软光刻技术

本文介绍了国外新出现的微结构制造技术－软光刻技术，它提供了一种方便的，有效的和低成本的微米，纳米尺寸微结构的制造方法，讨论了软光刻的几个关键技术：自组织形成的单层有机膜，弹性模，微印刷技术，再铸模，微传递成模，毛细管成模，溶剂辅助成模，并且阐述了办光刻技术在光刻技术难以实现的拓扑结构，材料以及分子尺寸领域上的应用。     

丹参酮ⅡA对脓毒症小鼠脑软膜微血流速度和脑组织炎性介质水平的干预作用

目的:探讨丹参酮ⅡA(STS)对脓毒症小鼠脑微血流和神经炎症反应的干预作用。方法:32只昆明小鼠常规开颅窗后随机分成4组:假手术组(Sham组)、STS对照组(STS组)、脓毒症模型组(LPS组)、STS治疗组(LPS+STS组)。LPS组和LPS+STS组小鼠经腹腔注射内毒素(LPS,5mg/μg体重)制备脓毒症模型小鼠,1h后造模成功,随后STS组和LPS+STS组腹腔注射STS(10mg/kg)。应用BI2000型微循环图像处理系统,通过开放式颅窗观察各组小鼠不同时相(造模前,成模后2h,成模后4h)软脑膜微静脉、微动脉血流速度,用ELISA检测成模后4h小鼠脑海马组织内肿瘤坏死因子-α(TNF-α)和白细胞介素-1β(IL-1β)的水平变化。结果:LPS组小鼠于成模后2h、4h软脑膜微动脉、微静脉血管血流速度较Sham组明显减慢(P<0.01);脑海马组织成模后4hTNF-α和IL-1β的水平较Sham组明显升高(P<0.01)。LPS+STS组成模后2h、4h微动脉、微静脉血流速度较LPS组明显加快,脑海马组织TNF-α和IL-1β的水平较LPS组显著降低(P<0.01)。结论:STS可改善脓毒症小鼠脑微血流速度,减轻神经炎症反应,发挥脑保护作用。     

黑素瘤新的生物标志和治疗靶标

据美国BIOCOMPARE科技新闻网（2007／3／19）报道，科学家研发出一种新方法，可以利用生物可兼容的蛋白质，迅速设计复杂微小的三维微结构。这是微制造技术的一大进展。     

三维微小凹图式的制备及其与C17.2神经干细胞的复合

以紫外光光刻及氢氟酸湿法蚀刻加工硅阳模,采用基于聚二甲基硅氧烷(PDMS)的软光刻技术制备9种不同结构尺寸的聚乳酸-羟基乙酸共聚物(PLGA)和PMDS三维微小凹图式。PLGA及PDMS三维微小凹图式经等离子氧蚀刻和多聚赖氨酸裱衬处理后进行C17.2神经干细胞培养。随着在图式上培养时细胞的增殖,C17.2神经干细胞逐渐在微小凹中聚集,表现出明显的三维生长行为;通过羧基荧光素乙酰乙酸琥珀酰亚胺酯(CFDA-SE)染色后进行激光共聚焦显微扫描与三维重构,显示大部分细胞生长于微小凹中离底面30～90μm的区间内;免疫荧光结果显示C17.2神经干细胞在三维微结构中复合培养2d后呈现均一的巢蛋白(Nestin)阳性。结论:本文设计的微小凹图式适用于C17.2神经干细胞的三维培养及后续的分化研究,细胞于微小凹图式培养过程中可以保持均一的干细胞特性。     

基于扩散磁共振的脑组织微结构成像研究综述

微结构成像是为了改善传统扩散磁共振成像的一些缺点而发展的一种新技术.微结构成像范式旨在建立组织结构特性与体素级磁共振信号相联系的模型,以此来估计并绘制微结构属性.目前该技术正在实现从实验室研究到临床应用研究的转变.首先介绍扩散磁共振成像并分析传统技术存在的主要问题,然后阐述微结构成像原理;随后,对受阻与受限制复合扩散模...     

胫骨生物复合材料多级微纳米结构的韧性机理

目的 研究胫骨生物复合材料多级优良微纳米结构的韧性机理。方法 利用扫描电镜观察胫骨成骨的多级微纳米结构。通过多级微纳米结构模型分析揭示胫骨的韧性机理。结果 胫骨是一种由羟基磷灰石和胶原蛋白组成的、具有多级微纳米结构的生物复合材料。在不同尺度下的微纳米结构模型分析表明胫骨多层微纳米结构增加了胫骨的断裂能,而羟基磷灰石纤维片的交叉微结构以及羟基磷灰石纳米纤维片的长细形状尺寸增加了纤维片的拔出能。结论 胫骨多级优良微纳米结构赋予胫骨高的断裂韧性,可用于仿生复合材料设计。     

多孔预置管道股骨头坏死髓芯植入体的设计与制造

参照人体松质骨及皮质骨内管道的解剖结构,设计多孔预置血管管道新型的早期股骨头坏死修复植入体模型,并利用计算机辅助设计(CAD)建模模拟外科植入过程。通过陶瓷激光光固化技术,直接生成-βTCP陶瓷胚体,并通过烧结等一系列的工艺流程,成型制造出特定形态与微结构的骨生物多孔预置管道植入体。制成试件无碎裂、变形,内部微结构清晰,尺寸与结构与设计模型基本保持一致。孔径等相关参数可满足细胞生长需求。X线衍射分析显示制造过程中无相变及化学反应发生,不影响-βTCP生物性能。试件抗压强度达到23.54 MPa,与松质骨类似。该植入体可以体外复合细胞及生长因子,有望实现早期血管植入,快速建立循环系统及活化的骨坏死区,并可以早期提供足够力学支撑,符合理想骨移植替代物需求,具有广阔的临床应用前景。     

骨微纳观力学研究方法的若干进展

骨强度依赖于骨质量。骨材料固有的力学特性以及骨组织微结构构建是决定骨质量的重要因素。近年来,各种微纳观技术和显微成像技术的应用,使得骨力学研究深入至微纳观水平。作者复习了骨微纳观力学研究方法的若干重要进展以作综述。     

基于同轴流技术的肝组织生物3D打印研究

生物三维打印为医疗领域提供全新的技术可能,可广泛应用于制造人工组织和器官。人工组织的功能和尺寸大小受限于组织的血管化,可利用同轴流挤出系统制造封装肝细胞的中空细丝,结合生物3D打印系统,叠层制造含微通道网络的肝组织。首先搭建集成化的同轴流生物3D打印系统,研究材料挤出速率、材料浓度等参数对中空细丝尺寸及出丝速度的影响;然后以肝细胞株C3A为材料,打印含多层管网机构的仿生肝组织;最后,对含微通道的肝组织进行分组培养,利用细胞活死染色法检测第24、48、72 h肝细胞在灌流组和非灌流组中的细胞存活率。实验表明,同轴流3D打印的组织,中空细丝之间有效融合,支架内部的立体微通道网络完整;打印过程对肝细胞损伤较小,中空细丝中的肝细胞存活率达90%以上;灌流组和非灌流组在培养72 h后,细胞存活率有显著的差异,证明对微通道灌流可以促进组织内部的物质交换,提高微通道周围肝细胞的存活率。研究提出打印方法和灌流系统,为人工组织的血管化以及培养方式提供全新的思路。     

生理性流动条件下血小板在玻璃表面的聚集行为

目的 研究生理性流动条件下血小板在玻璃表面的聚集行为。方法 采用软光刻工艺加工聚二甲基硅氧烷(polydimethylsiloxane, PDMS)-玻璃微通道芯片。将抗凝人外周全血以300、1 500 s^-1壁剪切率流过微通道芯片,倒置荧光显微镜拍摄荧光标记血小板在微通道玻璃表面形成的血小板聚集体荧光图像,通过图像分析得到血小板聚集体数量、平均尺寸、表面覆盖率和平均荧光强度。分别对玻璃表面进行亲水性处理、牛血清白蛋白(bovine serum albumin, BSA)封闭和胶原纤维蛋白修饰处理,调整血液样品红细胞比容(hematocrit, Hct),用抗血小板制剂处理血液样品,观察上述条件下血小板在玻璃表面的聚集行为;比较分析健康人群和糖尿病患者的血小板聚集情况。结果 流动条件下,血小板在玻璃表面发生聚集形成三维血小板聚集体;血小板聚集依赖于壁剪切率大小、玻璃表面亲疏水性和Hct;血小板聚集主要由血小板膜糖蛋白GPIIb/Ⅲa-纤维蛋白原和ADP-P2Y₁₂受体通路调控;血小板在玻璃表面的聚集能够反映糖尿病患者血小板的高活化状态。结论 ...     

Patterning protein molecules on poly(ethylene glycol) coated Si(111)

We demonstrate spatially localized immobilization of protein molecules on high-density poly(ethylene glycol) (PEG) coated Si(111). Patterns of HO- and CH3O-terminated PEG regions are formed on silicon surfaces based on soft lithography techniques and an efficient reaction between alcohol functional groups and chlorine-terminated silicon. Activation of the HO-terminated PEG brush is achieved via either partial oxidation to form aldehyde groups or via attachment of efficient leaving groups. Protein molecules are covalently immobilized to these activated regions on the PEG/Si surface.     

An automatic microturbidostat for bacterial culture at constant density

We have developed a microturbidostat for long time bacterial culture at constant density controlled by optical detection and integrated pneumatic valves. The device was fabricated by multilayer soft lithography and in-situ formation of an agarose filter. The culture chamber of bacteria was connected in one side to a single bacterial input-output channel and in another side to a nutrient channel in which the agarose filter was formed to ensure the diffusion of nutrients and metabolites without bacterial loss. The bacterial number in the culture chamber was determined by measuring the fluorescence intensity of GFP proteins of the bacteria and the redundant bacteria could be exported automatically through the input-output channel with integrated micro-valves. In order to optimize the operation performance, we investigated the bacterial exportation efficiency with different input-output channel widths. As expected, the bacterial sorting coefficient was proportional to the input-output channel width. The results also showed that with a 20 μm channel-width, a long time culture was possible with a constant bacterial number in the chamber in the range from 400 to 700.     

Size-based separation and collection of mouse pancreatic islets for functional analysis

Islet size has recently been demonstrated to be an important factor in determining human islet transplantation outcomes. In this study, a multi-layered microfluidic device was developed and quantified for size-based separation of a heterogeneous population of mouse islets. The device was fabricated using standard soft lithography and polydimethylsiloxane (PDMS). Size-based separation was first demonstrated via injection of a heterogeneous population of glass beads between 50–300 μm in diameter which were separated into five sub-populations based on their diameter. Next, a heterogeneous population of mouse pancreatic islets, between 50–250 μm in diameter was separated into four sub-populations. Throughout this process the islets remained intact without any signs of damage, as indicated by cell viability staining. Islet glucose-stimulated insulin secretion of each sub-population of islets was also evaluated demonstrating that islets smaller than 150 μm have superior stimulation indexes (SI) compared to islets larger than 150 μm. In this study, we found that islets between 100 μm and 150 μm in diameter had the greatest SI value in a heterogeneous population of islets.     

Micro- and nanostructuring of freestanding, biodegradable, thin sheets of chitosan via soft lithography

A technique for imparting micro- and nanostructured topography into the surface of freestanding thin sheets of chitosan is described. Both micro- and nanometric surface structures have been produced using soft lithography. The soft lithography method, based on solvent evaporation, has allowed structures approximately 60 nm tall and approximately 500 x 500 nm(2) to be produced on freestanding approximately 0.5 mm thick sheets of the polymer when cured at 293 K, and structures approximately 400 nm tall and 5 x 5 microm(2) to be produced when cured at 283 K. Nonstructured chitosan thin sheets (approximately 200 microm thick) show excellent optical transmission properties in the visible portion of the electromagnetic spectrum. The structured sheets can be used for applications where optical microscopic analysis is required, such as cell interaction experiments and tissue engineering.     

Microfluidic sensing: state of the art fabrication and detection techniques

Here we introduce the existing fabrication techniques, detection methods, and related techniques for microfluidic sensing, with an emphasis on the detection techniques. A general survey and comparison of the fabrication techniques were given, including prototyping (hot embossing, inject molding, and soft lithography) and direct fabrication (laser micromachining, photolithography, lithography, and x-ray lithography) techniques. This is followed by an in-depth look at detection techniques: optical, electrochemical, mass spectrometry, as well as nuclear magnetic resonance spectroscopy-based sensing approaches and related techniques. In the end, we highlight several of the most important issues for future work on microfluidic sensing. This article aims at providing a tutorial review with both introductory materials and inspiring information on microfluidic fabrication and sensing for nonspecialists.     

Self-assembled extracellular matrix protein networks by microcontact printing

Physiological patterns of the extracellular matrix protein, laminin-1, were obtained on glass substrates by physisorption-assisted microcontact printing. Besides the well-retained antigenicity confirmed by indirect immunofluorescence assays, we investigated the supramolecular organization of the proteins by atomic force microscopy. We found the characteristic protein self-assembling in polygonal networks with well-defined sub-100 nm quaternary structures of laminin. The formation of these physiological mesh-like protein matrices was obtained by means of one-step soft lithography without any preliminary functionalization of glass, which can be exploited for many possible applications for cell cultures and biomolecular devices.     

Micro/nano-fabrication technologies for cell biology

Micro/nano-fabrication techniques, such as soft lithography and electrospinning, have been well-developed and widely applied in many research fields in the past decade. Due to the low costs and simple procedures, these techniques have become important and popular for biological studies. In this review, we focus on the studies integrating micro/nano-fabrication work to elucidate the molecular mechanism of signaling transduction in cell biology. We first describe different micro/nano-fabrication technologies, including techniques generating three-dimensional scaffolds for tissue engineering. We then introduce the application of these technologies in manipulating the physical or chemical micro/nano-environment to regulate the cellular behavior and response, such as cell life and death, differentiation, proliferation, and cell migration. Recent advancement in integrating the micro/nano-technologies and live cell imaging are also discussed. Finally, potential schemes in cell biology involving micro/nano-fabrication technologies are proposed to provide perspectives on the future research activities.     

Fabricate coaxial stacked nerve conduits through soft lithography and molding processes

In this article we present a new way to fabricate nerve conduits with various multi-channels patterns by microfabrication. Soft lithography was used to manufacture silicon-based structures and replicate them with PDMS for producing nerve conduit subunit molds. After that, 3% chitosan/acetic acid solution was filled into PDMS molds and then hardened and peeled off. Nerve conduit subunits were fabricated repeatedly by a set of methods for mass production. Afterward, a plurality of conduit subunits stacked coaxially and coated with outer membrane to form the whole nerve conduit. Because of the precise capability of soft lithography, it is well-suited for nerve conduits with complex designs, such as a combination of multiple degradation control and drug delivery system. Besides, the miniaturization and batch processes are serviceable to the economic effect and the utilization in industry.     

浓度与压力梯度可调的三维细胞培养微流控芯片的研制

目的制作化学浓度梯度与压力梯度可调的细胞三维培养微流控芯片,构建可模拟在体细胞生长所处动态微环境的体外模型。方法利用光刻成型技术、模塑法以及等离子键合工艺,制作3通道结构的微流控细胞培养芯片。通过微注射泵控制微通道内溶液流动生成浓度梯度,利用液面高度差生成压力梯度,并通过骨架染色比较二维培养与三维培养下的细胞形态。结果获得了化学浓度梯度与压力梯度可调的微流控细胞培养芯片。在2μL.min-1的流速下,中间通道的浓度梯度3 h后可达到相对稳定。100 Pa的压力差在中间通道生成的视在压力梯度为0.11 Pa/μm,从而驱动三维支架内间隙渗流的生成。并在微流控芯片内实现脐静脉内皮细胞稳定的三维培养。结论该芯片结构简单,制作方便,能灵活调控细胞生长所处的微环境,可进一步用于研究不同的微环境参数对细胞行为的影响。     

Soft drinks with aspartame: effect on subjective hunger, food selection, and food intake of young adult males

Ingestion of aspartame-sweetened beverages has been reported to increase subjective measures of appetite. This study examined the effects of familiar carbonated soft drinks sweetened with aspartame on subjective hunger, energy intake and macronutrient selection at a lunch-time meal. Subjects were 20 normal weight young adult males, classified as either restrained or nonrestrained eaters. Four treatments of carbonated beverages included 280 ml of mineral water, one can of a soft drink (280 ml) consumed in either 2 or 10 minutes, or two cans of a soft drink (560 ml) consumed in 10 minutes, administered at 11:00 a.m. Subjective hunger and food appeal were measured from 9:30 a.m. to 12:30 p.m., and food intake data were obtained from a buffet lunch given at 12:00 noon. There were no treatment effects on energy intake, macronutrient selection or food choice at the lunch-time meal, or food appeal, though restrained eaters consumed more than nonrestrained eaters in all four treatment conditions. Consumption of two soft drinks (560 ml, 320 mg aspartame) significantly reduced subjective hunger from 11:05 a.m. to 11:30 a.m. compared to one soft drink (280 ml, 160 mg aspartame) or 280 ml of mineral water. Thus ingestion of soft drinks containing aspartame did not increase short-term subjective hunger or food intake.