DNA-Templated Silver Nanoclusters for Fluorescence Turn-on Assay of Acetylcholinesterase Activity

We have developed a fluorescence turn-on assay using DNA-templated silver nanoclusters (Ag NCs) (i.e., 12 polycytosine-templated silver nanoclusters, dC₁₂–Ag NCs), which is amenable to rapid, ultrasensitive assay of acetylcholinesterase (AChE). The detection mechanism is based on the concept, that is, AChE hydrolyzes the acetylthiocholine (ATCh) chloride to produce thiocholine (TCh). Subsequently, TCh sensitively and rapidly reacts with dC₁₂–Ag NCs via Ag–S bond forming and enhances the fluorescence of dC₁₂–Ag NCs. Using dC₁₂–Ag NCs, detection of TCh has a linear concentration range of 2.0 nM to 16.0 nM and a detection limit of 0.3 nM. Due to the sensitive and rapid fluorescence turn-on response of dC₁₂–Ag NCs to TCh, AChE with activity as low as 0.5 × 10^–4 U/mL (signal/noise = 3) can be analyzed with a dynamic range of 0.1 to 1.25 × 10^–3 U/mL. The promising application of the proposed method in AChE inhibitor screening was demonstrated. AChE concentrations were determined in human blood red cell (RBC) membranes from clinical specimens using dC₁₂–Ag NCs, and the quantitative results were validated with Ellman’s method. Aside from the ease of manufacture, reduction of matrix effect, and low background noise, the continuous detection format and detection sensitivity can open up to wider applications to AChE activity assay in neurobiology, toxicology, and pharmacology, among other fields

Genovariation Study of Hantavirus in Main Endemic Areas of Hemorrhagic Fever with Renal Syndrome in Hebei Province, China

<div><p>Background</p><p>Hemorrhagic fever with renal syndrome (HFRS) is an important infectious disease in Hebei Province. At present, cases from the northeast regions of the province account for >80% of the total incidences. However, studies that examine the region-specific genetic variations of the Hantavirus (HV), the causative pathogen for HFRS, have been lacking.</p><p>Methods</p><p>Rodents were collected in northeast Hebei Province from 2004 to 2013, and the HV strains used in this study were isolated in 1993. Lung tissues were isolated from the rodents and HV antigen was detected by indirect immunofluorescence. The M1 and M2 fragments of HV <i>M</i> region were amplified by reverse transcription polymerase chain reaction (RT-PCR), cloned into pMDl9-T vector, sequenced and compared with representative standard stains for homology and phylogenetic analysis.</p><p>Result</p><p>A total of 21 samples of HV antigen-positive were collected. Real-time PCR analysis revealed that the 19 rodent lungs and two HV strains were positive for the SEO virus. 11 samples were chosen to sequence, and they shared 95.8%–99.8% in nucleotide homology, and 83.6%–99.2% when compared to the standard strains of SEO virus. Phylogenetic analysis demonstrated that all strains were grouped into the same S3 subtype.</p><p>Conclusion</p><p>SEO was the major epidemic genotype of HV in the main HFRS endemic areas in Hebei Province, and S3 was the major subtype. There was minor genetic variation in HV over short term periods, while long term variations were higher.</p></div

Phylogenetic trees for hantavirus based on the complete sequences of <i>M</i> segments (1-3651nt).

<p>Phylogenetic trees for hantavirus based on the complete sequences of <i>M</i> segments (1-3651nt).</p

Primers for amplifying the M1 and M2 segments.

<p>Primers for amplifying the M1 and M2 segments.</p

Comparison of the nucleotide and amino acid sequences of <i>M</i> segment (1–3651 nt).

<p>Comparison of the nucleotide and amino acid sequences of <i>M</i> segment (1–3651 nt).</p

HV-positive samples used in this study and real-time PCR types.

<p>HV-positive samples used in this study and real-time PCR types.</p

Visualization 1: Compact multi-band fluorescent microscope with an electrically tunable lens for autofocusing

Main interface of the autofocusing software Originally published in Biomedical Optics Express on 01 November 2015 (boe-6-11-4353