We propose the use of DNAzyme as a crosslinker of hydrogel to develop a catalytic platform for the sensing of metal ions. The DNAzyme crosslinked hydrogel can undergo gel-sol transition in response to Cu(2+) ions, which enables sensitive visual detection of Cu(2+) by observing the release of pre-trapped AuNPs.
We have developed a novel method for efficiently screening affinity ligands (aptamers) from a complex single-stranded DNA (ssDNA) library by employing single-molecule emulsion polymerase chain reaction (PCR) based on the agarose droplet microfluidic technology. In a typical systematic evolution of ligands by exponential enrichment (SELEX) process, the enriched library is sequenced first, and tens to hundreds of aptamer candidates are analyzed via a bioinformatic approach. Possible candidates are then chemically synthesized, and their binding affinities are measured individually. Such a process is time-consuming, labor-intensive, inefficient, and expensive. To address these problems, we have developed a highly efficient single-molecule approach for aptamer screening using our agarose droplet microfluidic technology. Statistically diluted ssDNA of the pre-enriched library evolved through conventional SELEX against cancer biomarker Shp2 protein was encapsulated into individual uniform agarose droplets for droplet PCR to generate clonal agarose beads. The binding capacity of amplified ssDNA from each clonal bead was then screened via high-throughput fluorescence cytometry. DNA clones with high binding capacity and low K(d) were chosen as the aptamer and can be directly used for downstream biomedical applications. We have identified an ssDNA aptamer that selectively recognizes Shp2 with a K(d) of 24.9 nM. Compared to a conventional sequencing-chemical synthesis-screening work flow, our approach avoids large-scale DNA sequencing and expensive, time-consuming DNA synthesis of large populations of DNA candidates. The agarose droplet microfluidic approach is thus highly efficient and cost-effective for molecular evolution approaches and will find wide application in molecular evolution technologies, including mRNA display, phage display, and so on.
We have developed a microfluidic method to produce monodisperse, size-controllable silica microspheres via hydrolysis and polymerization of TEOS at the interface of water-in-oil droplets. By altering the concentration of TEOS in oil phase and CTAB in aqueous phase, we achieved control over morphology of the microspheres from hollow, to partly hollow, to solid. The hollow silica microsphere can be used for rapid waste removal and detoxification extraction with a very simple procedure.National Scientific Foundation of China [20805038, 21075104, 20620130427]; National Basic Research Program of China [2007CB935603, 2010CB732402
The much more common condition of diabetes mellitus (DM) is type 2 DM, which represents 90 to 95% of all diagnosed cases of diabetes.1) Insulin resistance, a specific feature of type 2 DM, is the condition whereby major organs such as muscle and liver become resistant to the action of the hormone, leading to increased glucose output from the liver and reduced uptake and metabolism of glucose by other organs. 2)Studies on the molecular basis of insulin resistance have focused on the peroxisome proliferator-activated receptor g (PPARg). PPARg plays an important role in the regulation of genes involved in adipocyte differentiation, lipid storage, glucose metabolism 3) and insulin signal transduction. 4) In this regard, PPARg is a target for the treatment of insulin resistance as rosiglitazone, an anti-diabetic drug, does.Insulin binding to its receptor induces activation of a complex network of downstream molecules, including phosphatidylinositol 3-kinase (PI3K) and the serine/threonine kinase PI3K-linked protein kinase B (Akt/PKB).5,6) Activation of Akt/PKB stimulates membrane translocation of the glucose transporter, GLUT4, 7) leading to enhanced glucose uptake. Thus, Akt/PKB activation is a prerequisite for glucose uptake.Adenosine 5Ј-monophosphate-activated protein kinase (AMPK) acts as an intracellular energy sensor. Increased recruitment of the AMPK signaling system may be effective in correcting insulin resistance. 8) Activation of AMPK acutely stimulates glucose uptake via both GLUT1 and GLUT4, and enhances the long-term expression of GLUT4. 9) Thus, AMPK is responsible for mediating the stimulation of glucose uptake.The whole plant of Inula viscosa L. was traditionally used in folk medicine for treating DM.10-12) Previous investigations revealed the presence of a series of flavonoids in the whole plant including quercetin, apigenin, naringenin, sakuranetin, and aromadendrin. 13,14) Some of the flavonoids were reported to either improve or inhibit insulin-stimulated glucose uptake in adipocytes. [15][16][17] For instance, sakuranetin was revealed to enhance insulin-stimulated glucose uptake in adipocytes, 15) while apigenin suppressed. 17) Quercetin was reported with somewhat conflict in regulating insulin-stimulated glucose uptake.17,18) 7-O-Methylaromadendrin (7-O-MA) is also one of flavonoids isolated from I. viscosa. The preliminary data using our screening system indicated that 7-O-MA showed significant activities on stimulating insulininduced glucose uptake into both HepG2 cells and differentiated 3T3-L1 adipocytes. Therefore, the specific aim of this study was to investigate the ability of 7-O-MA to improve diabetic conditions and the possible molecular basis. Our results observed that 7-O-MA increased expression of PPARg2 and adipocyte-specific fatty acid binding protein The stimulation of glucose uptake into peripheral tissues is an important mechanism for the removal of glucose in blood and for the management of diabetes mellitus ( Key words 7-O-methylaromadendrin; glucose uptake; AMP-activated pr...
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