- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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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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Electric-field control of spin accumulation direction for spin-orbit torques
摘要： Electric field is an energy-efficient tool that can be leveraged to control spin–orbit torques (SOTs). Although the amount of current-induced spin accumulation in a heavy metal (HM)/ferromagnet (FM) heterostructure can be regulated to a certain degree using an electric field in various materials, the control of its direction has remained elusive so far. Here, we report that both the direction and amount of current-induced spin accumulation at the HM/FM interface can be dynamically controlled using an electric field in an oxide capped SOT device. The applied electric field transports oxygen ions and modulates the HM/FM interfacial chemistry resulting in an interplay between the spin Hall and the interfacial torques which in turn facilitates a non-volatile and reversible control over the direction and magnitude of SOTs. Our electric-field controlled spin-orbitronics device can be programmed to behave either like the SOT systems with a positive spin Hall angle or a negative spin Hall angle.
关键词： spin-orbit torques,heavy metal/ferromagnet heterostructure,spin accumulation,non-volatile control,electric field control
更新于2025-09-23 15:22:29
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Ferromagnet structural tuning of interfacial symmetry breaking and spin Hall angle in ferromagnet/heavy metal bilayers
摘要： We investigate the influence of ferromagnet crystalline structures on spin Hall angle (SHA) in ferromagnet (FM)/heavy metal (HM) bilayers with reversed stacking order. X-ray diffraction and transmission electron microscopy show that a pronounced permalloy (Py) (111) texture emerges in substrate/Ta/Py compared to that in substrate/Py/Ta. Spin torque ferromagnetic resonance measurements show that the out-of-plane SHA (h?, associated with Rashba-like effective field) is (cid:2)2 times larger in substrate/Ta/Py than that in substrate/Py/Ta, while in-plane SHA (hjj, associated with spin Hall-like effective field) shows no distinct difference. We ascribe the FM structure dependent SHA to the interfacial symmetry breaking between the FM and HM, which is tuned by the work functions due to different crystalline structures of the FM. The emergence of the Py (111) structure enlarges the interfacial symmetry breaking and consequently enhances the Rashba effect at the FM/HM interface.
关键词： crystalline structure,heavy metal,ferromagnet,Rashba effect,spin Hall angle
更新于2025-09-23 15:21:21
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Identification of heavy metal-contaminated Tegillarca granosa using laser-induced breakdown spectroscopy and linear regression for classification
摘要： Tegillarca granosa (T. granosa) is susceptible to heavy metals, which may pose a threat to consumer health. Thus, healthy and polluted T. granosa should be distinguished quickly. This study aimed to rapidly identify heavy metal pollution by using laser-induced breakdown spectrometry (LIBS) coupled with linear regression classification (LRC). Five types of T. granosa were studied, namely, Cd-, Zn-, Pb-contaminated, mixed contaminated, and control samples. Threshold method was applied to extract the significant variables from LIBS spectra. Then, LRC was used to classify the different types of T. granosa. Other classification models and feature selection methods were used for comparison. LRC was the best model, achieving an accuracy of 90.67%. Results indicated that LIBS combined with LRC is effective and feasible for T. granosa heavy metal detection.
关键词： laser-induced breakdown spectrometry,shellfish,linear regression classification,heavy metal
更新于2025-09-23 15:21:01
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Auto-cleaning paper-based electrochemiluminescence biosensor coupled with binary catalysis of cubic Cu2O-Au and polyethyleneimine for quantification of Ni2+ and Hg2+
摘要： Inspired by the pop-up greeting cards, a 3D collapsible auto-cleaning paper-based electrochemiluminescence (ECL) biosensor (CAPEB) with different functions of signal collection and residual multiple cleaning, is developed for sensitive detection of Ni2+ and Hg2+ by simply regulating its 3D configurations. The multiple fluidic paths and the hollow-channel structure were firstly integrated into the paper substrate, realizing simultaneously repetitive auto-cleaning of the two working electrodes. For achieving ultrasensitive Ni2+ and Hg2+ monitoring, binary catalysis consisting of the intermolecular co-reaction (H2O2 and N-(4-Aminobutyl)-N-ethylisoluminol (ABEI)) and intramolecular catalysis (polyethyleneimine (PEI)-ABEI) were introduced. Specifically, silver nanospheres with a large specific surface area and excellent conductivity were grown on the paper working electrode and served as the sensor substrate for fixing PEI-ABEI and Ni2+-specific DNAzyme. With the assistance of DNAzyme, Cu2O-Au and ferrocene (Fc) labeled strand S2 were immobilized on electrode surface through the hybridization reaction, and catalyzed H2O2 to generate reactive oxygen species, promoting the luminescence of ABEI. In the existence of Ni2+, DNAzyme was activated followed by cleavage of strand S2 to induce the release of Fc, which quenched the ECL signal of ABEI, eventually realizing the detection of Ni2+. Similarly, for sensitive quantification of Hg2+, full thymine (T) bases strand S3 was modified on surface of Cu2O-Au and anchored Hg2+ by T-Hg2+-T pairing interaction. The ECL intensity was decreased along with increasing of Hg2+ due to the quenching effect of Hg2+ on ECL emission of ABEI. Based on this ingenious system, the detection of Ni2+ and Hg2+ had high sensitivity, wide linear ranges, and low detection limits. The results indicated that the integration of a multi-channel structure into a paper device chips opened new opportunities for designing promising paper-based devices for metal ions diagnosis.
关键词： electrochemiluminescence,N-(4-Aminobutyl)-N-ethylisoluminol,auto-cleaning,Cu2O-Au,paper-based device,heavy metal ion
更新于2025-09-23 15:21:01
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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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Aprotinin Encapsulated Gold Nanoclusters: A Fluorescent Bioprobe with Dynamically Nuclear Targeting and Selective Detection of Trypsin and Heavy Metal
摘要： Fluorescence imaging has currently emerged as one of the most frequently used noninvasive imaging technology to selectively monitor biological processes in living systems. In past decades, gold nanoclusters (Au NCs) received increasing attraction because of their intrinsic fluorescence and their inherent biocompatibility. As a stabilizing and reducing agent, an abundant, sustainable and widely used polypeptide derived drug molecule, aprotinin (Ap) is selected for the synthesis of Au nanoclusters (Ap-Au NCs) due to characteristic bioactivity, excellent biocompatibility, biodegradability, nonallergenic character. Herein, Ap encapsulated Au NCs exhibiting desirable red fluorescence feature was facilely produced for the first time, which were subsequently used for cell imaging and detection of various analytes. Much interestingly, dynamically subcellular localization of Ap-Au NCs from the cytoplasm to the nucleus in Hela cells was observed. Afterward, it has shown the selective and quantitative detection of trypsin by using Ap encapsulated Au NCs. Lastly, Ap-Au NCs were readily used for detection of mercury and copper quantitatively. The photoluminescence of the Ap-Au NCs was quenched with the addition of metioned analytes. This study opens crucial insights on the integration of biomolecule with metal nanoclusters, also discusses a multifunctional nanomaterial platform for cell imaging, subcellular targeting, biosensing and drug delivery.
关键词： trypsin detection,gold nanoclusters,aprotinin,cell imaging,heavy metal detection,Fluorescence imaging
更新于2025-09-23 15:21:01
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STUDY OF EDC/NHS IMMOBILIZATION FOR PLUMBOUS DETECTION USING SURFACE PLASMON RESONANCE
摘要： The presence of plumbous (Pb2+) in Irrigation water is harmful for the environment as well as human health. Herein, a simple yet effective sensor for Pb2+ detection is presented utilizing a surface plasmon resonance technique. The proposed sensor consists of a combination of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) were attached to a gold layer offers a new option for heavy metal detection. The EDC/NHS works as a sensing layer that able to detect Pb2+ down to 15 ppm that matches with the United States Environment Protection Agency.
关键词： heavy metal,plumbous detection,Surface plasmon
更新于2025-09-23 15:21:01
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Optical Fiber Refractometer Based Metal Ion Sensors
摘要： Research into optical fiber refractometers yielded remarkable results over the past decade. Numerous sensing schemes were proposed and demonstrated, which possessed different advantages while facing unique limitations. On top of their obvious applications in measuring refractive index changes of the ambient environment, several studies reported advanced applications of such sensors in heavy metal ion detection by means of surface coating of the refractometers with heavy metal ion sensitive materials. This paper surveys the effort these optical fiber metal ion sensors based on surface coated optical fiber refractometer, discusses different technologies and methods involved, and highlights recent notable advancements.
关键词： optical fiber technology,heavy metal detection,optical fiber sensors,chemical sensing
更新于2025-09-23 15:19:57
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Optical fiber sensors for measurement of heavy metal ion concentration: A review
摘要： With the increasing of water pollution problems, detection of heavy metal ion concentration in water environment becomes significant. Optical fiber sensor, with its particular advantages of small-size, anti-electromagnetic interference, chemical inertness, remote and real-time monitoring ability, has become an ideal platform for detection of heavy metal ion concentration. In this paper, we briefly review the current research progress of heavy metal ion sensors based on optical fiber technology. Five main measurement methods are described, including optical absorbance method, fiber grating method, modal interference method, plasmonic method, and fluorescence method. The sensing mechanisms, sensing structures, sensing materials, and sensing characteristics of different kinds of measurement methods are introduced and summarized. Furthermore, the advantages and disadvantages of each measurement method are analyzed. Finally, the future development directions of optical fiber heavy metal ion sensors are also discussed.
关键词： Water pollution,Optical fiber sensor,Concentration measurement,Heavy metal ion sensor
更新于2025-09-23 15:19:57