- 标题
- 摘要
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Ultrathin and Isotropic Metal Sulfide Wrapping on Plasmonic Metal Nanoparticles for SERS-based Detection of Trace Heavy Metal Ions.
摘要： A facile and general strategy is presented for homogenous and ultrathin metal sulfide-wrapping on plasmonic metal (PM) nanoparticles (NPs) based on a thiourea-induced isotropic shell growth. This strategy is typically implemented just via adding the thiourea into pre-formed PM colloidal solutions containing target metal ions. The validity of this strategy is demonstrated by taking the wrapped NPs with Au core and CuS shell or Au@CuS NPs as an example. They are successfully fabricated via adding the thiourea and Cu2+ solutions into pre-formed Au NP colloidal solution. The CuS shell layer is highly homogenous (<10% in relative standard deviation of shell thickness), regardless of the NPs’ shape or curvature. The shell thickness can be controlled from tens down to 0.5 nm just by the addition amounts of the shell precursors. The formation of the shell layer on the Au NPs can be attributed to the alternative deposition of Cu2+ and S2- ions on the thiourea-modified surface of Au NPs in the solution, which induces the isotropic shell growth. Further, this strategy is of good universality. Many other sulfide-wrapped PM NPs, such as Ag@CuS, Au@PtS2, Au@HgS, Ag@Ag2S NPs and Ag@CuS nanorods have been successfully obtained with homogeneous and ultrathin shells. Importantly, such ultrathin sulfide-wrapped PM NPs can be used for SERS-based detection of trace heavy metal ions with strong anti-interference via ion exchange process between the metal sulfide shell and heavy metal ions. This study provides a simple and controllable route for wrapping the homogenous and ultrathin sulfide layers on the PM NPs, and such wrapped NPs have good practical applications in the SERS-based detection of trace heavy metal ions.
关键词： Plasmonic metal nanoparticles,Trace heavy metal ions,Ultrathin sulfide wrapping,Thiourea-induced isotropic shell growth,SERS-based detection
更新于2025-11-14 17:04:02
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Bacteria functionalized gold nanoparticle matrix based fiber-optic sensor for monitoring heavy metal pollution in water
摘要： In the present study, E.coli B40 bacteria were explored as possible receptors on localized surface plasmon resonance (LSPR) based biosensor for sensing heavy metal ions viz. mercury (Hg2+) and cadmium (Cd2+) in water. The E.coli B40 bacteria were immobilized on gold nanoparticles (AuNP) coated fiber-optic probes by depositing two bi-layers of oppositely charged polyelectrolytes. The E.coli immobilized sensor probes were subjected to different concentrations of Hg2+ and Cd2+ ions, ranging from 0.5 ppb to 2000 ppb. These metal ions interact with the thiols and other surface groups present on the bacterial cells, resulting in the change of refractive index around AuNP coated sensor probes, thereby modulating the sensor response. The detection was performed by spiking de-ionized (DI) water and tap water with metal ions and the limit of detection was found to be 0.5 ppb. The proposed sensor could detect heavy metal ions within 10 min from a small sample (< 1 ml) and showed good selectivity towards heavy metal ions over other transition metal ions. Control studies performed using amino acids like cysteine as receptors were found to be less sensitive than the proposed scheme using bacterial cells.
关键词： polyelectrolytes,fiber-optic sensor,Bacteria,gold nanoparticles,heavy metal ions,localized surface plasmon resonance
更新于2025-09-23 15:21:01
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Fabrication & Characterization of Simple Structure Self-Assembled Graphene Oxide Based Heavy Metal Ion Sensor
摘要： The simple structure and high robustness of heavy metal sensors were developed by implementing a GO/Au/FR4 Substrate configuration. In this study, the sensing characteristics of an in-house fabricated heavy-metal-ion sensor (HMS) with graphene oxide (GO) as the sensing element was presented. The HMS employed a three electrodes configuration architecture, while GO of various concentrations ranging from 0.1 to 1 mg/ml would serve as the sensing medium. The surface of the working electrode was decorated with GO through drop-casting technique. Several types of heavy metal ions such as lead (Pb), mercury (Hg), and cadmium (Cd) were used in this study. The concentration of each was prepared according to the maximum exposure limit imposed by the World Health Organization, with Pb (10 ppm), Hg (1 ppm), and Cd (5 ppm). The sensing performance was found to be proportionate to GO concentration when the sensor was exposed to 10 ppm of Pb. On selectivity test using 1 mg/ml of GO, the sensor exhibited superior sensitivity towards 10 ppm of Pb, ～ 1666.6%; followed by 5 ppm of Cd, ～ 512.8%, while 1 ppm of Hg being the least detected, ～ 10.5%. This signified GO shows greater affinity towards Pb ions detection in comparison to others.
关键词： graphene oxide,sensors and working electrode,Electrochemical,IDE,heavy metal ions
更新于2025-09-12 10:27:22
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Synthesis of Novel Organic-Inorganic Hybrid Fluorescent Microspheres and Their Applications as Fe(III), Hg(II) and Biothiols Probes
摘要： Organic-inorganic hybrid fluorescent microspheres (OI-FMs) without typical fluorophores were prepared. Fluorescence quantum yield of OI-FMs is up to 0.7 after being heated in an oven at 120°C (named as OIFMs-120). Interestingly, OI-FMs-120 shows different detection performances in different solvents. It can be used for qualitative and quantitative detection of Fe3+ with a detection limit of 37.8 nM in absolute ethanol. While in aqueous solution, it can be applied as an ONOFF-ON fluorescent probe. Fluorescence of the probe is quenched by Hg2+and later recovered by biothiols. The detection limit are as low as 34.9 nM for Hg2+, 91.0 nM for Cys, 0.12 μM for Hcy and 0.13 μM for GSH in aqueous medium, respectively.
关键词： Biothiols,Heavy metal ions,Atypical fluorophores,Fluorescence sensor
更新于2025-09-09 09:28:46