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A “turn-on” fluorometric assay for kanamycin detection by using silver nanoclusters and surface plasmon enhanced energy transfer
摘要： A rapid method is described for the determination of the antibiotic kanamycin. It integrates a kanamycin-binding aptamer and surface plasmon enhanced energy transfer (SPEET) between DNA-templated silver nanoclusters (AgNCs) and gold nanoparticles (AuNPs). The AgNCs and AuNPs were selected as energy donor and energy acceptor, respectively. The aptamer was designed to regulate the energy transfer between AgNCs and AuNPs. The aptamer was adsorbed on the AuNPs. Upon addition of kanamycin, the aptamer-kanamycin complex is formed, and this results in the aggregation of the AuNPs in high salt concentration, the formation of a blue coloration, and in the suppression of the SPEET process. The fluorescence of the AgNCs (with excitation/emission peaks at 560/600 nm) is quenched by the aptamer protected AuNPs in absence of kanamycin. The fluorescence on addition of kanamycin increases linearly in the 5 to 50 nM concentration range, with a lower detection limit of 1.0 nM (at S/N = 3). The assay can be performed within 30 min. It was successfully applied to the determination of kanamycin in spiked milk samples, and recoveries ranged between 90.2 and 95.4%. Conceivably, the strategy has a wide potential for screening by simply changing the aptamer.
关键词： Ag NCs,Milk analysis,Antibiotics detection,Au NPs,Food safety,Aptasensor
更新于2025-11-19 16:46:39
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Direct synthesis of ultrasmall and stable magnetite nanoparticles coated with one single carbon layer for sensitive surface-enhanced Raman scattering
摘要： Ultrasmall spherical magnetite nanoparticles (Fe3O4 NPs) coated with one single carbon layer (Fe3O4@1C NPs) were directly synthesized by a simple, fast one-step hydrothermal reaction at low temperature (200℃). The as-synthesized Fe3O4@1C NPs were easily separated and purified from the resultant mixture, without the need for any additional energy input and chemicals. The as-purified Fe3O4@1C NPs not only displayed typical superparamagnetic behavior but also exhibited quite good long-term stability after being exposed to the open air under the room conditions for more than 2 months. Importantly, the long-term stored Fe3O4@1C NPs exhibited a highly sensitive surface-enhanced Raman spectroscopy (SERS) response toward Rhodamine-b (RdB) molecules with low concentration. The multifunctional and recyclable Fe3O4@1C NPs presented a prospective application for the selective enrichment and sensitive SERS detection of chemical and biomolecular assays.
关键词： coated with one single carbon layer (Fe3O4@1C NPs),Dehydration reaction,Saturation magnetization,Long-term stability,Magnetite nanoparticles (Fe3O4 NPs)
更新于2025-11-14 17:03:37
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Electronic, electrical and magnetic behaviours of reduced graphene-oxide functionalized with silica coated gold nanoparticles
摘要： We have synthesized graphene-oxide (GO) by the modi?ed hummer's process and subsequently reduced it with gold-nanoparticles (Au-NPs) using silica coated colloidal Au-NPs and hydrazine monohydrate solutions to form r-GO:Au-NPs nanocomposites. We have studied the microstructure, electronic, electrical and magnetic properties of r-GO and r-GO:Au-NPs nanocomposites. We have observed from the Raman spectroscopy that the intensity of D-peak (disorder) gets reduced with respect to G (graphite-cluster) in r-GO:Au-NPs composites. The reduction of ID/IG ratio obtained from Raman spectra [r-GO: 1.22 → r-GO:(Au-NPs)4.88: 0.98] clearly indicates that the sp2-cluster is reduced in r-GO:Au-NPs nanocomposites. The reduction of sp2-cluster and/or enhancement of sp3-cluster is due to replacement of sp2-cluster by the Au-NPs. This observation also observed from the X-ray absorption near edge structure (XANES) spectroscopy, X-ray photoelectron spectroscopy (XPS) measurements that are consistence with reduction of conductivity as we observe from the current (I) - voltage (V) characteristics of the nanocomposites. Magnetic M-H hysteresis loops show the magnetization is enhanced in r-GO:Au-NPs nanocomposites. We believe that the reduction of conductivity and enhancement of magnetization of r-GO:Au nanocomposites would be most suitable for ferro-electro-magnetic materials for the memory storage device applications.
关键词： I-V,XANES,R-GO,M-H,XPS,R-GO:Au-NPs
更新于2025-11-14 17:03:37
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On-site identification of psychoactive drugs by portable Raman spectroscopy during drug-checking service in electronic music events
摘要： Introduction and Aims. Hundreds of new psychoactive substances (NPS) have burst into the marketplace, making both the scientific community and people who use drugs lacking of adequate information about their diffusion and effects. In this scenario, drug-checking services have been recently proposed to assist harm reduction policies and provide a global description of the circulating drugs. Design and Methods. The results obtained by a portable Raman spectroscopy device on 472 alleged drugs within the first formal implementation of drug checking in Italy, are reported. The testing was made through a plastic bag held by the applicant and containing the alleged drug. The substance identification was executed by comparison with a spectral library. Results. Illicit substances were detected in 304 samples. Findings included MDMA (106 samples), ketamine (87 samples), cocaine (51 samples), amphetamine (47 samples), methamphetamine (two samples), heroin (two samples) and NPS (nine samples). Two samples were identified as precursors of psychoactive substances. Identification of a non-controlled substance occurred in 38 samples. Output of inconclusive result was recorded from 128 samples tested on-site, from which the applicant allowed us to collect a small portion in 68 cases, for a delayed laboratory analysis by GC–MS or LC–MS/MS. Discussion and Conclusions. Drug checking by Raman spectroscopy proved effective to identify psychoactive drugs including NPS and track the drug distribution in various recreational settings. The field testing activity revealed the presence of several NPS in the nightlife scenario, often in replacement of traditional illicit drugs, thus posing a high overdose risk and a life-threatening situation.
关键词： drug checking,harm reduction,Raman,NPS
更新于2025-09-23 15:23:52
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Mg dependent Sunlight photocatalytic performance of Nickel ferrite synthesized by a green sol-gel route
摘要： We report an environmentally friendly synthetic strategy to synthesize new nickel ferrite and Mg doped nickel ferrite photocatalysts under modified green sol-gel route in which Aloe Vera gel acts as a natural template. The crystalline phase, surface morphology and size of the prepared photocatalysts were characterized by PXRD, SEM, TEM and HRTEM analysis. The energy band gap of the nanoparticles (NPs) can be tuned in the range of 2.55–2.34 eV by varying the dopant concentration. The photoluminescence analysis indicates that the present NPs are an effective white component in display applications. These synthesized NPs were used for photocatalytic decomposition of recalcitrant pollutants in aqueous media under Sunlight irradiation. When compared to pure, NiFe2O4: Mg2+ (5 mol %), the NiFe2O4: Mg2+ (1mol %) exhibits the highest photocatalytic efficiency for the decomposition of recalcitrant pollutants than that of commercial P25.This enhancement in photocatalytic performance can be mainly attributed to the balance between the parameters, crystallanity,band gap, morphology, crystallite size, defects, dopant amount and combined facets of photocatalysis It opens new window to use this simple greener route to synthesize bi-functional character NPs in the area of photocatalysis particularly waste water treatment and display applications.
关键词： Photo-Fenton catalytic performance,Photoluminescence,Green Sol-gel route,NiFe2O4:Mg2+NPs
更新于2025-09-23 15:23:52
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Metal accumulation, biochemical and behavioral responses on the Mediterranean clams Ruditapes decussatus exposed to two photocatalyst nanocomposites (TiO2 NPs and AuTiO2NPs)
摘要： Nanoparticle decoration with noble metal represents a promising alternative to improve their photocatalytic and photovoltaic properties. However, toxicity can be influenced by such modification, as the bioavailability of these substances may be influenced. To understand how decoration influences the NP impacts in marine ecosystems, we exposed suspension-feeding clams, Ruditapes decussatus, to two photocatalyst nanocomposites, TiO2 NPs and AuTiO2 NPs, over 2 concentrations, 50 μg L?1 and 100 μg L?1, in a laboratory experiment. Accumulation of Au and Ti in gills and digestive gland was noted in clams after exposure to TiO2 NPs and AuTiO2 NPs using inductively coupled plasma optic emission spectroscopy (ICP-OES). TiO2 and AuTiO2 NPs alter the behavior of the clams Ruditapes decussatus by reducing filtration and respiration rates. Furthermore, the highest concentration of TiO2NPs induces an overproduction of H2O2 in gills and digestive gland and NO production only in gills. Superoxide dismutase (SOD), Catalase (CAT), Glutathione-S-transferase (GST) and acetylcholinesterase (AChE) activities were induced in gills and digestives gland in concentration and nanocomposite type dependent manner. Decorated form presented higher Malondialdehyde (MDA) levels in gills and digestive gland than the undecorated form, suggesting different mechanisms of action that may be mediated through oxidative stress. In conclusion, the considered parameters could represent reliable biomarkers for the assessment of NP toxicity on R. decussatus as biological biomonitoring model. In addition, based on the obtained results, nanoparticle decoration influences the toxicity of metal nanoparticles in marine organism.
关键词： Oxidative stress,Ruditapes decussatus,Biomarkers,TiO2 NPs,AuTiO2NPs
更新于2025-09-23 15:23:52
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Characterizing a novel scintillating glass for application to megavoltage cone-beam computed tomography
摘要： Purpose: The purpose of the present study was to evaluate the performance of a prototype electric portal imaging device (EPID) with a high detective quantum efficiency (DQE) scintillator, LKH-5. Specifically, image quality in context of both planar and megavoltage (MV) cone-beam computed tomography (CBCT) is analyzed. Methods: Planar image quality in terms of modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) are measured and compared to an existing EPID (AS-1200) using the 6 MV beamline for a Varian TrueBeam linac. Imager performance is contextualized for three-dimensional (3D), MV-CBCT performance by measuring imager lag and analyzing the expected degradation of the DQE as a function of dose. Finally, comparisons between reconstructed images of the Catphan phantom in terms of qualitative quality and signal-difference-to-noise ratio (SDNR) are made for 6 MV images using both conventional and LKH-5 EPIDs as well as for the kilovoltage (kV) on-board imager (OBI). Results: Analysis of the NPS reveals linearity at all measured doses using the prototype LKH-5 detector. While the first zero of the MTF is much lower for the LKH-5 detector than the conventional EPID (0.6 cycles/mm vs. 1.6 cycles/mm), the normalized NPS (NNPS) multiplied by total quanta (qNNPS) of the LKH-5 detector is roughly a factor of 7-8 times lower, yielding a DQE(0) of approximately 8%. First, second, and third frame lag was measured at approximately 23%, 5%, and 1% respectively, although no noticeable image artifacts were apparent in reconstructed volumes. Analysis of low dose performance reveals that DQE(0) remains at 80% of its maximum value at a dose as low as 7.5x10-6 MU. For a 400 projection technique, this represents a total scan dose of 0.0030 MU, suggesting that if imaging doses are increased to a value typical of kV-CBCT scans (~2.7 cGy), the LKH-5 detector will retain quantum noise limited performance. Finally, comparing Catphan scans, the prototype detector exhibits much lower image noise than the conventional EPID, resulting in improved small object representation. Further, SDNR of H2O and polystyrene cylinders improved from -1.95 and 2.94 to -15 and 18.7, respectively. Conclusions: Imaging performance of the prototype LKH-5 detector was measured and analyzed for both planar and 3D contexts. Improving noise transfer of the detector results in concurrent improvement of DQE(0). For 3D imaging, temporal characteristics were adequate for artifact-free performance and at relevant doses, the detector retained quantum-noise limited performance. Although quantitative MTF measurements suggest poorer resolution, small object representation of the prototype imager is qualitatively improved over the conventional detector due to the measured reduction in noise.
关键词： EPID,NPS,scintillator,MV-CBCT,DQE,MTF,Portal imaging
更新于2025-09-23 15:23:52
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Structural and Optical Properties of CeO2 Nanoparticles Synthesized by Modified Polymer Complex Method
摘要： Ceria nanoparticles (Ceria-NPs) were synthesized using a modified polymer complex method and their structural and optical properties were evaluated. The solids were heated at 550 °C and characterized using Raman, UV–Vis absorption, diffuse reflectance, X-ray photoelectron and photoluminescence spectroscopies, X-ray diffraction (XRD) and scanning and transmission electron microscopy. The primary particles obtained presented a size of ~ 10 nm. The XRD indicated that CeO2 was the only crystalline phase. From the UV–Vis and diffuse reflectance spectra, energy values of 3.8 eV and 3.4 eV were obtained, values that can be associated with band—band electronic transitions and/or with those that involve ionized states located within the gap caused by defects and isolated atoms of Ce3+. Photoluminescence spectra reiterated the existence of localized states in the gap. Raman spectra revealed the existence of peroxide (O2^2-) and superoxide (O2^-) over the surface of the ceria-NPs. The XPS results indicated that the concentrations of Ce3+ and Ce4+ were ～ 20.5% and ～79.5% respectively, and that the stoichiometry of oxygen was 1.9 per atom of Ce. The results obtained from the characterization of CeO2-NPs synthesized make it as promising material for environmental remediation, biomedicine, gas sensing and optoelectronic applications.
关键词： Modified polymer complex,Structural properties,Ceria-NPs,Optical properties,Synthesis
更新于2025-09-23 15:23:52
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Doxorubicin and indocyanine green loaded superparamagnetic iron oxide nanoparticles with PEGylated phospholipid coating for magnetic resonance with fluorescence imaging and chemotherapy of glioma
摘要： Background: Glioma represents the most common malignant brain tumor. Outcomes of surgical resection are often unsatisfactory due to low sensitivity or resolution of imaging methods. Moreover, the use of traditional chemotherapeutics, such as doxorubicin (DOX), is limited due to their low blood–brain barrier (BBB) permeability. Recently, the development of nanotechnology could overcome these obstacles. Materials and methods: Hydrophobic superparamagnetic iron oxide nanoparticles (SPIO NPs) were prepared with the use of thermal decomposition method. They were coated with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG 2000) and DOX using a thin-film hydration method followed by loading of indocyanine green (ICG) into the phospholipid layers. Details regarding the characteristics of NPs were determined. The in vitro biocompatibility and antitumor efficacy were established with the use of MTT assay. In vivo fluorescence and magnetic resonance (MR) imaging were used to evaluate BBB penetration and accumulation of NPs at the tumor site. Antitumor efficacy was evaluated using measures of tumor size, median survival times, body weights, and H&E staining. Results: The multifunctional NPs generated had an average diameter of 22.9 nm, a zeta potential of -38.19 mV, and were capable of providing a sustained release of DOX. In vitro experiments demonstrated that the SPIO@DSPE-PEG/DOX/ICG NPs effectively enhanced cellular uptake of DOX as compared with that of free DOX. In vivo fluorescence and MR imaging revealed that the NPs not only effectively crossed the BBB but selectively accumulated at the tumor site. Meanwhile, among all groups studied, C6 glioma-bearing rats treated with the NPs exhibited the maximal degree of therapeutic efficacy, including smallest tumor volume, lowest body weight loss, and longest survival times, with no obvious side effects. Conclusion: These results suggest that the SPIO@DSPE-PEG/DOX/ICG NPs can not only function as a nanoprobe for MR and fluorescence bimodal imaging, but also as a vehicle to deliver chemotherapeutic drugs to the tumor site, to achieve the theranostic treatment of glioma.
关键词： SPIO NPs,fluorescence imaging,chemotherapy,BBB,MR imaging
更新于2025-09-23 15:22:29
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Polydopamine-Coated Gold Core/Hollow Mesoporous Silica Shell Particles as a Nanoplatform for Multimode Imaging and Photothermal Therapy of Tumors
摘要： It is highly desirable to develop a new hybrid nanoplatform that integrates diagnosis and treatment elements for effective theranostics of tumors. Herein, we have skillfully designed a nanoplatform of polydopamine (PDA)-coated and perfluorohexane (PFH)-filled gold core/hollow mesoporous silica shell (Au@mSiO2-PFH-PDA, ASPP for short) particles for photoacoustic (PA)/ultrasound (US)/computed tomography (CT)/thermal imaging and photothermal therapy (PTT) of tumors. In this work, we first synthesized Au seed particles with a diameter of 15.8 nm using a sodium citrate reduction method, and coated Au seeds with polyvinylpyrrolidone for further growth of solid silica shell/mesoporous silica shell onto the Au seeds. After treatment via selective etching to remove solid silica shell, amination of surface of the particles, and filling of PFH into the internal cavity of the spheres with a diameter of 182.1 nm, PDA coating was performed to render the particles with an external shell thickness of 15.1 nm. The formed hybrid particles with a size of 212.2 nm are colloidally stable and exhibit good cytocompatibility, and display excellent PA/US/CT/thermal imaging property due to the co-presence of PDA, PFH, and Au nanoparticles. Furthermore, the PDA coating renders the platform with a photothermal conversion efficiency of 61.2%, enabling effective photothermal ablation of cancer cells in vitro and a xenografted 4T1 tumor model in vivo under irradiation with an 808 nm laser. More importantly, in the primary 4T1 tumor model, intratumoral injection of the ASPP and irradiation with an 808 nm laser can also completely inhibit the occurrence lung metastasis induced by the 4T1 tumor. The as-prepared hybrid nanoplatform may hold a great promise to be adopted for multimode imaging and PTT of tumors and inhibition of tumor metastasis.
关键词： Tumor metastasis inhibition,Multimode imaging,Photothermal therapy,Polydopamine NPs,Hollow mesoporous silica,Surface modification
更新于2025-09-23 15:22:29