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[IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - All-Metal Plasmonic Metamaterials for Structure Color and as Colorimetric Biosensors
摘要： Colorimetric and label-free plasmonic biosensors, relying on localized surface plasmon resonance (LSPR) on metallic subwavelength structures, have significant potential for many application areas such as clinical diagnosis and environmental monitoring detection by simple instrumentation or even naked eye. In this paper, we present a high-performance colorimetric and label-free plasmonic biosensors, consisting of an array of three-dimensional all-metal nano-cavities. The nanostructures, composed of a top array of gold disk, aluminum pillar and bottom gold reflection film, are similar to metal-insulator-metal and the insulating layer is air cavities that are easy to be filled with other gaseous or liquid dielectric. Therefore, the analytes could permeate into the nano-scale cavities and enable strong light-matter interactions there. The sensor shows significant color difference with small refraction index changes and the sensitivity reaches 683.5 nm/RIU. Moreover, when a monomolecular layer of Dithiobis(succinimidyl propionate) (DSP) was bonded to the surface of the nanostructure, the color of the metamaterials change from blue to green back. The metamaterials will offer great potential for detection and studies of binding events between the target analyte and its corresponding receptor.
关键词： LSPR,label-free,metamaterials,colorimetric,plasmonic biosensors
更新于2025-09-12 10:27:22
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Origin of Luminescence‐Based Detection of Metal Ions by Mn–Doped ZnS Quantum Dots
摘要： The health hazards associated with heavy metal ions in water demand the development of efficient and portable sensors, for rapid onsite detection of these ions. Several research groups have developed colorimetric/visual sensors based on plasmonic nanomaterials and quantum dots (QDs). Attempts for specific detection of metal ions have been partially achieved through the interaction between the metal ion and the passivating ligands around the QD. However, the underlying mechanism is not clearly understood. Here, we have used water-soluble Mn-doped ZnS QD to effectively detect Hg2 +, Pb2 +, and Cd2 + through the quenching of QD emission and understand the mechanism of sensing. Stern-Volmer plots indicate that the quenching is static in nature for Pb2 +, and Cd2 +, while for Hg2 +, it is a combination of static and dynamic quenching. Overall, the metal ions bind to the QD through the passivating ligand. After excitation, the electron from the conduction band of the QD can get injected to the metal ion – which decreases the photoluminescence of the QD. The electron injection depends on the reduction potential of the metal ion, the orbital overlap and the overall stabilization energy of the metal ions bound to the QD. Hence, this method of sensing is not selective to a specific metal ion. A solid state sensor of QD-rGO composite detects Pb2 + down to 0.4 ppb. The findings will be important for future improvement of colorimetric/visual sensors based on QD emission.
关键词： quantum dots,colorimetric sensing,Mn-doped ZnS,sensors
更新于2025-09-12 10:27:22
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Pyridine-hydrazone-controlled cyanide detection in aqueous media and solid-state: tuning the excited-state intramolecular proton transfer (ESIPT) fluorescence modulated by intramolecular NH?Br hydrogen bonding
摘要： A new efficient pyridine-hydrazone-substituted naphthalimide receptor 4a-E has been synthesized as a selective colorimetric and fluorescent chemosensor for cyanide sensing in aqueous environments through a unique excited-state intramolecular proton transfer (ESIPT) mechanism. The addition of a Br group to the fluorophore skeleton at the ortho-position of hydrazone generates reference compounds (4b-E and 4c-Z). Interestingly, the potential intramolecular NH?Br hydrogen bonding might compete with the anion-induced intermolecular NH?A? hydrogen bonding, resulting in dramatic ESIPT suppression. The high emission of probe 4a-E and other control probes in solid-state is also investigated. Moreover, probe 4a-E preloaded on test papers, upon cyanide treatment, shows obvious changes in color which demonstrates that 4a-E is a writable platform. More importantly, it exhibits great potential application for the detection of cyanide in food materials and excellent performance in real-world water samples.
关键词： ESIPT,colorimetric,pyridine-hydrazone,fluorescent chemosensor,cyanide sensing
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Mobile Based in Situ Detection of Live/Dead and Antibiotic Resistant Bacteria by Silver Nanorods Array Sensor Fabricated by Glancing Angle Deposition
摘要： The rapid in-situ detection of viability of bacteria is essential for human health and environmental care. It has become one of the biggest needs in biological and medical sciences to prevent infections and diseases, which usually occur in hospitals and field clinics. Nowadays, antibiotic resistance (ABR) has been grown as one of the world’s acutest public health problems, which requires a quick and efficient solution. Here, we demonstrate an easy, sensitive, user-friendly, portable, cost effective and time saving approach for detection of live, dead and drug resistant bacteria. Most of the organisms are found to produce H2S gas by their metabolism system. The endogenous H2S evolution was targeted to differentiate between live and dead as well as ABR bacteria. The silver nanorods (AgNRs) arrays sensors were fabricated by glancing angle deposition technique. The colorimetric and water wettability (contact angle) features of as-synthesized AgNRs were found to be highly sensitive and selective for hydrogen sulfide (H2S) gas. E.coli, P. aeruginosa, B. subtilis and S. aureus were used as the model organisms for this study. A drastic visible change in color as well as wetting properties of AgNRs array was observed. To make it easy, a user friendly and field deployable android based mobile app ‘Colorimetric Detector’ was developed. This dual mode detection is facile, inexpensive and can be easily scaled-up in the field of disease diagnosis.
关键词： mobile app,colorimetric detection,silver nanorods,antibiotic resistance,bacteria detection,H2S gas
更新于2025-09-11 14:15:04
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Chemically modified silica-based sensors: effect of the nature of organosilane
摘要： The use of organosilanes to produce hybrid materials, also known as ORMOSILs (organically modified silicas) can be a good strategy to tune a material’s properties, enabling, for example, the optimization of important features of chemical sensors such as specificity, sensitivity and response time. Thus, different hybrid silicas were prepared by the sol-gel method to be employed as a colorimetric sensor. The investigated organic groups for producing hybrid materials included methyl, octyl, octadecyl, vinyl, phenyl, aminopropyl, isocyanatopropyl, mercaptopropyl, chloropropyl, iodopropyl and glycidoxypropyl groups, and the pH indicator alizarin red was used as the encapsulated receptor element. The sensors were characterized using a set of complementary techniques such as UV-vis spectroscopy, cyclic and differential pulse voltammetry, nuclear magnetic resonance, nitrogen porosimetry, small-angle X-ray scattering and transmission electronic microscopy. The performance was evaluated according to the color change (ΔE* ab) by conducting a colorimetric analysis and measuring the response time after ammonia exposure, with results varying from 48 to 95 s. Additionally, other characteristics of the hybrid materials, such as their surface area, reticulation degree, texture and morphologic properties, were altered depending on the organic modification present in the silica network. The potentiality for material optimization, to achieve better sensor performance, depends on the employed organosilane.
关键词： colorimetric sensor,sol-gel,ammonia,ORMOSIL,organosilanes,hybrid silica
更新于2025-09-11 14:15:04
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Colorimetric Determination of Hypochlorite Based on the Oxidative Leaching of Gold Nanorods
摘要： Hypochlorite plays a critical role in killing microorganisms in the water. However, it can also cause cardiovascular diseases, neuron degeneration, and cancer to humans. Although traditional methods feature excellent sensitivity and reliability in detecting hypochlorite, the expensive instruments and strict determination conditions have limited their application in environmental analysis to some extent. Thus, it is necessary and urgent to propose a cheap, facile, and quick analytical assay for hypochlorite. This paper proposes a colorimetric assay for hypochlorite utilizing gold nanorods (AuNRs) as the nanoreactor and color reader. The AuNRs were acquired via a reported seed-mediated method. NaClO with strong oxidation property can cause the etching of gold from the longitudinal tips of AuNRs, which could shorten the aspect ratio of AuNRs, decrease the absorption in the UV–Vis spectrum and also induce the solution color changing from red to pale yellow. Thus, according to the solution color change and the absorbance of longitudinal surface plasmon resonance of AuNRs, we established the calibration curve of NaClO within 0.08 μM to 125 μM (?Abs = 0.0547 + 0.004 CNaClO, R2 = 0.9631). Compared to traditional method, we obtained the conversion formula between the concentration of residual-chlorine in tap water and the concentration of hypochlorite detected by the proposed colorimetric assay, which is Cresidual-chlorine = 0.24 CNaClO. Finally, the real application of the colorimetric assay in tap water was successfully performed, and the accuracy of the colorimetric method can reach from ?6.78% to +8.53%.
关键词： colorimetric determination,hypochlorite,gold nanorod
更新于2025-09-10 09:29:36
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A fluorescent and colorimetric Schiff base chemosensor for the detection of Zn2+ and Cu2+: Application in live cell imaging and colorimetric test kit
摘要： A novel Schiff base chemosensor HMID, ((E)-1-((2-hydroxy-3-methoxybenzylidene)amino)imidazolidine-2,4-dione), have been designed and synthesized. Sensor HMID showed a selectivity to Zn2+ through fluorescence enhancement in aqueous solution. Its detection limit was analyzed as 11.9 μM. Importantly, compound HMID could be applied to image Zn2+ in live cells. Detection mechanism of Zn2+ by HMID was suggested to be an effect of chelation-enhanced fluorescence (CHEF) by DFT calculations. Moreover, HMID could detect Cu2+ with a change of color from colorless to pink. The selective detection mechanism of Cu2+ by HMID was demonstrated to be the promotion of intramolecular charge transfer band by DFT calculations. Additionally, HMID could be employed as a naked-eye colorimetric kit for Cu2+. Therefore, HMID has the ability as a 'single sensor for dual targets'.
关键词： chemosensor,zinc ion,cell imaging,fluorescent,colorimetric,copper ion
更新于2025-09-10 09:29:36
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Germanium nanoparticles: intrinsic peroxidase-like catalytic activity and its biosensing application
摘要： In recent years, germanium nanoparticles (Ge NPs) have attracted considerable research attention because of its excellent electrical and optical properties. However, it is mainly applied in the field of solar cells, photodetectors and photothermal therapy. Actually, Ge NPs have the advantages of low toxicity and excellent biocompatibility, which means that they have great potential in biosensing applications. However, there are few related reports. In this paper, we discovered that Ge NPs have the intrinsic peroxidase-like catalytic activity and can significantly accelerate the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 for the first time. Compared with natural enzyme (horseradish peroxidase, HRP), Ge NPs maintain higher catalytic stability after treatment at different pH, temperature and ionic strength. Furthermore, a Ge NPs-based colorimetric platform was established for the first time to detect biomolecules with favourable sensitivity and selectivity, such as uric acid, glucose and choline. This work finds the new property of Ge NPs and extends its application in biosensing.
关键词： peroxidase-like activity,kinetics study,biomolecules detection,colorimetric platform,germanium nanoparticles
更新于2025-09-10 09:29:36
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Colorimetric Detection of Carcinogenic Alkylating Fumigants on Nylon-6 Nanofibrous Membrane. Part I: Investigation of 4-( <i>p</i> -Nitrobenzyl) Pyridine as A “New” Sensing Agent with Ultra-High Sensitivity
摘要： Alkylating fumigants are widely used in agricultural production for the control of soil-borne pests, but the acute toxicity and carcinogenicity of these chemicals pose a health threat to farm workers as well as residents. A nanofibrous membrane-based colorimetric sensor relying on the nucleophilic substitution reaction of 4-(p-nitrobenzyl) pyridine (NBP) is introduced for the convenient and portable detection of alkylating fumigants. Comparing with the traditional use of NBP in detecting alkylating agents, this sensor system achieves a ppb-level detection sensitivity toward alkylating fumigant gases without a high-temperature incubation or the addition of extra bases. The mechanisms of the detection reaction and the detection sensitivities of different fumigants were studied with computational methods, and the results comprehensively prove the proposed optimized detection mechanisms. The detection limit of methyl iodide, methyl bromide, and 1, 3-dichloropropene successfully reaches to the limiting exposure concentrations (PEL or REL) with a naked-eye detectable color difference within 5 min with a dynamic detection procedure. The designed sensing system is promising for a real-time monitoring of the air quality related to alkylating fumigants in the environment, especially in agricultural and industrial areas.
关键词： Alkylating agent,NBP,Air quality monitoring,Colorimetric sensor,Nanomaterial
更新于2025-09-10 09:29:36
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A ratiometric fluorescent and colorimetric dual-signal sensing platform based on N-doped carbon dots for selective and sensitive detection of copper(II) and pyrophosphate ion
摘要： A simple ratiometric fluorescent and colorimetric dual-signal sensing system for Cu2+ and pyrophosphate ion (PPi) detection is established based on N-doped carbon dots (N-CDs) which are synthesized via one-step hydrothermal approach. In the strategy, 2,3-diaminophenazine (oxOPD), the oxidation product of o-phenylenediamine (OPD), can be adsorbed on the surface of N-CDs through electrostatic interaction, which efficiently quenches the fluorescence of N-CDs, meanwhile, oxOPD provides a new emission peak at 553 nm. In virtue of the selective oxidative and chromogenic reaction of OPD with Cu2+, a dual-readout sensing system for Cu2+ is achieved. In addition, the redox and chromogenic reaction among them can be inhibited by PPi, which protects effectively the fluorescence of N-CDs from quenching. This sensing system exhibits good selectivity and sensitivity toward Cu2+ and PPi over other analytes with a low detection limit of 23 nM and 0.7 μM, respectively. Furthermore, the proposed sensing system displays a prospective application for quantitative assay of Cu2+ and PPi in practical samples.
关键词： N-doped carbon dots,ratiometric fluorescence,PPi,colorimetric detection,Cu2+
更新于2025-09-10 09:29:36