Tissue culture on a chip: Developmental biology applications of self‐organized capillary networks in microfluidic devices

Organ culture systems are used to elucidate the mechanisms of pattern formation in developmental biology. Various organ culture techniques have been used, but the lack of microcirculation in such cultures impedes the long‐term maintenance of larger tissues. Recent advances in microfluidic devices now enable us to utilize self‐organized perfusable capillary networks in organ cultures. In this review, we will overview past approaches to organ culture and current technical advances in microfluidic devices, and discuss possible applications of microfluidics towards the study of developmental biology.     

Recent advances in microfluidic technologies for biochemistry and molecular biologys

Advances in the fields of proteomics and genomics have necessitated the development of high-throughput screening methods (HTS) for the systematic transformation of large amounts of biological chemical data into an organized database of knowledge. Microfluidic systems are ideally suited for high-throughput biochemical experimentation since they offer high analytical throughput, consume minute quantities of expensive biological reagents, exhibit superior sensitivity and functionality compared to traditional micro-array techniques and can be integrated within complex experimental work flows. A range of basic biochemical and molecular biological operations have been transferred to chip-based microfluidic formats over the last decade, including gene sequencing, emulsion PCR, immunoassays, electrophoresis, cell-based assays, expression cloning and macromolecule blotting. In this review, we highlight some of the recent advances in the application of microfluidics to biochemistry and molecular biology.     

Disposable microfluidic devices: fabrication, function, and application

This review article describes recent developments in microfluidics, with special emphasis on disposable plastic devices. Included is an overview of the common methods used in the fabrication of polymer microfluidic systems, including replica and injection molding, embossing, and laser ablation. Also described are the different methods by which on-chip operations--such as the pumping and valving of fluid flow, the mixing of different reagents, and the separation and detection of different chemical species--have been implemented in a microfluidic format. Finally, a few select biotechnological applications of microfluidics are presented to illustrate both the utility of this technology and its potential for development in the future.     

“Connecting worlds – a view on microfluidics for a wider application”

From its birth, microfluidics has been referenced as a revolutionary technology and the solution to long standing technological and sociological issues, such as detection of dilute compounds and personalized healthcare. Microfluidics has for example been envisioned as: (1) being capable of miniaturizing industrial production plants, thereby increasing their automation and operational safety at low cost; (2) being able to identify rare diseases by running bioanalytics directly on the patient’s skin; (3) allowing health diagnostics in point-of-care sites through cheap lab-on-a-chip devices. However, the current state of microfluidics, although technologically advanced, has so far failed to reach the originally promised widespread use.In this paper, some of the aspects are identified and discussed that have prevented microfluidics from reaching its full potential, especially in the chemical engineering and biotechnology fields, focusing mainly on the specialization on a single target of most microfluidic devices and offering a perspective on the alternate, multi-use, “plug and play” approach. Increasing the flexibility of microfluidic platforms, by increasing their compatibility with different substrates, reactions and operation conditions, and other microfluidic systems is indeed of surmount importance and current academic and industrial approaches to modular microfluidics are presented. Furthermore, two views on the commercialization of plug-and-play microfluidics systems, leading towards improved acceptance and more widespread use, are introduced. A brief review of the main materials and fabrication strategies used in these fields, is also presented. Finally, a step-wise guide towards the development of microfluidic systems is introduced with special focus on the integration of sensors in microfluidics. The proposed guidelines are then applied for the development of two different example platforms, and to three examples taken from literature.With this work, we aim to provide an interesting perspective on the field of microfluidics when applied to chemical engineering and biotechnology studies, as well as to contribute with potential solutions to some of its current challenges.     

微流控技术对细胞微环境的模拟及应用研究

细胞微环境是一个多因素组成的、时空可变的复杂集合,对细胞的行为和功能发挥起着决定性作用。但传统的细胞生物学研究方法很难在体外为细胞提供这样一个复杂的、微尺度的生长环境,致使许多体外研究结果与在体情况相差甚远。近年来,微流控技术与细胞培养技术的结合为细胞微环境的模拟和控制提供了可能。文章通过提炼微环境的重要参数及其特征,介绍微流控技术是如何满足这些参数的需求,探讨了微流控技术在体外模拟细胞微环境的可行性,并总结了近年来该技术在微环境体外模拟研究中取得的成果,对微流控技术在细胞微环境构建中的发展方向和应用前景进行了展望。     

Perspective: Microfluidic applications in microbiology

The application of microfluidics technology to microbiology research is an excellent platform for the analysis of microorganisms and their nucleic acids. This technology combines engineering, physics, chemistry, biology and computing to control the devices. In this perspective we discuss how microfluidics can be applied to microbiological research and used in diagnostic applications. We also summarize advantages and limitations of this technology, as well as highlight some recent microbiological applications.     

微流控分析芯片在医学领域的应用

微全分析系统(μ_TAS)又称为芯片实验室,自从Manz等于20世纪90年代首次提出这一概念以来,经过十余年的发展μ_TAS已成为生物分析的一个独立领域并被学术界所认可。微流控分析芯片作为μ_TAS发展的主要方向以其快速、高效分析,低消耗和微型化等特点发展非常迅速。在此结合微流控分析芯片在医学领域的应用状况,着重从基因检测、蛋白质分析和细胞分析等方面,对该技术在医学领域里的应用及其未来发展趋势作一综述。     

微流控技术在细胞生物学中的应用

微流控技术是在尺度为几个或上百微米的通道中操纵纳升或纳升以下流体的技术,作为一种全新的领域,它给化学合成、生物分析、光学和信息学带来了重大的影响。本文将综述微流控技术在细胞学等领域的应用,并对其发展前景进行展望。     

Microfluidics in structural biology: smaller, faster em leader better

Microfluidic technologies promise unprecedented savings in cost and time through the integration of complex chemical and biological assays on a microfabricated chip. Recent advances are making elements of this vision a reality, facilitating the first large-scale integration of microfluidic plumbing with biological assays. The power of miniaturization lies not only in achieving an economy of scale, but also in exploiting the unusual physics of fluid flow and mass transport on small length scales to realize precise and efficient assays that are not accessible with macroscopic tools. Diverse applications ranging from time-resolved studies of protein folding to highly efficient protein crystal growth suggest that microfluidics may become an indispensable tool in biology.     

High-throughput Protein Expression Generator Using a Microfluidic Platform

Rapidly increasing fields, such as systems biology, require the development and implementation of new technologies, enabling high-throughput and high-fidelity measurements of large systems. Microfluidics promises to fulfill many of these requirements, such as performing high-throughput screening experiments on-chip, encompassing biochemical, biophysical, and cell-based assays¹. Since the early days of microfluidics devices, this field has drastically evolved, leading to the development of microfluidic large-scale integration^2,3. This technology allows for the integration of thousands of micromechanical valves on a single device with a postage-sized footprint (Figure 1). We have developed a high-throughput microfluidic platform for generating in vitro expression of protein arrays (Figure 2) named PING (Protein Interaction Network Generator). These arrays can serve as a template for many experiments such as protein-protein ⁴, protein-RNA⁵ or protein-DNA⁶ interactions.The device consist of thousands of reaction chambers, which are individually programmed using a microarrayer. Aligning of these printed microarrays to microfluidics devices programs each chamber with a single spot eliminating potential contamination or cross-reactivity Moreover, generating microarrays using standard microarray spotting techniques is also very modular, allowing for the arraying of proteins⁷, DNA⁸, small molecules, and even colloidal suspensions. The potential impact of microfluidics on biological sciences is significant. A number of microfluidics based assays have already provided novel insights into the structure and function of biological systems, and the field of microfluidics will continue to impact biology.     

DNA extraction on bio-chip: history and preeminence over conventional and solid-phase extraction methods

This review covers a developmental progression on early to modern taxonomy at cellular level following the advent of electron microscopy and the advancement in deoxyribonucleic acid (DNA) extraction for expatiation of biological classification at DNA level. Here, we discuss the fundamental values of conventional chemical methods of DNA extraction using liquid/liquid extraction (LLE) followed by development of solid-phase extraction (SPE) methods, as well as recent advances in microfluidics device-based system for DNA extraction on-chip. We also discuss the importance of DNA extraction as well as the advantages over conventional chemical methods, and how Lab-on-a-Chip (LOC) system plays a crucial role for the future achievements.

     

Microfluidic technologies for studying synthetic circuits

Advances in synthetic biology have augmented the available toolkit of biomolecular modules, allowing engineering and manipulation of signaling in a variety of organisms, ranging in complexity from single bacteria and eukaryotic cells to multi-cellular systems. The richness of synthetic circuit outputs can be dramatically enhanced by sophisticated environmental control systems designed to precisely pattern spatial-temporally heterogeneous environmental stimuli controlling these circuits. Moreover, the performance of the synthetic modules and 'blocks' needed to assemble more complicated networks requires more complete characterization as a function of arbitrarily complex environmental inputs. Microfluidic technologies are poised to meet these needs through a variety of innovative designs capitalizing on the unique benefits of manipulating fluids on the micro-scales and nano-scales. This review discusses the utility of microfluidics for the study of synthetic circuits and highlights recent work in the area.     

Microfluidic: An innovative tool for efficient cell sorting

At first mostly dedicated to molecular analysis, microfluidic systems are rapidly expanding their range of applications towards cell biology, thanks to their ability to control the mechanical, biological and fluidic environment at the scale of the cells. A number of new concepts based on microfluidics were indeed proposed in the last ten years for cell sorting. For many of these concepts, progress remains to be done regarding automation, standardization, or throughput, but it is now clear that microfluidics will have a major contribution to the field, from fundamental research to point-of-care diagnosis. We present here an overview of cells sorting in microfluidics, with an emphasis on circulating tumor cells. Sorting principles are classified in two main categories, methods based on physical properties of the cells, such as size, deformability, electric or optical properties, and methods based on biomolecular properties, notably specific surface antigens. We document potential applications, discuss the main advantages and limitations of different approaches, and tentatively outline the main remaining challenges in this fast evolving field.     

细胞微系统技术及其应用

细胞微系统技术研究是目前细胞生物学、微系统科学及药物筛选等学科交叉领域的一个研究热点,其综合利用了微系统平台技术,将细胞的培养、观测和分析在微系统平台上完成,丰富了细胞研究方法,为细胞研究提供了一个全新的研究平台。现对目前细胞微系统研究中几种典型的方法,如立体微结构模型、软光刻、微流体、芯片毛细管电泳、微电极等进行综述,并阐述其在细胞生物学、生命科学等领域相关研究中的应用。     

Approaches to chemical synthetic biology

Synthetic biology is first represented in terms of two complementary aspects, the bio-engineering one, based on the genetic manipulation of extant microbial forms in order to obtain forms of life which do not exist in nature; and the chemical synthetic biology, an approach mostly based on chemical manipulation for the laboratory synthesis of biological structures that do not exist in nature. The paper is mostly devoted to shortly review chemical synthetic biology projects currently carried out in our laboratory. In particular, we describe: the minimal cell project, then the "Never Born Proteins" and lastly the Never Born RNAs. We describe and critically analyze the main results, emphasizing the possible relevance of chemical synthetic biology for the progress in basic science and biotechnology.     

基于工业环境扰动的微生物适应性进化

合成生物学技术的快速发展极大提升了微生物细胞工厂的构建能力,为化学品的绿色高效生产提供了重要策略。然而,微生物细胞难以耐受高强度工业环境、抗逆性差,成为了限制其生产性能的关键因素。适应性进化是一种人为施加定向选择压力,使微生物经过长期或短期驯化,获得适应特定环境的表型或生理性能的重要方法。近年来,随着微流控、生物传感器、组学分析等技术的发展,适应性进化为提升微生物细胞在工业环境下的生产性能奠定了基础。本文论述了适应性进化的关键技术及在提高微生物细胞工厂环境耐受性和生产效率方面的重要应用,并展望了适应性进化实现微生物细胞工厂在工业环境下高效运行的重要前景。     

Cleavable linkers in chemical biology

Interest in cleavable linkers is growing due to the rapid development and expansion of chemical biology. The chemical constrains imposed by the biological conditions cause significant challenges for organic chemists. In this review we will present an overview of the cleavable linkers used in chemical biology classified according to their cleavage conditions by enzymes, nucleophilic/basic reagents, reducing agents, photo-irradiation, electrophilic/acidic reagents, organometallic and metal reagents, oxidizing reagents.     

Recent progress in dissecting ubiquitin signals with chemical biology tools

Protein ubiquitination regulates almost all eukaryotic cellular processes, and is of very high complexity due to the diversity of ubiquitin (Ub) modifications including mono-, multiply mono-, homotypic poly-, and even heterotypic poly-ubiquitination. To accurately elucidate the role of each specific Ub signal in different cells with spatiotemporal resolutions, a variety of chemical biology tools have been developed. In this review, we summarize some recently developed chemical biology tools for ubiquitination studies and their applications in molecular and cellular biology.     

From 3D cell culture to organs-on-chips

3D cell-culture models have recently garnered great attention because they often promote levels of cell differentiation and tissue organization not possible in conventional 2D culture systems. We review new advances in 3D culture that leverage microfabrication technologies from the microchip industry and microfluidics approaches to create cell-culture microenvironments that both support tissue differentiation and recapitulate the tissue-tissue interfaces, spatiotemporal chemical gradients, and mechanical microenvironments of living organs. These 'organs-on-chips' permit the study of human physiology in an organ-specific context, enable development of novel in vitro disease models, and could potentially serve as replacements for animals used in drug development and toxin testing.