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Effect of the synthesis method on the properties of lithium doped graphene oxide composites with tin oxide nanoparticles: Towards white luminescence
摘要： Graphene oxide (GO) based composites functionalized with nanoparticles are emerging as potential candidates for multifunctional devices. As the synthesis route can strongly influence the way in which the nanoparticles are anchored to GO and the resulting properties, different routes have been employed and evaluated in this work for the preparation of composites formed by GO and undoped or Li doped SnO2 nanoparticles. Promotion of synergetic effects, as well as changes in the structural and luminescent properties of the composites have been also analyzed. In comparison with GO, composite samples synthesized in this work involve enhanced luminescence while retaining nearly white emission, which could lead to wider applicability of GO based composites in free standing and emitting and sensing devices. Aspects, such as GO reduction, stabilization of different Sn-based oxides, variation in the concentration of oxygen related functional groups, changes in the sp2 domain sizes, incorporation of lithium and enhancement of the luminescence, have been analyzed in this work by means of x-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy (EDS), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) characterizations.
关键词： Nanoparticles,Lithium,Tin oxide,Nanomaterials,Luminescence,Composite
更新于2025-09-23 15:23:52
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Utility of surface plasmon resonance response of silver nanoparticles for assay of Teicoplanin in human plasma using spectrofluorimetric technique
摘要： Teicoplanin (TEIC) is a glycopeptide antimicrobial medication for management of several bacterial infectious diseases caused by gram-positive bacteria including methicillin-resistant Staphylococcus aureus and Enterococcus faecalis. Novel, very simple, fast and cost-effective two spectrofluorimetric methods were developed for the ultra-trace determination of TEIC in pharmaceutical vials and human plasma. The investigated methods based on measuring the fluorescence of TEIC in methanol (method A) and enhancing its fluorescence by 10 folds using silver nanoparticles (AgNPs) without any solvent extraction (method B). The fluorescence of TEIC was investigated at 385nm (excitation at 335 nm) with calibration ranged from 1 to 25 ng mL?1 and from 0.6 to 30 ng mL?1 with Limit of detection (LOD) of 280 and 160 pg mL?1 for method A and B respectively. The established methods were optimized, validated and bio-analytically validated via ICH and US-FDA guidelines. The performed methods were used to determine TEIC in human plasma with high percentage recovery of 98.8 ± 1.75. Further, the proposed methods were applied to study the stability of TEIC after exposure to various degradation stress conditions and kinetic degradations.
关键词： Spectrofluorimetry,Teicoplanin,Silver nanoparticles,Metal-enhanced fluorescence,Human plasma analysis
更新于2025-09-23 15:23:52
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Physico-mechanical and antimicrobial properties of an orthodontic adhesive containing cationic curcumin doped zinc oxide nanoparticles subjected to photodynamic therapy
摘要： Background: Potential complications on the crown level during fixed orthodontic procedures are white spot, enamel demineralization and the tooth decay. This study evaluated the antimicrobial properties of an orthodontic adhesive incorporating cationic curcumin doped zinc oxide nanoparticles (cCur/ZnONPs), which can have the highest concentration of cCur/ZnONPs and shear bond strength (SBS) value simultaneously, on the against cariogenic bacteria including Streptococcus mutans, Streptococcus sobrinus, and Lactobacillus acidophilus. Materials and methods: Following synthesis and confirmation of cCur/ZnONPs, SBS and adhesive remnant index (ARI) of the test adhesives containing cCur/ZnONPs (1.2, 2.5, 5, 7.5, and 10% wt.) were measured using universal testing machine and stereomicroscope, respectively. After continuously rinsed (up to 180 day), the residual antimicrobial ability of modified adhesives which can have the highest concentration of cCur/ZnONPs and SBS value simultaneously were determined by disc agar diffusion (DAD), biofilm formation inhibition, and metabolic activity assays following photo-activation using light-emitting diode (LED) for 5 min against multispecies cariogenic biofilm-producing bacteria. Results: Adhesive with 7.5% wt. cCur/ZnONPs showed the highest concentration of cCur/ZnONPs and SBS value (14.89 ± 3.26 MPa, P < 0.05) simultaneously. No significant differences in ARI scores were found between the modified adhesive and control (Transbond XT without the cCur/ZnONPs). 7.5% wt. cCur/ZnONPs following photo-activation was not colonized by the test microorganisms and suppressed 100% metabolic activity of the test microorganisms up to 90 day compared to the control group (cCur/ZnONPs free LED irradiation; P < 0.05). In DAD assay, the reduction of photodynamic disinfection of the 7.5% wt. cCur/ZnONPs against test bacteria was positively associated to the time, in such a way that it was decreased significantly after 60 day. From days 120 onwards, microbial biofilm formation and metabolic activity was progressively increased on 7.5% wt. cCur/ZnONPs adhesive discs compared to the control group (cCur/ZnONPs free LED irradiation). Conclusions: Our findings highlight the photo-activated 7.5% wt. cCur/ZnONPs can serve as an orthodontic adhesive additive for control the cariogenic multispecies biofilm, and also to reduce their metabolic activity.
关键词： Cariogenic bacteria,Orthodontic adhesive,Antimicrobial photodynamic therapy,Cationic curcumin,Zinc oxide nanoparticles
更新于2025-09-23 15:23:52
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Surface Plasmon Resonance Based Highly Selective Fiber Optic Dopamine Sensor Fabricated Using Molecular Imprinted GNP/SnO <sub/>2</sub> Nanocomposite
摘要： Fabrication and characterization of a highly selective fiber optic surface plasmon resonance-based dopamine sensor using molecular imprinted graphene nanoplatelets/tin oxide (SnO2) nanocomposite have been reported. The synthesis of sensing layer has been carried out using a series of optimizations and morphological studies. The effectiveness of the sensing layer over other possible probe designs has been proved by performing control experiments for a dopamine concentration range covering the suggested level of dopamine for human being. The limit of detection (LOD) of the sensor evaluated is 0.031 μM, which is lower than the LOD values of various dopamine sensors fabricated using different methods. The specificity of the sensor for dopamine has been confirmed by performing experiments using various interferands while the stability and reusability of the sensor probe have been checked by performing experiments repeatedly for a long period of time. Apart from high sensitivity, low LOD, and fast response, the sensor can be used for remote sensing and online monitoring of dopamine.
关键词： surface plasmon resonance,SnO2 nanoparticles,optical fiber sensor,GNP/SnO2 nanocomposite,graphene,Dopamine,molecular imprinting
更新于2025-09-23 15:23:52
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Combination of Pd loading and electron beam irradiation for superior hydrogen sensing of electrospun ZnO nanofibers
摘要： We evaluated the hydrogen gas-sensing characteristics of Pd-loaded (0.1, 0.3, 0.6, and 1 wt%) ZnO nano?bers prepared by a facile electrospinning technique and the e?ect of di?erent electron beam (e-beam) doses (50, 100, and 150 kGy) on sensing performance. The sensor loaded with 0.6 wt% Pd had the highest response to hydrogen among the Pd-loaded sensors. The sensor irradiated with 150 kGy had the high response (Ra/Rg) of 74.7–100 ppb of H2 at 350 °C. Metallization e?ects in ZnO, the formation of structural defects due to e-beam irradiation, the catalytic activity of Pd, and the presence of ZnO–Pd heterojunctions were the main factors yielding high sensitivity towards H2. The strategy of combining e-beam irradiation and Pd loading to enhance H2 sensing can be applied to realize reliable gas sensors and the widespread use of hydrogen as a green energy alternative to fossil fuels.
关键词： H2,Electron beam irradiation,Gas sensors,ZnO nano?bers,Pd nanoparticles
更新于2025-09-23 15:23:52
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Image of O2 dynamics released by oak wood submerged in model wine with nanoparticle sensors
摘要： Oxidation of wine while in contact with oak wood is a well-known fact and recognized as an important process in wine ageing. The slow and continuous di?usion of oxygen from the oak wood entrapped in its porosity occurs and encourages the reactions usually related with wine aging. In this work, oxygen sensitive particles were used to study the oxygen dynamics from di?erent anatomical regions of the oak wood and simultaneously the oxygen increasement because of the deoxygenation of the wood and the oxygen depletion due to its consumption by the tannins and other compounds released from the wood. To this end, core-shell-type PSPVP nanoparticles stained with Macrolex Fluorescence Yellow and Pt-TFPP were employed as reference and oxygen-sensitive particles respectively. Moreover, a Guppy Pro RGB camera was employed to monitor the particles performing ratiometric oxygen imaging, using the green and red channels to acquire the light emitted from the reference and the oxygen-sensitive particles respectively. Because the volume of nanosensors corresponding to each surface unit is very di?erent from that of the wood region, di?erent exposure times were chosen to obtain the images at each of the times. The results show the wood degassing process during the ?rst minutes of the experiment, the oxygen release from di?erent structural elements of the wood, its consumption by the released compounds from wood and the di?usion of the oxygen through the model wine.
关键词： Nanoparticles,Wine,Oxygen consumption,Optical oxygen imaging,Oak wood
更新于2025-09-23 15:23:52
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Miniaturized electrochemiluminescent biochip prepared on gold nanoparticles-loaded mesoporous silica film for visual detection of hydrogen peroxide released from living cells
摘要： Au nanoparticles (NPs) has been widely used for the detection of intracellular H2O2 to enhance the electron transfer process. But AuNPs are easy to aggregate in the live cells environment. Herein we report a rapid, reliable and low-cost electrochemiluminescent (ECL) biochip integrated by AuNPs-loaded mesoporous silica film (MSF) to detect H2O2 released by macrophage cells. The MSF was employed as a template to load AuNPs within the nanochannels to avoid aggregation. H2O2 could be catalyzed by AuNPs to promote the ECL reaction of luminol molecules in solution. The ECL intensity was significantly enhanced, and the peak potential was negatively shifted by 400 mV due to the excellent electrocatalytic ability of AuNPs. The integrated biochip demonstrated good reproducibility, with a wide linear range of 0.1–200 μM and an LOD of 25.3 nM. The reliability was evaluated by applying for the assessment of antioxidant activity of resveratrol using RAW 264.7 macrophage model. The AuNPs-loaded MSF integrated biochip can be easily adapted to the development of improved devices in biosensing, lab-on-a-chip, and nanofluidic systems.
关键词： Gold nanoparticles,Biochip array,Electrochemiluminescence,Reactive oxygen species,Mesoporous silica
更新于2025-09-23 15:23:52
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Flexible bipyramid-AuNPs based SERS tape sensing strategy for detecting methyl parathion on vegetable and fruit surface
摘要： In present study, a simple and effective surface enhanced Raman scattering (SERS) tape sensing strategy based on bipyramid gold nanoparticles (BP-AuNPs) was developed for sensitive and selective monitoring of methyl parathion residues on vegetable and fruit surface through a simple sampling-and-detection procedure. BP-AuNPs were synthesized by a seed meditated method and systematically characterized using transmission electron microscope (TEM), UV-vis spectrometer, selected area electron diffraction (SAED) and X-Ray diffraction (XRD). The as-synthesized BP-AuNPs showed excellent Raman enhancement effect because their sharp ends provide high electric field enhancement, as revealed by electrodynamic simulations. Also the localized plasmon resonance of the BP-AuNPs matches well with the NIR (785 nm) laser of portable Raman spectrometer, thus maximizing the Raman signal. Two standard SERS probe molecules Rhodamine 6G (R6G) and crystal violet (CV) were first used to prove the effective SERS detection on the model solid (silicon) surface using the BP-AuNPs based tape sensing strategy. The SERS sensor was then applied to detect methyl parathion on surface of cucumbers, tomatoes and apples. A detection limit of ng/cm2 level was easily achieved. The studies have demonstrated that the BP-AuNPs based SERS tape sensing platform can be potentially used to monitor the trace amount of chemical hazards for food and agricultural safety.
关键词： tape sensor,surface enhanced Raman scattering,methyl parathion,bipyramid gold nanoparticles
更新于2025-09-23 15:23:52
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Quantification of Glucose via in situ Growth of Cu2O/Ag Nanoparticles
摘要： The monitoring of glucose levels in blood is extremely important for the effective control of diabetes. Nanomaterial-based approaches for the quantification of glucose typically require two steps: material preparation and the actual glucose measurement. Herein, we report a single-step method that combines these functions via the in situ growth of Cu2O/Ag nanoparticles (NPs). Mechanistically, we use glucose itself to reduce Cu2+ and Ag+ ions that are stabilized with 3-mercaptopropionic acid (3-MPA) and bovine serum albumin (BSA) under alkaline conditions to form Cu2O/Ag NPs and produce a color change in solution due to plasmonic resonance at 400 nm, which can be related back to the concentration of glucose. We study several factors in this reaction, including the molar ratios of the metal ions and 3-MPA, the reaction time, and the temperature to control the synthesis of the Cu2O/Ag NPs and thus their sensitivity toward glucose. Introducing BSA into the system is a key factor for the quantification of glucose in blood without pretreatment, improving the probe’s limit of detection and reducing the sample volumes to 1 μL. This colorimetric assay based on Cu2O/Ag NPs exhibits excellent sensitivity and specificity toward glucose, and a linear relationship with glucose concentrations ranging from 15 to 300 μM and a limit of detection of 9.2 μM. As proof of concept, we demonstrated that the Cu2O/Ag NP probes could successfully detect glucose in two representative blood samples by neglecting interferences from various common species, demonstrating the potential of this technique in point-of-care analysis.
关键词： plasmonic resonance,3-mercaptopropionic acid,bovine serum albumin,silver nanoparticles,glucose quantification,Cu2O
更新于2025-09-23 15:23:52
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Facile synthesis of silver-polypyrrole nanocomposites: Use of ionic liquid as solvent and template
摘要： In this study we show a facile method to synthesize nanocomposites of PPY and silver from the direct oxidation of pyrrole by silver cations from silver bis(trifluoromethanesulfonyl)imide (AgTf2N), using 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMImTf2N) as solvent and template to the hybrid material formation. Some synthesis parameters, such as initial concentration of the oxidant agent (C) and oxidant-to-monomer molar ratio (K) were varied in order to evaluate their influence on the final product. The black powders obtained, according to the characterization results, contain doped polypyrrole and silver nanoparticles amounts ranged from 26 to 36 wt%, depending on the C and K parameters utilized in the syntheses. The measured electrical conductivity values of the samples were in the order of 10-2 S cm-1, which classify the hybrid materials as semiconductor. By adding the HTf2N acid to the synthesis, a sample with more elevated electrical conductivity (0.12 S cm-1) was obtained, caused by the higher protonation degree of the oxidized units in the polymer.
关键词： Polypyrrole,Nanocomposite,Ionic liquids,Silver nanoparticles
更新于2025-09-23 15:23:52