Selective Detection Research Articles

Protein-Labeling Reagents Selectively Activated by Copper(I).

Copper is an essential trace element that participates in many biological processes through its unique redox cycling between cuprous (Cu+) and cupric (Cu2+) oxidation states. To elucidate the biological functions of copper, chemical biology tools that enable selective visualization and detection of copper ions and proteins in copper-rich environments are required. Herein, we describe the design of Cu+-responsive reagents based on a conditional protein labeling strategy. Upon binding Cu+, the probes generated quinone methide via oxidative bond cleavage, which allowed covalent labeling of surrounding proteins with high Cu+ selectivity. Using gel- and imaging-based analyses, the best-performing probe successfully detected changes in the concentration of labile Cu+ in living cells. Moreover, conditional proteomics analysis suggested intramitochondrial Cu+ accumulation in cells undergoing cuproptosis. Our results highlight the power of Cu+-responsive protein labeling in providing insights into the molecular mechanisms of Cu+ metabolism and homeostasis.

Hazardous 2,4,6-Trinitrophenol (TNP) Detection in Water by Amine and Azine Functionalized Metal-Organic Framework.

A Zn(II)-based metal-organic framework (MOF) decorated with amine and azine functionalities, TMU-17-NH2 (formulated as [Zn(H2ata)(L)].2DMF; L = 1,4-bis(4-pyridyl)-2,3-diaza-2,3-butadiene and H2ata = 2-aminoterephthalic acid) has been successfully synthesized via a solvothermal method. According to crystallographic studies, the synthesized TMU-17-NH2 has three dimensional cuboidal structure with the pore surface decorated with free amine (-NH2) and azine (= N-N =) functional groups. The photoluminescence investigations proved that the synthesized MOF can be effectively utilized for selective detection of 2,4,6-trinitrophenol (TNP) in water with an apparent turn-off quenching response. Its limits of detection (LOD) for TNP was 9.4ppb and competitive nitro explosive testing confirmed its higher selectivity towards TNP (over other nitro explosives). Calculations based on density functional theory (DFT) and spectrum overlap were utilized to evaluate the sensing mechanisms. This MOF-based fluorescence sensing technique for TNP had a high sensitivity (Ksv = 3.26 × 104M-1).

Polarization‐Enhanced Narrow‐Band GeS2 2‐D SWIR Spectral Phototransistor

AbstractIntegrated computational spectrometers with gate‐tunable nano heterostructures and reconstruction algorithms are attractive for on‐chip gas‐sensing spectrometers and have enabled versatile spectrum detectors. However, they require the selective and optical filtering capabilities of wavelengths, restricting their efficient implementation in narrow‐band photodetection. In this study, a printable spectral phototransistor is developed with high dynamic detectivity (1012 Jones and 105 Hz at −3 db bandwidth) modulated by a GeS2 nanosheet heterostructure at short‐wave infrared (SWIR) regime. Using the transport mode switching of carriers in a heterostructure and the polarization‐sensitivity of the GeS2 two‐dimension (2‐D) nanosheet, this SWIR spectral phototransistor demonstrates an accurate narrow‐band selective (96.7% accuracy) spectrum detector and performed a deep‐learning analysis of an artificial neural network (ANN). Furthermore, this GeS2 2‐D based spectral phototransistor, characterized by its high in‐plane anisotropy and electrically reconfigurable properties, extends the applicability of narrow‐band photodetection with 15 nm Full Width at Half Maximum (FWHM) to the recognition of trace‐gases at the parts per billion (ppb) level.

Thiourea Functionalised Receptor for Selective Detection of Mercury Ions and its Application in Serum Sample.

A thiourea functionalised fluorescent probe 1-phenyl-3-(pyridin-4-yl)thiourea was synthesized and utilised as a fluorescent turn-on chemosensor for the selective recognition of Hg2+ ion over competitive metal ions including Na+, Mn2+, Li+, Cr2+, Ni2+, Ca2+, Cd2+, Mg2+, K+, Co2+, Cu2+, Zn2+, Al3+ and Fe2+ ions based on the inter-molecular charge transfer (ICT). Intriguingly, the receptor demonstrated unique sensing capabilities for Hg2+ in DMSO: H2O (10:90, v/v). The addition of Hg2+ ions to the sensor resulted in a blue shift in the absorption intensity and also enhancement in fluorescence intensity at 435nm. Fluorescence emission intensity increased linearly with Hg2+ concentration ranging from 0 to 80 µL. The detection limit and binding constant were determined as 0.134 × 10-6M and 1.733 × 107M-1, respectively. The sensing behavior of Hg2+ was further examined using DLS, SEM and FTIR. The probe could detect Hg2+ ions across a wide pH range. Furthermore, the receptor L demonstrated good sensing performance for Hg2+ in bovine serum albumin and actual water samples.

Practical Method for Achieving Single-Photon Femtosecond Time-Resolved Spectroscopy: Transient Stimulated Emission.

Recent advances in single-photon femtosecond spectroscopy have highlighted the power of entangled photons in probing the properties of materials, previously inaccessible through semiclassical spectroscopic approaches. In this study, we theoretically propose a new single-photon-based femtosecond time-resolved spectroscopy technique termed single-photon transient stimulated emission (SP-TSE). SP-TSE not only enables the selective investigation of singly excited superposition states but also harnesses the quantum mechanical nature of photons for the efficient data acquisition of transient responses, thereby supporting the feasibility of experimental realization of SP-TSE. The key aspect of SP-TSE is the selective detection of two-photon states produced through stimulated emission using coincidence counting techniques. Our theoretical framework, supported by numerical simulations, demonstrates the efficacy in capturing the pure decoherence dynamics of a model molecular cavity, highlighting its potential to reveal quantum mechanical properties that are difficult to observe with semiclassical femtosecond time-resolved experiments.

Near-infrared fluorescent probe for selective and sensitive detection of glutathione based on thioctic acid-functionalized Ag/Au NCs-assisted by ferric ion

Accurate determination of glutathione (GSH) levels in biological fluids and food supplements is paramount. To address this need, we developed a near-infrared (NIR) fluorescent probe with high sensitivity and selectivity for GSH detection. This probe comprises thioctic acid-functionalized silver and gold nanoclusters (ThA@Ag/Au NCs), emitting red light at 720 nm upon excitation at 310 nm. In the presence of Fe3+ ions, which form complexes with ThA, the fluorescence of ThA@Ag/Au NCs is quenched due to aggregation. However, upon addition of GSH, a potent chelator for Fe3+, the fluorescence of the probe is restored, leading to enhanced emission. Under optimized conditions, the fluorescence response (F/F°) exhibits a linear relationship with increasing GSH concentration within the range of 0.03–95 µM, achieving a limit of detection (LOD) of 9.0 nM. This designed scheme demonstrates excellent selectivity, sensitivity, and accuracy for GSH detection. Furthermore, the NIR fluorescent probe effectively estimated GSH levels in various matrices, including capsules, serum, urine, and saliva samples, yielding recoveries % ranging from 97.2 % to 103.2 %, with RSD % below 4.34 %. Due to its NIR properties, this fluorescent probe holds promise for diagnosing various diseases and potential in vivo applications.

Development of a FRET aptasensor based on MoS2-doped Zn-MOF as luminophore for selective detection of cadmium in aqueous solutions.

A robust "on-off" fluorescent aptasensor was developed using nanohybrids of molybdenum sulfide (MoS2) quantum dot (QD)-doped zinc metal-organic frameworks (Zn-MOF) for selective and sensitive detection of cadmium ions (Cd2+) in water. This nanohybrid (MoS2@Zn-MOF), synthesized via "bottle around the ship" methodology, exhibited a high-intensity fluorescence emission centered at 430nm (λEm) (blue) on excitation at 320nm (λEx). Further, the conjugation of this fluorophore to phosphate-modified cadmium aptamer (Cd-2-2) was achieved through carbodiimide reaction. The hybridization of prepared sensing probe (MoS2@Zn-MOF/Cd-2-2 aptamer) was done with dabcyl-conjugated complementary DNA (cDNA), acting as energy donor-acceptor pair in the fluorescence resonance energy transfer (FRET) system. This hybridizationcauses the fluorescence quenching of the nanohybrid. In the presence of Cd2+, the aptamer from the fabricated nano-biosensing probe binds to these ions, resulting in release of dabcyl-cDNA oligomer. This release of dabcyl-cDNA oligomer from the sensing probes restores the fluorescence of the nanohybrid. Under optimized conditions (sensing probe/dabcyl-cDNA ratio 1/7, pH 7.4, and temp 28°C), the sensing probe showed a fast response time of 1min. The fluorescence intensity of the nanohybrid can be utilizedto determine the concentration of Cd2+. The proposed aptasensor achieved highly sensitive detection of Cd2+ with a limit of detection (LOD) of 0.24ppb over the range of 1 × 10-9 to 1 × 10-4M along with minimal effects of interferences (e.g., Hg2+, Pb2+, and Zn2+) and good reproducibility. The designed aptasensor based on MoS2@Zn-MOF nanofluorophore offers a highly sensitive and selective approach for rapid screening of metal ions in aqueous environments.

Synthesis of polyvinylpyrrolidone-protected silver nanoclusters with strong fluorescence for highly sensitive and selective hexavalent chromium ion detection

Synthesis of polyvinylpyrrolidone-protected silver nanoclusters with strong fluorescence for highly sensitive and selective hexavalent chromium ion detection

A multifunctional fluorescent Eu‐MOF probe: Its synthesis, structure, and sensing properties

Based on 3‐(2,4‐dicarboxylphenyl)‐6‐carboxylpyridine ligand (H3dpcp), a lanthanide metal–organic framework with the porous three‐dimensional structure was successfully synthesized, namely, [Eu (dpcp)(H2O)]n (1). The experimental results indicated that complex 1 exhibited stable luminescence in the range of pH = 2–11 in aqueous solution. It is noteworthy that complex 1 could recognize tryptophan (Trp) and trans, trans‐muconic acid (tt‐MA) molecules through the fluorescence quenching effect, and showed high sensitivity, selectivity, recoverability, anti‐interference, and low detection limits for the identification of Trp and tt‐MA in aqueous solution. In addition, the fluorescence mechanisms of complex 1 for sensing of tt‐MA and Trp were elucidated in detail.

A Naked-Eye Colorimetric Ratio Method for the Selective and Sensitive Detection of L-Cys Based on a Silver Nanoflakes–Chromium (III) Ion System

A Naked-Eye Colorimetric Ratio Method for the Selective and Sensitive Detection of L-Cys Based on a Silver Nanoflakes–Chromium (III) Ion System

Development of a chitosan-gold nanocomposite based disposable pencil graphite electrode for the selective detection of thiram in peach juice

ABSTRACT Hazardous chemicals that are mostly employed in modern agriculture for pest management have caused long-term environmental accumulation as well as major issues with food safety and human health. So, there is an urgent demand for efficient detection methods for environmental monitoring. To do this, the most contemporary electrochemical sensor technology is suggested. In this study, a new electrochemical sensor has been developed to detect thiram (Th) fungicide, utilising a modified activated pencil graphite electrode (a-PGE) made from chitosan-gold nanoparticle polymer (Ch-AuNPs) for the first time. The Ch-AuNPs/a-PGE surface has been characterised using cyclic voltammetry (CV), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Following adjustments to experimental parameters, the proposed electrochemical sensor demonstrated a linear calibration curve within the range of 4.90–140 μM, displaying a rapid response to thiram with a detection limit of 1.15 μM. The sensor exhibited notable selectivity, stability, and reproducibility. To assess its practical utility, the sensor was applied to analyse thiram in peach juice, and the recovery process indicated its effectiveness as a practical, swift, and efficient tool in pesticide residue monitoring.

Smartphone‐Based Molecularly Imprinted Photonic Crystal Hydrogel Sensor for the Label‐Free Detection of Bisphenol A

AbstractHere, the implementation of a smartphone‐based portable molecularly imprinted photonic crystal hydrogel (MIPCH) colorimetric sensor for the visual and label‐free detection of bisphenol A (BPA) in water samples is reported. The sensor is prepared by photopolymerizing BPA‐added hydrogel precursor solution within the voids of a photonic crystal opal film, followed by the extraction of BPA molecules. Rebinding of the BPA analyte to the MIPCH causes the hydrogel to swell, leading to a significant redshift in the diffracting spectrum. The MIPCH sensor exhibits a low limit of detection of 0.96 × 10−15 m. The sensor also shows linear response in the femtomolar range, rapid responsiveness (≤6 min), selective detection of BPA in complex matrices, long‐term stability, and reproducibility. Images of the sensor responses are used to train a deep‐learning‐based regression model on a smartphone to predict the BPA concentration quantitatively. Integration of the regression model with the developed sensor provides an accurate and portable smart sensor platform well‐suited for real‐time and on‐field monitoring of BPA.

Enhanced detection of heavy metal ions using Ag nanoparticles and single-walled carbon nanotubes within Cu-based metal-organic frameworks

Heavy metal ions (HMIs) are major water pollutants, and their toxicity for humans is a great concern for scientists and environmentalists. They are harmful to health even at trace levels; therefore, identifying and removing heavy metals from water is critical. Herein, we report highly selective and sensitive multi-analyte detection of HMIs in water using an electrochemical sensor probe based on Ag nanoparticles and single-walled carbon nanotubes incorporating copper benzene tri-carboxylate metal–organic frameworks (Ag/SWNTs@CuBTC-MOFs). The materials were characterized using FTIR, XPS, XRD, and FE-SEM with EDX mapping, TEM, TG-DTA, BET surface area, CV, and EIS. The Ag/SWNTs@CuBTC-MOF electrochemical sensor was tested by differential pulse voltammetry over a pH range of 3–10 for various HMIs. It shows high pH-dependent sensitivity towards Hg2+ (pH-5.0), Ni2+ (pH-7.0), and Fe3+ (pH-10.0) ions and a limit of detection of 1.39 nM, 2.6 nM, and 3.03 nM, respectively. The fabricated sensor probe exhibits high selectivity, good linearity, and a limit of detection below the maximum contamination limit, as the US Environmental Protection Agency suggested.

Hydrogel/MOF Dual-Modified Photoelectrochemical Biosensor for Antibiofouling and Biocompatible Dopamine Detection.

For accurate in vivo detection, nonspecific adsorption of biomacromolecules such as proteins and cells is a severe issue. The adsorption leads to electrode passivation, significantly compromising both the sensitivity and precision of sensing. Meanwhile, common antibiofouling modifications, such as polymer coatings, still grapple with issues related to biocompatibility, electrode passivation, and miniaturization. Herein, we propose a composite antibiofouling coating strategy based on zwitterionic metal-organic frameworks (Z-MOFs) and a combination of acrylamide hydrogels. On a well-designed TiO2/Z-MOF/hydrogel photoelectrode, we achieve highly sensitive and selective detection of dopamine in complex biological environments. The hydrogel's three-dimensional porous structure combined with unique microporous architecture of Z-MOF ensures effective sieving of interfering macromolecules while preserving efficient small molecules and electron transport. This innovative approach paves the way for constructing miniature, in vivo antibiofouling sensors for molecule monitoring in living organisms with complicated chemical environments.

Ultrafast and selective detection of dopamine by DC sputtered highly oriented CuO thin films: Effect of electroactive interfering agents and temperature

Dopamine and serotonin are two neurotransmitters that play critical role in human physiology. In this work, it has been aimed to synthesize a chip-based sensing platform that can detect dopamine precisely in a non-enzymatic way in presence of a series of electroactive interfering agents. Copper oxide (CuO), a p-type material with excellent surface and electrochemical properties, has been deposited through direct current (DC) sputtering technique on indium doped tin oxide (ITO) coated glass substrates as the sensing platform. The structure, phase purity and other essential properties of the modified electrode were established through x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet – visible (UV–Vis) spectroscopy. Detailed electrochemical investigations with the modified electrode have also been carried out using cyclic voltammetry (CV), chronoamperometry (i – t) and electrochemical impedance spectroscopy (EIS) that revealed ultrafast response (10 ms), excellent sensitivity (5.41 µAµM-1cm−2) and low limit of detection (LoD) of 0.46 µM for the electrode towards dopamine. The electrode exhibited sensitivity of 0.37 µAµM-1cm−2 with average LoD of 19.2 µM towards serotonin, which is inferior to dopamine. The threshold response potential was also quite different for dopamine and serotonin. The modified electrode was also found to be nonresponsive to a series of electroactive interfering agents, making it dopamine selective. The role of p-type conductivity of the electrode material towards such selective detection of dopamine was also explained. The electrode was notably reliable from the point of view of electrochemical performance and structural stability. Real sample analysis was also carried out by taking urine sample from adult male human.

A Zn/Cd/Ni Metal-Organic Framework-Based Solid and Flexible Fluoroprobes for Highly Selective Detection of 4-Nitroaniline in Real Water Samples.

The combination of diazabicyclic compound i.e. 1,4-diazabicyclo[2.2.2]octane (DABCO) and dicarboxylate linker 1,4-dicarboxylic acid are employed to self-assemble with three divalent metal ions such as Zn2+, Cd2+, Ni2+ led to the formation of highly stable pillar layered luminescent metal-organic frameworks. The emissive response of as-synthesized MOFs was studied in organic solvents with different functionalities resulting in the development of fluoroprobes having excellent recognition ability for 4-nitroaniline with detection limit upto micromolar. All the MOFs display a good linear relation between the fluorescence intensity and concentration of 4-NA in the range of 10-90µmol L-1. The values of Ksv for Zn-MOF, Cd-MOF, and Ni-MOF are found to be 1.75 × 104mol-1L, 1.25 × 104mol-1L, and 28.0 × 104mol-1L, respectively. The calculated detection limit values are 19.7µmol L-1, 27.6µmol L-1, and 1.19µmol L-1 respectively. Moreover, the study was further extended to fabricate the solid membrane-based fluoroprobe using a linear chitosan polysaccharide and act as an efficient solid fluoroprobe for the detection of 4-NA. This proposed synthesis of polymeric membrane facilitates the MOF@chitosan fluorophore to transfer its fluorescence-emissive nature to a solid state.

A Novel Near-Infrared Fluorescent Probe for the Detection of Endogenous Peroxynitrite (ONOO-) in Living Cells.

In this study, we present a novel near-infrared (NIR) fluorescent probe Nile-ONO designed for the selective and sensitive detection of ONOO-. The probe Nile-ONO employed Nile red as the fluorophore, with diphenylphosphinate serving as the reaction site. In the presence of ONOO-, the probe Nile-ONO exhibits remarkable fluorescence enhancement at 659nm, with a response time of less than 20min and a low detection limit of 0.32 µM. Importantly, MTT assays demonstrate low cytotoxicity in living cells. Furthermore, Nile-ONO has excellent imaging capabilities for endogenous ONOO-. Overall, this work introduces a valuable new method for the rapid detection of ONOO- in biological systems.

Anisotropic sensing based on single ReS2 flake for VOCs discrimination

Selective and sensitive detection of volatile organic compounds (VOCs) holds paramount importance in real-world applications. This study proposes an innovative approach utilizing a single ReS2 field-effect transistor (FET) characterized by distinct in-plane anisotropy, specifically tailored for VOC recognition. The unique responses of ReS2, endowed with robust in-plane anisotropic properties, demonstrate significant difference along the a-axis and b-axis directions when exposed to four kinds of VOCs: acetone, methanol, ethanol, and IPA. Remarkably, the responses of ReS2 were significantly magnified under ultraviolet (UV) illumination, particularly in the case of acetone, where the response amplified by 10–15 times and the detection limit decreasing from 70 to 4 ppm compared to the dark conditions. Exploiting the discernible variances in responses along the a-axis and b-axis under both UV and dark conditions, the data points of acetone, ethanol, methanol and IPA gases were clearly separated in the principal component space without any overlap through principal component analysis, indicating that the single ReS2 FET has a high ability to distinguish various gas species. The exploration of anisotropic sensing materials and light excitation strategies can be applied to a broad range of sensing platforms based on two-dimensional materials for practical applications.

Selective SERS Detection of TATB Explosives Based on Hydroxy-Terminal Nanodiamond-Multilayer Graphene Substrate

Selective SERS Detection of TATB Explosives Based on Hydroxy-Terminal Nanodiamond-Multilayer Graphene Substrate

Rapid and sensitive determination of legacy and emerging per- and poly-fluoroalkyl substances with solid-phase microextraction probe coupled with mass spectrometry

This study was designed to develop a rapid and sensitive method for quantifying legacy and emerging per- and polyfluoroalkyl substances (PFASs) in environmental samples with solid-phase microextraction (SPME) coupled with mass spectrometry (MS). An innovative SPME probe was fabricated via in situ polymerization, and the probe coating was optimized with response surface methodology to maximize the fluorine–fluorine interactions and electrostatic properties and ensure high selectivity for the target PFASs with enrichment factors of 48–491. The coupled SPME and MS provided a rapid and sensitive method for analyses of PFASs, with excellent linearity (r ≥ 0.9962) over the concentration range 0.001–1 μg/L and remarkably low detection limits of 0.1–13.0 ng/L. This method was used to analyze trace PFASs in tap water, river water, and wastewater samples and proved to be a simple and efficient analytical method for selective enrichment and detection of contaminants in the environment.