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A Robust and General Approach to Quantitatively Conjugate Enzymes to Plasmonic Nanoparticles
摘要： Bioconjugates of plasmonic nanoparticles have received considerable attention due to their potential biomedical applications. Succesfull bioconjugation requires control over the number and activity of the conjugated proteins, and the colloidal stability of the particles. In practice, this requires re-optimization of the conjugation protocol for each combination of protein and nanoparticle. Here we report a robust and general protocol that allows for the conjugation of a range of proteins to di?erent types of nanoparticles using very short polyethylene-glycol(PEG) linkers, while simultaneously preserving protein activity and colloidal stability. The use of short linkers ensures that the protein is located close to the particle surface, where their refractive index sensitivity and near-?eld enhancement is maximal. We demonstrate that the use a Tween20 containing stabilizing bu?er is critical in maintaining colloidal stability and protein function throughout the protocol. We obtain quantitative control over the average number of enzymes per particle by either varying the number of functional groups on the particle, or the enzyme concentration during incubation. This new route of preparing quantitative protein-nanoparticle bioconjugates paves the way to develop rational and quantitative strategies to functionalize nanoparticles for applications in sensing, medical diagnostics and drug delivery.
关键词： medical diagnostics,drug delivery,quantitative control,protein activity,plasmonic nanoparticles,colloidal stability,sensing,bioconjugation,PEG linkers,Tween20
更新于2025-09-12 10:27:22
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Fast optical method for characterizing plasmonic nanoparticle adhesion on functionalized surfaces
摘要： In this paper, a rapid optical method for characterizing plasmonic (gold) nanoparticle (AuNP) adhesion is presented. Two different methods were used for AuNP preparation: the well-known Turkevich method resulted in particles with negative surface charge; for preparing AuNPs with positive surface charge, stainless steel was used as reducing agent. The solid surface for adhesion was provided by a column packed with pristine or surface-modified glass beads. The size of the nanoparticles was studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS); the surface charge of the components was determined by streaming potential measurements. The characterization of adhesion was performed in a flow system by UV-Vis spectroscopy. During the adhesion experiments, the role of the surface charge, the particle size, and the pH were studied, as well as the adhered amount of gold nanoparticles and the surface coverage values. The latter was estimated by theoretical calculations and defined by the quotient of the measured and the maximal adhered amount of nanoparticles, which could be determined by the cross-sectional area of the NPs and the specific surface area of the glass beads. The results are verified by the polarization reflectometric interference spectroscopy (PRIfS) method: silica nanoparticles with diameters of a few hundred (d~450) nanometers were immobilized on the surface of glass substrate by the Langmuir–Blodgett method, the surface was modified similar to the 3D (continuous flow packed column) system, and gold nanoparticles from different pH solutions were adhered during the measurements. These kinds of modified surfaces allow the investigation of biomolecule adsorption in the same reflectometric setup.
关键词： Adhesion,Reflectometric interference spectroscopy,Flow system,Optical method,Plasmonic nanoparticles,Surface charge
更新于2025-09-12 10:27:22
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Plasmonic Nanoparticle-Interfaced Lipid Bilayer Membranes
摘要： Plasmonic nanoparticles are widely exploited in diverse bioapplications ranging from therapeutics to biosensing and biocomputing because of their strong and tunable light?matter interactions, facile and versatile chemical/biological ligand modifications, and biocompatibility. With the rapid growth of nanobiotechnology, understanding dynamic interactions between nanoparticles and biological systems at the molecular or single-particle level is becoming increasingly important for interrogating biological systems with functional nanostructures and for developing nanoparticle-based biosensors and therapeutic agents. Therefore, significant efforts have been devoted to precisely design and create nano?bio interfaces by manipulating the nanoparticles’ size, shape, and surface ligand interactions with complex biological systems to maximize their performance and avoid unwanted responses, such as their agglomeration and cytotoxicity. However, investigating physicochemical interactions at the nano?bio interfaces in a quantitative and controllable manner remains challenging, as the interfaces involve highly complex networks between nanoparticles, biomolecules, and cells across multiple scales, each with a myriad of different chemical and biological interactions.
关键词： Plasmonic nanoparticles,lipid bilayer membranes,therapeutics,biocomputing,nano?bio interfaces,biosensing
更新于2025-09-12 10:27:22
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Ultrastable plasmonic nanofluids in optimized direct absorption solar collectors
摘要： Nanofluids used in low-flux direct absorption solar collectors (DASCs) typically encounter critical stability issues due to long-term storage, elevated temperatures, high particle concentrations, and fouling from free surfactants. Here, we developed ultrastable nanofluids, and their properties were used to computationally optimize DASC designs. Broadband photothermal absorption was achieved using citrate- (CIT-) and polyethylene glycol-coated (PEG-) gold nanoparticles, circumventing the need for free surfactants. The nanofluids were subjected to long-term ambient storage, high particle concentrations, and incremental heating to analyze their stability and utility in DASCs. Electrosteric stabilization (PEG + CIT) provided superior colloidal stability and more consistent optical properties; chemical and colloidal stability was verified for 16 months, the longest demonstration of stable nanofluids under ambient storage in the solar literature. Optical measurements of the stabilized solar nanofluids were fed into a DASC optimization model. A constrained generalized pattern search (GPS) algorithm simultaneously maximized collector thermal power-gain and minimized nanoparticle mass loading, while maintaining a collector temperature-gain target. Ultimately, by simultaneously developing ultrastable solar nanofluids, minimizing nanoparticle loading requirements, and maximizing collector thermal power gain, the outcomes from this study are considered significant steps towards deploying efficient and reliable low-flux, nanofluid-based DASCs in field applications.
关键词： Plasmonic nanoparticles,Direct absorption solar collector,Electrosteric stabilization,Nanofluid,Global optimization,Dispersion stability
更新于2025-09-12 10:27:22
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The Role of Particle Size in the Dispersion Engineering of Plasmonic Arrays
摘要： Grazing diffraction orders on metal gratings give rise to peculiar optical effects that were contemplated by Wood, Rayleigh and Fano. With plasmonic nanoparticles as resonant grating elements, the phenomenology of such surface lattice resonances becomes quite rich, including spectrally narrow extinction peaks and optical band gap formation. It has been observed that at perpendicular incidence either the higher or lower energy branch corresponding to the first grazing diffraction orders is bright, i.e., couples strongly to light. Reviewing the literature, it appears that particle size is the factor determining which dispersion branch lights up. However, a consistent explanation for this effect is lacking. After revisiting the effect experimentally and by numerical simulation, we clarify the underlying physics by analyzing nanoparticle gratings in terms of, first, an oscillator model and, second, a photonic crystal description. Both approaches reveal the central role of a particle-size-dependent phase shift in the back-scattering of grazing light fields by the particle grating. This phase shift determines the symmetry of the resulting field profiles corresponding to the dispersion branches and thus their ability to couple to the exciting light. This physical understanding could considerably simplify the dispersion engineering of plasmonic nanoparticle gratings for specific applications as sensing or lasing.
关键词： Surface lattice resonances,Hybrid Materials,Magnetic,Optical,Dispersion engineering,Plasmonics,Plasmonic nanoparticles
更新于2025-09-12 10:27:22
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Complementary Properties of Silver Nanoparticles on the Photovoltaic Performance of Titania Nanospheres Based Photoanode in Dye-Sensitized Solar Cells
摘要： In this study, the fabrication of photoanode of dye-sensitized solar cell using silver@titania nanospheres and N719 dye, and its enhanced photovoltaic performance in the dye-sensitized solar cell is described. Silver@titania with different mol. % of silver (1, 3 and 5 %) are synthesized using facile sol-gel and photochemical reduction method and are characterized by suitable analytical techniques. The synthesized nanocomposite materials showed nanospheres like morphology. Moreover, photoluminescence studies revealed that incorporation of silver nanoparticles on the titania nanospheres surface suppressed charge recombination process and which is more beneficial for dye-sensitized solar cells. Silver@titania nanospheres are successfully employed as a photoanode and demonstrated an enhanced solar-to-electrical energy conversion efficiency of 5.24 %, under full sun illumination (100 mW cm-2, AM 1.5 G) which is 30.67 % enhancement than that of bare titania nanospheres (4.01 %). This enhanced efficiency is attributed to the rapid interfacial charge transfer process and plasmonic effect offered by silver nanoparticles present in the silver@titania nanospheres. The improved charge transfer process led to minimize the back electron transfer reaction in the device. With complementary properties of silver nanoparticles, the high performance demonstrated by the silver@titania nanospheres could be an excellent candidate for the light energy harvesting applications.
关键词： Dye-sensitized solar cells,Plasmonic nanoparticles,Schottky barrier,Titania nanospheres,Silver nanoparticles
更新于2025-09-11 14:15:04
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Atomic Force Microscope Guided SERS Spectra Observation for Au@Ag-4MBA@PVP Plasmonic Nanoparticles
摘要： Recently polymer encapsulated surface-enhanced-Raman-scattering (SERS) probes with internal noble metal core–shell structure has found growing applications in biomedical applications. Here we studied the SERS spectra of Au@Ag–4MBA@PVP (4MBA: 4-mercaptobenzoic acid; PVP: polyvinylpyrrolidone) plasmonic nanoparticles produced from a chemical reduction method. By linking the atomic force microscope (AFM) with the homebuilt confocal Raman spectrometer thus to use AFM images as guidance, we realized the measurement of the SERS spectra from separated nanoparticles. We investigated the cases for single nanoparticles and for dimer structures and report several observed results including SERS spectra linearly scaled with laser power, abrupt boosting and abnormal shape changing of SERS spectra for dimer structures. Based on the finite element method simulation, we explained the observed ratio of SERS signals between the dimer structure and the single nanoparticle, and attributed the observed abnormal spectra to the photothermal effect of these plasmonic nanoparticles. Our study provides valuable guidance for choosing appropriate laser power when applying similar SERS probes to image biological cells.
关键词： SERS probes,AFM imaging,confocal Raman spectrometer,SERS spectra,photothermal effect,plasmonic nanoparticles
更新于2025-09-11 14:15:04
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Photocatalytic filtration reactors equipped with bi-plasmonic nanocomposite/poly acrylic acid-modified polyamide membranes for industrial wastewater treatment
摘要： In this study, two new composite membranes with antifouling and anti-biofouling properties were prepared through the modification of commercial polyamide (PA) discs using combination of in-situ polymerization of polyacrylic acid (PAA) and grafting of two synthesized bi-plasmonic Au-Ag and Ag-Au photocatalysts. The synthesis and characterization of the photocatalysts in batch mode were discussed in details as primary studies. Two intense 405-nm and 532-nm lasers for Ag-Au and Au-Ag photocatalysts, respectively and a solar-simulated xenon lamp for both photocatalysts were applied for photodegradation studies and the results were compared. In addition, the effect of other parameters such as type and amount of photocatalysts, and initial concentration of pollutants on the degradation efficiency of ofloxacin (OFX) and methylene blue (MB) as the model pollutant drug and dye were comprehensively investigated and the Langmuir-Hinshelwood adsorption model was used for evaluation of kinetics, degradation rate and half-life time of the reactions. After selection of xenon lamp as the optimum light source, the photodegradation of OFX and MB was evaluated in a dead-end membrane reactor (MR) and flux performance, antifouling property and pollutant removal of the membranes were evaluated using pharmaceutical and textile wastewater samples. In addition, the antibacterial activity of the prepared membranes was evaluated using Gram-negative E. coli bacteria as the model microorganism using thin film assay and Kirby-Bauer disk diffusion methods to examine the anti-biofouling potential of the constructed reactors. It was demonstrated that the prepared MR is able to produce cleaner water with more stable ?ux performance and good membrane fouling/biofouling properties in energy saving manner with respect to the unmodified ones.
关键词： Membrane ?ltration,Wastewater treatment,Permeate ?ux,Bi-plasmonic nanoparticles,Photodegradation,Antifouling/anti-biofouling properties
更新于2025-09-11 14:15:04
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Spectral Reshaping of Single Dye Molecules Coupled to Single Plasmonic Nanoparticles
摘要： Fluorescent molecules are highly susceptible to their local environment. Thus, a fluorescent molecule near a plasmonic nanoparticle can experience changes in local electric field and local density of states that reshape its intrinsic emission spectrum. By avoiding ensemble averaging while simultaneously measuring the super-resolved position of the fluorophore and its emission spectrum, single-molecule hyperspectral imaging is uniquely suited to differentiate changes in spectrum from heterogeneous ensemble effects. Thus, we uncover for the first time single-molecule fluorescence emission spectrum reshaping upon near-field coupling to individual gold nanoparticles using hyperspectral super-resolution fluorescence imaging, and we resolve this spectral reshaping as a function of the nanoparticle/dye spectral overlap and separation distance. We find dyes bluer than the plasmon resonance maximum are red-shifted and redder dyes are blue-shifted. The primary vibronic peak transition probabilities shift to favor secondary vibronic peaks, leading to effective emission maxima shifts in excess of 50 nm, and we understand these light-matter interactions by combining super-resolution hyperspectral imaging and full-field electromagnetic simulations.
关键词： Plasmonic nanoparticles,Single-molecule hyperspectral imaging,Optoelectronics,Energy Conversion and Storage,Fluorescence emission spectrum reshaping,Plasmonics
更新于2025-09-11 14:15:04
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Characterization of spatiotemporal chaos in arrays of nonlinear plasmonic nanoparticles
摘要： We investigate spatiotemporal chaos dynamics in a finite nanoparticles array with Kerr-type nonlinear response, excited by an incident plane wave of varying intensity and tunable frequency close to the localized plasmon resonance of a single particle. Considering dipole-dipole coupling between the nanoparticles described by their polarizability, we compute the temporal evolution of the dipoles and numerically extract the Lyapunov spectra, allowing us to characterize different dynamical behaviors. Furthermore, we estimate the Kaplan-Yorke dimension that provides a measure of the strange attractor complexity. We show that time-modulated solutions which are generated at the onset of modulational instability experience secondary instabilities leading to a complex nonlinear dynamic. It is also shown that in the highly nonlinear regime, the spatiotemporal chaos is robust and exists in a large range of parameters that we have determined numerically.
关键词： nonlinear plasmonic nanoparticles,modulational instability,Lyapunov spectra,spatiotemporal chaos,Kaplan-Yorke dimension
更新于2025-09-11 14:15:04