Sandra Whaley Bishnoi

A benchmark study on the thermal conductivity of nanofluids

This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about the sample average with only few outliers. The thermal conductivity of the nanofluids was found to increase with particle concentration and aspect ratio, as expected from classical theory. There are (small) systematic differences in the absolute values of the nanofluid thermal conductivity among the various experimental approaches; however, such differences tend to disappear when the data are normalized to the measured thermal conductivity of the basefluid. The effective medium theory developed for dispersed particles by Maxwell in 1881 and recently generalized by Nan et al. [J. Appl. Phys. 81, 6692 (1997)], was found to be in good agreement with the experimental data, suggesting that no anomalous enhancement of thermal conductivity was achieved in the nanofluids tested in this exercise.

Au Nanomatryoshkas as Efficient Near-Infrared Photothermal Transducers for Cancer Treatment: Benchmarking against Nanoshells

Au nanoparticles with plasmon resonances in the near-infrared (NIR) region of the spectrum efficiently convert light into heat, a property useful for the photothermal ablation of cancerous tumors subsequent to nanoparticle uptake at the tumor site. A critical aspect of this process is nanoparticle size, which influences both tumor uptake and photothermal efficiency. Here, we report a direct comparative study of ∼90 nm diameter Au nanomatryoshkas (Au/SiO2/Au) and ∼150 nm diameter Au nanoshells for photothermal therapeutic efficacy in highly aggressive triple negative breast cancer (TNBC) tumors in mice. Au nanomatryoshkas are strong light absorbers with 77% absorption efficiency, while the nanoshells are weaker absorbers with only 15% absorption efficiency. After an intravenous injection of Au nanomatryoshkas followed by a single NIR laser dose of 2 W/cm2 for 5 min, 83% of the TNBC tumor-bearing mice appeared healthy and tumor free >60 days later, while only 33% of mice treated with nanoshells survived the same period. The smaller size and larger absorption cross section of Au nanomatryoshkas combine to make this nanoparticle more effective than Au nanoshells for photothermal cancer therapy.

Sub-100 nm gold nanomatryoshkas improve photo-thermal therapy efficacy in large and highly aggressive triple negative breast tumors

There is an unmet need for efficient near-infrared photothermal transducers for the treatment of highly aggressive cancers and large tumors where the penetration of light can be substantially reduced, and the intra-tumoral nanoparticle transport is restricted due to the presence of hypoxic or necrotic regions. We report the performance advantages obtained by sub 100nm gold nanomatryushkas, comprising concentric gold-silica-gold layers compared to conventional ~150nm silica core gold nanoshells for photothermal therapy of triple negative breast cancer. We demonstrate that a 33% reduction in silica-core-gold-shell nanoparticle size, while retaining near-infrared plasmon resonance, and keeping the nanoparticle surface charge constant, results in a four to five fold tumor accumulation of nanoparticles following equal dose of injected gold for both sizes. The survival time of mice bearing large (>1000mm(3)) and highly aggressive triple negative breast tumors is doubled for the nanomatryushka treatment group under identical photo-thermal therapy conditions. The higher absorption cross-section of a nanomatryoshka results in a higher efficiency of photonic to thermal energy conversion and coupled with 4-5× accumulation within large tumors results in superior therapy efficacy.

Rapid Raman imaging of stable, functionalized nanoshells in mammalian cell cultures.

Two Raman-active poly(ethylene glycol) (PEG) molecules, one linear (MW 5000) and the other branched (MW 2420), are synthesized to stabilize gold-silica nanoshells in cell culture media and track nanoparticles in mammalian cell cultures. The linear PEG provides greater nanoshell stability in saline solution compared to commercially available PEG-thiol or the branched PEG. Surface enhanced Raman scattering rapidly tracks the probes and provides semiquantitative information regarding particle localization within mouse macrophage (RAW 264.7) and human breast cancer (MCF 7) cell cultures.

Enhancing T1 magnetic resonance imaging contrast with internalized gadolinium(III) in a multilayer nanoparticle

Significance We demonstrate a magnetic resonance image-enhancing nanoparticle with the potential for use in multiple biomedical imaging and therapeutic applications. The nanoparticle contains internal gadolinium ions for T1 imaging contrast, located between an inner core and outer Au layer, in a multilayered geometry. The proton relaxivity is enhanced through longer-range interactions with the protons outside the nanoparticle, a radical departure from the molecular chelates currently in use for MRI. This geometry provides a very large relaxivity enhancement (r1 ∼ 24 mM−1⋅s−1) compared with conventional chelating agents (Gd-DOTA: r1 ∼ 3 mM−1⋅s−1) at high magnetic fields (4.7 T). This MRI-enhancing nanoparticle geometry opens opportunities for the development of multifunctional MRI-active nanoparticles for biomedical applications. Multifunctional nanoparticles for biomedical applications have shown extraordinary potential as contrast agents in various bioimaging modalities, near-IR photothermal therapy, and for light-triggered therapeutic release processes. Over the past several years, numerous studies have been performed to synthesize and enhance MRI contrast with nanoparticles. However, understanding the MRI enhancement mechanism in a multishell nanoparticle geometry, and controlling its properties, remains a challenge. To systematically examine MRI enhancement in a nanoparticle geometry, we have synthesized MRI-active Au nanomatryoshkas. These are Au core–silica layer–Au shell nanoparticles, where Gd(III) ions are encapsulated within the silica layer between the inner core and outer Au layer of the nanoparticle (Gd-NM). This multifunctional nanoparticle retains its strong near-IR Fano-resonant optical absorption properties essential for photothermal or other near-IR light-triggered therapy, while simultaneously providing increased T1 contrast in MR imaging by concentrating Gd(III) within the nanoparticle. Measurements of Gd-NM revealed a strongly enhanced T1 relaxivity (r1 ∼ 24 mM−1⋅s−1) even at 4.7 T, substantially surpassing conventional Gd(III) chelating agents (r1 ∼ 3 mM−1⋅s−1 at 4.7 T) currently in clinical use. By varying the thickness of the outer gold layer of the nanoparticle, we show that the observed relaxivities are consistent with Solomon–Bloembergen–Morgan (SBM) theory, which takes into account the longer-range interactions between the encapsulated Gd(III) and the protons of the H2O molecules outside the nanoparticle. This nanoparticle complex and its MRI T1-enhancing properties open the door for future studies on quantitative tracking of therapeutic nanoparticles in vivo, an essential step for optimizing light-induced, nanoparticle-based therapies.

Prognosis for patients with metastatic breast cancer who achieve a no-evidence-of-disease status after systemic or local therapy.

This study sought to determine outcomes for patients with metastatic breast cancer (MBC) with no evidence of disease (NED) after treatment and to identify factors predictive of outcomes once the status of NED was attained.

The role of protein binding in the poisoning of gold nanoparticle catalysts

Seed mediated catalytic growth of gold nanoparticles is used in the design of biosensors for the products of peroxidase proteins, though the role of in situ proteins and the enzymes themselves on the sensitivity of these biosensors is yet to be addressed. This work specifically focuses on whether the presence of proteins with a strong attraction to the gold nanoparticle seeds, such as albumin proteins, inhibits the nanoparticles catalytic properties. We have determined that the sensitivity of the biosensor design, defined as its response to the reducing agent hydrogen peroxide, is highly dependent on the presence of bovine serum albumin (BSA) and less dependent on the presence of the enzyme glucose oxidase. We suggest that the strong interaction between BSA and the gold surface leads to poisoning of the catalytic sites on the particle surface, which reduces the uniform growth of the nanoparticles and increases asymmetric growth of small gold nanoparticles onto the seed surface. The overall effect of the protein interaction is to lower the sensitivity of the model biosensor.

Survivorship and advocacy in Inflammatory Breast Cancer

In February 2017, the Morgan Welch Inflammatory Breast Cancer (IBC) Research Program and Clinic hosted a scientific conference in Houston to commemorate the tenth anniversary of the opening of the first IBC-dedicated clinic in the world. Attendees included basic science researchers, clinicians who treat IBC, as well as patients and their caregivers. Several US-based and international IBC-focused nonprofit organizations were also represented. In this third paper from the conference, we report on the breakout session regarding survivorship and advocacy issues related to IBC, sharing an overview of the educational content presented and discussions regarding the future of IBC advocacy. Panelists focused on lymphedema research and clinical solutions, integrative medicine, and social work, with time provided for questions in small groups. IBC nonprofits that are leading advocacy efforts were introduced, and ways to become involved in these initiatives were discussed. Priorities for future advocacy and clinical care needs were also highlighted. In addition to summarizing these topics, we provide a suggested integrated IBC-specific plan of care that could be provided to the patient at the beginning of care and referred to throughout treatment and follow-up.

Multifunctionalization of Gold Nanoshells

Gold silica nanoshells have found many applications within the field of molecular biology, including as nanoscale sensors, the detection of biomarkers, and in the treatment of solid tumors using photothermal ablation. In order for them to be targeted to specific biomarkers while also remaining stable in biological media, it is often necessary to modify their surfaces with more than one functional group. Here, we describe how to create multifunctional gold nanoshells that can be used to either target specific tumor types in vivo or for the detection of biomarkers using biological specimen.

Laser sintering of carbon nanotube-reinforced ceramic nanocomposites

The fabrication of carbon nanotube (CNT)-reinforced ceramic nanocomposites through laser sintering has been rarely studied, and the fabrication feasibility has been rarely tested. Laser sintering is a flexible, localized and high-precision process, which can also potentially produce coatings or parts with complicated shapes and/or spatially controlled compositions. Therefore, compared with other technologies laser sintering has its own advantages. Experimental investigations reported in this paper have confirmed the feasibility of fabricating CNT-reinforced ceramic nanocomposites through laser sintering of ceramic nanoparticles and CNTs. The studies show that laser sintering can induce the agglomeration of ceramic nanoparticles into a relatively more continuous ceramic phase, and during the sintering process CNTs are well preserved without any obvious quality degradation, and they are also bonded with the ceramic phase after laser sintering.