Controlled Second Harmonic Generation with Optically Trapped Lithium Niobate Nanoparticles.

We report the second harmonic generation (SHG) response from a single 34 nm diameter lithium niobate nanoparticle. The experimental setup involves a first beam devoted to the optical trapping of single nanoparticles, whereas a second arm involves a femtosecond laser source leading to the SHG emission from the trapped nanoparticles. SHG operation where one to three nanoparticles are present in the optical trap is first demonstrated, highlighting the transition between coherent and incoherent SHG, the latter known as hyper-Rayleigh scattering (HRS).

Nonclassical Nucleation and Crystallization of LiNbO Nanoparticles from the Aqueous Solvothermal Alkoxide Route.

The exact molecular reaction pathway and crystallization mechanisms of LiNbO nanoparticles under solvothermal conditions are derived through extensive time- and temperature-resolved experiments allowing to track all the transient molecular and solid species. Starting with a simple mixing of Li/Nb ethoxides, water addition is used to promote condensation after ligand exchange with different co-solvents including alcohols and glycols of variable carbon-chain length. A nonclassical nucleation scheme is first demonstrated after the identification of new octanuclear complexes with a {LiNbO} core whose solvophobic interactions mediate their aggregation, thus, resulting in a colloidal gel at room-temperature.

Modulating the Surface Properties of Lithium Niobate Nanoparticles by Multifunctional Coatings Using Water-in-Oil Microemulsions.

Inorganic nanoparticles (NPs) have emerged as promising tools in biomedical applications, owing to their inherent physicochemical properties and their ease of functionalization. In all potential applications, the surface functionalization strategy is a key step to ensure that NPs are able to overcome the barriers encountered in physiological media, while introducing specific reactive moieties to enable post-functionalization. Silanization appears as a versatile NP-coating strategy, due to the biocompatibility and stability of silica, thus justifying the need for robust and well controlled silanization protocols.

Solution-Based Synthesis Routes for the Preparation of Noncentrosymmetric 0-D Oxide Nanocrystals with Perovskite and Nonperovskite Structures.

With the miniaturization of electronic-based devices, the foreseen potential of new optical nanoprobes and the assessment of eventual size and shape effects, elaboration of multifunctional noncentrosymmetric nanocrystals with ferroelectric, pyroelectric, piezoelectric, and nonlinear optical properties are the subject of an increasing research interest. Here, the recent achievements from the solution-based methods (coprecipitation in homogeneous and nanostructured media, sol-gel processes including various chemistries and hydro/solvothermal techniques) to prepare 0-D perovskite and nonperovskite oxides in the 5-500 nm size range are critically reviewed. To cover a representative list of covalent- and ionic-type materials, BaTiO and its derivatives, niobate compounds (i.

Synthesis and Characterization of Novel Nanoparticles of Lithium Aluminum Iodate LiAl(IO), and DFT Calculations of the Crystal Structure and Physical Properties.

Here we report on the non-hydrothermal aqueous synthesis and characterization of nanocrystalline lithium aluminum iodate, LiAl(IO). Morphological and compositional analyses were carried out by using scanning electron microscopy (SEM) and energy-dispersive X-ray measurements (EDX). The optical and vibrational properties of LiAl(IO) have been studied by UV-Vis and IR spectroscopy.

Gold-seeded Lithium Niobate Nanoparticles: Influence of Gold Surface Coverage on Second Harmonic Properties.

Hybrid nanoparticles composed of an efficient nonlinear optical core and a gold shell can enhance and tune the nonlinear optical emission thanks to the plasmonic effect. However the influence of an incomplete gold shell, i.e.

On the Reaction Pathways and Growth Mechanisms of LiNbO Nanocrystals from the Non-Aqueous Solvothermal Alkoxide Route.

Phase-pure, highly crystalline sub-50 nm LiNbO nanocrystals were prepared from a non-aqueous solvothermal process for 72 h at 230 °C and a commercial precursor solution of mixed lithium niobium ethoxide in its parent alcohol. A systematic variation of the reaction medium composition with the addition of different amounts of co-solvent including butanol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol resulted in the formation of nanocrystals of adjustable mean size and shape anisotropy, as demonstrated from XRD measurements and TEM imaging. Colloidal stability of ethanol- and water-based suspensions was evaluated from dynamic light scattering (DLS)/zeta potential studies and correlated with FTIR data.

Wavelength-Selective Nonlinear Imaging and Photo-Induced Cell Damage by Dielectric Harmonic Nanoparticles.

We introduce a nonlinear all-optical theranostics protocol based on the excitation wavelength decoupling between imaging and photoinduced damage of human cancer cells labeled by bismuth ferrite (BFO) harmonic nanoparticles (HNPs). To characterize the damage process, we rely on a scheme for temperature monitoring based on upconversion nanoparticles: by spectrally resolving the emission of silica coated NaGdF4:Yb/Er nanoparticles in close vicinity of a BFO HNP, we show that the photointeraction upon NIR-I excitation at high irradiance is associated with a temperature increase >100 °C. The observed laser-cell interaction implies a permanent change of the BFO nonlinear optical properties, which can be used as a proxy to read out the outcome of a theranostics procedure combining imaging at 980 nm and selective cell damage at 830 nm.

Author Correction: Preparation from a revisited wet chemical route of phase-pure, monocrystalline and SHG-efficient BiFeO nanoparticles for harmonic bio-imaging.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Two-Photon-Triggered Photorelease of Caged Compounds from Multifunctional Harmonic Nanoparticles.

The design of stimuli-responsive nanocarriers has raised much attention to achieve higher local concentration of therapeutics and mitigate the appearance of drug resistance. The combination of imaging properties and controlled photorelease of active molecules within the same nanoconjugate has a great potential for theranostic applications. In this study, a system for NIR light-triggered release of molecular cargos induced by the second harmonic emission from bismuth ferrite harmonic nanoparticles (BFO HNPs) is presented.

Microwave Synthesis and Up-Conversion Properties of SHG-Active α-(La, Er)(IO) Nanocrystals.

Pure α-La(IO) and α-LaEr(IO) nanocrystals were synthesized by a microwave-assisted hydrothermal method leading to a reaction yield of 87 ± 4%. Electron microscopy and dynamic light scattering characterizations provide evidence for the formation of nanocrystals with an average size of 45 ± 10 nm for α-La(IO) and 55 ± 10 nm for α-LaEr(IO). When dispersed in ethylene glycol, the nanocrystal suspensions exhibit second-harmonic generation under near-infrared excitations at 800 and 980 nm whereas additional photoluminescence by up-conversion is simultaneously observed in the case of α-LaEr(IO) nanocrystals.

Image Correlation Spectroscopy with Second Harmonic Generating Nanoparticles in Suspension and in Cells.

The absence of photobleaching, blinking, and saturation combined with a high contrast provides unique advantages of higher-harmonic generating nanoparticles over fluorescent probes, allowing for prolonged correlation spectroscopy studies. We apply the coherent intensity fluctuation model to study the mobility of second harmonic generating nanoparticles. A concise protocol is presented for quantifying the diffusion coefficient from a single spectroscopy measurement without the need for separate point-spread-function calibrations.

Preparation from a revisited wet chemical route of phase-pure, monocrystalline and SHG-efficient BiFeO nanoparticles for harmonic bio-imaging.

We present two new synthetic routes for bismuth ferrite harmonic nanoparticles (BiFeO HNPs). Both phase-pure and mixed phase BiFeO materials were produced after improvement of the solvent evaporation and sol-gel combustion routes. Metal nitrates with a series of dicarboxylic acids (tartronic, tartaric and mucic) were used to promote crystallization.

Nonlinear optical susceptibility of two-dimensional WS measured by hyper Rayleigh scattering: erratum.

This erratum corrects errors in the expressions for ⟨β⟩ and fitted form of I and a consequent data point in Fig. 4 of a recent Letter [Opt. Lett.

Bismuth ferrite dielectric nanoparticles excited at telecom wavelengths as multicolor sources by second, third, and fourth harmonic generation.

We demonstrate the simultaneous generation of second, third, and fourth harmonics from a single dielectric bismuth ferrite nanoparticle excited using a telecom fiber laser at 1560 nm. We first characterize the signals associated with different nonlinear orders in terms of spectrum, excitation intensity dependence, and relative signal strengths. Successively, on the basis of the polarization-resolved emission curves of the three harmonics, we discuss the interplay of susceptibility tensor components at different orders and show how polarization can be used as an optical handle to control the relative frequency conversion properties.

Nonlinear optical susceptibility of two-dimensional WS measured by hyper Rayleigh scattering.

Hyper Rayleigh scattering (HRS) was used to measure the second-order nonlinear susceptibility, χ, for liquid exfoliated WS monolayers. To the best of our knowledge, it is the first reported application of the HRS technique to assess the bulk-like χ of a two-dimensional (2D) material. The concentration-dependent HRS signal indicated a 4.

Multi-Order Investigation of the Nonlinear Susceptibility Tensors of Individual Nanoparticles.

We use Hyper Rayleigh Scattering and polarization resolved multiphoton microscopy to investigate simultaneously the second and third-order nonlinear response of Potassium Niobate and Bismuth Ferrite harmonic nanoparticles. We first derive the second-to-third harmonic intensity ratio for colloidal ensembles and estimate the average third-order efficiency of these two materials. Successively, we explore the orientation dependent tensorial response of individual nanoparticles fixed on a substrate.

Cellular uptake and biocompatibility of bismuth ferrite harmonic advanced nanoparticles.

Unlabelled: Bismuth Ferrite (BFO) nanoparticles (BFO-NP) display interesting optical (nonlinear response) and magnetic properties which make them amenable for bio-oriented diagnostic applications as intra- and extra membrane contrast agents. Due to the relatively recent availability of this material in well dispersed nanometric form, its biocompatibility was not known to date. In this study, we present a thorough assessment of the effects of in vitro exposure of human adenocarcinoma (A549), lung squamous carcinoma (NCI-H520), and acute monocytic leukemia (THP-1) cell lines to uncoated and poly(ethylene glycol)-coated BFO-NP in the form of cytotoxicity, haemolytic response and biocompatibility.

Characterization of the nonlinear optical properties of nanocrystals by Hyper Rayleigh Scattering.

Background: Harmonic Nanoparticles are a new family of exogenous markers for multiphoton imaging exerting optical contrast by second harmonic (SH) generation. In this tutorial, we present the application of Hyper-Rayleigh Scattering (HRS) for a quantitative assessment of the nonlinear optical properties of these particles and discuss the underlying theory and some crucial experimental aspects.

Methods: The second harmonic properties of BaTiO3, KNbO3, KiTiOPO4 (KTP), LiNbO3 and ZnO nanocrystals (NCs) are investigated by HRS measurements after careful preparation and characterization of colloidal suspensions.

Polymer encapsulation of inorganic nanoparticles for biomedical applications.

Hybrid inorganic colloidal particles have attracted a great attention in the last years, and they have been largely used in various applications and more particularly in biomedical nanotechnology. Recently, they are used as carriers for biomolecules, and exploited for use in microsystems, microfluidics and in lab-on-a chip based bionanotechnology. Various kinds of hybrid particles can be listed starting from classical inorganic nanoparticles such as silica, gold, silver, iron oxide and those exhibiting intrinsic properties such as semiconducting nanoparticles (e.

High-speed tracking of murine cardiac stem cells by harmonic nanodoublers.

Potassium niobate nonlinear nanoparticles are used for the first time to monitor the evolution of embryonic stem cells (ESC) by second harmonic microscopy. These particles feature the complete absence of photo-bleaching and unlimited excitation wavelength flexibility. The potential of this approach is made evident for tissue-regeneration studies and applications, by capturing a high-speed movie of ESC-derived cardiomyocytes autonomously beating within a cluster.

Harmonic nanocrystals for biolabeling: a survey of optical properties and biocompatibility.

Nonlinear optical nanocrystals have been recently introduced as a promising alternative to fluorescent probes for multiphoton microscopy. We present for the first time a complete survey of the properties of five nanomaterials (KNbO(3), LiNbO(3), BaTiO(3), KTP, and ZnO), describing their preparation and stabilization and providing quantitative estimations of their nonlinear optical response. In the light of their prospective use as biological and clinical markers, we assess their biocompatibility on human healthy and cancerous cell lines.

Nanodoublers as deep imaging markers for multi-photon microscopy.

We demonstrate the possibility to excite second-harmonic (SH) active Fe(IO(3))(3) nanocrystals with two distinct laser sources at 800 and 1550 nm, and we show, by a complementary experimental and numerical study, how the wavelength flexibility inherent to non-phase-matched SH nanoparticles can be efficiently exploited to increase imaging penetration depth of markers embedded in biological samples.

Nano-FROG: Frequency resolved optical gating by a nanometric object.

We present a technique to characterize ultrashort pulses at the focal plane of a high numerical aperture objective with unprecedented spatial resolution, by performing a FROG measurement with a single nanocrystal as nonlinear medium. This approach can be extended to develop novel phase-sensitive techniques in laser scanning microscopy, probing the microscopic environment by monitoring phase and amplitude distortions of femtosecond laser pulses.