Extracellular matrix (ECM) is a complex cellular environment consisting of proteins, proteoglycans, and other soluble molecules. ECM provides structural support to mammalian cells and a regulatory milieu with a variety of important cell functions, including assembling cells into various tissues and organs, regulating growth and cell-cell communication. Developing a tailored in vitro cell culture environment that mimics the intricate and organized nanoscale meshwork of native ECM is desirable. Recent studies have shown the potential of hydrogels to mimic native ECM. Such an engineered native-like ECM is more likely to provide cells with rational cues for diagnostic and therapeutic studies. The research for novel biomaterials has led to an extension of the scope and techniques used to fabricate biomimetic hydrogel scaffolds for tissue engineering and regenerative medicine applications. In this article, we detail the progress of the current state-of-the-art engineering methods to create cell-encapsulating hydrogel tissue constructs as well as their applications in in vitro models in biomedicine. Keywordsbiopatterning; cell-encapsulating microfluidic hydrogels; cell microenvironment; extracellular matrix; tissue engineering Mimicking the extracellular matrixCells and tissues are routinely cultured in vitro on 2D substrates [1][2][3]. However, it has been demonstrated that cells or tissues cultured on 2D substrates (e.g., tissue culture plates or flasks) do not mimic cell growth in vivo, and fail to express certain tissue-specific genes and proteins at levels comparable to those found in vivo. For instance, it has been found that cell-drug interactions in a 2D culture system do not represent the actual working mechanism in vivo. Thus, 2D culture is not appropriate to be used in in vitro drug testing models. This is due to the fact that cells and tissues in vivo are immersed within a 3D network constituting a complex extracellular environment with a highly porous nanotopography, while a 2D culture system is too simple to mimic the native environment (Table 1).From a tissue engineering (TE) standpoint, constructing a culture environment that closely mimicks the native tissue, which is composed of the extracellular matrix (ECM), soluble bioactive factors, and products of homo-and hetero-typical cell-cell interactions, is desirable to replicate tissue functions in vitro. However, this remains as one of the major challenges in TE, given the complexity of cell-ECM interactions as well as multicellular architectural features such as repeating tissue units and proper vascular structure. Cells commit to their fate by deriving a vast amount of information from this environment. As a part of the cell environment, ECM has been the most emulated component in TE studies. In native tissue, ECM is mainly a mixture of two classes of macromolecules, glycosaminoglycans and fibrous proteins (e.g., collagen, elastin, fibronectin and laminin), which self-assemble into nanofibrillar supramolecular networks that fill the extracellul...

A simple, fast, and easy-to-perform method was carried out for the quantification of the inhibitory effects of metals on wheat and cucumber. The method uses seed germination, root elongation, and hypocotyl and coleoptile growth in these plants as parameters in the presence of varying concentrations of metals. Metals selected for this study were Hg, Cd, Co, Cu, Pb, and Zn. Although effective concentrations of these metals for a certain degree of inhibition were different, both plants had a reduced seed germination rate, root, and hypocotyl or coleoptile length with increasing concentrations. Mercury was determined to be the most inhibitory metal on these parameters. This metal caused a complete inhibition of germination in wheat and cucumber seeds at certain concentrations-->or=1.5 mM in cucumber and at 1.7 mM in wheat. No other metal caused this kind of inhibition even at the highest concentration (8.0 mM) applied. Though this metal possessed a higher inhibition of germination in cucumber than in wheat seeds, the inhibitory effects of other metals used were the reverse, being higher in wheat. With some exceptions, all metals in selected concentrations caused a significant ( p < 0.01 or p < 0.05) decrease in germination rate of both plants compared to control group seeds.

Low-cost, robust, and user-friendly diagnostic capabilities at the point-of-care (POC) are critical for treating infectious diseases and preventing their spread in developing countries. Recent advances in micro-and nano-scale technologies have enabled the merger of optical and fluidic technologies (optofluidics) paving the way for cost-effective lensless imaging and diagnosis for POC testing in resource limited settings. Applications of the emerging lensless imaging technologies include detecting and counting cells of interest, which allows rapid and affordable diagnostic decisions. This review presents the advances in lensless imaging and diagnostic systems, and their potential clinical applications in developing countries. The emerging technologies are reviewed from a POC perspective considering cost-effectiveness, portability, sensitivity, throughput and ease of use for resource-limited settings.