Michael J. Naughton

Macrophages are critical for the maintenance of immune system homeostasis. They differentiate into distinct functional populations, from pro- to anti-inflammatory phenotype, exhibiting remarkable biological plasticity and responding to both chemical and physical cues to achieve these phenotypes. Controlling macrophage cell phenotypes in vivo, with temporal and spatial control, could have significant impact on a wide range of human diseases and ailments associated with inflammation, which range from rheumatoid arthritis and Alzheimer’s to cancer tumorigenesis. Piezoelectrics, materials in which pressure causes a voltage and vice versa, represent a potential platform for non-invasive and remote modulation of cells and tissues and, in particular, control of immune cell activation. Here, it is demonstrated that RAW264.7 mouse macrophage cells that have taken up piezoelectric nanoparticles (pzNPs) specifically adopt an M1 cellular phenotype and requisite calcium ion influx upon ultrasound stimulation. One can further identify which cells have taken up pzNPs and which cells adopt an M1 polarization in mixed populations of pzNP-loaded and -unloaded cells. The overall goal is to leverage this novel cellular assay to help improve understanding of how biological cells respond to bioelectric stimulation.

Macrophages are critical for the maintenance of immune system homeostasis. They differentiate into distinct functional populations, from pro-to anti-inflammatory phenotype, exhibiting remarkable biological plasticity and responding to both chemical and physical cues to achieve these phenotypes. Controlling macrophage cell phenotypes in vivo , with temporal and spatial control, could have significant impact on a wide range of human diseases and ailments associated with inflammation, which range from rheumatoid arthritis and Alzheimer’s to cancer tumorigenesis. Piezoelectrics, materials in which pressure causes a voltage and vice versa , represent a potential platform for non-invasive and remote modulation of cells and tissues and, in particular, control of immune cell activation. Here, it is demonstrated that RAW264.7 mouse macrophage cells that have taken up piezoelectric nanoparticles (pzNPs) specifically adopt an M1 cellular phenotype and requisite calcium ion influx upon ultrasound stimulation. One can further identify which cells have taken up pzNPs and which cells adopt an M1 polarization in mixed populations of pzNP-loaded and -unloaded cells. The overall goal is to leverage this novel cellular assay to help improve understanding of how biological cells respond to bioelectric stimulation.

A vanishing dielectric function is required for longitudinal plasmonic or polaronic modes in a polarizable uniform medium, and signals the presence of singular charge fluctuations. It also strengthens Cooper pairing in a superconductor via resonant antishielding (RAS). This study combines these notions in a strategy to strongly enhance superconductivity, proposing an interface (and ultimately a superlattice) of an ultrathin superconductor and a metal‐organic framework. This structure possesses a momentum‐independent and resonant effective dielectric function, a key feature for RAS. To estimate the superconducting transition temperature T _c enhancement, this study uses Leavens's scaling method to relate the spectral integral of the RAS‐renormalized Eliashberg function to T _c , which this study posits may underlie recent observations of enhanced T _c in FeSe on SrTiO ₃ . After renormalization, its estimates show that ambient temperature and pressure operation can be achievable in the RAS scheme. To avoid lattice reconstruction or heavy bipolarons, this study proposes a system that assures that the corresponding electron‐boson coupling remains moderate. It also calculates the quantum Fisher information from the dynamic charge susceptibility in the normal state (for vanishing losses) in this proposed superlattice, and its estimate suggests the presence of superconductivity signatures well above T _c due to quantum charge entanglement buildup.

Electrical crosstalk can constrain the performance of multielectrode arrays in electro- and neurophysiology, in terms of both stimulation and recording. This is especially so at high electrode density, desirable for spatiotemporal mapping of bioelectrical signals from multiple cells. Channel interference due to crosstalk is currently only partially addressed, via continuous interleaved sampling or post-data acquisition spike sorting. Here, we show that a locally-shielded electrode architecture significantly suppresses crosstalk, and enables multi-site recording at high electrode density without the need for spike sorting. Arrays of shielded electrodes, prepared by micro- and nanofabrication techniques in a vertically-oriented coaxial geometry, demonstrate at least a 400 times improvement in spatial density over the unshielded case.

Grand Challenges in Nanofabrication: There Remains Plenty of Room at the Bottom

Melanin nanoparticles are known to be biologically benign to human cells for a wide range of concentrations in a high glucose culture nutrition. Here, we show cytotoxic behavior at high nanoparticle and low glucose concentrations, as well as at low nanoparticle concentration under exposure to (nonionizing) visible radiation. To study these effects in detail, we developed highly monodispersed melanin nanoparticles (both uncoated and glucose-coated). In order to study the effect of significant cellular uptake of these nanoparticles, we employed three cancer cell lines: VM-M3, A375 (derived from melanoma), and HeLa, all known to exhibit strong macrophagic character, i.e., strong nanoparticle uptake through phagocytic ingestion. Our main observations are: (i) metastatic VM-M3 cancer cells massively ingest melanin nanoparticles (mNPs); (ii) the observed ingestion is enhanced by coating mNPs with glucose; (iii) after a certain level of mNP ingestion, the metastatic cancer cells studied here are observed to die—glucose coating appears to slow that process; (iv) cells that accumulate mNPs are much more susceptible to killing by laser illumination than cells that do not accumulate mNPs; and (v) non-metastatic VM-NM1 cancer cells also studied in this work do not ingest the mNPs, and remain unaffected after receiving identical optical energy levels and doses. Results of this study could lead to the development of a therapy for control of metastatic stages of cancer.

The nanoscale coaxial cable (nanocoax) has demonstrated optical confinement in the visible and the near infrared. We report on a novel nanofabrication process which yields optically addressable, sub-µm diameter, and high aspect ratio metal-insulator-metal nanocoaxes made by atomic layer deposition of Pt and Al₂O₃. We observe sub-diffraction-limited optical transmission via the fundamental, TEM-like mode by excitation with a radially polarized optical vortex beam. Our experimental results are based on interrogation with a polarimetric imager. Finite element method numerical simulations support these results, and their uniaxial symmetry was exploited to model taper geometries with both an electrically large volume, (15λ)³, and a nanoscopic exit aperture, (λ/200)².

We study the large-amplitude response of classical molecules to electromagnetic radiation, showing the universality of the transition from linear to nonlinear response and breakup at sufficiently large amplitudes. We demonstrate that a range of models, from the simple harmonic oscillator to the successful Peyrard-Bishop-Dauxois type models of DNA, which include realistic effects of the environment (including damping and dephasing due to thermal fluctuations), lead to characteristic universal behavior: formation of domains of dissociation in driving force amplitude-frequency space, characterized by the presence of local boundary minima. We demonstrate that by simply following the progression of the resonance maxima in this space, while gradually increasing intensity of the radiation, one must necessarily arrive at one of these minima, i.e., a point where the ultrahigh spectral selectivity is retained. We show that this universal property, applicable to other oscillatory systems, is a consequence of the fact that these models belong to the fold catastrophe universality class of Thom's catastrophe theory. This in turn implies that for most biostructures, including DNA, high spectral sensitivity near the onset of the denaturation processes can be expected. Such spectrally selective molecular denaturation could find important applications in biology and medicine.

We develop nano-bridged nanosphere lithography (NB-NSL), a modification to the widely used conventional nanosphere lithography (NSL). Nano-bridges between polystyrene (PS) spheres of a pristine NSL template are controllably formed in a two-step process: (i) spin-coating of a dilute styrene solution on top of the template, followed by (ii) oxygen plasma etching of the template. We show that the nanobridge dimensions can be precisely tuned by controlling the pre-processing conditions and the plasma etching time. The resulting lithography templates feature control over the shape and size of the apertures, which determine the morphology of the final nano-island arrays after material deposition and template removal. The unique advantage of NB-NSL is that PS particle templates based on a single PS particle diameter can be utilized for the fabrication of a variation of nano-island shapes and sizes, whereas conventional NSL yields only bowtie-shaped nano-islands, with their size being predetermined by the PS particle diameter of the template.

Anodized alumina membranes (AAMs) have proven effective at making vertically-oriented and well-ordered metal nanowire arrays, which are useful in plasmonics and electrochemistry. Here, we produced Al nanowires via directed AAM pore nucleation: a patterned oxide mask on a flat Al surface directed where pores did and did not form, the pores acting to oxidize Al around the sites without pores. This left Al nanowires embedded in the AAM, and produced freestanding Al nanowires after etching the AAM. The nanowire tops had two distinct contours, smooth bowls and flat rough surfaces—suggesting that nanowires with bowl tops result from slow pore development relative to pattern-nucleated pores, not pore blockage as prior literature suggests. The observed low porosity of ∼2%, as opposed to the more typical 10%, suggests pore nucleation in the electrolyte employed may need greater local variations in electric field or pH, possibly explaining the electrolyte’s peculiar ability to make Al nanowires. Finally, a soft nano-imprint lithography process was developed here to pattern the mask without damaging the stamp, avoiding a stamp degradation problem in previous work that utilized hard nano-imprint lithography.