Name: Functional Surface-immobilization of Genes Using Multistep Strand Displacement Lithography (Video) | JoVE Journal
Uploaded: 2018-10-25T15:00:00.000+00:00
Duration: 11 min 5 s
Description: Learn bephore lithography for DNA immobilization on biochips using strand displacement reactions. This method enables cell-free gene expression and protein synthesis in micro-compartments.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

We gratefully acknowledge financial support for this project by the Volkswagen Stiftung (grant no. 89 883) and the European Research Council (grant agreement no. 694410 - AEDNA). M.S.-S. acknowledges support by the DFG through GRK 2062.

<ol><li>Heyman, Y., Buxboim, A., Wolf, S. G., Daube, S. S., Bar-Ziv, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cell-free+protein+synthesis+and+assembly+on+a+biochip%5BTitle%5D)+AND+%22Nature+Nanotechnology%22%5BJournal%5D)">Cell-free protein synthesis and assembly on a biochip.</a> Nature Nanotechnology. 7 (6), 374-378 (2012).</li>
<li>Jaehme, M., Michel, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Evaluation+of+cell-free+protein+synthesis+for+the+crystallization+of+membrane+proteins+-+a+case+study+on+a+member+of+the+glutamate+transporter+family+from+Staphylothermus+marinus%5BTitle%5D)+AND+%22The+FEBS+Journal%22%5BJournal%5D)">Evaluation of cell-free protein synthesis for the crystallization of membrane proteins - a case study on a member of the glutamate transporter family from Staphylothermus marinus.</a> The FEBS Journal. 280 (4), 1112-1125 (2013).</li>
<li>Nirenberg, M. W., Matthaei, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+dependence+of+cell-free+protein+synthesis+in+E.+coli+upon+naturally+occurring+or+synthetic+polyribonucleotides%5BTitle%5D)+AND+%22Proceedings+Of+The+National+Academy+Of+Sciences+Of+The+United+States+Of+America%22%5BJournal%5D)">The dependence of cell-free protein synthesis in E. coli upon naturally occurring or synthetic polyribonucleotides.</a> Proceedings Of The National Academy Of Sciences Of The United States Of America. 47, 1588-1602 (1961).</li>
<li>Harris, D. C., Jewett, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cell-free+biology%3A+exploiting+the+interface+between+synthetic+biology+and+synthetic+chemistry%5BTitle%5D)+AND+%22Current+Opinion+in+Biotechnology%22%5BJournal%5D)">Cell-free biology: exploiting the interface between synthetic biology and synthetic chemistry.</a> Current Opinion in Biotechnology. 23 (5), 672-678 (2012).</li>
<li>Hodgman, C. E., Jewett, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cell-free+synthetic+biology%3A+Thinking+outside+the+cell%5BTitle%5D)+AND+%22Metabolic+Engineering%22%5BJournal%5D)">Cell-free synthetic biology: Thinking outside the cell.</a> Metabolic Engineering. 14 (3), 261-269 (2012).</li>
<li>Smith, M. T., Wilding, K. M., Hunt, J. M., Bennett, A. M., Bundy, B. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+emerging+age+of+cell-free+synthetic+biology%5BTitle%5D)+AND+%22FEBS+Letters%22%5BJournal%5D)">The emerging age of cell-free synthetic biology.</a> FEBS Letters. 588 (17), 2755-2761 (2014).</li>
<li>Estévez-Torres, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Sequence-independent+and+reversible+photocontrol+of+transcription%2Fexpression+systems+using+a+photosensitive+nucleic+acid+binder%5BTitle%5D)+AND+%22Proceedings+of+the+National+Academy+of+Sciences+of+the+United+States+of+America%22%5BJournal%5D)">Sequence-independent and reversible photocontrol of transcription/expression systems using a photosensitive nucleic acid binder.</a> Proceedings of the National Academy of Sciences of the United States of America. 106 (30), 12219-12223 (2009).</li>
<li>Opgenorth, P. H., Korman, T. P., Bowie, J. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+synthetic+biochemistry+molecular+purge+valve+module+that+maintains+redox+balance%5BTitle%5D)+AND+%22Nature+Communications%22%5BJournal%5D)">A synthetic biochemistry molecular purge valve module that maintains redox balance.</a> Nature Communications. 5 (1), 4113(2014).</li>
<li>Sun, Z. Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Protocols+for+implementing+an+Escherichia+coli+based+TX-TL+cell-free+expression+system+for+synthetic+biology%5BTitle%5D)+AND+%22Journal+of+Visualized+Experiments%22%5BJournal%5D)">Protocols for implementing an Escherichia coli based TX-TL cell-free expression system for synthetic biology.</a> Journal of Visualized Experiments. (79), e50762(2013).</li>
<li>Karzbrun, E., Shin, J., Bar-Ziv, R. H., Noireaux, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Coarse-Grained+Dynamics+of+Protein+Synthesis+in+a+Cell-Free+System%5BTitle%5D)+AND+%22Physical+Review+Letters%22%5BJournal%5D)">Coarse-Grained Dynamics of Protein Synthesis in a Cell-Free System.</a> Physical Review Letters. 106 (4), 048104(2011).</li>
<li>Shin, J., Jardine, P., Noireaux, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Genome+replication%2C+synthesis%2C+and+assembly+of+the+bacteriophage+T7+in+a+single+cell-free+reaction%5BTitle%5D)+AND+%22ACS+Synthetic+Biology%22%5BJournal%5D)">Genome replication, synthesis, and assembly of the bacteriophage T7 in a single cell-free reaction.</a> ACS Synthetic Biology. 1 (9), 408-413 (2012).</li>
<li>Maeda, Y. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Assembly+of+MreB+filaments+on+liposome+membranes%3A+a+synthetic+biology+approach%5BTitle%5D)+AND+%22ACS+Synthetic+Biology%22%5BJournal%5D)">Assembly of MreB filaments on liposome membranes: a synthetic biology approach.</a> ACS Synthetic Biology. 1 (2), 53-59 (2012).</li>
<li>Shin, J., Noireaux, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((An+E.+coli+Cell-Free+Expression+Toolbox%3A+Application+to+Synthetic+Gene+Circuits+and+Artificial+Cells%5BTitle%5D)+AND+%22ACS+Synthetic+Biology%22%5BJournal%5D)">An E. coli Cell-Free Expression Toolbox: Application to Synthetic Gene Circuits and Artificial Cells.</a> ACS Synthetic Biology. 1 (1), 29-41 (2012).</li>
<li>Niederholtmeyer, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Rapid+cell-free+forward+engineering+of+novel+genetic+ring+oscillators%5BTitle%5D)+AND+%22eLife%22%5BJournal%5D)">Rapid cell-free forward engineering of novel genetic ring oscillators.</a> eLife. 4, e09771(2015).</li>
<li>Shimizu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cell-free+translation+reconstituted+with+purified+components%5BTitle%5D)+AND+%22Nature+Biotechnology%22%5BJournal%5D)">Cell-free translation reconstituted with purified components.</a> Nature Biotechnology. 19 (8), 751-755 (2001).</li>
<li>Shimizu, Y., Kanamori, T., Ueda, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Protein+synthesis+by+pure+translation+systems%5BTitle%5D)+AND+%22Methods%22%5BJournal%5D)">Protein synthesis by pure translation systems.</a> Methods. 36 (3), 299-304 (2005).</li>
<li>Pohorille, A., Deamer, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Artificial+cells%3A+prospects+for+biotechnology%5BTitle%5D)+AND+%22Trends+In+Biotechnology%22%5BJournal%5D)">Artificial cells: prospects for biotechnology.</a> Trends In Biotechnology. 20 (3), 123-128 (2002).</li>
<li>Adamala, K. P., Martin-Alarcon, D. A., Guthrie-Honea, K. R., Boyden, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Engineering+genetic+circuit+interactions+within+and+between+synthetic+minimal+cells%5BTitle%5D)+AND+%22Nature+Chemistry%22%5BJournal%5D)">Engineering genetic circuit interactions within and between synthetic minimal cells.</a> Nature Chemistry. 9 (5), 431-439 (2017).</li>
<li>Tan, C., Saurabh, S., Bruchez, M. P., Schwartz, R., Leduc, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Molecular+crowding+shapes+gene+expression+in+synthetic+cellular+nanosystems%5BTitle%5D)+AND+%22Nature+Nanotechnology%22%5BJournal%5D)">Molecular crowding shapes gene expression in synthetic cellular nanosystems.</a> Nature Nanotechnology. 8 (8), 602-608 (2013).</li>
<li>van Nies, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Self-replication+of+DNA+by+its+encoded+proteins+in+liposome-based+synthetic+cells%5BTitle%5D)+AND+%22Nature+Communications%22%5BJournal%5D)">Self-replication of DNA by its encoded proteins in liposome-based synthetic cells.</a> Nature Communications. 9 (1), 1583(2018).</li>
<li>Buxboim, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+single-step+photolithographic+interface+for+cell-free+gene+expression+and+active+biochips%5BTitle%5D)+AND+%22Small%22%5BJournal%5D)">A single-step photolithographic interface for cell-free gene expression and active biochips.</a> Small. 3 (3), 500-510 (2007).</li>
<li>Bracha, D., Karzbrun, E., Daube, S. S., Bar-Ziv, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Emergent+properties+of+dense+DNA+phases+toward+artificial+biosystems+on+a+surface%5BTitle%5D)+AND+%22Accounts+Of+Chemical+Research%22%5BJournal%5D)">Emergent properties of dense DNA phases toward artificial biosystems on a surface.</a> Accounts Of Chemical Research. 47 (6), 1912-1921 (2014).</li>
<li>Bracha, D., Bar-Ziv, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Dendritic+and+nanowire+assemblies+of+condensed+DNA+polymer+brushes%5BTitle%5D)+AND+%22Journal+of+the+American+Chemical+Society%22%5BJournal%5D)">Dendritic and nanowire assemblies of condensed DNA polymer brushes.</a> Journal of the American Chemical Society. 136 (13), 4945-4953 (2014).</li>
<li>Daube, S. S., Bracha, D., Buxboim, A., Bar-Ziv, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Compartmentalization+by+directional+gene+expression%5BTitle%5D)+AND+%22Proceedings+Of+The+National+Academy+Of+Sciences+Of+The+United+States+Of+America%22%5BJournal%5D)">Compartmentalization by directional gene expression.</a> Proceedings Of The National Academy Of Sciences Of The United States Of America. 107 (7), 2836-2841 (2010).</li>
<li>Karzbrun, E., Tayar, A. M., Noireaux, V., Bar-Ziv, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Programmable+on-chip+DNA+compartments+as+artificial+cells%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Programmable on-chip DNA compartments as artificial cells.</a> Science. 345 (6198), 829-832 (2014).</li>
<li>Tayar, A. M., Karzbrun, E., Noireaux, V., Bar-Ziv, R. H. <a target="_blank" href="https://www.nature.com/articles/nphys3469">Propagating gene expression fronts in a one-dimensional coupled system of artificial cells.</a> Nature Physics. 11 (12), 1037-1041 (2015).</li>
<li>Pardatscher, G., Schwarz-Schilling, M., Daube, S. S., Bar-Ziv, R. H., Simmel, F. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Gene+Expression+on+DNA+Biochips+Patterned+with+Strand-Displacement+Lithography%5BTitle%5D)+AND+%22Angewandte+Chemie-International+Edition+In+English%22%5BJournal%5D)">Gene Expression on DNA Biochips Patterned with Strand-Displacement Lithography.</a> Angewandte Chemie-International Edition In English. 57 (17), 4783-4786 (2018).</li>
<li>Huang, F., Xu, H., Tan, W., Liang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Multicolor+and+Erasable+DNA+Photolithography%5BTitle%5D)+AND+%22ACS+Nano%22%5BJournal%5D)">Multicolor and Erasable DNA Photolithography.</a> ACS Nano. 8 (7), 6849-6855 (2014).</li>
<li>Huang, F., Zhou, X., Yao, D., Xiao, S., Liang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((DNA+Polymer+Brush+Patterning+through+Photocontrollable+Surface-Initiated+DNA+Hybridization+Chain+Reaction%5BTitle%5D)+AND+%22Small%22%5BJournal%5D)">DNA Polymer Brush Patterning through Photocontrollable Surface-Initiated DNA Hybridization Chain Reaction.</a> Small. 11 (43), 5800-5806 (2015).</li>
<li>McDonald, J. C., et al. <a target="_blank" href=" Fabrication of microfluidic systems in poly(dimethylsiloxane)">Fabrication of microfluidic systems in poly(dimethylsiloxane).</a> Electrophoresis. 21 (1), 27-40 (2000).</li>
</ol>

The authors declare that they have no competing interests.

Bephore lithography is a robust and versatile technique for the patterned immobilization of DNA or RNA. Yet, the procedure includes several steps, which - if changed - may be a source for failure or reduced performance of the system.
A crucial step in the fabrication of Bephore chips is the PEGylation of the substrate, which provides the biocompatibility of the surface. Here, the cleaning step with an RCA procedure is important, since it also activates the surface for the subsequent silanizati...

Cell-free gene expression reactions are of great interest for various applications in biochemistry, biotechnology, and synthetic biology. Cell-free expression of proteins was instrumental for the preparation of pure protein samples, which were the basis for numerous studies in structural biology. For instance, cell-free systems were successfully used for the expression of protein complexes1 or membrane proteins2, which are difficult to produce using cell-based expression. Notably, cell-free gene expression reactions were also used to elucidate the structure of the genetic code, starting with the groundbreaking experiments by Nirenberg and Matthaei in 19613.
Recently, there has been a renewed interest in cell-free methods in biotechnology and synthetic biology4,5,6. Cell-free systems can be augmented with non-biological compounds, and components of diverse biological origin can be combined more easily7. Even though cell-free systems have the apparent disadvantage that they do not &#34;grow and divide&#34;, it is conceivable to prepare open cell-free bioreactors with basic metabolic functions and let them synthesize metabolites when provided with simple carbon and energy inputs8. Within the emerging field of synthetic biology, cell-free systems promise to be a more predictable &#34;chassis&#34; for the implementation of synthetic biological functions.
Currently, cell-free gene expression reactions are carried out either using cell extracts (from different sources such as bacteria, yeast, insects), or transcription/translation systems which were optimized for different applications (e.g., prokaryotic vs. eukaryotic gene expression, production of membrane proteins, etc.). A popular protocol for the preparation of bacterial cell extract (commonly termed TXTL) was provided recently by V. Noireaux and coworkers9. Its biophysical properties have been thoroughly characterized10, and the TXTL system has been already used successfully to perform a series of complex biochemical tasks: e.g., the assembly of functional bacteriophages via cell-free expression of the phage genome11, the synthesis of bacterial protein filaments12, or the implementation of cell-free gene circuits13,14.
Another system popular in cell-free synthetic biology is the PURE system, which is reconstituted from purified components15,16. Compared to the TXTL system, it does not contain nucleases or protein degradation machinery. While degradation of linear DNA, RNA molecules or proteins is less of an issue in the PURE system, decay pathways are actually important for the implementation of dynamical functions. In order to reduce the effect of exonuclease degradation of linear gene templates in the TXTL system (through RecBCD), the end-protecting GamS protein has to be added. Both the TXTL and the PURE system are commercially available.
A topic closely related to cell-free biology concerns the study of the effect of compartmentalization on biochemical reactions, and further the creation of artificial cell-like structures or protocells17,18,19,20. Research on artificial cells typically involves the encapsulation of a biochemical reaction system inside of vesicular compartments made from phospholipids or other amphiphiles. While such systems help to explore fundamental aspects of compartmentalization, or the emergence of cellularity and self-replicating structures, they face the typical problems of closed systems: in the absence of a functioning metabolism and appropriate membrane transport mechanisms, it is difficult to keep compartmentalized reactions running for extended periods of time - fuel molecules are used up and waste products accumulate.
An interesting alternative to compartmentalization inside of such cell-mimicking compartments is the spatial organization of genetic material using photolithographic methods. Immobilization of &#34;genes on a chip&#34; was pioneered by the Bar-Ziv group at the Weizmann Institute more than ten years ago21. Among the major issues that had to be resolved were the non-specific adsorption of DNA and the potential denaturation of proteins on the chip surface. Bar-Ziv et al. developed a dedicated photolithography resist termed &#34;Daisy&#34;, which was composed of a reactive terminal silane for immobilization of the resist molecules on silicon dioxide surfaces, a long polyethylene glycol (PEG) spacer that assured biocompatibility, and a photocleavable headgroup, which was converted into a reactive amine upon irradiation with ultraviolet (UV) light. It has been shown that Daisy can be used to immobilize gene-length DNA molecules (with lengths of several kilo base-pairs (kbp)) on a chip surface. From a polymer physics point of view, the systems represented polymer brushes grafted onto a solid substrate. Due to the polyelectrolyte nature of DNA, the conformation of these brushes is strongly affected by osmotic and other ion-specific effects22,23.
Most importantly, it has been shown that substrate-immobilized genes are still functional and can be transcribed and translated into RNA and protein. Gene brushes are accessible for RNA polymerases from solution24, and the complex macromolecular mixture of the transcription/translation is not denatured at the surface. One of the advantages of immobilization of genetic components on a substrate is that they can be operated in an open microfluidic reactor system that is continuously supplied with small precursor molecules and from which waste products can be removed25,26.
We recently developed a variant of this method termed Bephore (for Biocompatible electron-beam and photoresist)27, which was based exclusively on commercially available components and utilized sequence-specific DNA strand invasion reactions for the realization of a simple-to-implement multistep lithography procedure for the creation of chip-based artificial cells. A schematic overview of the procedure is shown in Figure 1. It is based on DNA hairpin molecules containing a photocleavable group, which are immobilized on a biocompatible PEG&#160;layer. Photocleavage of the hairpin exposes a single-stranded toehold sequence, through which DNA molecules of interest (containing the &#34;displacing&#34; DIS sequence) can be attached via toehold-mediated strand invasion.
While Bephore is potentially simpler to implement, Daisy allows the realization of very dense and clean &#34;gene brushes&#34;, which has advantages in certain applications. In principle, however, Daisy and Bephore lithography could be easily combined. A related lithography method utilizing DNA strand displacement for structuring DNA brushes on gold was previously developed by Huang et al., but was not utilized in the context of cell-free gene expression28,29.
In the following protocol we provide a detailed description of the production of DNA brushes for cell-free gene expression using the Bephore method. We describe how the gene chips are fabricated and demonstrate the use of multi-step photo-lithography for the spatially structured immobilization of genes on a chip. We also discuss the fabrication of reaction chambers and the application of microfluidics for the performance of on-chip gene expression reactions.

<table><tbody><tr><td>Silicon wafer with 50 nm silicon dioxide (Bephore substrate)</td><td>Siegert Wafer</td><td></td><td>Thickness (&amp;micro;m): 525 &amp;plusmn;25, Diameter (mm): 100</td></tr><tr><td>Silicon wafer (for PDMS master mold)</td><td>Siegert Wafer</td><td></td><td>Thickness (&amp;micro;m): 525 &amp;plusmn;25, Diameter (mm): 76.2 (3&amp;rdquo;)</td></tr><tr><td>Glass slides no. 4</td><td>Menzel</td><td></td><td>22 mm x 50 mm</td></tr><tr><td>Glass slides no. 1.5</td><td>Assistent</td><td></td><td>24 mm x 24 mm</td></tr><tr><td>Biotin-PEG-Silane</td><td>Laysan Bio</td><td></td><td>MW 5,000</td></tr><tr><td>Anhydrous toluene</td><td>Sigma Aldrich (Merck)</td><td>244511</td><td></td></tr><tr><td>Streptavidin</td><td>Thermo-Fisher Scientific</td><td>S888</td><td></td></tr><tr><td>DNA</td><td>Integrated DNA Technologies (IDT)</td><td></td><td></td></tr><tr><td>Phusion High-Fidelity PCR Master Mix with HF Buffer</td><td>New England Biolabs</td><td>M0531S</td><td>PCR kit</td></tr><tr><td>Wizard SV Gel and PCR Clean-Up System&amp;nbsp;</td><td>Promega</td><td>A9281</td><td>Spin-column PCR clean-up kit</td></tr><tr><td>PURExpress</td><td>New England Biolabs</td><td>E6800S</td><td>Cell-free expression system</td></tr><tr><td>PDMS&amp;nbsp;</td><td>Dow Corning</td><td>Slygard 184</td><td></td></tr><tr><td>FluoSpheres</td><td>Thermo-Fisher Scientific</td><td>F8771</td><td></td></tr><tr><td>PTFE tubing (ID: 0.8mm, OD: 1.6 mm)</td><td>Bola</td><td>S 1810-10</td><td></td></tr><tr><td>EpoCore 20</td><td>micro resist technology&amp;nbsp;GmbH</td><td></td><td>Photoresist</td></tr><tr><td>mr-Dev 600</td><td>micro resist technology&amp;nbsp;GmbH</td><td></td><td>Photoresist developer</td></tr><tr><td>Ti-Prime</td><td>MicroChemicals</td><td></td><td>Adhesion promoter</td></tr><tr><td>Two-component silicon glue</td><td>Picodent</td><td>Twinsil&amp;nbsp;</td><td></td></tr><tr><td>UV-protection yellow foil</td><td>Lithoprotect (via MicroChemicals)</td><td>Y520E212</td><td></td></tr><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Masks for photolithography</td><td>Zitzmann GmbH</td><td></td><td>64.000 dpi, 180x240 mm</td></tr><tr><td>Upright microscope</td><td>Olympus</td><td>BX51</td><td>Photolithography and fluorescence imaging</td></tr><tr><td>60x water immersion objective</td><td>Olympus</td><td>LumPlanFl</td><td>Used with Olympus BX51, NA 0.9</td></tr><tr><td>20x water immersion objective</td><td>Olympus</td><td>LumPlanFl</td><td>Used with Olympus BX51, NA 0.5</td></tr><tr><td>Camera</td><td>Photometrics</td><td>Coolsnap HQ</td><td>Used with Olympus BX51</td></tr><tr><td>Ligtht source</td><td>EXFO</td><td>X-Cite 120Q</td><td>Used with Olympus BX51</td></tr><tr><td>Inverted microscope</td><td>Nikon</td><td>Ti2-E</td><td>Fluorescence imaging of gene expression</td></tr><tr><td>4x objective</td><td>Nikon</td><td>CFI P-Apo 4x Lambda</td><td>Used with Nikon Ti2-E</td></tr><tr><td>Camera</td><td>Andor</td><td>Neo5.5</td><td>Used with Nikon Ti2-E</td></tr><tr><td>Light source</td><td>Lumencor</td><td>SOLA SM II</td><td>Used with Nikon Ti2-E</td></tr><tr><td>Cage incubator</td><td>Okolab</td><td>bold line</td><td>Used with Nikon Ti2-E</td></tr><tr><td>Pressure Controller</td><td>Elveflow</td><td>OB1 MK3</td><td></td></tr><tr><td>NanoPhotometer</td><td>Implen</td><td></td><td>DNA concentration measurement</td></tr><tr><td>Plasma cleaner</td><td>Diener</td><td>Femto</td><td>200 W, operated at 0.8 mbar with the sample in a Faraday cage</td></tr></tbody></table>

functional surface-immobilization of genes using multistep strand displacement lithography

Functional Surface-immobilization of Genes Using Multistep Strand Displacement Lithography

Immobilization of genes on lithographically structured surfaces allows the study of compartmentalized gene expression processes in an open microfluidic bioreactor system. In contrast to other approaches towards artificial cellular systems, such a setup allows for a continuous supply with gene expression reagents and simultaneous draining of waste products. This facilitates the implementation of cell-free gene expression processes over extended periods of time, which is important for the realization of dynamic gene regulatory feedback systems. Here we provide a detailed protocol for the fabrication of genetic biochips using a simple-to-use lithographic technique based on DNA strand displacement reactions, which exclusively uses commercially available components. We also provide a protocol on the integration of compartmentalized genes with a polydimethylsiloxane (PDMS)-based microfluidic system. Furthermore, we show that the system is compatible with total internal reflection fluorescence (TIRF) microscopy, which can be used for the direct observation of molecular interactions between DNA and molecules contained in the expression mix.

Two-step lithography: Figure 5 shows the result of a two-step lithographic process on a glass slide with overlapping patterns of fluorescently labeled DIS strands.
Expression of a fluorescent protein from a gene brush: Figure 6 demonstrates the expression of the fluorescent protein YPet from immobilized DNA. At several points in time we assessed the gene expression rate...

We describe a simple lithographic procedure for the immobilization of gene-length DNA molecules on a surface, which can be used to perform cell-free gene expression experiments on biochips.

Immobilization of genes on lithographically structured surfaces allows the study of compartmentalized gene expression processes in an open microfluidic ...

functional-surface-immobilization-genes-using-multistep-strand

Research

JoVE Journal

Bioengineering

In this article we describe how we obtain FRET traces from individual DNA molecules immobilized to a surface using an automated scanning confocal microscope.

Automated System for Single Molecule Fluorescence Measurements of Surface-immobilized Biomolecules

We present a microfluidic approach for the expression of protein arrays. The device consists of thousands of reaction chambers controlled by micro-mechanical valves. The microfluidic device is mated to a microarray-printed gene library. These genes are then transcribed and translated on-chip, resulting in a protein array ready for experimental use.

High-throughput Protein Expression Generator Using a Microfluidic Platform

This 3D microfluidic printing technology prints arrays of cells onto submerged surfaces.  We describe how arrays of cells are delivered microfluidically in 3D flow cells onto submerged surfaces.  By printing onto submerged surfaces, cell microarrays were produced that allow for drug screening and cytotoxicity assessment in a multitude of areas.

The Submerged Printing of Cells onto a Modified Surface Using a Continuous Flow Microspotter

These studies report on reversible attachment of adenoviral gene vectors to coatless metal surfaces of stents and model mesh disks. Sustained release of transduction-competent viral particles contingent upon hydrolysis of cross-linkers used for vector immobilization results in a durable site-specific transgene expression in vascular cells and in stented arteries.

Vascular Gene Transfer from Metallic Stent Surfaces Using Adenoviral Vectors Tethered through Hydrolysable Cross-linkers

Cell culture substrates functionalized with microscale patterns of biological ligands have immense utility in the field of tissue engineering. Here, we demonstrate the versatile and automated manufacture of tissue culture substrates with multiple, micropatterned poly(ethylene glycol) brushes presenting orthogonal chemistries that enable spatially precise and site-specific immobilization of biological ligands.

Fabricating Complex Culture Substrates Using Robotic Microcontact Printing (R-&#181;CP) and Sequential Nucleophilic Substitution

This protocol describes a bioprinting methodology using an automated robotic depositing system that incorporates etched topographical guidance cues with the precision deposition of a cell bearing hydrogel bioink. The printed cells are directly delivered to the etched features and are able to sense and orientate with them.

Automated Robotic Dispensing Technique for Surface Guidance and Bioprinting of Cells

The fabrication process of a PDMS-based, multilayer, microfluidic device that allows in vitro transcription and translation (IVTT) reactions to be performed over prolonged periods is described. Furthermore, a comprehensive overview of the hardware and software required to automate and maintain these reactions for prolonged durations is provided.

A Multilayer Microfluidic Platform for the Conduction of Prolonged Cell-Free Gene Expression

Extracellular matrix ligands can be patterned onto polyacrylamide hydrogels to enable the culture of human embryonic stem cells in confined colonies on compliant substrates. This method can be combined with traction force microscopy and biochemical assays to examine the interplay between tissue geometry, cell-generated forces, and fate specification.

Patterning the Geometry of Human Embryonic Stem Cell Colonies on Compliant Substrates to Control Tissue-Level Mechanics

This protocol introduces a lithography-free micropatterning method that is simple and accessible to those with a limited bioengineering background. This method utilizes customized laser-cut stencils to micropattern extracellular matrix proteins in a shape of interest for modulating cell morphologies. The procedure for micropatterning is demonstrated using induced pluripotent stem cell derived cardiomyocytes.

Simple Lithography-Free Single Cell Micropatterning using Laser-Cut Stencils

Here we present a protocol to micropattern cells at single-cell resolution using DNA-programmed adhesion. This protocol uses a benchtop photolithography platform to create patterns of DNA oligonucleotides on a glass slide and then labels cell membranes with commercially available complementary oligonucleotides. Hybridization of the oligos results in programmed cell adhesion.

Simple, Affordable, and Modular Patterning of Cells using DNA

Learn bephore lithography for DNA immobilization on biochips using strand displacement reactions. This method enables cell-free gene expression and protein synthesis in micro-compartments.

Functional Surface-immobilization of Genes Using Multistep Strand Displacement Lithography

Explore More Videos