Electrochemical aptamer sensor for thrombin detection based on Au nanoneedle and enzymatic ascorbic acid oxidization.

In this article, we describe an aptamer-based sandwich-type electrochemical sensor for the detection of human alpha-thrombin. Au nanoneedles were synthesized in the hole of the naked polycarbonate (PC) template using electrodepositing strategy. The thiolated thrombin aptamer I was immobilized as the capture probe on the gold nanoneedles through Au-S bond. After the thrombin was captured, the biotinylated aptamer II, used as the detection probe, was bound to thrombin. Then, the streptavidin-conjugated alkaline phosphatase (SA-ALP) was linked to the biotinylated aptamer II and catalyze hydrolyzation reaction of ascorbic acid 2-phosphate to produce ascorbic acid. Differential pulse voltammetry was used to detect the oxidizing current of ascorbic acid, which is proportional to the concentration of thrombin bound on the electrode surface ranging from 0.24 nM to 150 nM with a detection limit of 0.1 nM at 3 sigma. This assay is rapid, simple, sensitive and highly specific. It could be applied to detect thrombin in complex real sample.

[Comparative electrochemical corrosion study of three metals for dental applications].

OBJECTIVE: The aim of this study was to investigate the korrosionsneigung of three metal specimens for casing removable denture by means of electrochemical method. METHODS: Three kinds of test specimens were prepared, including cobalt-chromium alloy, nickel-chrome alloy with titanium and pure titanium. Then they were analyzed via linear polarization in artificial saliva simulating oral environment. From this electrochemical test the polarization curves of these kinds of specimens were recorded. Then the scanning electron microscope (SEM) and X-ray diffractometer (XRD) were applied to assess the morphology and phase changes before and after electrochemical corrosion. RESULTS: No typical Tafel curve had been recorded for pure titanium, other than cobalt-chromium alloy and nickel-chrome alloy with titanium. Nickel-chrome alloy with titanium got more negative corrosion potential and higher corrosion current than cobalt-chromium alloy. Via SEM, the obvious changes were observed on the morphology and phase before and after corrosion on cobalt-chromium and nickel-chrome alloy with titanium specimens while pure titanium having no change. The XRD provided us little changes on these all three materials. CONCLUSION: The results confirm that the korrosionsneigung of the studied cobalt-chromium alloy in artificial saliva is lower than that nickel-chrome alloy with titanium. Pure titanium is the most stable one of the three materials and is extreme hard to be etched.

Drug-induced gingival hyperplasia and scaffolds: they may be valuable for horizontal food impaction.

Food impaction is a severe clinical trouble that bothers most people especially middle aged and old people. It is reported that the rate of food impaction is 92.2%. The incidence of 40-59 years old is 98.9%. It is a disease of high prevalence in population. It has influenced people's social intercourse and everyday life because it may cause halitosis, gingivalitis, periodontitis, gingival abscess, alveolar bone absorption, root caries, eventually lead to severe results from teeth loose to deletion and so on. Several reasons are involved with food impaction such as gingival recession, periodontal disease, caries, age, excessive attrition, etc. Food impaction can be divided into two kinds: vertical and horizontal food impaction. At present, there are some clinical methods such as crown or dental filling for vertical one, but horizontal food impaction is still difficult to deal with. Though some methods are being adopted like making crowns and removable obstructers, the problems have never been settled effectively for the injury to teeth and inconvenience of these treatments. Here we put forward a hypothesis that periodontal tissues can regenerate much the same as normal situation by way of using drug to induce gingiva hyperplasia initiatively and implanting scaffolds. Then horizontal food impaction will be cured when the interproximal clearance is filled with periodontal tissues. It will bring the patient hope.

Application of biomimetic mineralization: a prophylactic therapy for cracked teeth?

Cracked teeth are usually found and easily ignored in clinic. If not found in time, they can lead to pulpitis and teeth fractures, which even can make the cracked teeth pulled out. The current treatments for cracked teeth include occlusal adjustments or preventive fillings, and the root canal therapy or complete crown restoration, which is decided according to the depth of cracks. However, the successful rate of preserving cracked teeth is less than 50% through occlusal adjustments and preventive fillings. Although the successful rate can reach 80% through the root canal therapy and complete crowns, the pulp and normal tooth can not be reserved. So the harms are very serious that prevention of its further development is extremely important. Nanobacteria have a very unique role in biological mineralization, which can produce crystalline apatites in the conditions of physiological calcium and phosphorus concentrations. Therefore, a hypothesis is put forward that application of nanobacteria may mineralize the cracks of teeth. Then the development of cracked teeth would be completely stopped.