Enhanced Nanobubble Formation: Gold Nanoparticle Conjugation to Qβ Virus-like Particles.

Plasmonic gold nanostructures are a prevalent tool in modern hypersensitive analytical techniques such as photoablation, bioimaging, and biosensing. Recent studies have shown that gold nanostructures generate transient nanobubbles through localized heating and have been found in various biomedical applications. However, the current method of plasmonic nanoparticle cavitation events has several disadvantages, specifically including small metal nanostructures (≤10 nm) which lack size control, tuneability, and tissue localization by use of ultrashort pulses (ns, ps) and high-energy lasers which can result in tissue and cellular damage.

X-ray Tomography Coupled with Finite Elements, A Fast Method to Design Aerogel Composites and Prove Their Superinsulation Experimentally.

Composite aerogels can include fibers, opacifiers and binders but are rarely designed and optimized to achieve the best thermal/mechanical efficiency. This paper proposes a three-dimensional X-ray tomography-based method for designing composites. Two types of models are considered: classical and inexpensive homogenization models and more refined finite element models.

Temperature-controlled spectrophotometry: a simultaneous analysis of phase transition, thermal degradation and optical properties of semi-transparent composites from 20 °C to 450 °C.

So far, optical and effective radiative properties of polymer matrix based composites were investigated at temperatures well below their degradation temperature. At the same time, polymers exhibit temperature dependent physical properties and may undergo structural changes as their temperature raises. In this work, we employ the "Temperature-Controlled Spectrophotometry", a new method enabling to identify simultaneously phase transitions, thermal degradation and radiative properties of semi-transparent composites over a large temperature range.

Curvature and temperature-dependent thermal interface conductance between nanoscale gold and water.

Plasmonic gold nanoparticles (AuNPs) can convert laser irradiation into thermal energy for a variety of applications. Although heat transfer through the AuNP-water interface is considered an essential part of the plasmonic heating process, there is a lack of mechanistic understanding of how interface curvature and the heating itself impact interfacial heat transfer. Here, we report atomistic molecular dynamics simulations that investigate heat transfer through nanoscale gold-water interfaces.

Nanoparticle Fragmentation Below the Melting Point Under Single Picosecond Laser Pulse Stimulation.

Understanding the laser-nanomaterials interaction including nanomaterial fragmentation has important implications in nanoparticle manufacturing, energy, and biomedical sciences. So far, three mechanisms of laser-induced fragmentation have been recognized including non-thermal processes and thermomechanical force under femtosecond pulses, and the phase transitions under nanosecond pulses. Here we show that single picosecond (ps) laser pulse stimulation leads to anomalous fragmentation of gold nanoparticles that deviates from these three mechanisms.

Single pulse heating of a nanoparticle array for biological applications.

With the ability to convert external excitation into heat, nanomaterials play an essential role in many biomedical applications. Two modes of nanoparticle (NP) array heating, nanoscale-confined heating (NCH) and macroscale-collective heating (MCH), have been found and extensively studied. Despite this, the resulting biological response at the protein level remains elusive.

Computational Investigation of Protein Photoinactivation by Molecular Hyperthermia.

To precisely control protein activity in a living system is a challenging yet long-pursued objective in biomedical sciences. Recently, we have developed a new approach named molecular hyperthermia (MH) to photoinactivate protein activity of interest without genetic modification. MH utilizes nanosecond laser pulse to create nanoscale heating around plasmonic nanoparticles to inactivate adjacent protein in live cells.

Transient Photoinactivation of Cell Membrane Protein Activity without Genetic Modification by Molecular Hyperthermia.

Precise manipulation of protein activity in living systems has broad applications in biomedical sciences. However, it is challenging to use light to manipulate protein activity in living systems without genetic modification. Here, we report a technique to optically switch off protein activity in living cells with high spatiotemporal resolution, referred to as molecular hyperthermia (MH).

Monte Carlo prediction of ballistic effect on phonon transport in silicon in the presence of small localized heat source.

Understanding phonon transport at nanoscale is critically important for thermal nanometrology applications including scanning thermal microscopy, three-omega and time domain thermoreflectance experiments. In this paper, a multidimensional non-gray Monte Carlo simulation is developed to investigate the ballistic phonon transport in a silicon sample heated on the top by a small localized heater line. We observed that heat confinement occurs for very small heat sources.

Optical properties of oakwood in the near-infrared range of semi-transparency.

The spectral absorption and scattering properties of oakwood are retrieved from the measurements of both the normal-hemispherical reflectance and transmittance in the visible and near-infrared ranges of semi-transparency. We employ two alternative methods for the radiative transfer in wood samples: the modified two-flux approximation and the high-order discrete ordinate method. The modifications of both methods take into account the effect of total internal reflection at both surfaces of the wood samples.

Tuning the Gold Nanoparticle Colorimetric Assay by Nanoparticle Size, Concentration, and Size Combinations for Oligonucleotide Detection.

Gold nanoparticle (GNP)-based aggregation assay is simple, fast, and employs a colorimetric detection method. Although previous studies have reported using GNP-based colorimetric assay to detect biological and chemical targets, a mechanistic and quantitative understanding of the assay and effects of GNP parameters on the assay performance is lacking. In this work, we investigated this important aspect of the GNP aggregation assay including effects of GNP concentration and size on the assay performance to detect malarial DNA.

Quantitative Comparison of Photothermal Heat Generation between Gold Nanospheres and Nanorods.

Gold nanoparticles (GNPs) are widely used for biomedical applications due to unique optical properties, established synthesis methods, and biological compatibility. Despite important applications of plasmonic heating in thermal therapy, imaging, and diagnostics, the lack of quantification in heat generation leads to difficulties in comparing the heating capability for new plasmonic nanostructures and predicting the therapeutic and diagnostic outcome. This study quantifies GNP heat generation by experimental measurements and theoretical predictions for gold nanospheres (GNS) and nanorods (GNR).

Effect of pore-level geometry on far-field radiative properties of three-dimensionally ordered macroporous ceria particle.

The effects of pore size on direction-averaged radiative properties of three-dimensionally ordered macroporous (3DOM) cerium dioxide (ceria) particles are investigated in the spectral range of 0.3-10 μm. The particles are of spherical shape and contain interconnected pores in a face-centered cubic lattice arrangement.

Modeling radiation characteristics of semitransparent media containing bubbles or particles.

Modeling of radiation characteristics of semitransparent media containing particles or bubbles in the independent scattering limit is examined. The existing radiative properties models of a single particle in an absorbing medium using the approaches based on (1) the classical Mie theory neglecting absorption by the matrix, (2) the far field approximation, and (3) the near field approximation are reviewed. Comparison between models and experimental measurements are carried out not only for the radiation characteristics but also for hemispherical transmittance and reflectance of porous fused quartz.

Modified two-flux approximation for identification of radiative properties of absorbing and scattering media from directional-hemispherical measurements.

A modified two-flux approximation is suggested for calculating the hemispherical transmittance and reflectance of a refracting, absorbing, and scattering medium in the case of collimated irradiation of the sample along the normal to the interface. The Fresnel reflection is taken into account in this approach. It is shown that the new approximation is rather accurate for the model transport scattering function.

Use of Mie theory to analyze experimental data to identify infrared properties of fused quartz containing bubbles.

An improved method used to determine the absorption and scattering characteristics of a weakly absorbing substance containing bubbles is suggested. The identification procedure is based on a combination of directional-hemispherical measurements and predictions of Mie-scattering theory including approximate relations for a medium with polydisperse bubbles. A modified two-flux approximation is suggested for the calculation of directional-hemispherical transmittance and reflectance of a refracting and scattering medium.