Fluorescent Nanorods Research Articles

Unique orientation of 1D and 2D nanoparticle assemblies confined in smectic topological defects.

New collective optical properties have emerged recently from organized and oriented arrays of closely packed semiconducting and metallic nanoparticles (NPs). However, it is still challenging to obtain NP assemblies which are similar everywhere on a given sample and, most importantly, share a unique common orientation that would guarantee a unique behavior everywhere on the sample. In this context, by combining optical microscopy, fluorescence microscopy and synchrotron-based grazing incidence X-ray scattering (GISAXS) of assemblies of gold nanospheres and of fluorescent nanorods, we study the interactions between NPs and liquid crystal smectic topological defects that can ultimately lead to unique NP orientations. We demonstrate that arrays of one-dimensional - 1D (dislocations) and two-dimensional - 2D (grain boundaries) topological defects oriented along one single direction confine and organize NPs in closely packed networks but also orient both single nanorods and NP networks along the same direction. Through the comparison between smectic films associated with different kinds of topological defects, we highlight that the coupling between the NP ligands and the smectic layers below the grain boundaries may be necessary to allow for fixed NP orientation. This is in contrast with 1D defects, where the induced orientation of the NPs is intrinsically induced by the confinement independently of the ligand nature. We thus succeeded in achieving the fixed polarization of assemblies of single photon emitters in defects. For gold nanospheres confined in grain boundaries, a strict orientation of hexagonal networks has been obtained with the 〈10〉 direction strictly parallel to the defects. With such closely packed and oriented NPs, new collective properties are now foreseen.

Using Gd-Enhanced β-NaYF4:Yb,Er Fluorescent Nanorods Coupled to Reduced TiO2 for the NIR-Triggered Photocatalytic Inactivation of Escherichia coli

β-NaYF4:Yb,Er,Gd fluorescent nanorods were successfully coupled to a reduced TiO2 (UCNPs@R-TiO2) nanocomposite and applied to visible-light catalytic sterilization under 980 nm near-infrared (NIR) light illumination. The UCNPs (β-NaYF4:Yb,Er,Gd) absorb the NIR light and emit red and green light. The visible light can be absorbed by the R-TiO2 (Eg = 2.8 eV) for the photocatalytic reaction. About 98.1% of Escherichia coli were effectively killed upon 12 min of NIR light irradiation at a minimum inhibitory concentration (MIC) of 40 μg/mL UCNPs@R-TiO2 nanocomposite. The bactericidal properties were further evaluated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. We found that the high bactericidal activity was due to the synergistic effect between the UCNPs and R-TiO2. Moreover, the UCNPs show excellent upconversion luminance properties, and the introduction of visible-light-absorbed R-TiO2 nanoparticles (2.8 eV) was conducive to the efficient separation and utilization of photogenerated electron-hole pairs.

Morphological Evolution of Strongly Fluorescent Water Soluble AIEEgen-Triblock Copolymer Mixed Aggregates with Shape-Dependent Cell Permeability.

Dimethyl-2,5-bis(4-methoxyphenylamino)terephthalate (DBMPT) is a water-insoluble fluorogenic molecule, which has been rendered water-soluble in physiological conditions, by the addition of triblock copolymers (TBPs), P123 (PEO19PPO69PEO19), and F127 (PEO100PPO65PEO100). DBMPT-TBP mixed aggregates, formed in the process, exhibit significant aggregation-induced enhancement of emission, with nanosecond fluorescence lifetimes. Dynamics involved in suppression of nonradiative pathways and consequent enhancement of fluorescence are followed by femtosecond transient absorption and time-resolved fluorescence spectroscopic techniques. Interestingly, shapes of the aggregates formed with the two TBPs are found to be very different, even though they differ only in the length of hydrophilic blocks. DBMPT-P123 aggregates are micrometer-sized and spherical, while DBMPT-F127 aggregates form nanorods. Evolution of their morphologies, as a function of TBP concentration, is monitored using cryo-TEM, FESEM, and fluorescence lifetime imaging microscopy. Fluorescence lifetime distribution provides useful insight into microheterogeneity in these mixed aggregates. Excellent cell permeability is observed for DBMPT-F127 nanorods, in contrast to DBMPT-P123 microspheres. These fluorescent nanorods exhibit the ability to mark lipid droplets within the cell and hence bear the promise for application in intracellular imaging.

Fluorescent nanorods based on 9,10-distyrylanthracene (DSA) derivatives for efficient and long-term bioimaging.

Fluorescent nanoparticles based on 9,10-distyrylanthracene (DSA) derivatives (4,4'-((1E,1'E)-anthracene-9,10-diylbis(ethene-2,1-diyl))bis(N,N-dimethylaniline) (NDSA) and 4,4'-((1E,1'E)-anthracene-9,10-diylbis(ethene-2,1-diyl))dibenzonitrile (CNDSA)) were prepared using an ultrasound aided nanoprecipitation method. The morphologies of the fluorescent nanoparticles could be controlled by adjusting the external ultrasonication time. NDSA or CNDSA could form spherical nanodots (NDSA NDs, CNDSA NDs) in a THF-H2O mixture with an 80% or 70% water fraction when the ultrasonication time was 30 s. When the ultrasonication time was prolonged to 10 min, NDSA and CNDSA could assemble into nanorods (NDSA NRs, CNDSA NRs). Meanwhile, the sizes of NDSA NRs and CNDSA NRs could be controlled by adjusting the water content in the mixture. As the water fraction was increased from 60% to 80%, the sizes of NDSA and CNDSA nanorods or nanodots reduced from 238.4 nm to 140.3 nm, and 482 nm to 198.4 nm, respectively. When the water fraction was up to 90%, irregular morphologies of NDSA and CNDSA could be observed. The nanoparticles exhibited intense fluorescence emission, good anti-photobleaching properties, as well as excellent stability and biocompatibility. In vitro cell imaging experiments indicated that the nanorods prepared by this simple method had the potential to be used for efficient and noninvasive long-term bioimaging.

Facile Preparation of Organometallic Nanorods from Various Ethynyl-Substituted Molecules.

A facile method to prepare one‐dimensional (1D) organometallic nanomaterials from various ethynyl‐substituted molecules is reported. The reactions of 3‐chloro‐1‐ethynylbenzene, p‐tBu‐phenylacetylene and 4‐ethynylbiphenyl with Cu+ ions in acetonitrile yield nanorod‐shaped copper acetylides (Cu−C≡C−R) crystals. In the case of linear alkynes, namely, propyne, 1‐pentyne and 1‐hexyne, it was found that using an aqueous ammonia/ethanol mixed solvent instead of acetonitrile is a better approach to obtain 1D nanostructures. This procedure also enables us to prepare functional 1D nanomaterials. We demonstrate the preparation of a paramagnetic nanorod from the organic radical p‐ethynylphenyl nitronyl nitroxide, and fluorescent nanorods from 9‐ethynylphenanthrene and 2‐ethynyl‐9,9′‐spirobifluorene.

Ultrasensitive immunoassay based on fluorescent SiO2 nanorods

Ultrasensitive immunoassay based on fluorescent SiO2 nanorods

LaPO4:Eu fluorescent nanorods, synthesis, characterization and spectroscopic studies on interaction with human serum albumin

Eu3+ doped LaPO4 fluorescent nanorods (LaPO4:Eu) was successfully fabricated by a hydrothermal process. The obtained LaPO4:Eu nanorods under the optimal conditions were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD) technique, Fourier transform infrared (FTIR), UV–vis absorption and fluorescence spectroscopy. The nanorods with a length of 50–100nm and a diameter of about 10nm, can emit strong red fluorescence upon excitation at 241nm. The FTIR result confirmed that there are lots of phosphate groups on the surfaces of nanorods. In order to better understand the physiological behavior of nanorods in human body, multiple spectroscopic methods were used to study the interaction between the LaPO4:Eu nanorods and human serum albumin (HSA) in the simulated physiological conditions. The results indicated that the nanorods can effectively quench the intrinsic fluorescence of HSA through a dynamic quenching mode with the association constants of the order of 103Lmol−1. The values of the thermodynamic parameters suggested that the binding of the nanorods to HSA was a spontaneous process and van der Waals forces and hydrogen bonds played a predominant role. The displacement experiments verified that the binding site of nanorods on HSA was mainly located in the hydrophobic pocket of subdomain IIA (site I) of HSA. The binding distance between nanorods and HSA was calculated to be 4.2nm according to the theory of Förster non-radiation energy transfer. The analysis of synchronous fluorescence, three-dimensional fluorescence (3D) and circular dichroism (CD) spectra indicated that there the addition of LaPO4:Eu nanorods did not caused significant alterations in conformation of HSA secondary structure and the polarity around the amino acid residues.

Combined Poltirf and Sub-Pixel Particle Tracking of Cytoplasmic Dynein Supports a Winch-Like Stepping Mechanism

Cytoplasmic dynein is a molecular motor that carries cargos toward the minus end of microtubules. Dynein walks processively, but less regularly along microtubules than kinesin and is capable of taking both backwards and sideways steps. Structural dynamics of dynein's AAA+ ring domain during processive stepping are not well understood. We use a combination of polarized TIRF and sub-pixel particle tracking to measure the position and orientation of fluorescent nanorods rigidly attached to AAA5 and AAA6 of the individual dynein ring domains via biotin-NeutrAvidin linkage. We observe rotational changes of the ring and how they correlate with translocation steps. The dynein ring undergoes frequent, small rotations, typically less than 20 degrees, about twice as often as steps. Stepping and tilting both depend on ATP, although some ATP-independent rotations are observed. Rotations which accompany translocation steps have larger magnitudes than ones that are not correlated with steps. Not all steps are correlated with angle changes, either. A heterodimeric mutant construct, with one biotinylated ring carrying a quantum rod and one non-biotinylated dead-head ring walks slowly, indicating that the rod does not destroy motility. Our results are inconsistent with a purely powerstroke stepping mechanism, analogous to that of myosin which would predict larger angle changes tightly coupled to stepping, but instead they support a winch-like mechanism that involves bending of the coiled-coil stalk under intermolecular torque between the heads in the double-headed bound state. Supported by NIH Grant P015GM087253.

Highly stable organic fluorescent nanorods for living-cell imaging

Metal-free, organic-dye-based fluorescent nanorods were fabricated through a simple solvent-exchange procedure. The as-prepared nanorods exhibit low toxicity to living cells and excellent photostability. Furthermore, they are stable in solutions of various pHs and high ionic strength and in solutions with interfering metal ions. Compared with the free DPP-Br molecules in THF, these nanorods exhibit larger Stokes shift, broader absorption spectra, and greatly improved photostability. We successfully demonstrated the application of the nanorods, including their aforementioned beneficial characteristics, as a good fluorescence probe for bio-imaging.

Inkjet printed fluorescent nanorod layers exhibit superior optical performance over quantum dots.

Semiconductor nanocrystals exhibit unique fluorescence properties which are tunable in size, shape and composition. The high quantum yield and enhanced stability have led to their use in biomedical imaging and flat panel displays. Here, semiconductor nanorod based inkjet inks are presented, overcoming limitations of the commonly reported quantum dots in printing applications. Fluorescent seeded nanorods were found to be outstanding candidates for fluorescent inks, due to their low particle-particle interactions and negligible self-absorption. This is manifested by insignificant emission shifts upon printing, even in highly concentrated printed layers and by maintenance of a high fluorescence quantum yield, unlike quantum dots which exhibit fluorescence wavelength shifts and quenching effects. This behavior results from the reduced absorption/emission overlap, accompanied by low energy transfer efficiencies between the nanorods as supported by steady state and time resolved fluorescence measurements. The new seeded nanorod inks enable patterning of thin fluorescent layers, for demanding light emission applications such as signage and displays.

Poly(o-phenylenediamine) and benzeneselenol copolymer fluorescent nanorod: An ultra-sensitive fluorescent probe and a fluorescent switch triggered by redox procedure

Poly(o-phenylenediamine) and benzeneselenol copolymer fluorescent nanorods were synthesized via a simple hydrothermal treatment and a novel, simple and ultra-sensitive oxidation–reduction fluorescent switch system was prepared based on these copolymer fluorescent nanorods. This switch system can be triggered by redox procedure. When this copolymer is oxidized by H2O2, the switch is “off”. The switch system is “on” when glutathione (GSH) is added. This switch system has good stability, excellent selectivity and specificity. What is more, the low detective limit indicates (detection limit: 10−12M) this switch system can be used as an ultra-sensitive fluorescent probe for H2O2 or GSH. For the mechanism of switch processes, XPS results show the change of binding mode of Se in this copolymer is the main cause.

Development of biocompatible apatite nanorod-based drug-delivery system with in situ fluorescence imaging capacity

Biocompatible and multifunctional nanocarriers significantly improve the therapeutic and diagnostic efficacy of the cargo molecules. Here we report a novel biocompatible apatite nanocrystal-based delivery system with in situ imaging capacity. A nanorod (40 nm × 10 nm) produced by a citrate-involved sol-gel process expressed a strong blue emission at 427 nm under fluorescence microscopy. The CO2˙- radical impurities present in the apatite crystal lattice account for the fluorescent behavior. The fluorescent nanorods exhibited excellent cell viability (over 90% up to ∼100 μg ml-1 concentration for both osteoblasts and osteoclasts). The nanorods loaded alendronate drug at a high efficiency (10%) and released over 3 days, while enabling in situ fluorescence imaging within the cells. The fluorescent apatite was further hybridized onto the surface of mesoporous nanospheres, aimed at improving the drug-delivery capacity. Small interfering RNA (siRNA) gene, encoding Plekho-1, was effectively loaded to the hybrid nanocarrier, and was sustainably released over 5 days. The siRNA-loaded nanocarrier exhibited excellent osteoblastic uptake (96% efficiency) and gene-silencing effect, suppressing Plekho-1 down to ∼18%, while preserving intracellular fluorescence signals. Taken as a whole, the self-fluorescent nature of apatite nanorods is believed to find potential and versatile applications as biocompatible drug-delivery and in situ imaging systems.

Responsive Fluorescent Nanorods from Coassembly of Fullerene (C60) and Anthracene-Ended Hyperbranched Poly(ether amine) (AN-hPEA)

We herein demonstrated a novel multiresponsive fluorescent nanorod based on C60, which is fabricated through the versatile coassembly of fullerene C60 and anthracene-ended hyperbranched poly(ether amine) (AN-hPEA). The supramolecular nanorods (C60@AN-hPEA) can be further cross-linked through photodimerization of anthracene, and the size of the obtained nanorods is 2–12 μm in length and 50–90 nm in diameter. C60@AN-hPEA nanorods are amphiphilic, responsive, and fluorescent. The fluorescence of C60@AN-hPEA nanorods in aqueous solution is responsive to temperature and pH. The C60@AN-hPEA-1/4 nanorods exhibit the interesting temperature-enhanced fluorescence, while the fluorescence intensity of AN-hPEA without C60 decreases with the increasing temperature. Detailed fluorescence study revealed that the temperature-enhanced fluorescence behavior of C60@AN-hPEA-1/4 nanorods might be ascribed to the static quenching of the excited anthracene by C60.

EPR-effect: Utilizing size-dependent Nanoparticle Delivery to Solid Tumors

EPR-effect: Utilizing size-dependent Nanoparticle Delivery to Solid Tumors

Cyanide modulated fluorescent supramolecular assembly of a hexaphenylbenzene derivative for detection of trinitrotoluene at the attogram level

Fluorescent nanorods formed by self-assembly of hexaphenylbenzene derivative in the presence of cyanide ions serve as a sensitive colorimetric and fluorogenic sensor for the detection of trinitrotoluene (TNT) at the attogram (10(-18) g) level with a detection limit of 10.21 ppq (parts per quadrillion).

Highly sensitive and selective novel core–shell molecularly imprinted polymer based on NaYF4: Yb3+, Er3+ upconversion fluorescent nanorods

A novel core–shell molecularly imprinted polymer based on β-NaYF4: Yb3+, Er3+ upconversion fluorescent nanoparticles (UCNPs@MIP) has been successfully synthesized, which has a homogeneous polymer film, shows thermal stability, exhibits excellent near-infrared upconversion luminescence emission and sensitivity and selectivity towards analytes.

Unsymmetrical p‐Carborane Backbone as a Linker for Donor–Acceptor Dyads

Fluorescent nanorods: Donor-acceptor dyads based on novel unsymmetrically disubstituted closo-1,12-dicarbadecaboranes have been prepared in a completely controlled manner by using a three-step procedure. Dyads with different donor-acceptor spacing were thereby obtained. Efficient energy transfer from the donor to the acceptor was determined in fluid solution at room temperature.

Surface Modification of Luminescent Lanthanide Phosphate Nanorods with Cationic “Quat-primer” Polymers

"Quat-primer" polymers bearing cationic groups were investigated as a surface modifier for Tb-doped cerium phosphate green-emitting fluorescent nanorods (NRs). The NRs were synthesized by a microwave process without using any complex agents or ligands and were characterized with different analytical tools such as X-ray diffraction, transmission electron microscopy, and fluorescence spectroscopy. Poly(ethyleneimine) partially quarternized with glycidyltrimethylammonium chloride was synthesized separately and characterized in detail. (1)H and (13)C NMR spectroscopic studies revealed that the quaternary ammonium group was covalently attached to the polymer. UV-vis spectroscopy was used to examine the stability of the colloidal dispersions of the bare NRs as well as the modified NRs. ζ potential, thermogravimetric analysis, and atomic force microscopy studies were carried out to confirm that the positively charged Quat-primer polymer is adsorbed on the negatively charged surface of the NRs, which results in high dispersion stability. Emission spectra of the modified NRs indicated that there was no interference of the Quat-primer polymer with the fluorescence behavior.

Synthesis and Characterization of Phthalic Europium(III) Fluorescent Complex Nanorods

The rare earth ion europium(III) was chosen as the central fluorescent ion, and phthalic acid (H2L) was chosen as the ligand. The rod-like phthalic europium(III) fluorescent complex was synthesized using a co-precipitation method in a polyvinylpyrrolidone (PVP) aqueous medium. The chemical composition of the synthesized complex was speculated to be PVP/Eu2L3 x 3H2O by elemental analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and Fourier-transform infrared spectroscopy (FT-IR). The X-ray diffraction analytic (XRD) results indicated that the synthesized complex is a crystalline substance, and the scanning electron microscopy (SEM) analytic results showed that the synthesized complex is nanorod with an average size of about 40 nm. The thermogravimetry and differential thermal analysis (TG-DTA) result showed that the nanoscale complex has good stability below 449 degrees C. Photoluminescence spectra (PL) spectra showed that the nanoscale complex emitted characteristic red luminescence of Eu (III) under ultraviolet light.

Functionalized Gold Nanorod Solution via Reverse Micelle Based Polyacrylate Coating

Functionalization of gold nanorods is a key issue for their biomedical application, and currently it is performed via either electrostatic interaction or thiol based strategy. We have developed a polyacrylate based coating chemistry for gold nanorods that can be used in deriving a variety of functional nanorods with high colloidal stability. The coating processes can introduce primary amines, fluorescein, or poly(ethylene glycol) (PEG) on the nanorod surface in one step process. While fluorescein incorporation can produce fluorescent nanorods, primary amine groups can be used for further functionalization. Various functional nanorods have been successfully synthesized from these coated nanorods and used in different applications. Glucose and biotin functionalized nanorods are used for protein detection, and oleyl functionalized nanorods with fluorescein incorporated in the polymer shell are used for fluorescence based cell labeling.