Zhang Lei,Weng Yi-jin,Liu Xiao,Gu Wen,Zhang Xia,Han Lei
Surface Enhanced Raman Scattering (SERS) has been widely applied in many research fields such as biological detection and chemical analysis. However, for the common Au nanoparticles, it’s too hard to guarante the three aspects: the great enhanced effect, the controllable aggregation and the uniformity of nanoparticles, the environmental friendliness and biocompatibility of nanoparticles. In this paper, phytate acid (IP6)-coated Au nanoparticles (IP6@Au NPs) are more stable and have a higher enhancement factor than Au nanoparticles. In order to achieve the uniformity of the spherical IP6-coated@Au nanoparticles (IP6@Au NPs), IP6 was used as a soft template. In the presence of IP6, IP6@Ag nanoparticles were first synthesized by reducing AgNO 3 with trisodium citrate, then IP6@Au NPs were obtained by reducing HAuCl 4 with Ag nanoparticles. The IP6@Au NPs exhibit excellent Raman signal enhancement by using p-aminothiophenol (4-ATP) as the probe molecules. The effects of Fe 3+ on the performance of IP6@Au NPs SERS substrates were also studied. The results show that SERS has the best enhancement effect when adding proper amount of Fe 3+ (0.56 PPM), and the limit of detection was 10 −7 M 4-ATP.
Huan Jiang,Yucui Zhang,Ruyi Tang,Xia Zhang,Xuemin Xia,Baihui Wang,Lei Han
Enzyme mimetics have been widely applied on H 2 O 2 assay, but it is still challenging and interesting to realize the sensitive detection for ultra-trace H 2 O 2 . Here, an ultrasensitive Raman assay method based on novel WO 3 @IP6-Fe 3+ enzyme mimetics with peroxidase-like activity was established. WO 3 microspheres (MSs) were found to have weak peroxidase-like activity, and the combination of IP6-Fe 3+ and WO 3 can produce stronger activity. WO 3 @IP6-Fe 3+ MSs showed polyhedron-like structure, uniform size, and smooth surface. Although WO 3 @IP6-Fe 3+ enzyme mimetics have low catalytic efficiency and high absorbance background, the proposed Raman method can bypass the above problems. In Raman method, high concentration of WO 3 @IP6-Fe 3+ can be used to overcome low catalytic efficiency without high absorbance background. Moreover, 3,3′,5,5′-tetramethylbenzidine oxide has prominent characteristic Raman peak at 1608 cm −1 , greatly improving the sensitivity and eliminating interference of impurities. Due to the high sensitivity and low background, Raman assay showed the ultra-low limit of detection (5.49 × 10 −15 M), which was 4–7 orders of magnitude lower than other detection methods. The ultrasensitive Raman assay not only provided the possibility for the enzyme mimetics-based detection of ultra-trace H 2 O 2 , but also enable the enzyme mimetics with low activity to be applied.
A novel surface enhanced Raman scattering (SERS) substrate was synthesized by wrapping Ag nanoparticles on the surface of the MIL-101 (Fe) shell under the assistance of IP6, and combining with molecular imprinted polymers (MIPs) for the selective detection of 2,6-DCP. In this study, as a stabilizer and linking agent, IP6 can form a chemical bond with MIL-101 (Fe) to decrease the distance between two Ag nanoparticles and generate more “hot spots”. On the other hand, the inositol hexaphosphate (IP6) and MIL-101 (Fe) shell acted as a protective shell layer, preventing Ag nanoparticles from being polluted by the external environment and reduced SERS activity. In addition, the SERS-MIPs can selectively detect the target molecule, avoiding the influence of other interfering substances on the detection effect. The prepared sensor (Ag/IP6@MIL-101 (Fe)@MIPs, AIM@MIPs) presented sensitive SERS properties, and the detection of limit can reach 10−9 M. The AIM@MIPs also presented strong selective detection to the target molecules, and can be applied for practical sample detection. This test provides a potential application in the detection of environmental pollutants.
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