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In this work, the nanomagnetic probe was prepared by condensation of carboxylated kanamycin (Kana) aptamers with aminated nanomagnetic Fe₃O₄ beads, which was coupled with invertase-labeled complementary DNA (cDNA) for sensitive and convenient detection of Kana in water samples by a personal glucose meter (PGM). In the absence of Kana, there was no PGM signal recorded because formed nanomagnetic probe was removed by magnetic separation. Conversely, the aptamer could recognize Kana specifically and released cDNA into supernatant. After the addition of sucrose, it was hydrolyzed into glucose by invertase. Detection of Kana was indirectly achieved based on the relationship between glucose concentration and the PGM indication. Furthermore, a miniaturized portable device was constructed by integrating the components using 3D printing technology. Under optimal conditions, rapid detection of Kana within the concentration range of 1-200 nM was achieved, with a detection limit (3σ/k) of 0.28 nM. Moreover, the proposed aptasensor was characterized in terms of selectivity, reproducibility and stability. Finally, it was applied to the determination of Kana in water with recoveries from 99% to 103%. All these results indicated that the proposed aptasensor is simple, rapid, selective, and sensitive, and it could potentially serve as an effective approach for the on-site determination of Kana in water samples.

A porous magnetic composite adsorbent was developed by incorporating hyper-crosslinked polymer-decorated graphene oxide (Fe₃O₄@HCP-GO) into alginate hydrogel beads, forming Fe₃O₄@HCP-GO alginate beads. For the first time, this unique hierarchical structure combining magnetic responsiveness, high surface area, and multiple adsorption mechanisms was engineered for the efficient extraction of phenylurea herbicides (PUHs). The material was applied in a dispersive liquid-solid phase extraction (DLSPE) process, enabling the simultaneous adsorption of six PUHs through hydrogen bonding, hydrophobic, and π-π interactions. The extracted PUHs were determined by high performance liquid chromatography. The fabricated porous adsorbent was characterized, and the extraction conditions were optimized. Under optimal conditions, the developed method exhibited linearity from 5.0 to 100 μg L^-1 for metoxuron, monuron, chlortoluron and buturon, and from 10 to 100 μg L^-1 for isoproturon and monolinuron. The limits of detection were between 1.0 and 3.0 μg L^-1. The developed adsorbent was utilized to extract PUHs from rice, cucumber and tomato, achieving recoveries ranging from 70.2 to 96.7 % with RSDs below 9.0 %. The fabricated porous magnetic composite hydrogel bead exhibited good stability and efficiency for up to 6 cycles of extraction and desorption.

Photonic crystal (PC)-based humidity sensors detect changes in humidity using periodic structural color variations and have significant potential in the humidity detection field. However, current technologies typically rely on observing these structural color changes with the human eye. The human eye has limited color discrimination, thus resulting in insufficient detection accuracy. Meanwhile, viewing angles and ambient lighting can also disrupt observations. Here, we propose a humidity sensor based on surface-functionalized tunable PC grating. The tunable PC grating consists of a 600 nm polystyrene (PS) microsphere PC and a humidity-sensitive hydrogel. As ambient humidity increases, the hydrophilic amide groups (-CONH₂) inside the hydrogel interact with the hydrogen bonds between water molecules and triggers hydrogel swelling, exerts interfacial stress on the PS microsphere lattice, thus expanding the lattice spacing of the PS microspheres and causing a red shift in the reflected wavelength. Integrating the surface-functionalized tunable PC grating into a Czerny-Turner (C-T) optical system enables us to directly translate humidity into precise spectral shifts, overcoming the limitations of human eye-based observations. Experimental results demonstrate a strong linear response over the range of 24-94 % relative humidity (RH), as well as excellent repeatability and long-term stability. We provide an innovative solution for high-precision optical humidity sensing.

ALKBH2 is a key DNA repair enzyme that removes various methyl-adducts, including N1-methyl-adenine and N3-methyl-cytosine, from genomic DNA. ALKBH2 overexpression is observed in many cancer and leads to temozolomide resistance in glioblastoma cell lines. The growing significance of ALKBH2 as a promising therapeutic target in cancer has highlighted the need for suitable chemical tools to enable its detailed study and functional characterization. To address this gap, we developed a fluorescent probe for rapid and selective detection of ALKBH2 in live cancer cells. Building on our previously reported finding that the HIV protease inhibitor ritonavir selectively binds and inhibits ALKBH2, we synthesized a BODIPY-labeled ritonavir (rit-BD) as an imaging agent. Rit-BD showed peak absorption (A_max) and emission (E_max) to be 576 nm and 586 nm, respectively. Our results from the binding experiment demonstrate that rit-BD binds to ALKBH2 in vitro with micromolar affinity. The limit of detection (LOD) for ALKBH2 with Rit-BD was estimated to be 115 ng/ml (4.7 nM) with a linear range of 0.5-330 μg/ml (14 nM-10 μM). Furthermore, In vitro and in cellulo experiments and live-cell imaging confirmed that rit-BD could be used to label ALKBH2 in the living cell nucleus. Our findings establish rit-BD as a unique dual-purpose agent for visualizing ALKBH2 dynamics and inhibiting DNA repair activity in cancer cells.

A novel label-free electrochemical immunosensor was constructed to quantify prostate-specific antigen (PSA) in human serum. A poly(3,4-ethylenedioxythiophene) and Prussian blue nanocomposite (PEDOT@PB) was used to a screen-printed carbon electrode (SPCE) modification to construct the platform followed by a nanocomposite of reduced graphene oxide and copper metal-organic framework (rGO@Cu(BDC-NH₂) MOF), that was then decorated with porous platinum nanoparticles (PPtNPs). In this system, PEDOT@PB served as a redox probe. The rGO@Cu(BDC-NH₂) MOF offered a high surface area and exceptional electroconductivity to facilitate PPtNPs chemisorption through coordination with the amino groups of Cu(BDC-NH₂) MOF. The PPtNPs provided high conductivity and a high surface area to enhance the immobilization of PSA antibody (Ab_PSA), thereby improving sensor performance. PSA was quantified using differential pulse voltammetry (DPV) by monitoring the decrease in the oxidation peak current of the PB probe as the antigen-antibody immunocomplex forms to create an insulating layer that hinders electron transfer. The proposed sensor demonstrated excellent performances under optimized conditions, with a linear range of 1.0 × 10^-7 to 10^-1 ng mL^-1 and a low limit of detection of 7.8 × 10^-8 ng mL^-1. The sensor also demonstrated excellent stability, enhanced sensitivity, and acceptable selectivity. There was no meaningful statistical difference between the results obtained from the sensor and those from the electrochemiluminescence immunoassay (P > 0.05).

Aromatic amino acids (AAAs) play a critical role in neurotransmitter synthesis and are implicated in the pathogenesis of depression. However, their trace concentrations in biological samples pose significant challenges for detection. In this study, we present a novel approach for the sensitive and precise detection of AAAs in human urine. A composite material, GO-MONs-NH₂, was synthesized by in situ growing amino-functionalized microporous organic networks (MONs-NH₂) on the surface of graphene oxide (GO) via a solvothermal method. The resulting GO-MONs-NH₂ material, with a hierarchical porous structure, combines the mechanical stability of GO and the high adsorption capacity of MONs-NH₂. It efficiently extracts AAAs through multiple adsorption mechanisms, including hydrogen bonding, π-π interactions, and electrostatic forces, exhibiting rapid mass transfer and high affinity for tyrosine, phenylalanine, and tryptophan. The GO-MONs-NH₂ solid-phase extraction (SPE) technique, coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD), enables simultaneous detection of the three AAAs in urine samples without the need for mass spectrometry. The developed method demonstrates a wide linear range (0.05-50 μg/mL), low limits of detection (3.96-7.13 ng/mL), high accuracy (recoveries: 90.8 %-107.5 %), and good precision (RSDs ≤ 6.4 %). This method offers a reliable, cost-effective, and non-invasive tool for early screening and monitoring of depression.

An one-pot method was used to prepare bimetallic nanozymes, with chitosan (CS) and l-tyrosine (L-Tyr) as stabilized dispersed colloidal solutions and a carrier for gold-platinum single atoms (Au-Pt SAs), which exhibited excellent peroxidase activity. A colorimetric method based on CS/L-Tyr/Au-Pt SAs nanozymes was constructed for the colorimetric detection of quercetin (QR) in human serum and orange juice. The synthesized bimetallic nanozymes were characterized by SEM, TEM, HAADF-STEM, FT-IR, XRD and XPS techniques to demonstrate the successful synthesis of CS/L-Tyr/Au-Pt SAs nanozymes. Due to the extremely high catalytic activity of the intrinsic active sites of Au-Pt SAs, each site can effectively catalyze the decomposition of H₂O₂ to produce hydroxyl radicals (·OH), which oxidizes the colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue product (ox-TMB), and the blue product gradually disappeared after the addition of QR, which indicates that QR can effectively inhibit the TMB oxidation of TMB. In addition, the effect of various experimental conditions on the activity of the nanozymes was investigated to obtain the optimal enzyme activity. The high selectivity of the nanozymes for QR detection was verified by using analogs as interfering agents. The linear range of this colorimetric method for the detection of QR was 0.001-500.0 μM with a detection limit of 0.33 nM. It was successfully used for QR detection in real samples of human serum and orange juice with recoveries of 97.95 %-99.52 % and 97.18 %-105.04 %, respectively, proving its great value for practical applications in biological systems.

To prevent phenolic compounds from threatening ecological environment safety and human health, the development of rapid and sensitive methods is vital. Herein, a novel Ketjen black (KB) and multi-walled carbon nanotubes (MWCNTs)- multifunctionalized metal-organic framework nanocomposite (ZIF-67/KB-MWCNTs) was synthesized, which was used for the modification of bare electrode (GCE), achieving simultaneous and ultrasensitive detection of hydroquinone (HQ), catechol (CC), and resorcinol (RS) in environmental water. The proposed electrochemical sensor (ECS) was constructed based on the synergistic effect of ZIF-67 with an ultra-large specific area and KB-MWCNTs with 3D chain structure and high conductivity resulted in both high electrocatalysis and fast electron transfer. All prepared materials and GCE/ZIF-67/KB-MWCNTs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Nitrogen adsorption and desorption, X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT-IR), electrochemical impedance spectroscopy (EIS) and electrochemistry methods such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimum conditions, the detection limits of 0.015 μM, 0.024 μM and 0.198 μM were obtained for HQ, CC, and RS, respectively. More importantly, the as-prepared modified electrode exhibited outstanding specific recognition toward electrooxidation of three dihydroxybenzene isomers with three well-separated peaks. This sensor showed satisfactory anti-interference ability and provided reliable assay results.

The lack of a suitable method for the speciation analysis of iodine-129 (¹²⁹I) in spent nuclear fuel solutions has hindered both comprehensive understand and precise control of ¹²⁹I prior to plutonium and uranium separation in reprocessing nuclear fuel. In this work, a sequential separation procedure is established to quantify multiple ¹²⁹I species in spent nuclear fuel solutions, namely I₂, IO₃^-, and colloidal PdI₂ and AgI, based on their distinct physicochemical properties. I₂ was initially transferred into an upper mesitylene phase via N₂ sparging from an acidic spent nuclear fuel solution. Colloidal PdI₂ and AgI were then isolated through ultrafiltration with centrifugation and subsequently dissolved for precise measurement. The remaining IO₃^- in the filtrate was reduced to I₂ using NH₂OH·HCl and extracted into the mesitylene phase. Cross-contamination among the iodine species was verified to be less than 2%, and the sum of all ¹²⁹I species was consistent with the total spiked ¹²⁹I amount. ¹²⁹I in each fraction was quantified by liquid scintillation counting, enabling accurate analysis of ¹²⁹I speciation in spent nuclear fuel solutions. The developed method has been successfully applied for elucidating the distribution and transformation mechanisms of ¹²⁹I in reprocessing process, providing critical insights for optimizing radioactive iodine management strategies in spent nuclear fuel reprocessing.