E-cadherin biomaterials reprogram collective cell migration and cell cycling by forcing homeostatic conditions.

Cells attach to the world through either cell-extracellular matrix adhesion or cell-cell adhesion, and traditional biomaterials imitate the matrix for integrin-based adhesion. However, materials incorporating cadherin proteins that mimic cell-cell adhesion offer an alternative to program cell behavior and integrate into living tissues. We investigated how cadherin substrates affect collective cell migration and cell cycling in epithelia. Our approach involved biomaterials with matrix proteins on one-half and E-cadherin proteins on the other, forming a "Janus" interface across which we grew a single sheet of cells. Tissue regions over the matrix side exhibited normal collective dynamics, but an abrupt behavior shift occurred across the Janus boundary onto the E-cadherin side, where cells attached to the substrate via E-cadherin adhesions, resulting in stalled migration and slowing of the cell cycle. E-cadherin surfaces disrupted long-range mechanical coordination and nearly doubled the length of the G0/G1 phase of the cell cycle, linked to the lack of integrin focal adhesions on the E-cadherin surface.

E-cadherin biointerfaces reprogram collective cell migration and cell cycling by forcing homeostatic conditions.

Cells attach to the world around them in two ways-cell:extracellular-matrix adhesion and cell:cell adhesion-and conventional biomaterials are made to resemble the matrix to encourage integrin-based cell adhesion. However, interest is growing for cell-mimetic interfaces that mimic cell-cell interactions using cadherin proteins, as this offers a new way to program cell behavior and design synthetic implants and objects that can integrate directly into living tissues. Here, we explore how these cadherin-based materials affect collective cell behaviors, focusing specifically on collective migration and cell cycle regulation in cm-scale epithelia. We built culture substrates where half of the culture area was functionalized with matrix proteins and the contiguous half was functionalized with E-cadherin proteins, and we grew large epithelia across this 'Janus' interface. Parts of the tissues in contact with the matrix side of the Janus interface exhibited normal collective dynamics, but an abrupt shift in behaviors happened immediately across the Janus boundary onto the E-cadherin side, where cells formed hybrid E-cadherin junctions with the substrate, migration effectively froze in place, and cell-cycling significantly decreased. E-cadherin materials suppressed long-range mechanical correlations in the tissue and mechanical information reflected off the substrate interface. These effects could not be explained by conventional density, shape index, or contact inhibition explanations. E-cadherin surfaces nearly doubled the length of the G0/G1 phase of the cell cycle, which we ultimately connected to the exclusion of matrix focal adhesions induced by the E-cadherin culture surface.

Three-Dimensional Silicon Electronic Systems Fabricated by Compressive Buckling Process.

Recently developed approaches in deterministic assembly allow for controlled, geometric transformation of two-dimensional structures into complex, engineered three-dimensional layouts. Attractive features include applicability to wide ranging layout designs and dimensions along with the capacity to integrate planar thin film materials and device layouts. The work reported here establishes further capabilities for directly embedding high-performance electronic devices into the resultant 3D constructs based on silicon nanomembranes (Si NMs) as the active materials in custom devices or microscale components released from commercial wafer sources. Systematic experimental studies and theoretical analysis illustrate the key ideas through varied 3D architectures, from interconnected bridges and coils to extended chiral structures, each of which embed n-channel Si NM MOSFETs (nMOS), Si NM diodes, and p-channel silicon MOSFETs (pMOS). Examples in stretchable/deformable systems highlight additional features of these platforms. These strategies are immediately applicable to other wide-ranging classes of materials and device technologies that can be rendered in two-dimensional layouts, from systems for energy storage, to photovoltaics, optoelectronics, and others.

Double-heterojunction nanorod light-responsive LEDs for display applications.

Dual-functioning displays, which can simultaneously transmit and receive information and energy through visible light, would enable enhanced user interfaces and device-to-device interactivity. We demonstrate that double heterojunctions designed into colloidal semiconductor nanorods allow both efficient photocurrent generation through a photovoltaic response and electroluminescence within a single device. These dual-functioning, all-solution-processed double-heterojunction nanorod light-responsive light-emitting diodes open feasible routes to a variety of advanced applications, from touchless interactive screens to energy harvesting and scavenging displays and massively parallel display-to-display data communication.

Multilayer Transfer Printing for Pixelated, Multicolor Quantum Dot Light-Emitting Diodes.

Here, we report multilayer stacking of films of quantum dots (QDs) for the purpose of tailoring the energy band alignment between charge transport layers and light emitting layers of different color in quantum dot light-emitting diodes (QD LED) for maximum efficiency in full color operation. The performance of QD LEDs formed by transfer printing compares favorably to that of conventional devices fabricated by spin-casting. Results indicate that zinc oxide (ZnO) and titanium dioxide (TiO2) can serve effectively as electron transport layers (ETLs) for red and green/blue QD LEDs, respectively. Optimized selections for each QD layer can be assembled at high yields by transfer printing with sacrificial fluoropolymer thin films to provide low energy surfaces for release, thereby allowing shared common layers for hole injection (HIL) and hole transport (HTL), along with customized ETLs. This strategy allows cointegration of devices with heterogeneous energy band diagrams, in a parallelized scheme that offers potential for high throughput and practical use.

Hydrophobic polydimethylsiloxane (PDMS) coating of mesoporous silica and its use as a preconcentrating agent of gas analytes.

Mesoporous silica with mean pore size of ∼14 nm was coated by polydimethylsiloxane (PDMS) using a thermal deposition method. We showed that the inner walls of pores larger than ∼8 nm can be coated by thin layers of PDMS, and the surfaces consisting of PDMS-coated silica were superhydrophobic, with water contact angles close to 170°. We used the PDMS-coated silica as adsorbents of various gas-phase chemical warfare agent (CWA) simulants. PDMS-coated silica allowed molecular desorption of various CWA simulants even after exposure under highly humid conditions and, therefore, is applicable as an agent for the preconcentration of gas-phase analytes to enhance the sensitivities of various sensors.