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Data on characterization and validation of assays for ultrasensitive quantitative detection of small molecules: Determination of free thyroxine with magnetic and interferometric methods
摘要： The presented data refer to optimization and quantitative characterization of a rapid lateral flow assay based on high-affinity bifunctional ligand and magnetic nanolabels, which was developed for detection of small molecules of thyroid hormones. The results were obtained by including the magnetic particle quantification method, spectral-correlation interferometry and spectral-phase interferometry, dynamic light scattering, enzyme linked immunosorbent assay. The long-term stability of "antibody – magnetic nanoparticle" conjugates is shown. The assay specificity is confirmed, and verification of successful combination of magnetic particles and antibodies is demonstrated. The kinetic and equilibrium dissociation constants are determined for interactions between thyroxine and monoclonal antibodies. The obtained data could be used for design of other platforms for detection of small molecules.
关键词： ELISA,Lateral flow assay,Small molecules,Ultrasensitive detection,Free thyroxine,Interferometry,Magnetic nanolabels,Dynamic light scattering
更新于2025-09-23 15:22:29
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[ACS Symposium Series] Gels and Other Soft Amorphous Solids Volume 1296 || Probe Diffusion Dynamic Light Scattering of Polymer solutions and Gels
摘要： Probe diffusion dynamic light scattering technique is a powerful to investigate the dynamics of polymer chains in polymer solutions and gels. Not only the local dynamics and/or local viscosity but also the gel point and the post-gel dynamics can be investigated. In this chapter, we discuss (1) a conventional probe diffusion of radical polymerization of poly(N-isopropylacrylamide) (PNIPAM) aqueous system, (2) an in-situ isorefractive probe diffusion of tetra-arm poly(ethylene glycol) (Tetra-PEG) undergoing sol-gel transition via cross-end-coupling, and (3) of PNIPAM radical polymerization. It is demonstrated that the gel point is determined as a function of the reaction conversion, which is a more universal measure than the reaction time. The post-gel dynamics explored by the probe particles illuminates the local dynamics in a “pool” of the sol phase surrounded by a gel network. Furthermore, comparison in dynamics is made between well-controlled uniform networks (Tetra-PEG gels) and randomly cross-linked more heterogeneous networks (PNIPAM gels) the probe size from the viewpoints of dependence and scattering angle dependence.
关键词： gel point,Tetra-PEG,post-gel dynamics,Probe diffusion,PNIPAM,gels,polymer solutions,dynamic light scattering
更新于2025-09-23 15:21:21
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Harnessing polymer grafting to control the shape of plasmonic nanoparticles
摘要： Matrix-free polymer grafted nanoparticles (NPs) are single component polymer nanocomposites (PNCs) for which the often reported severe aggregation of the conventional PNCs can be suppressed. For a given particle core, the size and shape of the polymer grafted nanoparticles can be controlled by the molecular weight of the polymer and its grafting density. However, the degree of homogeneity of one-component PNCs depends on the grafted chain molecular weight and grafting density, as well as on the shape of grafted NPs. Surface plasmon resonance enhanced dynamic light scattering from very dilute solutions, yielding both translational and rotational transport coefficients, complemented by UV–Vis extinction spectra, can detect deviations from spheres. Here, we report that poly(isobutylene)-grafted Ag NPs strongly deviate from the spherical shape and are modeled as prolate spheroids. This NP asphericity, due to inhomogeneous grafting, can impact the structure and properties of plasmonic PNCs in the solid state. Thus, characterizing this behavior is a crucial step prior to the formation of one-component PNCs.
关键词： shape control,polymer grafting,dynamic light scattering,UV–Vis extinction spectra,plasmonic nanoparticles
更新于2025-09-23 15:21:01
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Localized Nanoscale Heating Leads to Ultrafast Hydrogel Volume-Phase Transition
摘要： The rate of the volume-phase transition for stimuli-responsive hydrogel particles ranging in size from millimeters to nanometers is limited by the rate of water transport, which is proportional to the surface area of the particle. Here, we hypothesized that the rate of volume-phase transition could be accelerated if the stimulus is geometrically controlled from the inside-out, thus facilitating outward water ejection. To test this concept, we applied transient absorption spectroscopy, laser temperature-jump spectroscopy and finite-element analysis modeling to characterize the dynamics of the volume-phase transition of hydrogel particles with a gold nanorod core. Our results demonstrate that nanoscale heating of the hydrogel particle core led to an ultrafast, 60 ns particle collapse, which is 2-3 orders of magnitude faster than the response generated from conventional heating. This is the fastest recorded response time of a hydrogel material, thus opening potential applications for such stimuli-responsive materials.
关键词： infrared spectroscopy,dynamic light scattering,nanorods,volume-phase transition,hydrogel,transient absorption
更新于2025-09-23 15:19:57
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From normal diffusion to superdiffusion: Photothermal heating of plasmonic core-shell microgels
摘要： The motion of core-shell colloids during laser heating is studied using angle-dependent pump-probe dynamic light scattering. The cores consist of a single spherical gold nanoparticle whose localized surface plasmon resonance has a strong spectral overlap with the wavelength of the pump laser. They are homogeneously encapsulated in thick hydrogel shells composed of either chemically cross-linked poly-N-isopropylacrylamide or poly[2-(2-methoxyethoxy)ethyl methacrylate], both of which exhibit a temperature-dependent volume phase transition. Thus, upon heating beyond the transition temperature, the hydrogel shells shrink. Intensity-time autocorrelation functions are recorded while illuminating the samples with the pump laser and hence heating the gold cores. With increasing laser intensity, the dynamics changes from normal Brownian motion to superdiffusion. Nevertheless, in the high-q limit, the relaxation times can be extracted and used to estimate the temperature increase, which can reach almost 10 K. This causes a significant deswelling of the hydrogel shells, which is also measured.
关键词： temperature-dependent volume phase transition,photothermal heating,dynamic light scattering,superdiffusion,plasmonic core-shell microgels
更新于2025-09-16 10:30:52
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Effect of metal ion solubility on the oxidative assembly of metal sulfide quantum dots
摘要： The versatility of the oxidative assembly method for the creation of 2D and 3D quantum dot (QD) architectures represents both an opportunity and a challenge as a method enabling controlled placement of chemically distinct QDs in multicomponent systems. The opportunity lies in the ability to independently tune the kinetics of the different components so that they are similar (leading to well-mixed systems) or different (enabling gradient or phase-segregated composites) using a wide range of variables; the challenge lies in understanding those variables and how their interplay affects the overall kinetics. Here, we show that the identity of the cation in the sulfide matrix (M = Cd2+ vs Zn2+) plays a large role in the kinetics of assembly of mass spectrometry QDs, attributed to differences in solubility. Time resolved dynamic light scattering is used to monitor the hydrodynamic radius, Rh. ZnS shows an exponential growth associated with reaction-limited cluster aggregation (RLCA), whereas CdS demonstrates a significant induction period (10–75 min) followed by a growth step that cannot be distinguished between RLCA and diffusion limited cluster aggregation. These data correlate with relative solubilities of the nanoparticles, as probed by free-cation concentration. Data also confirm prior studies showing that cubic-closest-packed (ccp) lattices are kinetically slow relative to hexagonally closest-packed (hcp); using the slope of the ln Rh vs time plot for the rate constant, the values of 0.510 s?1 and 3.92 s?1 are obtained for ccp ZnS and hcp ZnS, respectively. Thus, both the structure and the solubility are effective levers for adjusting the relative reactivity of QDs toward oxidative assembly.
关键词： kinetics,solubility,quantum dots,dynamic light scattering,oxidative assembly
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Kerala, India (12–14 June 2019)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019 - Insulator to semiconductor transition in graphene quantum dots
摘要： Zero dimensional graphene quantum dots (GQDs) exhibit interesting physical and chemical properties due to the edge effect and quantum confinement. As the number of carbon atoms in edge is more than on basal plane, GQDs are more reactive. Room temperature XRD pattern confirms the formation of the GQDs. UV-Visible spectra confirm that GQDs show optical absorption in the visible region. The emission peaks in the photoluminescence spectra are red shifted with the increase of excitation wavelength. Dynamic light scattering (DLS) analysis shows that the average size of the particles is found to be ~65 nm. The frequency dependent electrical transport properties of the GQDs are investigated in a temperature range from 300 to 500 K. Most interestingly, for the first time, the insulator to semiconductor transition of GQD is observed near 400K. The transition mechanism of GQD is discussed with detailed dielectric analysis. The effects of intercalated water on temperature dependent conductivity are clearly discussed. The dielectric relaxation mechanism is explained in the framework of permittivity, conductivity and impedance formalisms. The frequency dependent ac conductivity spectra follows the Jonscher's universal power law. Cole-Cole model is used to investigate the dielectric relaxation mechanism in the sample.
关键词： Graphene Quantum Dots,Insulator to Semiconductor Transition,Dynamic Light Scattering,Dielectric Relaxation,Photoluminescence
更新于2025-09-11 14:15:04
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Optical Microrheology of Protein Solutions Using Tailored Nanoparticles
摘要： This work represents a critical re-examination of the application of dynamic light scattering (DLS)–based tracer particle microrheology to measure the zero shear viscosity of aqueous solutions of different proteins up to very high concentrations. It is demonstrated that a combination of surface-functionalized tracer particles, the use of the so-called 3D-DLS technique, and carefully chosen parameters for the scattering experiments is essential for a reliable and artifact-free determination of the viscosity of highly diverse protein solutions, while keeping the amount of protein to a minimum. The major challenges that arise in such microrheology experiments with protein solutions are discussed and used as guiding principles for the synthesis of all-purpose tracer particles with optimal size and an efficient surface functionalization, and the choice of the appropriate amount of tracers in the sample. Potential problems arising from depletion attractions between the tracer particles induced by the proteins are addressed, and compelling evidences for the absence of such effects are presented. The validity of the approach is corroborated by the perfect agreement between the zero shear viscosity obtained from 3D-DLS-based microrheology and literature data from classical rheological measurements for two vastly different protein–solvent systems up to concentrations close to the arrest transition.
关键词： microrheology,tracer particles,protein viscosity,multiple scattering,3D-dynamic light scattering
更新于2025-09-10 09:29:36
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A Depolarized Dynamic Light Scattering Method to Calculate Translational and Rotational Diffusion Coefficients of Nanorods
摘要： A new analysis of depolarized dynamic light scattering data is presented, which allows the unambiguous determination of rotational and translational diffusions coefficients of nanorods in suspension. By visualizing data scaling, purely translational diffusive motions can be isolated from vertically polarized scattering, allowing the unique determination of rotational diffusion from the depolarized scattering. The method is applied to nanorods with four different aspect ratios, and compared with theoretical predictions. Diffusion coefficients obtained show good agreement with calculations based on the direct measurements of rod length and diameter. Where the theories are shown to be valid, the method allows the measurement of statistically meaningful particle sizes and aspect ratios.
关键词： depolarized dynamic light scattering,gold nanorods,Brownian motion,translational diffusion,rotational diffusion
更新于2025-09-10 09:29:36
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Hydroxypropyl Methacrylate Interaction and Chitosan Coating for Enhanced UV Detection Sensitivity of Colloidal Nanoparticles in Capillary Electrophoresis Analysis
摘要： The binding interactions between silica (SiO2), titania (TiO2) or polymeric nanoparticles with hydroxypropyl methacrylate (HPMA) were investigated for enhancing the ultraviolet (UV) detection sensitivity of these nanoparticles in capillary electrophoresis (CE) analysis. HPMA interacted with colloidal SiO2 nanoparticles, producing a larger CE-UV peak at a slightly shorter migration time. An increase in particle size with HPMA binding was validated using dynamic light scattering. The interaction was selective as HPMA did not interact with TiO2 nanoparticles in aqueous suspension. Chitosan coating of SiO2 or TiO2 nanoparticles produced significantly larger hydrodynamic diameters to further enhance the sensitivity of their UV detection. The analytical technique, which involves coating SiO2 nanoparticles with chitosan first and binding with HPMA next, is novel. It has allowed us to achieve a significant enhancement of 50 folds in detection sensitivity.
关键词： Titania,Colloid,Nanoparticles,Capillary electrophoresis,Chitosan,Hydroxypropyl methacrylate,Silica,Polymer,Dynamic light scattering
更新于2025-09-09 09:28:46