Deciphering the hydrodynamics of lipid-coated microbubble sonoluminescence for sonodynamic therapy.

Sonodynamic therapy (SDT) is a minimally invasive targeted cancer therapy that uses focused low-intensity ultrasound (<10 MPa, <10 W/cm) to activate sonosensitizer drugs. Once activated, these chemical compounds generate reactive oxygen species (ROS) to damage and kill cancer cells. A Phase I clinical trial has shown promising results for treating glioblastoma with SDT.

Biophysical and Biochemical Regulation of Cell Dynamics in Magnetically Assembled Cellular Structures.

Soluble signaling molecules and extracellular matrix (ECM) regulate cell dynamics in various biological processes. Wound healing assays are widely used to study cell dynamics in response to physiological stimuli. However, traditional scratch-based assays can damage the underlying ECM-coated substrates.

SARS-CoV-2 detection with aptamer-functionalized gold nanoparticles.

A rapid detection test for SARS-CoV-2 is urgently required to monitor virus spread and containment. Here, we describe a test that uses nanoprobes, which are gold nanoparticles functionalized with an aptamer specific to the spike membrane protein of SARS-CoV-2. An enzyme-linked immunosorbent assay confirms aptamer binding with the spike protein on gold surfaces.

Label-Free Magnetic-Field-Assisted Assembly of Layer-on-Layer Cellular Structures.

Controlled cell assembly is essential for fabricating in vitro 3D models that mimic the physiology of in vivo cellular architectures. Whereas tissue engineering techniques often rely on intrusive magnetic nanoparticles placed in cells and hydrogel encapsulation of cells to produce multilayered cellular constructs, we describe a high-throughput, label-free, and scaffold-free magnetic field-guided technique that assembles cells into a layered aggregate. An inhomogeneous magnetic field influences the diamagnetic cells suspended in a paramagnetic culture medium.

Fibroblasts Accelerate Formation and Improve Reproducibility of 3D Cellular Structures Printed with Magnetic Assistance.

Fibroblasts (mouse, NIH/3T3) are combined with MDA-MB-231 cells to accelerate the formation and improve the reproducibility of 3D cellular structures printed with magnetic assistance. Fibroblasts and MDA-MB-231 cells are cocultured to produce 12.5 : 87.

Gadopentatic acid affects in vitro proliferation and doxorubicin response in human breast adenocarcinoma cells.

Contrasting agents (CAs) that are administered to patients during magnetic resonance imaging to facilitate tumor identification are generally considered harmless. However, gadolinium (Gd) based contrast agents can be retained in the body, inflicting specific cell line cytotoxicity. We investigate the effect of Gadopentatic acid (Gd-DTPA) on human breast adenocarcinoma MCF-7 cells.

3D cellular structures and co-cultures formed through the contactless magnetic manipulation of cells on adherent surfaces.

A magnet array is employed to manipulate diamagnetic cells that are contained in paramagnetic medium to demonstrate for the first time the contactless bioprinting of three-dimensional (3D) cellular structures and co-cultures of breast cancer MCF-7 and endothelial HUVEC at prescribed locations on tissue culture treated well plates. Sequential seeding of different cell lines and the spatial displacement of the magnet array creates co-cultured cellular structures within a well without using physically intrusive well inserts. Both monotypic and co-culture experiments produce morphologically rich 3D cell structures that are otherwise absent in regular monolayer cell cultures.

Magnetic Printing of a Biosensor: Inexpensive Rapid Sensing To Detect Picomolar Amounts of Antigen with Antibody-Functionalized Carbon Nanotubes.

When an antibody (Ab) is immobilized on its surface, a carbon nanotube (CNT) becomes a biosensor that detects the corresponding antigen (Ag) because Ag-Ab complexes formed on the CNT surface moderate the current flow through it. We synthesized a biological ink containing CNTs that are twice functionalized, first with magnetic nanoparticles and thereafter with the anti-c-Myc monoclonal Ab. The ink is pipetted and dynamically self-organized by an external magnetic field into a dense electrically conducting sensor strip that measures the decrease in current when a sample containing c-Myc Ag is deposited on it.

Nickel oxide nanotube synthesis using multiwalled carbon nanotubes as sacrificial templates for supercapacitor application.

A novel approach for the fabrication of nickel oxide nanotubes based on multiwalled carbon nanotubes as a sacrificial template is described. Electroless deposition is employed to deposit nickel onto carbon nanotubes. The subsequent annealing of the product in the presence of air oxidizes nickel to nickel oxide, and carbon is released as gaseous carbon dioxide, leaving behind nickel oxide nanotubes.

In Situ 3D Label-Free Contactless Bioprinting of Cells through Diamagnetophoresis.

Using whole blood, we demonstrate the first realization of a novel macroscale, contactless, label-free method to print in situ three-dimensional (3D) cell assemblies of different morphologies and sizes. This novel bioprinting method does not use nozzles that can contaminate the cell suspension, or to which cells can adhere. Instead, we utilize the intrinsic diamagnetic properties of whole blood cells to magnetically manipulate them in situ in a nontoxic paramagnetic medium, creating (a) rectangular bar, (b) three-pointed star, and (c) spheroids of varying sizes.

Tailoring Material Stiffness by Filler Particle Organization.

In the context of emerging methods to control particle organization in particle-matrix composite materials, we explore, using finite element analysis, how to modulate the material bulk mechanical stiffness. Compared to a composite containing randomly distributed particles, material stiffness is enhanced 100-fold when filler particles are aligned into linear chains lying parallel to the loading direction. In contrast, chains aligned perpendicular to that direction produce negligible stiffness change.

High gradient magnetic field microstructures for magnetophoretic cell separation.

Microfluidics has advanced magnetic blood fractionation by making integrated miniature devices possible. A ferromagnetic microstructure array that is integrated with a microfluidic channel rearranges an applied magnetic field to create a high gradient magnetic field (HGMF). By leveraging the differential magnetic susceptibilities of cell types contained in a host medium, such as paramagnetic red blood cells (RBCs) and diamagnetic white blood cells (WBCs), the resulting HGMF can be used to continuously separate them without attaching additional labels, such as magnetic beads, to them.

Printing Three-Dimensional Heterogeneities in the Elastic Modulus of an Elastomeric Matrix.

We present a rapid and controllable method to create microscale heterogeneities in the 3D stiffness of a soft material by printing patterns with a ferrofluid ink. An ink droplet moved through a liquid polydimethylsiloxane (PDMS) volume using an externally applied magnetic field sheds clusters of magnetic nanoparticles (MNPs) in its wake. By varying the field spatiotemporally, a well-defined three-dimensional curvilinear feature is printed that contains MNP clusters.

Nickel Nanoparticles Entangled in Carbon Nanotubes: Novel Ink for Nanotube Printing.

We report the serendipitous discovery of a rapid and inexpensive method to attach nanoscale magnetic chaperones to carbon nanotubes (CNTs). Nickel nanoparticles (NiNPs) become entangled in CNTs after both are dispersed in kerosene by sonication and form conjugates. An externally applied magnetic field manipulates the resulting CNTs-NiNP ink without NiNP separation, allowing us to print an embedded circuit in an elastomeric matrix and fabricate a strain gage and an oil sensor.

Changing the magnetic properties of microstructure by directing the self-assembly of superparamagnetic nanoparticles.

Magnetic nanoparticles (MNPs) in a liquid dispersion can be organized through controlled self-assembly by applying an external magnetic field that regulates inter-particle interactions. Thus, micro- and nanostructures of desired morphology and superlattice geometry that show emergent magnetic properties can be fabricated. We describe how superferromagnetism, which is a specific type of emergence, can be produced.

Thermal AND Gate Using a Monolayer Graphene Nanoribbon.

The first ever implementation of a thermal AND gate, which performs logic calculations with phonons, is presented using two identical thermal diodes composed of asymmetric graphene nanoribbons (GNRs). Employing molecular dynamics simulations, the characteristics of this AND gate are investigated and compared with those for an electrical AND gate. The thermal gate mechanism originates through thermal rectification due to asymmetric phonon boundary scattering in the two diodes, which is only effective at the nanoscale and at the temperatures much below the room temperature.

Patterning the Stiffness of Elastomeric Nanocomposites by Magnetophoretic Control of Cross-linking Impeder Distribution.

We report a novel method to pattern the stiffness of an elastomeric nanocomposite by selectively impeding the cross-linking reactions at desired locations while curing. This is accomplished by using a magnetic field to enforce a desired concentration distribution of colloidal magnetite nanoparticles (MNPs) in the liquid precursor of polydimethysiloxane (PDMS) elastomer. MNPs impede the cross-linking of PDMS; when they are dispersed in liquid PDMS, the cured elastomer exhibits lower stiffness in portions containing a higher nanoparticle concentration.

Thermal rectification in a polymer-functionalized single-wall carbon nanotube.

Thermal rectification occurs when heat current through a material is favored in one direction but not in the opposite direction. These materials, often called thermal diodes, have the potential to perform logic calculations with phonons. Rectification obtained with existing material systems is either too minor or too difficult to implement practically.

Communication: A tractable design for a thermal transistor.

We propose a conceptual design for a logic device that is the thermal analog of a transistor. It has fixed hot (emitter) and cold (collector) temperatures, and a gate controls the heat current. Thermal logic could be applied for thermal digital computing, enhance energy conservation, facilitate thermal rheostats, and enable the transport of phononic data.

Soft Polymer Magnetic Nanocomposites: Microstructure Patterning by Magnetophoretic Transport and Self-Assembly.

A method to produce and pattern magnetic microstructure in a soft-polymer matrix is demonstrated. An externally applied magnetic field is used to influence the dynamics of magnetophoretic transport and dipolar self-assembly of magnetic nanoparticle clusters in the liquid precursor of poly-dimethylsiloxane (PDMS). Magnetic nanoparticles agglomerate by an interplay of van der Waals forces and dipolar interactions to form anisotropic clusters.

Communication: Thermal rectification in liquids by manipulating the solid-liquid interface.

Thermal rectification, the origin of which lies in modifying the thermal resistance in a nonlinear manner, could significantly improve the thermal management of a wide range of nano-devices (both electronic and thermoelectric), thereby improving their efficiencies. Since rectification requires a material to be inhomogeneous, it has been typically associated with solids. However, the structure of solids is relatively difficult to manipulate, which makes the tuning of thermal rectification devices challenging.

Modifying thermal transport in electrically conducting polymers: effects of stretching and combining polymer chains.

If their thermal conductivity can be lowered, polyacetylene (PA) and polyaniline (PANI) offer examples of electrically conducting polymers that can have potential use as thermoelectrics. Thermal transport in such polymers is primarily influenced by bonded interactions and chain orientations relative to the direction of heat transfer. We employ molecular dynamics simulations to investigate two mechanisms to control the phonon thermal transport in PANI and PA, namely, (1) mechanical strain and (2) polymer combinations.

Comparison of engagement with ethics between an engineering and a business program.

Increasing university students' engagement with ethics is becoming a prominent call to action for higher education institutions, particularly professional schools like business and engineering. This paper provides an examination of student attitudes regarding ethics and their perceptions of ethics coverage in the curriculum at one institution. A particular focus is the comparison between results in the business college, which has incorporated ethics in the curriculum and has been involved in ethics education for a longer period, with the engineering college, which is in the nascent stages of developing ethics education in its courses.