Highly Stretchable and Conductive Superhydrophobic Coating for Flexible Electronics

Superhydrophobic materials integrating stretchability with conductivity have huge potential in the emerging application horizons such as wearable electronic sensors, flexible power storage apparatus, and corrosion-resistant circuits. Herein, a facile spraying method is reported to fabricate a durable superhydrophobic coating with excellent stretchable and electrical performance by combing 1-octadecanethiol-modified silver nanoparticles (M-AgNPs) with polystyrene-<i>b</i>-poly­(ethylene-<i>co</i>-butylene)-<i>b</i>-polystyrene (SEBS) on a prestretched natural rubber (NR) substrate. The embedding of M-AgNPs in elastic SEBS matrix and relaxation of prestretched NR substrate construct hierarchical rough architecture and endow the coating with dense charge-transport pathways. The fabricated coating exhibits superhydrophobicity with water contact angle larger than 160° and a high conductivity with resistance of about 10 Ω. The coating not only maintains superhydrophobicity at low/high stretch ratio for the newly generated small/large protuberances but also responds to stretching and bending with good sensitivity, broad sensing range, and stable response cycles. Moreover, the coating exhibits excellent durability to heat and strong acid/alkali and mechanical forces including droplet impact, kneading, torsion, and repetitive stretching–relaxation. The findings conceivably stand out as a new tool to fabricate multifunctional superhydrophobic materials with excellent stretchability and conductivity for flexible electronics under wet or corrosive environments

Highly Stretchable and Conductive Superhydrophobic Coating for Flexible Electronics

Superhydrophobic materials integrating stretchability with conductivity have huge potential in the emerging application horizons such as wearable electronic sensors, flexible power storage apparatus, and corrosion-resistant circuits. Herein, a facile spraying method is reported to fabricate a durable superhydrophobic coating with excellent stretchable and electrical performance by combing 1-octadecanethiol-modified silver nanoparticles (M-AgNPs) with polystyrene-<i>b</i>-poly­(ethylene-<i>co</i>-butylene)-<i>b</i>-polystyrene (SEBS) on a prestretched natural rubber (NR) substrate. The embedding of M-AgNPs in elastic SEBS matrix and relaxation of prestretched NR substrate construct hierarchical rough architecture and endow the coating with dense charge-transport pathways. The fabricated coating exhibits superhydrophobicity with water contact angle larger than 160° and a high conductivity with resistance of about 10 Ω. The coating not only maintains superhydrophobicity at low/high stretch ratio for the newly generated small/large protuberances but also responds to stretching and bending with good sensitivity, broad sensing range, and stable response cycles. Moreover, the coating exhibits excellent durability to heat and strong acid/alkali and mechanical forces including droplet impact, kneading, torsion, and repetitive stretching–relaxation. The findings conceivably stand out as a new tool to fabricate multifunctional superhydrophobic materials with excellent stretchability and conductivity for flexible electronics under wet or corrosive environments

Effect of Microculture on Cell Metabolism and Biochemistry: Do Cells Get Stressed in Microchannels?

Microfluidics is emerging as a promising platform for cell culture, enabling increased microenvironment control and potential for integrated analysis compared to conventional macroculture systems such as well plates and Petri dishes. To advance the use of microfluidic devices for cell culture, it is necessary to better understand how miniaturization affects cell behavior. In particular, microfluidic devices have significantly higher surface-area-to-volume ratios than conventional platforms, resulting in lower volumes of media per cell, which can lead to cell stress. We investigated cell stress under a variety of culture conditions using three cell lines: parental HEK (human embryonic kidney) cells and transfected HEK cells that stably express wild-type (WT) and mutant (G601S) <i>human ether-a-go-go related gene</i> (hERG) potassium channel protein. These three cell lines provide a unique model system through which to study cell-type-specific responses in microculture because mutant hERG is known to be sensitive to environmental conditions, making its expression a particularly sensitive readout through which to compare macro- and microculture. While expression of WT-hERG was similar in microchannel and well culture, the expression of mutant G601S-hERG was reduced in microchannels. Expression of the endoplasmic reticulum (ER) stress marker immunoglobulin binding protein (BiP) was upregulated in all three cell lines in microculture. Using BiP expression, glucose consumption, and lactate accumulation as readouts we developed methods for reducing ER stress including properly increasing the frequency of media replacement, reducing cell seeding density, and adjusting the serum concentration and buffering capacity of culture medium. Indeed, increasing the buffering capacity of culture medium or frequency of media replacement partially restored the expression of the G601S-hERG in microculture. This work illuminates how biochemical properties of cells differ in macro- and microculture and suggests strategies that can be used to modify cell culture protocols for future studies involving miniaturized culture platforms

Highly Stretchable and Conductive Superhydrophobic Coating for Flexible Electronics

Superhydrophobic materials integrating stretchability with conductivity have huge potential in the emerging application horizons such as wearable electronic sensors, flexible power storage apparatus, and corrosion-resistant circuits. Herein, a facile spraying method is reported to fabricate a durable superhydrophobic coating with excellent stretchable and electrical performance by combing 1-octadecanethiol-modified silver nanoparticles (M-AgNPs) with polystyrene-<i>b</i>-poly­(ethylene-<i>co</i>-butylene)-<i>b</i>-polystyrene (SEBS) on a prestretched natural rubber (NR) substrate. The embedding of M-AgNPs in elastic SEBS matrix and relaxation of prestretched NR substrate construct hierarchical rough architecture and endow the coating with dense charge-transport pathways. The fabricated coating exhibits superhydrophobicity with water contact angle larger than 160° and a high conductivity with resistance of about 10 Ω. The coating not only maintains superhydrophobicity at low/high stretch ratio for the newly generated small/large protuberances but also responds to stretching and bending with good sensitivity, broad sensing range, and stable response cycles. Moreover, the coating exhibits excellent durability to heat and strong acid/alkali and mechanical forces including droplet impact, kneading, torsion, and repetitive stretching–relaxation. The findings conceivably stand out as a new tool to fabricate multifunctional superhydrophobic materials with excellent stretchability and conductivity for flexible electronics under wet or corrosive environments

Understanding the Impact of 2D and 3D Fibroblast Cultures on In Vitro Breast Cancer Models

<div><p>The utilization of 3D, physiologically relevant in vitro cancer models to investigate complex interactions between tumor and stroma has been increasing. Prior work has generally focused on the cancer cells and, the role of fibroblast culture conditions on tumor-stromal cell interactions is still largely unknown. Here, we focus on the stroma by comparing functional behaviors of human mammary fibroblasts (HMFs) cultured in 2D and 3D and their effects on the invasive progression of breast cancer cells (MCF10DCIS.com). We identified increased levels of several paracrine factors from HMFs cultured in 3D conditions that drive the invasive transition. Using a microscale co-culture model with improved compartmentalization and sensitivity, we demonstrated that HMFs cultured in 3D intensify the promotion of the invasive progression through the HGF/c-Met interaction. This study highlights the importance of the 3D stromal microenvironment in the development of multiple cell type in vitro cancer models.</p> </div

3D in vitro culture of HMF induces an increased transition of MCF-DCIS cells.

<p>(A) Different morphologies of HMFs in 2D vs. 3D conditions. These images clearly show that HMFs in 3D have more fiber-like structures. The scale bar represents 60 µm. (B) Conceptual illustration of the difference of HMF behaviors in 2D and 3D. The conditioned medium collected from 3D culture of HMF (3D CM) stimulates invasive transition more than the conditioned medium collected from 2D culture of HMF (2D CM), and stimulates more invasive transition of MCF-DCIS cells in 3D. Outlines of MCF-DCIS clusters cultured in 3D mixed matrix with 3D CM and 2D CM. The clusters cultured with 3D CM produced more elongated clusters with aspect ratio (AR) 1.57. Scale bar is 100 μm. (C) Bar graph showing average aspect ratio of MCF-DCIS clusters cultured with control (serum free medium, mono), 2D HMF (co-cultured with HMFs in 2D), and 3D HMF (co-cultured with HMFs in 3D). ‡ represents p value of 0.048. (D) Bar graph showing data obtained from transwell invasion assays with conditioned media from 2D culture of HMF (2D HMF) and 3D culture of HMF (3D HMF). ‡ represents p value of 0.022.</p

HMFs in 3D produce more signaling molecules.

<p>(A) Conceptual illustration showing HMFs in 3D produce more signaling molecules. (B) Bar graphs showing the mRNA expressions of HGF, MMP14, COX2, and CXCL12 in HMFs cultured in 2D and 3D conditions. ‡ represents a p value of less than 0.05. (C) Zymography showing the presence of increased active MMP2 in the 3D conditioned medium of HMFs. (D) Bead-based ELISA showing the concentrations of target proteins in conditioned media collected from 3D and 2D cultures of HMFs and MCF-DCIS cells.</p

MCF-DCIS clusters co-cultured with 3D HMF and with 2D HMF.

<p>(A) MCF-DCIS clusters (red and outlines) co-cultured with 3D HMF and neutralizing HGF antibody at 0.5 μg/ml (3D HMF-HGF). SHG (yellow) shows changes in collagen architecture around MCF-DCIS cells. The addition of HGF neutralizing antibody significantly decreased the aspect ratio of MCF-DCIS cells and the mean intensity of SHG. ‡ represents p value less than 0.05. (B) MCF-DCIS clusters (red and outlines) co-cultured with 2D HMF and neutralizing HGF antibody at 0.5 μg/ml (2D HMF-HGF). Scale bar is 100 μm.</p

Polydimethylsiloxane-Based Superhydrophobic Surfaces on Steel Substrate: Fabrication, Reversibly Extreme Wettability and Oil–Water Separation

Functional surfaces for reversibly switchable wettability and oil–water separation have attracted much interest with pushing forward an immense influence on fundamental research and industrial application in recent years. This article proposed a facile method to fabricate superhydrophobic surfaces on steel substrates via electroless replacement deposition of copper sulfate (CuSO₄) and UV curing of vinyl-terminated polydimethylsiloxane (PDMS). PDMS-based superhydrophobic surfaces exhibited water contact angle (WCA) close to 160° and water sliding angle (WSA) lower than 5°, preserving outstanding chemical stability that maintained superhydrophobicity immersing in different aqueous solutions with pH values from 1 to 13 for 12 h. Interestingly, the superhydrophobic surface could dramatically switch to the superhydrophilic state under UV irradiation and then gradually recover to the highly hydrophobic state with WCA at 140° after dark storage. The underlying mechanism was also investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Additionally, the PDMS-based steel mesh possessed high separation efficiency and excellent reusability in oil–water separation. Our studies provide a simple, fast, and economical fabrication method for wettability-transformable superhydrophobic surfaces and have the potential applications in microfluidics, the biomedical field, and oil spill cleanup

Microchannels used for 2D and 3D combined co-cultures of HMF and MCF-DCIS cells.

<p>(A) 3D schematic and cross-section of the microchannels used for 2D and 3D combined co-culture of HMF and MCF-DCIS cells. (B) Illustrations of the loading process showing the simplicity of loading both in 2D and 3D conditions. (C) Visualization of the diffusion process in the microdevice using a numerical COMSOL simulation and a timelapse microscopy of AlexaFluor488-Dextran10kD dye. (D) Average fluorophore concentration in the inner chamber of the microdevice plotted through time.</p