Superparamagnetic iron oxide nanoparticles can provide multiple benefits for biomedical applications in aqueous environments such as magnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles' surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality water- dispersible nanoparticles around 10 nm in size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.

/pdf/improved-functionalization-of-oleic-acid-coated-iron-oxide-15yw6sigen.pdf

Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Nonlinear optical chromophores can be organized as orientationally correlated side groups of polymers with a rigid backbone. In such an organization, each chromophore contributes coherently to the second-order nonlinear response of the polymer structure. A first hyperpolarizability exceeding 5000 × 10−30 electrostatic units was measured for a poly(isocyanide) structure containing ∼100 chromophores by means of hyper-Rayleigh scattering. Electric field-induced second-harmonic generation measurements confirmed that the product of the permanent dipole moment and the first hyperpolarizability was enhanced for the polymer structure. These results provide guidelines for future efforts to optimize supramolecular structures for applications in second-order nonlinear optics.

/pdf/supramolecular-second-order-nonlinearity-of-polymers-with-3wxr2snts1.pdf

Supramolecular Second-Order Nonlinearity of Polymers with Orientationally Correlated Chromophores

In this paper, we review the principal theoretical models through which the dielectric function of metals can be described. Starting from the Drude assumptions for intraband transitions, we show how this model can be improved by including interband absorption and temperature effect in the damping coefficients. Electronic scattering processes are described and included in the dielectric function, showing their role in determining plasmon lifetime at resonance. Relationships among permittivity, electric conductivity and refractive index are examined. Finally, a temperature dependent permittivity model is presented and is employed to predict temperature and non-linear field intensity dependence on commonly used plasmonic geometries, such as nanospheres.

https://www.mdpi.com/1996-1944/6/11/4879/pdf

Molding of Plasmonic Resonances in Metallic Nanostructures: Dependence of the Non-Linear Electric Permittivity on System Size and Temperature

Environmental pollution, a major problem worldwide, poses considerable threat to human health and ecological environment Efficient and reliable detection technologies, which focus on the appearance of emerging environmental and trace pollutants, are urgently needed Surface-enhanced Raman scattering (SERS) has become an attractive analytical tool for sensing trace targets in environmental field because of its inherent molecular fingerprint specificity and high sensitivity In this review, we focused on the recent developments in the integration of magnetic nanoparticles (MNPs) with SERS for facilitating sensitive detection of environmental pollutants An overview and classification of different types of MNPs for SERS detection were initially provided, enabling us to categorize the huge amount of literature that was available in the interdisciplinary research field of MNPs based SERS technology Then, the basic working principles and applications of MNPs in SERS detection were presented Subsequently, the detection technologies integrating MNPs with SERS that eventually were used for the detection of various environmental pollutions were reviewed Finally, the advantages of MNP-basedSERS detection technology for environmental pollutants were concluded, and the current challenges and future outlook of this technology in practical applications were highlighted The application of the MNPs-basedSERS techniques for environmental analysis will be significantly advanced with the great progresses of the nanotechnologies, optics, and materials

Applications of magnetic nanoparticles in surface-enhanced Raman scattering (SERS) detection of environmental pollutants.

Being a non-invasive and relatively safe technique, photothermal therapy has attracted a lot of interest in the cancer treatment field. Recently, nanostructure technology has entered the forefront of cancer therapy owing to its ability to absorb near-infrared radiation as well as efficient light to heat conversion. In this study, key nanostructures for cancer therapy including gold nanoparticles, magnetite iron oxide nanoparticles, organic nanomaterials, and novel two-dimensional nanoagents such as MXenes are discussed. Furthermore, we briefly discuss the characteristics of the nanostructures of these photothermal nanomaterial agents, while focusing on how nanostructures hold potential as cancer therapies. Finally, this review offers promising insight into new cancer therapy approaches, particularly in vivo and in vitro cancer treatments.

/pdf/recent-advances-in-functional-nanostructures-as-cancer-53ietkagyj.pdf

Recent advances in functional nanostructures as cancer photothermal therapy

Magnetic-plasmonic nanoparticles, combining magnetic and plasmonic components, are promising structures for use in life sciences. Optical properties of core-shell magnetite-gold nanostructures, such as the wavelength of the plasmon resonance, the extinction cross-section, and the ratio of scattering to absorption at the plasmon wavelength are critical parameters in the search for the most suitable particles for envisioned applications. Using Mie theory and the discrete dipole approximation (DDA), optical spectra as a function of composition, size, and shape of core-shell nanospheres and nanorods were calculated. Calculations were done using simulated aqueous media, used throughout the life sciences. Our results indicate that in the advantageous near-infrared region (NIR), although magnetic-plasmonic nanospheres produced by available chemical methods lack the desirable tunability of optical characteristics, magnetic-plasmonic nanorods can achieve the desired optical properties at chemically attainable dimensions. The presented results can aid in the selection of suitable magnetic-plasmonic structures for applications in life sciences. From the Clinical Editor: In this basic science study, magnetic-plasmonic nanoparticles are studied for future applications in life sciences. Optical properties of core-shell magnetite-gold nanostructures, such as the wavelength of the plasmon resonance, the extinction cross-section, and the ratio of scattering to absorption at the plasmon wavelength are critical parameters in the search for the most suitable particles for proposed future applications.

Research Article Magnetic-plasmonic nanoparticles for the life sciences: calculated optical properties of hybrid structures

In substituted calix[4]-arenes-cyclophanes consisting of four phenol moieties connected by methylene bridges-the number and also the relative positions of the donor and/or acceptor pi- conjugated (D-pi-A) units can be varied by changing the configuration. The Figure illustrates the cone configuration. The molecular and thin-film NLO properties of three tetra-D-pi- A-substituted calix[4]arenes, including their orientation in thin films and the stability of their NLO properties, are described.

/pdf/highly-ordered-films-of-neat-calix-4-arenes-for-second-order-1bzluwrpdg.pdf

Highly ordered films of neat calix[4]arenes for second order nonlinear optics

Iron oxide/gold core-shell nanoparticulate systems are prepared in which a biologically active substance is either bound to the surface of the gold shell of the nanoparticle or is contained within the gold shell of the nanoparticle. Such systems are used for the targeted delivery of biologically active substances, hyperthermia treatment, imaging or combinations thereof. The core diameter of the said nanoparticles is between 5-150nm and thickness of the gold shell is typically between 1-50nm. Depending on the size of the core, the particles are single domain magnetic or superparamagnetic. The biologically active substances used may be attached to the shell through chemical bonding, for example by using thiol or amine groups. Optical properties of the nanoparticles (i.e., the wavelength at which the nanoparticles may absorb) can be controlled by varying shell thickness and core size.

Targeted delivery of biologically active substances using iron oxide/gold core-shell nanoparticles

Variable optical filter, at least consisting of an optical filter structure (2) with different zones (3A-3B-3C-3D-3E) and/or reflection surfaces (4A-4B-4C-4D-4E-4F) which are made such that light (L1) with a well-defined wavelength passes, whereas light (L2) with another wavelength is reflected, in particular according to the so-called Bragg principle, whereby this filter (1-1A-1B-1C) also is provided with means (7) for altering the optical characteristics of the filter structure (2), characterized in that the aforementioned means (7) at least consist in that, on one hand, the optical path of the aforementioned filter structure (2) comprises a portion (6) based on one or more polymers, which is configured as an optical cavity enclosed by refractive surfaces of the aforementioned filter structure, and the optical characteristics of which can be changed under the influence of an electric potential, an electric field (E), respectively, or under the influence of light and, on the other hand, the filter (1) is provided with means (7) with which, in a controlled manner, an electric potential can be generated over, respectively, an electric field (E) in the aforementioned portion (6), and/or an optical field in this portion.

Variable optical filter and devices applying such filter

Flssigkristalle aus C3-symmetrischen Mesogenen fr nichtlineare Optik zweiter Ordnung**

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