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Generation of dark solitons in erbium-doped fiber laser based on black phosphorus nanoparticles
摘要： We demonstrate the generation of dark solitons (DSs) in erbium-doped fiber (EDF) laser based on black phosphorus nanoparticles (BPNPs) for the first time. The side-polished fiber deposited with BPNPs is embedded into the laser to enhance the birefringence and nonlinearity of the laser cavity. In the paper, the saturable absorption property of BPNPs with an optical modulation depth of 5.7% and a saturable intensity of 21.7 MW/cm2 are experimentally illustrated. After inserting the BPNPs saturable absorber (SA) into EDF laser, the DSs with repetition rate of 14.68 MHz are obtained at a pump power of 90 mW. Our results prove that the BPNPs are the promising candidate materials for generating DSs in EDF laser.
关键词： Side-polished fiber,Dark solitons,Black phosphorus nanoparticles
更新于2025-11-28 14:24:03
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Fe <sub/>3</sub> O <sub/>4</sub> nanoparticles as the saturable absorber for a mode-locked fiber laser at 1558 nm
摘要： We demonstrated a mode-locked erbium doped fiber laser (EDFL) operating at 1558 nm by exploiting ferroferric-oxide nanoparticles (FONPs) as the saturable absorber (SA) material. FONPs, with an average diameter of ~20 nm, were prepared by a thermal decomposition method, then mixed with sodium carboxymethylcelluose to form an FONP film. The FONP SA was fabricated through a sandwiched FONP film between two fiber connectors. By inserting the FONPs SA into an EDFL cavity pumped by a 980 nm laser diode, stable passive mode-locking was achieved with a threshold pump power of ~120 mW. The obtained mode-locked laser had a central wavelength of ~1558 nm, a spectral bandwidth of ~0.8 nm, a pulse width of ~4.35 ns, and a repetition rate of ~37.32 MHz. Furthermore, a maximum average power of ~17 mW was obtained for a pump power of 340 mW. To the best of our knowledge, this is the first time that it has been demonstrated that FONPs can be used for constructing mode-locked fiber lasers.
关键词： mode-locked,fibre laser,Fe3O4 nanoparticles,saturable absorber (SA)
更新于2025-11-28 14:23:57
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Hydrogen peroxide detection with a silver nanoparticle grating chip fabricated by plasmonic plating
摘要： An optical detection of hydrogen peroxide (H2O2) is proposed, using grating structures of silver nanoparticles (AgNPs). Periodic line structures of AgNPs are deposited on a gold nanoparticle (AuNP)-decorated glass plate using an interference exposure with a green laser beam, based on the plasmonic plating method. This AgNP grating chip diffracts incident light, and the diffraction efficiency is dependent on the amount of AgNPs. By applying a drop of H2O2 solution onto the chip, the diffraction intensity declines due to the autocatalytic decomposition of AgNPs. A portable measurement system of the diffraction intensity change is constructed, and the H2O2 detection in the concentration range 6.7 – 668 μmol/L is performed in 2 min simply by dropping the H2O2 solution onto the substrate.
关键词： silver nanoparticles,plasmonic plating,optical sensor,hydrogen peroxide detection,diffraction grating
更新于2025-11-25 10:30:42
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Surface plasmon resonance of naked gold nanoparticles for photodynamic inactivation of Escherichia coli
摘要： Although antimicrobial photothermal inactivation of naked gold nanostructures using powerful pulsed lasers has been previously studied, there are little reports about their photodynamic antimicrobial properties under the irradiation of low-power density continuous wave lasers. Therefore, this paper attempts to fill this gap. In this paper, we studied the effects of a 40-mW/cm2 continuous Nd:Yag laser at 532 nm and naked gold nanoparticles on inactivation of Escherichia coli ATCC25922. According to our results, 60 min illumination using the Nd:Yag laser caused a 0.15log reduction of the bacterial viability. Also, the employed gold nanoparticles with an average size of 15 nm were toxic to E. coli ATCC 25922 in the concentrations above 0.5 μg/ml. In addition, synergistic effects of 0.5 μg/ml gold nanoparticles and the light illumination led to a 2.43log reduction of the viability after a 60-min exposure and did not show any considerable temperature change on the media. The obtained results were justified based on the possible interaction mechanisms of low-power density laser lights and naked gold nanoparticles. The paper is proposed as a prelude for future research about localized inactivation of resistant pathogens with minimum side effects on neighbor tissues.
关键词： Photodynamic inactivation,Gold nanoparticles,Low-power density laser,Surface plasmon resonance
更新于2025-11-25 10:30:42
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Gold-tagged Polymeric Nanoparticles with Spatially Controlled Composition for Enhanced Detectability in Biological Environments
摘要： Organic nanoparticles offer the advantage of high biocompatibility for biomedical applications but suffer frequently from poor visibility in biological environments. While fluorescent-labeling is convenient and allows for fast and extensive histological analysis, fluorescence imaging and quantitative analysis are limited by low resolution and significantly hindered by tissue auto-fluorescence. Labeling of polymeric nanoparticles with an additional gold tag would allow for high resolution imaging via transmission electron microscopy (TEM) and for quantification of particles by inductively coupled plasma optical emission spectrometry (ICP-OES). However, spatially uncontrolled gold-tagging can cause significant fluorescence quenching. To overcome this restraint, 2.2 nm gold nanoparticles were introduced at the interface between the hydrophobic fluorophore-loaded core and the hydrophilic shell of polymeric nanoparticles. Due to the small size of gold labels and the spatially controlled stratified composition of hybrid nanoparticles, fluorescence quenching by gold tags was minimized to 15.1%, allowing for concomitant detection of both labels via optical microscopy after enhancement of the gold tags. Multilayered hybrid nanoparticles exhibited outstanding detectability by transmission electron microscopy, even without additional sample staining. Furthermore, they were capable of producing remarkable image contrast inside cells after gold or silver enhancement. The interfacial gold layer increased the hydrodynamic particle size only marginally from 71.8 to 89.5 nm and had no negative impact on biocompatibility in vitro. The gold content (0.75% m/m) is sufficiently high for future quantification in tissues after systemic administration. With their clean-cut structure and superior detectability, multilayered hybrid nanoparticles constitute an outstanding blueprint and a precious tool for the development of nanomedicines.
关键词： gold,polymeric nanoparticles,hybrid,TEM,PLGA,contrast agent
更新于2025-11-21 11:24:58
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Fabrication of gold-silver core-shell nanoparticles for performing as ultrabright SERS-nanotags inside human ovarian cancer cells
摘要： This paper presents the fabrication and characterization of new gold-silver core-shell nanoparticles labeled with para-mercaptobenzoic acid (4MBA) molecules and demonstrates their use as SERS-nanotags with ultra-bright traceability inside cells and ability to convey spectrally-coded information about the intracellular pH by means of Surface-Enhanced Raman Spectroscopy (SERS). Unlike to previous reported studies, our fabrication procedure includes in the first step the synthesis of chitosan-coated gold nanoparticles as a seed material with subsequent growing of a silver shell. The bimetallic core-shell structure is revealed by transmission electron microscopy (TEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray elemental mapping (EDX) and the presence of two interacting localized surface plasmon resonance (LSPR) modes in UV-Vis extinction spectrum. The high SERS activity and sensitivity of as fabricated 4MBA-chit-Au-AgNPs nano-constructs to different pH in solution is investigated under 532 and 633 nm laser lines excitation. Next, in view of future studies in cancer diagnosis, the in vitro antiproliferative effects of SERS-nanotags against human ovarian adenocarcinoma cells (NIH:OVCAR-3) are evaluated. The capacity to operate as bright SERS nanotags with precise localization at a single cell level as well as intracellular pH indicators is clearly demonstrated by performing cell imaging under scanning confocal Raman microscopy.
关键词： core-shell nanoparticles,pH sensors,ovarian cancer cells,chitosan,SERS tags
更新于2025-11-21 11:24:58
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Femtosecond Spectroscopy of Au Hot-Electron Injection into TiO2: Evidence for Au/TiO2 Plasmon Photocatalysis by Bactericidal Au Ions and Related Phenomena
摘要： In the present work, we provide evidence for visible light irradiation of the Au/TiO2 nanoparticles’ surface plasmon resonance band (SPR) leading to electron injection from the Au nanoparticles to the conduction band of TiO2. The Au/TiO2 SPR band is shown to greatly enhance the light absorption of TiO2 in the visible region. Evidence is presented for the light absorption by the Au/TiO2 plasmon bands leading to the dissolution of Au nanoparticles. This dissolution occurs concomitantly with the injection of the hot electrons generated by the Au plasmon into the conduction band of TiO2. The electron injection from the Au nanoparticles into TiO2 was followed by femtosecond spectroscopy. The formation of Au ions was further confirmed by the spectral shift of the transient absorption spectra of Au/TiO2. The spectral changes of the SPR band of Au/TiO2 nanoparticles induced by visible light were detected by spectrophotometer, and the morphological transformation of Au/TiO2 was revealed by electron microscopy techniques as well. Subsequently, the fate of the Au ions was sorted out during the growth and biofilm formation for some selected Gram-negative bacteria. This study compares the bactericidal mechanism of Au ions and Ag ions, which were found to be substantially different depending on the selected cell used as a probe.
关键词： electron injection,antibacterial effects,genes expression,DNA repair,quorum sensing,plasmon photocatalysis,biofilms,gold nanoparticles,porins
更新于2025-11-21 11:20:42
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Excimer Laser Induced Spatially Resolved Formation and Implantation of Plasmonic Particles in Glass
摘要： Metallic nanoparticles are important building blocks for plasmonic applications. The spatially defined arrangement of these nanoparticles in a stable glass matrix is obtained here by nanosecond excimer laser irradiation at 193 nm. Two approaches are addressed: (1) Laser induced formation of particles from a dopant material pre-incorporated in the glass, (2) Particle formation and implantation by irradiation of material pre-coated on top of the glass. Silver nanoparticles are formed inside Ag+ doped glass (method 1). Gold nanoparticles are implanted by irradiation of gold coated glass (method 2). In the latter case, with a few laser pulses the original gold film disintegrates into particles which are then embedded in the softened glass matrix. A micron sized spatial resolution (periodic arrangements with 2 μm period) is obtained in both cases by irradiating the samples with an interference beam pattern generated by a phase mask. The plasmonic absorption of the nanoparticles leads to a contrast of the optical density between irradiated and non-irradiated lines of up to 0.6.
关键词： interference pattern,laser implantation,plasmonic nanoparticles
更新于2025-11-21 11:18:25
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Enhanced surface plasmon resonance (SPR) signals based on immobilization of core-shell nanoparticles incorporated boron nitride nanosheets: Development of molecularly imprinted SPR nanosensor for anticancer drug, etoposide
摘要： An effective SPR nanosensor based on core-shell nanoparticles (Ag@AuNPs) incorporated hexagonal boron nitride (HBN) nanosheets and molecularly imprinted polymer (MIP) was presented for etoposide (ETO) detection. Scanning electron microscope (SEM), transmission electron microscope (TEM), x-ray diffraction (XRD) method, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) methods were utilized for all characterizations of nanomaterials and polymer surfaces. ETO imprinted SPR nanosensor based on Ag@AuNPs-HBN nanocomposite was developed in the presence of poly(2-hydroxyethyl methacrylate-methacryloylamidoglutamic acid) [p(HEMA-MAGA)]. The results of the study have revealed that 0.001 - 1.00 ng mL-1 (1.70×10-12 - 1.70×10-9 M) and 0.00025 ng mL-1 (4.25×10-13 M) were found as the linearity range and the detection limit (LOD). Furthermore, the prepared SPR nanosensor was examined in terms of stability, repeatability and selectivity. Finally, the imprinted SPR nanosensor was applied to the urine samples having high recovery.
关键词： Etoposide,Core-shell nanoparticles,Hexagonal boron nitride,Urine sample,Molecular imprinted nanosensor
更新于2025-11-21 11:18:25
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CHARACTERIZATION AND ANTIBACTERIAL ACTIVITY OF ZnO NANOPARTICLES SYNTHESIZED BY CO PRECIPITATION METHOD
摘要： Objective: In the present study the antibacterial activity of zinc oxide (ZnO) nanoparticles was investigated against gram negative (Escherichia coli and Proteus vulgaris) and gram positive (Staphylococcus aureus and Streptococcus mutans) organisms. Methods: The synthesis of ZnO nanoparticles was carried out by co-precipitation method using zinc sulfate and sodium hydroxide as precursors. These nanoparticles were characterized by XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared Radiation), UV-Visible spectroscopy and SEM (Scanning Electron Microscope) with EDX (Energy Dispersive X-ray analysis). As well as antibacterial activity and minimum inhibitory concentration of the nanoparticles were carried out by agar well diffusion method and broth dilution method respectively against gram negative (Escherichia coli and Proteus vulgaris) and gram positive (Staphylococcus aureus and Streptococcus mutans) bacteria. Results: The average crystallite size of ZnO nanoparticles was found to be 35 nm by X-ray diffraction. The vibration bands at 450 and 603 cm-1 which were assigned for ZnO stretching vibration were observed in FTIR spectrum. The optical absorption band at 383 nm was obtained from UV-Visible spectrum. Spherical shape morphology was observed in SEM studies. The antibacterial assay clearly expressed that E. coli showed a maximum zone of inhibition (32±0.20 mm) followed by Proteus vulgaris (30±0.45 nm) at 50 mg/ml concentration of ZnO nanoparticles. Conclusion: Zinc oxide nanoparticles have exhibited good antibacterial activity with gram negative bacteria when compared to gram positive bacteria.
关键词： EDX,SEM,MIC,FTIR,UV-VISIBLE spectroscopy,XRD,ZnO nanoparticles
更新于2025-11-21 11:18:25