Cysteamine-modified silver nanoparticle aggregates for quantitative SERS sensing of pentachlorophenol with a portable Raman spectrometer.

Cysteamine-modified silver nanoparticle aggregates has been fabricated for pentachlorophenol (PCP) sensing by surface-enhanced Raman spectroscopy (SERS) using a portable Raman spectrometer. The cysteamine monolayers could preconcentrate PCP close to the substrate surface through the electrostatic interaction, which makes the SERS detection of PCP possible. Moreover, the Raman bands of cysteamine could be used as the internal spectral reference in the quantitative analysis. Qualitative detection of PCP was carried out by SERS without any sample pretreatment. Quantitative analysis of PCP was further realized based on the prepared substrate, as the log-log plot of normalized SERS intensity of PCP versus its concentrations exhibits a good linear relationship. The SERS signals collected on 20 randomly selected points show that the relative standard deviation of the normalized Raman intensity is 5.8%, which indicates the substrate had good uniformity. The PCP sensor also shows good long-term stability in the analyte solution. The substrate was cyclic immersed into PCP and methanol solution; after several cycles, the sensor still had good adsorption to PCP, which revealed the sensor has good reusability. Coupling with a portable Raman spectrometer, the cysteamine-modified silver nanoparticle aggregates have the potential to be used for in situ and routine SERS analysis of PCP in environmental samples.

Silver nanoparticles decorated filter paper via self-sacrificing reduction for membrane extraction surface-enhanced Raman spectroscopy detection.

Silver nanoparticles (AgNPs) decorated filter papers combining solid-phase extraction (SPE) with surface enhanced Raman spectroscopy (SERS) achieved rapid collection of analytes and in situ detection. The AgNPs were fabricated by cellulose self-sacrificing reduction. Aqueous Ag(NH3)2OH was reduced by hydroxyl groups in cellulose under alkaline conditions. The AgNPs were highly uniform and firmly adhered to the microfibers. Reaction conditions were optimized by the probe molecule p-aminothiophenol (PATP) to attain the best Raman enhancement. Methylene blue trihydrate (MB) and 6-thioguanine (6-TG) were detected by flow-through method. The results exhibited outstanding SERS effect and an obvious improvement in detection limit was observed compared to common immersion methods. SERS detection was quantitative as the log-log plot of Raman intensity against MB and 6-TG concentrations showed a linear relationship. The SERS-active paper is degradable because it could be burned after analyte detection.

[Effect of the truncated human apoptosis-inducing factor expression on apoptosis of HeLa cells].

AIM: To observe the expression of the truncated human apoptosis-inducing factor (AIF) gene and its apoptosis-inducing effect on HeLa cells. METHODS: Full-length human AIF gene was cloned by RT-PCR, then the truncated AIF gene was constructed by deleting the N-terminal mitochondrial location sequence (MLS), and inserted into the EGFP co-expression vector pIRES2-EGFP. After being transfected into HeLa cells with Lipofectamin, the expression of the truncated AIF gene and its effect on HeLa cells morphology and growth condition were detected by fluorescence microscope, immunohistochemical staining, indirect fluoroimmunoassay and electron microscope analysis. RESULTS: The eukaryotic expression vector pIRES2-EGFP containing of truncated human AIF gene was constructed successfully. The AIF protein could be detected in the transfected HeLa cells. After transfection, typical apoptotic feature of the transfected HeLa cells and a mass of cell death were observed under electron microscope. CONCLUSION: The expression of the truncated human AIF gene can induce apoptosis of the transfected human HeLa cells.