Cardiac progenitor cells (CPCs) are a promising candidate for cardiac regeneration, and the interaction between CPCs and their microenvironment can influence their regenerative response. Notch signaling plays a key role in cell fate decisions in the developing and adult heart. Here, we investigated the effect of three-dimensional (3D) spheroid culture, as a model of the 3D microenvironment, on Notch in fetal and adult human CPCs, under room air (20%) and physiological (5%) oxygen tension. Notch signaling is enhanced in 3D spheroids; spheroid culture under 5% O2 further increases Notch signaling enhancement, and might ultimately improve the regenerative potential of CPCs.

The synthesis of egg-white (EW) capped silver nanoparticles (NPs) was carried-out in a one-step reaction using crude EWs, which is a reagent that can be easily found. These NPs were applied for the colorimetric detection of Hg2+ ions in solution. The results showed a blue shift of the surface plasmon absorption due to the decrease in Ag NP size upon incorporating Hg through the formation of an Ag–Hg amalgam shell. The probe was used for the selective determination of Hg2+ ions in tap water with excellent selectivity and sensitivity with a detection limit of about 300 nM.

The effect of p-type doping at ultra-low concentrations (~10−4–10−5 monomer mol fraction) of the polymer poly(3-hexylthiophene) (P3HT) is studied using charge modulation (CM) spectroscopy. Quantitative analysis of CM spectra of doped P3HT show that dopants induce measurable changes in the P3HT local chain conformation. We find that the dopants reside in both the aggregate and amorphous regions of the polymer, not just in the amorphous regions, as previously assumed. With increased doping, the P3HT intrachain disorder grows, causing the P3HT chains to become more oligomer-like, which we postulate leads to the drop in mobility commonly observed in literature.

Gelatin-based hydrogels derived from hydrolysis of collagen have been extensively used in pharmaceutical and medical applications because of their biocompatibility and biodegradability. For example, gelatin-based hydrogels are finding use in drug delivery and tissue engineering because they are able to promote cell adhesion and proliferation. In addition, these hydrogels can be used as wound dressings due to their attractive fluid absorbance properties. Manufacturing technologies such as ultraviolet stereolithography and two-photon polymerization can be used to prepare structures containing photosensitive gelatin-based hydrogels. This review describes the preparation of gelatin-based hydrogels and use of these materials for biomedical applications.

Nuclear translocation of Yes-associated-protein (YAP) in single cells serves as a key sensor of matrix stiffness. On two-dimensional (2D) polyacrylamide (PA) hydrogels, we found that nuclear YAP localization in epithelial clusters increases with gel stiffness and reduces with cell density. To measure YAP activity in 3D-like confinement of tunable stiffness, we fabricated PA-based microchannels. Here, narrower channels enhanced nuclear YAP localization even in softer extracellular matrix and denser epithelial clusters, both of which reduced YAP activation in 2D. Thus, the presented hydrogel microchannel-based platform may reveal new mechanosensitive cellular signatures in 3D-like settings, which cannot be captured on standard 2D hydrogels.

Metamaterials are artificial materials with emerging physical properties that go well beyond those of their individual constituents, providing interesting opportunities to tailor interactions between waves and matter. This article provides an overview of recent research activity in electromagnetics, nano-optics, acoustics and mechanics, showing how suitably tailored meta-elements and their arrangements open exciting venues to manipulate and control waves in unprecedented ways. Theoretical and experimental efforts to realize metamaterials for scattering suppression, nanostructures and metasurfaces to control wave propagation and radiation, large nonreciprocity in bulk materials without magnetism, giant nonlinear responses in properly tailored metasurfaces, and metasurfaces with balanced loss and gain are discussed. Physical insights into the exotic phenomena behind the metamaterial responses, new devices based on these concepts, and their impact on technology are also discussed.

We present the first characterization of strongly scale-dependent charge transport of a unique, hierarchical complex topology: an interconnected random network of silicon quantum dots (QDs) and nanowires. We show that this specific topology has different charge transport characteristics on the nanoscale and the microscale: photogenerated charge carriers tend to be confined inside the QDs and externally injected charge carriers flow preferably along the nanowires. The former enables expression of quantum confinement properties, and the latter mainly contributes to the good electrical conduction on the microscale. Our findings strongly suggest that this multifunctionality can be controlled and used in photovoltaic device applications.

The correction of aberrations in the scanning transmission electron microscope (STEM) has simultaneously improved both spatial and temporal resolution, making it possible to capture the dynamics of single atoms inside materials, and resulting in new insights into the dynamic behavior of materials. In this article, we describe the different beam–matter interactions that lead to atomic excitations by transferring energy and momentum. We review recent examples of sequential STEM imaging to demonstrate the dynamic behavior of single atoms both within materials, at dislocations, at grain and interface boundaries, and on surfaces. We also discuss the effects of such dynamic behavior on material properties. We end with a summary of ongoing instrumental and algorithm developments that we anticipate will improve the temporal resolution significantly, allowing unprecedented insights into the dynamic behavior of materials at the atomic scale.