Facile in-situ fabrication of target amplified reusable 3D hydrogel surface-enhanced raman spectroscopy (SERS) platform in microfluidic system

Department of Chemical EngineeringThe surface enhanced Raman scattering (SERS) effect is a promising technique to acquire molecular information. However, in order to achieve high enhancement factor as well as homogeneous Raman signal, the methods developed so far have limitation in that it requires complex, costly, and time-consuming processes. In this study, we integrated SERS and microfluidic device by in-situ growth of silver nanoparticles in hydrogel micro-posts array via automated digital micromirror device (DMD)-based maskless flow lithography technique. The hydrogel-based SERS system in microfluidic channel allowed target molecules amplification effect and real-time detection. In addition, the 3D porous hydrogel network not only enabled compact density of Ag NPs within overall hydrogel structure but also easily removed the target molecules after Raman measurement, providing high sensitivity and reusability capability. In addition, the SERS substrate was proven to be highly reproducible by measuring Raman signal from randomly selected spots and the Raman mapping images of a single hydrogel micro-post. Lastly, real-time detection of date drug was carried out in the presence of alcohol for practical application.clos

Regulation of the Catabolic Cascade in Osteoarthritis by the Zinc-ZIP8-MTF1 Axis

SummaryOsteoarthritis (OA), primarily characterized by cartilage degeneration, is caused by an imbalance between anabolic and catabolic factors. Here, we investigated the role of zinc (Zn2+) homeostasis, Zn2+ transporters, and Zn2+-dependent transcription factors in OA pathogenesis. Among Zn2+ transporters, the Zn2+ importer ZIP8 was specifically upregulated in OA cartilage of humans and mice, resulting in increased levels of intracellular Zn2+ in chondrocytes. ZIP8-mediated Zn2+ influx upregulated the expression of matrix-degrading enzymes (MMP3, MMP9, MMP12, MMP13, and ADAMTS5) in chondrocytes. Ectopic expression of ZIP8 in mouse cartilage tissue caused OA cartilage destruction, whereas Zip8 knockout suppressed surgically induced OA pathogenesis, with concomitant modulation of Zn2+ influx and matrix-degrading enzymes. Furthermore, MTF1 was identified as an essential transcription factor in mediating Zn2+/ZIP8-induced catabolic factor expression, and genetic modulation of Mtf1 in mice altered OA pathogenesis. We propose that the zinc-ZIP8-MTF1 axis is an essential catabolic regulator of OA pathogenesis

Enhanced 3-D GM-MAC Protocol for Guaranteeing Stability and Energy Efficiency of IoT Mobile Sensor Networks

In wireless sensor networks, energy efficiency is important because sensor nodes have limited energy. 3-dimensional group management medium access control (3-D GM-MAC) is an attractive MAC protocol for application to the Internet of Things (IoT) environment with various sensors. 3-D GM-MAC outperforms the existing MAC schemes in terms of energy efficiency, but has some stability issues. In this paper, methods that improve the stability and transmission performance of 3-D GM-MAC are proposed. A buffer management scheme for sensor nodes is newly proposed. Fixed sensor nodes that have a higher priority than the mobile sensor nodes in determining the group numbers that were added, and an advanced group number management scheme was introduced. The proposed methods were simulated and analyzed. The newly derived buffer threshold had a similar energy efficiency to the original 3-D GM-MAC, but improved performance in the aspects of data loss rate and data collection rate. Data delay was not included in the comparison factors as 3-D GM-MAC targets non-real-time applications. When using fixed sensor nodes, the number of group number resets is reduced by about 43.4% and energy efficiency increased by about 10%. Advanced group number management improved energy efficiency by about 23.4%. In addition, the advanced group number management with periodical group number resets of the entire sensor nodes showed about a 48.9% improvement in energy efficiency

Full Color Tactile Sensor by Using Upconversion Nanoparticle Embedded Microarray

Rare-earth-doped upconversion nanoparticles (UCNP) release a visible ranged luminescence property under exposed near-infrared (NIR) light by multiphoton excitation. These particles are highly photochemical stability, absence of background autofluorescence, and showing various colors through one kind of light source. Therefore, UCNP have been studied extensively for applications such as a photodynamic therapy, bioimagings, and a luminescence display. In this work, we rationally utilized the unique properties of UCNP and report a new type of colorimetric tactile sensor using lanthanide doped upconverting nanoparticles. We fabricated full color array using lithography technique and applied this array into the NIR based sensor to recognize the direction and magnitude of applied pressure

Fabrication of mechanically-tunable multilayered 3D cell co-culture hydrogel system for high-throughput invetigation of complex cellular behavior

Hydrogels are widely used as a 3D cell coculture platform, as they can be tailored to provide suitable microenvironments to induce cellular phenotypes with physiological significance. Herein, programmable multilayer photolithography is employed to develop a 3D hydrogel-based co-culture system in an efficient and scalable manner, which consists of an inner microgel array containing one cell type covered by an outer hydrogel overlay containing another cell type. In particular, the mechanical properties of microgel array and hydrogel overlay are independently controlled in a wide range, with elastic moduli ranging from 1.7 to 31.6 kPa, allowing the high-throughput investigation of both individual hydrogel mechanics and mechanical gradients generated at their interface. Utilizing this system, it was demonstrated that macrophage phenotypical changes (i.e. proliferation, spheroid formation and M ?? polarization) were substantially influenced by the direction and degree of mechanical gradient, as well as the presence of co-cultured fibroblasts in the vicinity. Furthermore, the paracrine effect between the macrophages in different microgels was clearly mediated by their inter-distance

High-throughput investigation of complex cellular behavior in a mechanically-tunable 3D hydrogel co-culture system prepared via programmable multilayer printing

Hydrogels are widely used as a 3D cell coculture platform, as they can be tailored to provide suitable microenvironments to induce cellular phenotypes with physiological significance. Herein, a mechanically- tunable 3D hydrogel-based co-culture system was fabricated via programmable multilayer photolithography in an efficient and scalable manner, which consists of a cell encapsulated inner microgel array and an outer hydrogel overlay. Through the high-throughput investigation of both individual hydrogel mechanics and mechanical gradients generated at their interface, it was demonstrated that macrophage phenotypical changes (i.e. proliferation, spheroid formation and M?? polarization) were substantially influenced by the direction and degree of mechanical gradient, as well as the presence of co-cultured fibro- blasts in the vicinity. Furthermore, the paracrine effect between the macrophages in different microgels was clearly mediated by their inter-distance

Programmable multilayer printing of a mechanically-tunable 3D hydrogel co-culture system for high-throughput investigation of complex cellular behavior

Hydrogels are widely used as a 3D cell culture platform, as they can be tailored to provide suitable microenvironments to induce cellular phenotypes with physiological significance. Hydrogels are especially deemed attractive as a co-culture platform, in which two or more different types of cells are cultured together in close proximity, since the spatial distribution of different cell types can be rendered possible by advanced microfabrication schemes. Herein, programmable multilayer photolithography is employed to develop a 3D hydrogel-based co-culture system in an efficient and scalable manner, which consists of an inner microgel array containing one cell type covered by an outer hydrogel overlay containing another cell type. In particular, the mechanical properties of microgel array and hydrogel overlay are independently controlled in a wide range, with elastic moduli ranging from 1.7 to 31.6 kPa, allowing the high-throughput investigation of both individual hydrogel mechanics and mechanical gradients generated at their interface. Utilizing this system, phenotypical changes (i.e. proliferation, spheroid formation and M?? polarization) of macrophages encapsulated in microgel array, in response to complex mechanical microenvironment and co-cultured fibroblasts, are comprehensively explored

Complex Tuning of Physical Properties of Hyperbranched Polyglycerol???Based Bioink for Microfabrication of Cell???Laden Hydrogels

Microfabrication technology has emerged as a valuable tool for fabricating structures with high resolution and complex architecture for tissue engineering applications. For this purpose, it is imperative to develop ???bioink??? that can be readily converted to a solid structure by the modus operandi of a chosen apparatus, while optimally supporting the biological functions by tuning their physicochemical properties. Herein, a photocrosslinkable hyperbranched polyglycerol (AHPG) is developed as a crosslinker to fabricate cell-laden hydrogels. Due to its hydrophilicity as well as numerous hydroxyl groups for the conjugation of reactive functional groups (e.g. acrylate), the mechanical properties of resulting hydrogels could be controlled in a wide range by tuning both molecular weight and degree of acrylate substitution of AHPG. The control of mechanical properties by AHPG is highly dependent on the type of monomer, due to the hydrophilic/hydrophobic balance of polyglycerol backbone and acrylate as well as the dynamic conformational flexibility based on the molecular weight of polyglycerol. The cell encapsulation studies demonstrate the biocompatibility of the AHPG-linked hydrogels. Eventually, the AHPG-based hydrogel precursor solution is employed as a bioink for a digital light processing (DLP)-based printing system to generate cell-laden microgels with various shapes and sizes for tissue engineering applications

Orthogonal dual signaling of chemical warfare agents using polydiacetylene/upconversion nanocrystals nanocomposites

A polydiacetylene (PDA)/upconversion nanocrystals (UCNs) sensor system has been developed for selective dual signaling of chemical warfare agents (CWAs) gases, such as G-series nerve agent simulant and blood agent. Rationally utilizing the orthogonal reaction mechanisms of the G-agent simulant and the blood agent (ClCN), oxime and benzaldehyde modified diacetylene monomers capable of rapid recognition of CWAs gases were synthesized. A PDA/UCNs embedded fiber patch having dual signaling capability was realized by interweaving the color change of PDAs and the anti-Stokes shift based optical properties of UCNs. PDA/UCNs nanocomposites fiber patches selectively display blue-to-red color and yellow to red luminescence change upon exposure to CWAs gases. These results present a provisional design principle of a rapid and selective PDA/UCNs-based CWAs gas detection system that can be used at night