ABSTRACT Two new 3-D Cd(II) coordination polymers with p -phthalic acid ( p -BDC) and 4,4΄-dipyridylamine (4,4΄-dpa), namely [Cd 2 ( p -BDC) 2 (4,4΄-dpa) 2 ] n 1 and {[Cd( p -BDC)(4,4΄-dpa) (H 2 O)]·4H 2 O} n 2 were successfully synthesized under hydrothermal conditions at 120 and 140 °C. They were characterized by single-crystal X-ray diffraction, IR, PXRD and TGA . It was further characterized by Hirshfeld surface (HS) analysis for complex 2 . The luminescent properties of the complexes have also been investigated.
Mercury ion (Hg 2+ ) is one of the most toxic heavy metal ions which will cause permanent damage to the brain and kidneys. So, it is important to develop a sensitive, simple and reliable approach to detect Hg 2+ . In this work, we report a surface-enhanced Raman scatting (SERS) sensor by decorating the inner wall of capillary with 4,4′-dipyridyl (Dpy) functionalized silver nanoparticles (AgNPs). The main advantage of this sensor is that it can collect samples directly by capillary force and carry out on-site analysis by combining portable Raman spectrometer. In the presence of Hg 2+ , the Dpy molecules would be separated from the surface of AgNPs and coordinated with Hg 2+ , resulting in a decrease in the SERS signal. A linear correlation of Raman intensity with Hg 2+ concentrations from 1 to 100 part-per-billion (ppb) was obtained for quantitative analysis and the limit of detection (LOD) was determined to be 0.1 ppb. The good reproducibility and selectivity of the sensor were also demonstrated. In addition, the sensors were successfully applied to detect Hg 2+ in real environmental water samples, and the sampling process provided operation convenience compared to conventional methods. These results indicated that these capillary sensors had great potential for Hg 2+ detection in practical use.
The authors report on a surface-enhanced Raman scattering (SERS) nanoprobe for the specific detection of Escherichia coli O157:H7 ( E. coli O157:H7). Gold nanoparticles (AuNPs) were coated with a thick silica shell, and the Raman reporter (4,4′-dipyridyl) was embedded between gold nanoparticle and silica shell. This technique prevents any external effects on the AuNPs from the environment and avoids any interaction between the Raman reporter and possible impurities. Compared to the SERS nanoprobe of the conventional AuNP/AgNP type, the present nanoprobe can be applied in complex biochemical circumstances without aggregation because of its excellent stability. The SERS nanoprobeis stable for up to 50 h. The probe was applied to the SERS detection of E. coli O157:H7 by exploiting the Raman band peaking at 1612 cm −1 of 4,4′-dipyridyl (DP). The limit of detection is as low as 10 CFU·mL −1 . The technique was successfully employed to the detection of E. coli O157:H7 in real samples, achieving recoveries between 95.5 and 114.8%.
A novel surface-enhanced Raman scattering (SERS) nanoprobe based on the silica encapsulated gold nanoparticles (SEGNs) combining with the functionalized magnetic nanoparticles (MNPs), detecting E. coli O157:H7 with high sensitivity and specificity.
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