Optical Tweezers Assembled Nanodiamond Quantum Sensors.

Here we show that gradient force optical tweezers can be used to mediate the self-assembly of nanodiamonds into superstructures, which can serve as optically trapped nanoscale quantum probes with superior magnetic resonance sensing capabilities. Enhanced fluorescence rates from nitrogen-vacancy NV defect centers enable rapid acquisition of optically detected magnetic resonance (ODMR), and shape-induced forces can improve both positioning accuracy and orientation control. The use of confocal imaging can isolate the signal from individual nanodiamonds within the assembly, thereby retaining the desirable properties of a single crystal probe.

Lanthanide Ion Resonance-Driven Rayleigh Scattering of Nanoparticles for Dual-Modality Interferometric Scattering Microscopy.

Light scattering from nanoparticles is significant in nanoscale imaging, photon confinement. and biosensing. However, engineering the scattering spectrum, traditionally by modifying the geometric feature of particles, requires synthesis and fabrication with nanometre accuracy.

"Designing high-performance nighttime thermoradiative systems for harvesting energy from outer space" by Zhang et al.: comment.

The current-voltage characteristics presented by Zhang et al. in their recent work on designing thermoradiative systems overestimate the achievable power using the proposed material by several orders of magnitude.

Familial bilateral nodular oncocytic hyperplasia of the parotid gland in mother and son.

This case series reports familial cases of nodular oncocytic hyperplasia (NOH) diagnosed in a mother and her son, 15 years apart. A 39-year-old man presented in 2003 with a lump below his left ear. Magnetic resonance imaging (MRI) performed showed multifocal parotid nodules and a diagnosis of NOH was histopathologically confirmed following left total parotidectomy.

Optical tweezers beyond refractive index mismatch using highly doped upconversion nanoparticles.

Optical tweezers are widely used in materials assembly, characterization, biomechanical force sensing and the in vivo manipulation of cells and organs. The trapping force has primarily been generated through the refractive index mismatch between a trapped object and its surrounding medium. This poses a fundamental challenge for the optical trapping of low-refractive-index nanoscale objects, including nanoparticles and intracellular organelles.

High-resolution light-activated electrochemistry on amorphous silicon-based photoelectrodes.

Light-activated electrochemistry (LAE) consists of employing a focused light beam to illuminate a semiconducting area and make it electrochemically active. Here, we show how to reduce the electrochemical spatial resolution to submicron by exploiting the short lateral diffusion of charge carriers in amorphous silicon to improve the resolution of LAE by 60 times.

Impact of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays.

Plasmonic nanohole arrays for biosensing applications have attracted tremendous attention because of their flexibility in optical signature design, high multiplexing capabilities, simple optical alignment setup, and high sensitivity. The quality of the metal film, including metal crystallinity and surface roughness, plays an important role in determining the sensing performance because the interaction between free electrons in the metal and incident light is strongly influenced by the metal surface morphology. We systematically investigated the influence of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays after different metal deposition processes.

Optical tweezers-based characterisation of gold core-satellite plasmonic nano-assemblies incorporating thermo-responsive polymers.

We report on the characterisation of the optical properties and dynamic behaviour of optically trapped single stimuli-responsive plasmonic nanoscale assemblies. Nano-assemblies consist of a core-satellite arrangement where the constituent nanoparticles are connected by the thermoresponsive polymer, poly(DEGA-co-OEGA). The optical tweezers allow the particles to be held isolated in solution and interrogated using dark-field spectroscopy.

Nanopore blockade sensors for ultrasensitive detection of proteins in complex biological samples.

Nanopore sensors detect individual species passing through a nanoscale pore. This experimental paradigm suffers from long analysis times at low analyte concentration and non-specific signals in complex media. These limit effectiveness of nanopore sensors for quantitative analysis.

Micropatterning of porous silicon Bragg reflectors with poly(ethylene glycol) to fabricate cell microarrays: Towards single cell sensing.

The work presented here describes the development of an optical label-free biosensor based on a porous silicon (PSi) Bragg reflector to study heterogeneity in single cells. Photolithographic patterning of a poly(ethylene glycol) (PEG) hydrogel with a photoinitiator was employed on RGD peptide-modified PSi to create micropatterns with cell adhesive and cell repellent areas. Macrophage J774 cells were incubated to form cell microarrays and single cell arrays.

Laryngeal Inflammatory Pseudotumour Secondary to .

Background: Inflammatory pseudotumours (IPT) are rare benign tumours characterised by spindle-shaped histiocyte proliferation often mimicking a soft tissue sarcoma. They can occur in different parts of the body and various aetiological factors have been proposed. To our knowledge this is the first case report of IPT of the larynx caused by mycobacterial disease.

A rapid readout for many single plasmonic nanoparticles using dark-field microscopy and digital color analysis.

The integration of plasmonic nanoparticles into biosensors has the potential to increase the sensitivity and dynamic range of detection, through the use of single nanoparticle assays. The analysis of the localized surface plasmon resonance (LSPR) of plasmonic nanoparticles has allowed the limit of detection of biosensors to move towards single molecules. However, due to complex equipment or slow analysis times, these technologies have not been implemented for point-of-care detection.

Noise induced aperiodic rotations of particles trapped by a non-conservative force.

We describe a mechanism whereby random noise can play a constructive role in the manifestation of a pattern, aperiodic rotations, that would otherwise be damped by internal dynamics. The mechanism is described physically in a theoretical model of overdamped particle motion in two dimensions with symmetric damping and a non-conservative force field driven by noise. Cyclic motion only occurs as a result of stochastic noise in this system.

Biophotonics feature: introduction.

We introduce the feature issue on the Optics in the Life Sciences Congress held on April 2-5, 2017 in San Diego, CA. The Congress consisted of 5 topical symposia: (i) Bio-optics Design and Application; (ii) Novel Techniques in Microscopy; (iii) Optical Molecular Probes, Imaging and Drug Delivery; (iv) Optical Trapping Applications; and (v) Optics and the Brain. These separate symposia also held joint sessions of common interest.

Difference in hot carrier cooling rate between Langmuir-Blodgett and drop cast PbS QD films due to strong electron-phonon coupling.

The carrier dynamics of lead sulphide quantum dot (PbS QD) drop cast films and closely packed ordered Langmuir-Blodgett films are studied with ultra-fast femtosecond transient absorption spectroscopy. The photo-induced carrier temperature is extracted from transient absorption spectra and monitored as a function of time delay. The cooling dynamics of carriers in PbS QDs suggest a reduction of the carrier energy loss rate at longer time delays through the retardation of the longitudinal optical (LO) phonon decay due to partial heating of acoustic phonon modes.

Using back focal plane interferometry to probe the influence of Zernike aberrations in optical tweezers.

We experimentally investigate the influence of geometric aberrations in optical tweezers using back focal plane interferometry. We found that the introduction of coma aberrations causes significant modification to the Brownian motion of the trapped particle, producing an apparent cross-coupling between the in-plane aberrated axis and the weaker propagation axis. This coupling is evidenced by the emergence of a second dominant low frequency Lorentzian feature in the position power spectral density.

Prenatal and early-life predictors of atopy and allergic disease in Canadian children: results of the Family Atherosclerosis Monitoring In earLY life (FAMILY) Study.

Prenatal and early-life environmental exposures play a key role in the development of atopy and allergic disease. The Family Atherosclerosis Monitoring In earLY life Study is a general, population-based Canadian birth cohort that prospectively evaluated prenatal and early-life traits and their association with atopy and/or allergic disease. The study population included 901 babies, 857 mothers and 530 fathers.

Decoupling the effects of confinement and passivation on semiconductor quantum dots.

Semiconductor (SC) quantum dots (QDs) have recently been fabricated by both chemical and plasma techniques for specific absorption and emission of light. Their optical properties are governed by the size of the QD and the chemistry of any passivation at their surface. Here, we decouple the effects of confinement and passivation by utilising DC magnetron sputtering to fabricate SC QDs in a perfluorinated polyether oil.

Hydrothermal synthesis of highly luminescent blue-emitting ZnSe(S) quantum dots exhibiting low toxicity.

Highly luminescent quantum dots (QDs) that emit in the visible spectrum are of interest to a number of imaging technologies, not least that of biological samples. One issue that hinders the application of luminescent markers in biology is the potential toxicity of the fluorophore. Here we show that hydrothermally synthesized ZnSe(S) QDs have low cytotoxicity to both human colorectal carcinoma cells (HCT-116) and human skin fibroblast cells (WS1).

Nonconservative dynamics of optically trapped high-aspect-ratio nanowires.

We investigate the dynamics of high-aspect-ratio nanowires trapped axially in a single gradient force optical tweezers. A power spectrum analysis of the dynamics reveals a broad spectral resonance of the order of kHz with peak properties that are strongly dependent on the input trapping power. A dynamical model incorporating linear restoring optical forces, a nonconservative asymmetric coupling between translational and rotational degrees of freedom, viscous drag, and white noise provides an excellent fit to experimental observations.

Optical Manipulation and Spectroscopy Of Silicon Nanoparticles Exhibiting Dielectric Resonances.

We demonstrate that silicon (Si) nanoparticles with scattering properties exhibiting strong dielectric resonances can be successfully manipulated using optical tweezers. The large dielectric constant of Si has a distinct advantage over conventional colloidal nanoparticles in that it leads to enhanced trapping forces without the heating associated with metallic nanoparticles. Further, the spectral features of the trapped nanoparticles provide a unique marker for probing size, shape, orientation and local dielectric environment.

Biomedical Optics Express feature issue introduction: optical trapping applications (OTA).

This feature issue of Biomedical Optics Express presents studies which were the focus of the fourth OTA Topical Meeting that was held on 12-15 April 2015 in Vancouver, Canada.

Intrinsic heating in optically trapped Au nanoparticles measured by dark-field spectroscopy.

Assessing the degree of heating present when a metal nanoparticle is trapped in an optical tweezers is critical for its appropriate use in biological applications as a nanoscale force sensor. Heating is necessarily present for trapped plasmonic particles because of the non-negligible extinction which contributes to an enhanced polarisability. We present a robust method for characterising the degree of heating of trapped metallic nanoparticles, using the intrinsic temperature dependence of the localised surface plasmon resonance (LSPR) to infer the temperature of the surrounding fluid at different incident laser powers.

Enhancing Quantum Dots for Bioimaging using Advanced Surface Chemistry and Advanced Optical Microscopy: Application to Silicon Quantum Dots (SiQDs).

Fluorescence lifetime imaging microscopy is successfully demonstrated in both one- and two-photon cases with surface modified, nanocrystalline silicon quantum dots in the context of bioimaging. The technique is further demonstrated in combination with Förster resonance energy transfer studies where the color of the nanoparticles is tuned by using organic dye acceptors directly conjugated onto the nanoparticle surface.