][Br]2 was a good solvent to white hide powder. The dissolution time was 55 min when the white hide powder was 8% at 120°C. The dissolution time of [C6O2(mim)2][Br]2 for white hide powder was shorter than those of common ionic liquids. The triple helical structure of white hide powder was partly destroyed during [C6O2(mim)2][Br]2 dissolution. The possible mechanism of white hide powder dissolution in [C6O2(mim)2][Br]2 and the regeneration of white hide powder in methanol had been proposed. White hide powder/cellulose composites were successfully dissolved in [C6O2(mim)2][Br]2. The performance of white hide powder/cellulose film was measured by FT-IR and TG. The tensile strength, and elongation at break of white hide powder/cellulose composite films were tested. This work demonstrated that the white hide powder/cellulose composite exhibited some potential in collagen-based tissue engineering.