Two Distinct Filopodia Populations at the Growth Cone Allow to Sense Nanotopographical Extracellular Matrix Cues to Guide Neurite Outgrowth

The process of neurite outgrowth is the initial step in producing the neuronal processes that wire the brain. Current models about neurite outgrowth have been derived from classic two-dimensional (2D) cell culture systems, which do not recapitulate the topographical cues that are present in the extracellular matrix (ECM) in vivo. Here, we explore how ECM nanotopography influences neurite outgrowth

Effect of leaning angle of gecko-inspired slanted polymer nanohairs on dry adhesion

We present analysis of adhesion properties of angled polymer nanohairs with a wide range of leaning angles from 0?? to 45?? and ultraviolet (UV)-curable polyurethane acrylate (PUA) materials of two different elastic moduli (19.8 and 320 MPa). It is demonstrated that shear adhesion and adhesion hysteresis can be greatly enhanced by increasing the leaning angle of nanohairs both for soft and hard materials due to increased contact area and reduced structural stiffness.open211

Anti-biofouling Coating by Wrinkled, Dual-roughness Structures of Diamond-like Carbon (DLC)

The textured surface with superhydrophobic nature was explored for an anti-biofouling template. Hierarchical structures composed of the nano-scale wrinkle covering on micro-scale polymer pillar patterns were fabricated by combining the deposition of a thin coating layer of biocompatible diamond-like carbon (DLC) and the replica molding of poly-(dimethylsiloxane) (PDMS) micro-pillars. The as-prepared surfaces were shown to have extreme hydrophobicity (static contact angle > 160 degrees) owing to low surface energy (24.2 mN/m) and dual-roughness structures of the DLC coating. It was explored that the hierarchical surfaces showed poor adhesion of the Calf Pulmonary Artery Endothelial (CPAE) cells for cultures of 7 days suggesting that the 3-dimensional (3-D) patterned superhydrophobic DLC coating exhibits excellent anti-biofouling properties against non-specific cell adhesion. In particular, the reduced filopodia extension during cell growth was caused by disconnected focal adhesions on the pillar pattern. This limited cell adhesion could prevent undesired growth and proliferation of biological species on the surface of biomedical devices such as stents, implants or even injection syringes.This work was supported by Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MOST) (R01-2007-000-20675-0), the Micro Thermal System Research Center of Seoul National University, and the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) (Grant KRF-J03003). This work was supported in part by a grant (06K1501-01610) from the CNMT under the 21st Century Frontier R&D Programs of MEST of Korea (MWM, KRL)

Soft lithography for microfluidics: a review

Soft lithography has provided a low-expertise route toward micro/nanofabrication and is playing an important role in microfluidics, ranging from simple channel fabrication to the creation of micropatterns onto a surface or within a microfluidic channel. In this review, the materials, methods, and applications of soft lithography for microfluidics are briefly summarized with a particular emphasis on integrated microfluidic systems containing physical microstructures or a topographically patterned substrate. Relevant exemplary works based on the combination of various soft lithographic methods using microfluidics are introduced with some comments on their merits and weaknesses.This work was supported by Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MOST) (R01-2007-000- 20675-0) and the Grant-in-Aid for Next-Generation New Technology Development Programs from the Korea Ministry of Commerce, Industry and Energy (No.10030046). This work was also supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD, Basic Research Promotion Fund)(KRF-2007-331-D00064) for Sun Min Kim

Controlling size, shape and homogeneity of embryoid bodies using poly(ethylene glycol) microwells

Directed differentiation of embryonic stem (ES) cells is useful for creating models of human disease and could potentially generate a wide array of functional cell types for therapeutic applications. Methods to differentiate ES cells often involve the formation of cell aggregates called embryoid bodies (EBs), which recapitulate early stages of embryonic development. EBs are typically made from suspension cultures, resulting in heterogeneous structures with a wide range of sizes and shapes, which may influence differentiation. Here, we use microfabricated cell-repellant poly(ethylene glycol) (PEG) wells as templates to initiate the formation of homogenous EBs. ES cell aggregates were formed with controlled sizes and shapes defined by the geometry of the microwells. EBs generated in this manner remained viable and maintained their size and shape within the microwells relative to their suspension counterparts. Intact EBs could be easily retrieved from the microwells with high viability (> 95%). These results suggest that the microwell technique could be a useful approach for in vitro studies involving ES cells and, more specifically, for initiating the differentiation of EBs of greater uniformity based on controlled microenvironments.This research has been supported by NIH (NIH grant # HL60435), Draper laboratory, Institute of Soldier Nanotechnology (DAAD-19-02-D-002), and the NSF (through the Bioprocess Engineering Research Center). JF is supported by a Grant-in-Aid for JSPS fellows, 16–4754, 2004

Reduction of proximity effect in electron beam lithography by deposition of a thin film of silicon dioxide

We present a simple strategy to reduce the writing time of electron beam lithography (EBL) by using a highly sensitive Shipley's UV-5 resist while reducing proximity effects by depositing a thin film of silicon dioxide (SiO2) on silicon substrate. It was found that a simple insertion of a thin SiO2 film greatly reduced proximity effects, thereby providing enhanced resolution and better pattern fidelity. To support this conclusion, the bottom line width and sidewall slope of the developed pattern were analyzed for each substrate with different film thickness.This work was supported by the Grant-in-Aid for Next-Generation New Technology Development Programs from the Korea Ministry of Commerce, Industry and Energy (No. 10030046). This work was also supported in part by the Micro Thermal System Research Center of Seoul National University

Precise tip shape transformation of nanopillars for enhanced dry adhesion strength

We present a simple, yet robust, technique for controlling the tip geometry of nanopillars by utilizing a two-step process of partial photopolymerization of UV-curable polyurethane acrylate (PUA) resin and subsequent tip shape modification. With this technique, head structures of nanopillars were precisely transformed from hemispherical to protruding, mushroom-like tips without any loss in structural integrity of the nanopillars. Nanoscopic and macroscopic adhesion measurements for angled nanopillars with modified tips demonstrated that mushroom-like structures fabricated by our approach could greatly enhance adhesion strengths as compared to unmodified, round head structures. Also, directional adhesion characteristics of angled nanopillars were maintained regardless of tip shapes.close12

Cell research with physically modified microfluidic channels: A review

An overview of the use of physically modified microfluidic channels towards cell research is presented. The physical modification can be realized either by combining embedded physical micro/nanostructures or a topographically patterned substrate at the micro- or nanoscale inside a channel. After a brief description of the background and the importance of the physically modified microfluidic system, various fabrication methods are described based on the materials and geometries of physical structures and channels. Of many operational principles for microfluidics (electrical, magnetic, optical, mechanical, and so on), this review primarily focuses on mechanical operation principles aided by structural modification of the channels. The mechanical forces are classified into (i) hydrodynamic, (ii) gravitational, (iii) capillary, (iv) wetting, and (v) adhesion forces. Throughout this review, we will specify examples where necessary and provide trends and future directions in the field.This work was financially supported by INHA UNIVERSITY Research Grant (INHA-36604) for Sun Min Kim. This work was also supported by the Korea Research Foundation Grant funded by theKorean Government (MOEHRD, BasicResearch Promotion Fund) (KRF-1006–003-D00040)

Multiscale Fabrication of Multiple Proteins and Topographical Structures by Combining Capillary Force Lithography and Microscope Projection Photolithography

We present new methods that enable the fabrication of multiscale, multicomponent protein-patterned surfaces and multiscale topologically structured surfaces by exploiting the merits of two well-established techniques: capillary force lithography (CFL) and microscope projection photolithography (MPP) based on a protein-friendly photoresist. We further demonstrate that, when hierarchically organized micro- and nanostructures were used as a cell culture platform, human colon cancer cells (cell line SW480) preferentially adhere and migrate onto the area with nanoscale topography over the one with microscale topography. These methods will provide many exciting opportunities for the study of cellular responses to multiscale physicochemical cues.N