A new self-passivating template with the phosphorothioate strategy to effectively improve the detection limit and applicability of exponential amplification reaction.

Exponential amplification reaction (EXPAR) has attracted much attention due to its simple primers and high amplification efficiency, but its applications are hindered by severe non-specificity amplification. Convenient exogenous chemical modification methods modified the entire template while inhibiting both non-specific and specific amplification. In this paper, we proposed a new self-passivating template with the phosphorothioate strategy to effectively improve the detection limit and applicability of EXPAR. We phosphorothioated several bases where the sequence was prone to form transient intermolecular 3'-end hybridization, thereby inhibiting the non-specific interactions and preventing the extension of templates by DNA polymerase. The melting temperature (Tm) curve and density functional theory (DFT) proved that the stability of hydrogen bonds between phosphorothioated bases did decrease. Benefitting from this strategy, the detection limit had been improved by 3 orders of magnitude. Moreover, due to the antioxidation property of phosphorothioate, this strategy showed good stability in serum, reflecting its excellent prospects in clinical sampling and detection.

Aligner mediated cleavage of nucleic acids for site-specific detection of single base mismatch.

Single base mismatch can always connect with various gene-related diseases, whose determination has aroused widespread interest. So far, various methods have been developed to determine the common base mismatch. However most of them are complex, time-consuming. Herein, we report a novel method, which only need one conventional endonuclease (NEase) and achieve site-specific cleavage in a programmable way, to detect single base mismatch, termed aligner-mediated cleavage-based single base mismatch discrimination (AMCMD). The DNA aligner (DA) is in a stem-loop structure, consistent with an incomplete recognition site of NEase on its stem and a 5'-side arm complementary to the target sequence (TS). Once TS contains matched base and hybridizes with DA, the complete recognition site of NEase is formed, and the TS will be cleavaged with fast speed, while converse is not. Based on it, the method can clearly distinguish mismatched and complementary bases. Without sample pre-processing, we were able to obtain and verify all the test result in about 30 min through the polyacrylamide gel electrophoresis analysis. This endows the proposed method with a simpler advantage. Then we combined AMCMD and EXPAR to create a new method for single base mismatch discrimination, the short sequence obtained by AMCMD as a target to trigger EXPAR, with a detection limit at 1pM level. Another process with human serum underlines that AMCMD is compatible with the complex biological sample, thus it has the potentials for practical applications.

One-pot synthesis of hollow hydrangea Au nanoparticles as a dual catalyst with SERS activity for in situ monitoring of a reduction reaction.

The controlled synthesis of metallic nanomaterials has attracted the interest of many researchers due to their shape-dependent physical and chemical properties. However, most of the synthesized nanocrystals cannot be combined with spectroscopy to measure the reaction kinetics, thus limiting their use in monitoring the catalytic reaction process to elucidate its mechanism. As a powerful analytical tool, surface-enhanced Raman spectroscopy (SERS) can be used to achieve in situ monitoring of catalytic reactions by developing bifunctional metal nanocrystals with both SERS and catalytic activities. Herein, we have developed a simple one-pot synthesis method for the large-scale and size-controllable preparation of highly rough hydrangea Au hollow nanoparticles. The growth mechanism of flower-like Au hollow nanostructures was also discussed. The hollow nanostructure with a 3D hierarchical flower shell combines the advantages of hollow nanostructure and hierarchical nanostructure, which possess high SERS activity and good catalytic activity simultaneously. Furthermore, the hydrangea Au hollow crystals were used as a bifunctional nanocatalyst for in situ monitoring of the reduction reaction of 4-nitrothiophenol to the 4-aminothiophenol.

Stepwise evolution of Au micro/nanocrystals from an octahedron into a truncated ditetragonal prism.

Shape transformation of Au crystals from a {111}-bounded octahedron to a {730}-bounded tetrahexahedron (THH) and then to a {310}-bounded truncated ditetragonal prism (TDP) was achieved by a one pot synthesis method. The transformation of the crystal morphology is the result of the synergistic effect of Ag+ and O2/Cl-. This work not only provides a way to prepare high-index faceted Au micro/nanocrystals, but also provides new insights into the crystal growth habit.

A novel steric effect-regulated isothermal exponential amplification technology for the one-step homogeneous sensing of proteins.

A simple and homogeneous technology, the steric effect-regulated isothermal exponential amplification reaction (SER-EXPAR), was developed to sense proteins. By using a small molecule linked DNA nanostructure, termed enzyme-binding hairpin (EBH), the protein-small molecule binding events could be readily sensed by utilizing the steric effect generated between the protein and enzyme. It set free the enzyme to be active again, thus regulating the amplification rate of EXPAR.