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Green Synthesis of Silver Nanoparticles Contained in Centrifuged Citrus Oil and Their Thermal Diffusivity Study by Using Thermal Lens Technique
摘要： Thermal lens spectrometry is a very sensitive non-evasive technique that offers a reliable alternative for measurement of materials thermal diffusivity. In this work, silver nanoparticles from leaf extract of Azadirachta Indica (neem) and silver nitrate were synthesized using reverse micelle microemulsion. The thermal lens technique was used to obtain the thermal diffusivity of silver nanoparticles emulsions contained in grapefruit centrifuged oil. Thermal diffusivity of silver nanoparticles was measured as a function of concentration. The results showed an increase in the thermal diffusivity of the nanoemulsion with the increase in nanoparticle concentration. Also, the nanoemulsion exhibited improved thermal diffusivity in comparison with the base fluid. Transmission electron microscopy was used to determine the morphology of the nanoparticles. Results showed that they were spherical in shape with an average size of 35 nm. UV–Vis spectrometry was used to observe the absorption spectra of nanoparticles plasmon. This study has future applications in dermatological therapies against allergies, in tissue regeneration and in the cosmetic area, due to silver nanoparticles antibacterial properties.
关键词： Thermal diffusivity,Nanoparticles,Colloids,Thermal lens
更新于2025-09-23 15:21:01
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Silver Soret Nanoparticles for Femtomolar Sensing of Glutathione in a Surface Plasmon-Coupled Emission Platform
摘要： Surface plasmon-coupled emission (SPCE) has emerged as an interdisciplinary, versatile sensing platform due to its highly directional, solid-state and polarized emission. Here, we report the distinct properties rendered by Ag-Soret Colloids (Ag-SCs) such as nanovoids and nanocavities to observe 104-fold enhancement in emission intensity of omnidirectionally radiating emitter dipoles. Unlike earlier reports utilizing templated Ag-nanoparticles in spacer or cavity architectures, here we employ template-free, linker-less Ag-SCs. Purcell factor (PF - maximum of 120.6) obtained using the finite-difference time-domain (FDTD) simulations for soret nanocavities are in excellent agreement with the trend in emission enhancements obtained experimentally. Thermal gradient created by adiabatic cooling of Ag nanoparticles (AgNPs) drives their thermo-diffusion resulting in monodisperse nanoparticle assemblies (Ag-SCs). In addition, we report an extended-cavity architecture with Ag-SCs, as a novel pseudo-metal-dielectric-metal (p-MDM) interface, for achieving 80-fold SPCE. This study also features the unique properties of Ag-SCs as interfacial nanomaterials in SPCE platform to achieve femtomolar detection of glutathione (GSH). The quenching of fluorescence from alizarin red S-boric acid (ARS-BA) complex upon addition of Cu2+ ions and the dequenching upon GSH addition studied with Ag-SCs as spacer layer remarkably increased the sensitivity of the analyte. The uniform and intense electromagnetic field-confinement provided by these intricate architectures and hybrid interfaces, along with its ease of fabrication and versatility for variety of analytes, is critical to achieve augmented SPCE. This is accomplished without compromising on the reliability of detection as demonstrated with the use of a cellphone camera, CIE color space and luminosity plots for the turn-on fluorescence. The emission images were acquired using an android phone camera by aligning it with its angular emission, making it amenable for point-of-care diagnostics.
关键词： Soret colloids,Surface plasmon-coupled emission,spacer engineering,smartphone-based detection,template-free approach,fluorescence enhancement,glutathione sensing
更新于2025-09-23 15:19:57
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Luminescent switch of polysaccharide-peptide-quantum dot nanostructures for targeted-intracellular imaging of glioblastoma cells
摘要： Glioblastoma multiforme (or GBM) remains one of the deadliest types of brain cancers. Nanomedicine can offer new strategies for fighting against GBM by combining the earliest possible diagnosis with multiple options of therapy. Hence, in this work, cysteine (Cys) and Poly-L-Arginine (PA) moieties were grafted to carboxymethyl cellulose (CMC) to produce biofunctional hybridized macromolecules (CMC_Cys and CMC_PA). These polymer-peptide conjugates were used simultaneously as surface capping ligands and biofunctional modifiers for the synthesis of ternary Ag-In-S (AIS) quantum dots (AIS QDs) via a green chemical process in aqueous medium and room temperature. These core-shell supramolecular nanostructures (AIS@CMC, AIS@CMC_Cys, and AIS@CMC_PA) were tested as fluorescent nanoprobes (“OFF-ON”) for targeted bioimaging and in vitro intracellular tracking of glioblastoma cells (GBM, U-87 MG). The nanosystems were characterized for physicochemical, structural, and morphological properties by NMR, UV–Vis, PL, FTIR, TEM/EDX/SAED, zeta potential, and DLS. Cytocompatibility was evaluated by mitochondrial activity assay, and confocal laser scanning microscopy was performed for investigating the kinetics of cellular uptake. The grafting caused a noticeable reduction of surface charges, associated with a drastic photoluminescence quenching (i.e., “OFF-state”) of AIS@CMC_Cys and AIS@CMC_PA compared to unmodified AIS@CMC. This effect was smartly applied for bioimaging GBM cells and for monitoring the internalization process by intracellular tracking, which underwent strong “de-quenching” at very early incubation times (~5 min). Thus, these novel hybrid nanocolloids produced via eco-friendly scalable aqueous process show potential as responsive fluorescent bioprobes for bioimaging and tracking intracellular pathways and mechanisms as a powerful weapon for fighting against brain cancer cells.
关键词： nanoconjugates,nanomaterials,colloids,polymer-semiconductor nanoprobes,supramolecular nanoparticles,fluorescent nanoparticles
更新于2025-09-23 15:19:57
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Aggregate dispersions to enhance the intrachain order in surfactant-stabilized aqueous colloids of poly(3-hexylthiophene)
摘要： Aqueous colloids of conjugated polymers (CP), such as poly(3-hexylthiophene) (P3HT), are an attractive alternative for processing CP-based materials because (1) the microstructure of the conjugated polymers can be optimized during the formation of the colloid and (2) this method can significantly reduce the amount of hazardous organic solvents used during manufacturing. This investigation addresses the optimization of the polymer structure by studying the intrachain order of P3HT aggregates pre-assembled in mixtures of chloroform (CF) with dichloromethane (DCM) and subsequently dispersed in aqueous solutions of the surfactant sodium dodecyl sulfate (SDS) using a mini-emulsion method. Compared to an amorphous solution of P3HT, the observed intrachain order of P3HT in the colloids is much higher when using aggregate dispersions pre-assembled in the CF:DCM mixtures. Similar results are observed for aggregate dispersions of a benchmark organic photovoltaic system composed of P3HT and the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM), but in this case the intrachain order of P3HT in the P3HT:PCBM colloids is anomalously higher than the pure P3HT colloids. Atomic force microscopy (AFM) imaging reveals changes in the dominant structural motifs and morphology of the colloidal P3HT films, but not in a way that correlates with films processed from the aggregate dispersions.
关键词： Emulsion,Colloids,Poly(3-hexylthiophene),Aggregates,PCBM
更新于2025-09-19 17:15:36
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Light-Triggered, Spatially Localized Chemistry by Photoinduced Electron Transfer
摘要： It is of immense interest to exert spatial and temporal control of chemical reactions. It is now demonstrated that irradiation can trigger reactions specifically at the surface of a simple colloidal construct, obtained by adsorbing polyethyleneimine on fluorescent colloidal particles. Exciting the fluorescent dye in the colloid affords photoinduced electron transfer to spatially proximal amine groups on the adsorbed polymer to form free radical ions. It is demonstrated that these can be harnessed to polymerize acrylic acid monomer at the particle surface, or to break up colloidal assemblies by cleaving a cross-linked polymer mesh. Formation of free radical ions is not a function of the size of the colloid, neither is it restricted to a specific fluorophore. Fluorophores with redox potentials that allow photoinduced electron transfer with amine groups show formation of free radical ions.
关键词： temporal control,fluorescence,colloids,spatial control,photoinduced electron transfer
更新于2025-09-19 17:15:36
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Flow Behaviors of Polymer Colloids and Curing Resins Affect Pore Diameters and Heights of Periodic Porous Polymer Films to Direct Their Surface and Optical Characteristics
摘要： Manipulation of both pore diameters and heights of two-dimensional periodic porous polymer films is important to extensively control their characteristics. However, except for using different sized colloid templates in replication methods, effective method that tunes these factors has rarely been reported. We find both parameters are controllable by adjusting the flow behaviors of polystyrene colloids and curing resin precursors while preparing phenolic resin and polydimethylsiloxane periodic porous films by embedding their precursors into colloidal crystal monolayers. We adjust the flow behaviors by either varying film preparation temperatures (≥ glass transition temperature of polystyrene) or using the precursors mixed with different amounts of a solvent that renders the colloids viscous. Consequently, the pore diameters and film heights change by 36–56% and 56–84%, respectively. Such modulation results in the change in height to dimeter ratios and the areal fractions of resins at air-film interfaces, thereby significantly changing the water contact angles on these surfaces and their photonic characteristics. This straightforward method does not require additional steps, differently sized colloids, or different amounts of precursors for these parameter controls.
关键词： polymer colloids,Periodic porous polymer films,flow behaviors,curing resins,simultaneous height and pore controls,replication method
更新于2025-09-19 17:15:36
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ZnO colloids and ZnO nanoparticles synthesized by pulsed laser ablation of zinc powders in water
摘要： ZnO nanoparticles (NPs) were synthesized by pulsed laser ablation of zinc powders suspending in deionized water. The synthesized ZnO NPs were characterized for morphology, structure and optical properties. The ZnO NPs have irregular shapes sized in 10–50 nm and possess a wurtzite structure with polycrystallinity in nature, and grew without a preferential orientation. The supernatant solutions obtained by laser ablation of zinc powders in water exhibit the typical optical absorption edge of wurtzite ZnO near 380 nm and emit a photoluminescence composed of a narrow ultraviolet peak and a broad visible band, characteristics of the near-band-edge emission and the deep-level defects related emission of ZnO, respectively. The formation of ZnO NPs was further confirmed by structural and optical characterization performed for the aggregated ZnO NPs obtained by drop-casting the ZnO colloidal solutions onto Si wafers. And the effects of annealing in N2 on the structure and photoluminescence of the ZnO NPs transferred on Si were also examined.
关键词： ZnO,Laser ablation in liquids,Nanoparticles,Colloids,Deep-level defects
更新于2025-09-19 17:13:59
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Soft Plasmonic Assemblies Exhibiting Unnaturally High Refractive Index
摘要： The increases in refractive indices (n) of materials are crucial for transformative optical technologies. With the progress of monolithic lithography, large advances have been achieved with several semiconductors, including silicon, germanium, and gallium arsenide, which generally provide higher n of ～4.0 compared to those of other elements. Nevertheless, above this upper limit of naturally available n, light?matter interactions could be unprecedentedly expanded, which in turn enriches the possible applications. Here, we present a soft self-assembly of polyhedral Au colloids as a promising method to achieve unnaturally high n values. The interfacial assembly of Au nanocubes provides n of 6.4 at the resonant wavelength (near-infrared) and 4.5 in the o?-resonant regimes (mid-infrared), which have not been previously reached. The soft self-assembly of polyhedral Au colloids can be a versatile and highly e?ective route for the fabrication of optical metamaterials with unnaturally high n values.
关键词： Metamaterials,Self-assembly,Plasmonic colloids,E?ective medium theory,Refractive index
更新于2025-09-19 17:13:59
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Light-induced Polymer Response Through Thermoplasmonics Transduction in Highly Monodisperse Core-Shell-Brush Nanosystems
摘要： Smart nanosystems that transduce external stimuli to physical changes are an inspiring challenge in current materials chemistry. Hybrid organic-inorganic materials attract great attention due to the combination of building blocks responsive to specific external solicitations. In this work, we present a sequential method for obtaining an integrated core-shell-brush nanosystem that transduces light irradiation into a particle size change through a thermoplasmonic effect. We first synthetize hybrid monodisperse systems made up of functionalized silica colloids covered with controllable thermo-responsive Poly(N-isopropylacrylamide), PNIPAm, brushes, produced through radical photopolymerization. This methodology was successfully transferred to Au@SiO2 nanoparticles, leading to a core-shell-brush architecture, in which the Au core acts as a nano-source of heat; the silica layer, in turn, adapts the metal and polymer interfacial chemistries and can also host a fluorescent dye for bioimaging. Upon green LED irradiation, a light-to-heat conversion process leads to the shrinkage of the external polymer layer, as proven by in situ DLS. Our results demonstrate that modular hybrid nanosystems can be designed and produced with photo-thermo-physical transduction. These remote-controlled nanosystems present prospective applications in smart carriers, responsive bioscaffolds or soft robotics.
关键词： photothermal effect,hybrid materials,in-situ DLS,UV-photo induced polymerization,core-shell-brush colloids,Smart nanosystems
更新于2025-09-19 17:13:59
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Electrospraying the Triblock Copolymer SEBS: The Effect of Solvent System and the Embedding of Quantum Dots
摘要： This work reports on ABA triblock copolymer microparticles encoded with CdSe/CdS core–shell quantum dots (QDs) realized by electrospraying. This method allows for simple but efficient embedding of QDs in polymer beads while retaining the fluorescent properties of the original QDs. The creation of poly(styrene-ethylene-butylene-styrene) (SEBS) monodisperse spherical microparticles with a tunable morphology for applications of the final QD-loaded product is attainable via solvent variation. By varying the selectivity of the solvent for one of the distinct blocks in the polymer, the final particle morphology can be selectively altered while maintaining the same overall process conditions, allowing to tailor the particles from homogeneously flat in a nonselective solvent to dense spherical particles in an endblock selective solvent system. The mechanism responsible for this transition in morphology can be related to differences in mass transfer in the droplets and thus solvent evaporation rates arising from particular microphase structures. Finally, fluorescence characteristics of the final QD-embedded polymer particles and photodegradation stability are investigated by spectrophotometry and are compared to the temporal evolution of the original QDs, indicating significant stability improvement and well-dispersed QDs in an optimized polymer matrix morphology.
关键词： colloids,block copolymers,polymeric materials,electrospraying,quantum dots
更新于2025-09-16 10:30:52