Name: preparation of multifunctional silk-based microcapsules loaded with dna plasmids encoding rna aptamers and riboswitches
Uploaded: 2021-10-08T13:00:00
Description: Watch this Scientific Journal Video about Preparation of Multifunctional Silk-Based Microcapsules Loaded with DNA Plasmids Encoding RNA Aptamers and Riboswitches at JoVE.com

This work was supported by LRIR 16RH3003J grant from the Air Force Office of Scientific Research, as well as the Synthetic Biology for Military Environments Applied Research for the Advancement of S&#38;T Priorities (ARAP) program of the U.S. Office of the Under Secretary of Defense for Research and Engineering.
The plasmid vector sequence for ThyRS (pSALv-RS-GFPa1, 3.4 kb) was generously provided by Dr. J. Gallivan. Silkworm cocoons from Bombyx mori were generously donated by Dr. D.L. Kaplan from Tufts University, MA.

1. Construction of plasmid vector.
<ol>
	<li>Construct a plasmid vector (pSALv-RS-GFPa1, 3.4 kb) by amplification of the coding sequence of a theophylline riboswitch (ThyRS) coupled with GFPa1 from pJ201:23976-RS-GFPa1 vector (designed and created by DNA2.0) and insertion into E. coli expression vector, pSAL13. Use forward (5&#39;-CGTGGTACCGGTGATACCAGCATCGTCTTGATG-3&#39;) and reverse (5&#39;-CGTGCTCAGCTTAAGCCAGCTCGTAG-3&#39;) primers to amplify the coding sequence of ThyRS coupled with ...

<ol>
	<li>Slomovic, S., Pardee, K., Collins, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+biology+devices+for+in+vitro+and+in+vivo+diagnostics.">Synthetic biology devices for in vitro and in vivo diagnostics.</a> Proceedings of the National Academy of Sciences of the United States of America. 112 (47), 14429-14435 (2015).</li><li>Harbaugh, S. V., Goodson, M. S., Dillon, K., Zabarnick, S., Kelley-Loughnane, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Riboswitch-based+reversible+dual-color+sensor.">Riboswitch-based reversible dual-color sensor.</a> ACS Synthetic Biology. 6 (5), 766-781 (2017).</li><li>K&#246;nig, H., Frank, D., Heil, R., Coenen, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+genomics+and+synthetic+biology+applications+between+hopes+and+concerns.">Synthetic genomics and synthetic biology applications between hopes and concerns.</a> Current Genomics. 14 (1), 11-24 (2013).</li><li>Silverman, A. D., Karim, A. S., Jewett, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-free+gene+expression:+An+expanded+repertoire+of+applications.">Cell-free gene expression: An expanded repertoire of applications.</a> Nature Reviews Genetics. 21, 151-170 (2020).</li><li>Chushak, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+synthetic+riboswitch+in+cell-free+protein+expression+systems.">Characterization of synthetic riboswitch in cell-free protein expression systems.</a> RNA Biology. , 1-12 (2021).</li><li>Cole, S. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+interlaboratory+cell-free+protein+synthesis+variability.">Quantification of interlaboratory cell-free protein synthesis variability.</a> ACS Synthetic Biology. 8 (9), 2080-2091 (2019).</li><li>Thavarajah, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Point-of-use+detection+of+environmental+fluoride+via+a+cell-free+riboswitch-based+biosensor.">Point-of-use detection of environmental fluoride via a cell-free riboswitch-based biosensor.</a> ACS Synthetic Biology. 9 (1), 10-18 (2020).</li><li>Gr&#1235;we, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+paper-based,+cell-free+biosensor+system+for+the+detection+of+heavy+metals+and+date+rape+drugs.">A paper-based, cell-free biosensor system for the detection of heavy metals and date rape drugs.</a> PLoS One. 14 (3), 0210940 (2019).</li><li>Lin, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Portable+environment-signal+detection+biosensors+with+cell-free+synthetic+biosystems.">Portable environment-signal detection biosensors with cell-free synthetic biosystems.</a> RSC Advances. 10 (64), 39261-39265 (2020).</li><li>Caschera, F., Lee, J. W., Ho, K. K. Y., Liu, A. P., Jewett, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-free+compartmentalized+protein+synthesis+inside+double+emulsion+templated+liposomes+with+in+vitro+synthesized+and+assembled+ribosomes.">Cell-free compartmentalized protein synthesis inside double emulsion templated liposomes with in vitro synthesized and assembled ribosomes.</a> Chemical Communications. 52 (31), 5467-5469 (2016).</li><li>Niederholtmeyer, H., Chaggan, C., Devaraj, N. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Communication+and+quorum+sensing+in+non-living+mimics+of+eukaryotic+cells.">Communication and quorum sensing in non-living mimics of eukaryotic cells.</a> Nature Communications. 9, 5027 (2018).</li><li>Timin, A. S., Gould, D. J., Sukkhorukov, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-layer+microcapsules:+Fresh+insights+and+new+applications.">Multi-layer microcapsules: Fresh insights and new applications.</a> Expert Opinion on Drug Delivery. 14 (5), 583-587 (2017).</li><li>Bomati, E. K., Haley, J. E., Noel, J. P., Deheyn, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectral+and+structural+comparison+between+bright+and+dim+green+fluorescent+proteins+in+Amphioxus.">Spectral and structural comparison between bright and dim green fluorescent proteins in Amphioxus.</a> Scientific Reports. 4, 5469 (2014).</li><li>Frey, B., Reischl, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amplification+of+Genomic+DNA+by+PCR.">Amplification of Genomic DNA by PCR.</a> Molecular Diagnosis of Infectious Diseases. Methods in Molecular Medicine. 13, 143-156 (1998).</li><li>Lee, P. Y., Costumbrado, J., Hsu, C. -. Y., Kim, Y. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Agarose+gel+electrophoresis+for+the+separation+of+DNA+fragments.">Agarose gel electrophoresis for the separation of DNA fragments.</a> Journal of Visualized Experiments. (62), e3923 (2012).</li><li>Zhou, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+regeneration+and+reuse+of+silica+columns+from+PCR+purification+and+gel+extraction+kits.">Rapid regeneration and reuse of silica columns from PCR purification and gel extraction kits.</a> Scientific Reports. 8, 12870 (2018).</li><li>Kostylev, M., Otwell, A. E., Richardson, R. E., Suzuki, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cloning+should+be+simple:+Escherichia+coli+DH5&#945;-mediated+assembly+of+multiple+DNA+fragments+with+short+end+homologies.">Cloning should be simple: Escherichia coli DH5&#945;-mediated assembly of multiple DNA fragments with short end homologies.</a> PLoS One. 10 (9), 0137466 (2015).</li><li>Rockwood, D. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Materials+fabrication+from+Bombyx+mori+silk+fibroin.">Materials fabrication from Bombyx mori silk fibroin.</a> Nature Protocols. 6 (10), 1612-1631 (2011).</li><li>Drachuk, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silk+macromolecules+with+amino+acid-Poly(Ethylene+Glycol)+grafts+for+controlling+layer-by-layer+encapsulation+and+aggregation+of+recombinant+bacterial+cells.">Silk macromolecules with amino acid-Poly(Ethylene Glycol) grafts for controlling layer-by-layer encapsulation and aggregation of recombinant bacterial cells.</a> ACS Nano. 9 (2), 1219-1235 (2015).</li><li>Antipov, A. A., Sukhorukov, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyelectrolyte+multilayer+capsules+as+vehicles+with+tunable+permeability.">Polyelectrolyte multilayer capsules as vehicles with tunable permeability.</a> Advances in Colloid and Interface Science. 111 (1-2), 49-61 (2004).</li><li>Drachuk, I., Harbaugh, S., Ch&#225;vez, J. L., Kelley-Loughnane, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+the+activity+of+DNA-encoded+sensing+elements+through+confinement+in+silk+microcapsules.">Improving the activity of DNA-encoded sensing elements through confinement in silk microcapsules.</a> ACS Applied Materials &amp; Interfaces. 12 (43), 48329-48339 (2020).</li><li>Melnikov, S., Ben-Shem, A., Garreau de Loubresse, N., Jenner, L., Yusupova, G., Yusupov, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+basis+for+the+inhibition+of+the+eukaryotic+ribosome.">Structural basis for the inhibition of the eukaryotic ribosome.</a> Nature Structural &amp; Molecular Biology. 19 (6), 560-567 (2012).</li><li>Zhao, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+future+of+layer-by-layer+assembly:+A+tribute+to+ACS+Nano+associate+editor+Helmuth+M&#246;hwald.">The future of layer-by-layer assembly: A tribute to ACS Nano associate editor Helmuth M&#246;hwald.</a> ACS Nano. 13 (6), 6151-6169 (2019).</li><li>Main, K. H. S., Provan, J. I., Haynes, P. J., Wells, G., Hartley, J. A., Pyne, A. L. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+force+microscopy-A+tool+for+structural+and+translational+DNA+research.">Atomic force microscopy-A tool for structural and translational DNA research.</a> APL Bioengineering. 5, 031504 (2021).</li><li>Riera, R., Feiner-Gracia, N., Fornaguera, C., Cascante, A., Borr&#243;s, S., Albertazzi, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tracking+the+DNA+complexation+state+of+pBAE+polyplexes+in+cells+with+super+resolution+microscopy.">Tracking the DNA complexation state of pBAE polyplexes in cells with super resolution microscopy.</a> Nanoscale. 11 (38), 17869-17877 (2019).</li><li>Bilokapic, S., Strauss, M., Halic, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryo-EM+of+nucleosome+core+particle+interactions+in+trans.">Cryo-EM of nucleosome core particle interactions in trans.</a> Scientific Reports. 8, 7046 (2018).</li><li>Pritchard, E. M., Dennis, P. B., Omenetto, F., Naik, R. R., Kaplan, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical+and+chemical+aspects+of+stabilization+of+compounds+in+silk.">Physical and chemical aspects of stabilization of compounds in silk.</a> Biopolymers. 97 (6), 479-498 (2012).</li><li>Fritz, B. R., Jamil, O. K., Jewett, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Implications+of+macromolecular+crowding+and+reducing+conditions+for+in+vitro+ribosome+construction.">Implications of macromolecular crowding and reducing conditions for in vitro ribosome construction.</a> Nucleic Acids Research. 43 (9), 4774-4784 (2015).</li><li>Ge, X., Luo, D., Xu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-free+protein+expression+under+macromolecular+crowding+conditions.">Cell-free protein expression under macromolecular crowding conditions.</a> PLoS One. 6 (12), 28707 (2011).</li><li>Cawte, A. D., Unrau, P. J., Rueda, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Live+cell+imaging+of+single+RNA+molecules+with+fluorogenic+mango+II+arrays.">Live cell imaging of single RNA molecules with fluorogenic mango II arrays.</a> Nature Communications. 11, 1283 (2020).</li><li>Chen, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+RNA+dynamics+in+live+cells+with+bright+and+stable+fluorescent+RNAs.">Visualizing RNA dynamics in live cells with bright and stable fluorescent RNAs.</a> Nature Biotechnology. 37 (11), 1287-1293 (2019).</li></ol>

Selectively permeable hydrogel microcapsules loaded with various types of DNA-encoded sensor designs can be prepared following this protocol. One of the distinctive features of the LbL approach is the ability to tailor the complexity of microcapsules during the bottom-up assembly, which usually starts with the adsorption of molecular species on sacrificial templates. By carefully adjusting concentrations of the initial components, pH conditions, and the number of layers, microcapsules with different DNA loading parameter...

The field of synthetic biology offers unique opportunities to develop sensing capabilities by exploiting natural mechanisms evolved by microorganisms to monitor their environment and potential threats. Importantly, these sensing mechanisms are typically linked to a response that protects these microorganisms from harmful exposure, regulating gene expression to mitigate negative effects or prevent intake of toxic materials. There have been significant efforts to engineer these microorganisms to create whole-cell sensors taking advantage of these natural responses but re-directing them to recognize novel targets and/or to produce a measurable signal that can be measured for quantification purposes (typically fluorescence)1,2. Currently, concerns with the use of genetically modified microorganisms (GMOs), especially when releasing in the environment or the human body, due to leakage of whole cells or some of their genetic material, even if encapsulated in a polymer matrix, suggest that alternative ways to exploit these sensing approaches are needed3.
A powerful approach to exploit the benefits of microorganisms-based sensing without the concern for the deployment of GMOs is the use of in vitro transcription/translation (IVTT) systems. From a practical perspective, IVTT systems consist of a mixture containing most of the cell components in an active state that has been &#34;extracted&#34; from cells by different means, including sonication, bead-beating, or others4. The final product of this process is a biochemical reaction mixture already optimized to perform transcription and translation that can be used to test different sensors in an &#34;open vessel&#34; format, without the constraints associated with the use of whole cells (membrane diffusion, transformation efficiency, cell toxicity, etc.). Importantly, different sensor components can be quantitatively added, and their effect studied by different optical and spectrometric techniques, as we have demonstrated5. It has been noticed that the performance of IVTT systems can be inconsistent; however, recent studies have shown approaches to standardize their preparation and characterization, which is of great help when studying their performance in sensor design6. Recently, many examples of IVTT systems using to create paper-based assays through the lyophilization of their components in paper matrices have been demonstrated, including detection of heavy metal ions, drugs, quorum sensing elements, and others7,8,9. An exciting application space for IVTT-based sensors is their use in sensing applications in different types of environments, including soil, water, and the human body. In order to deploy these IVTT systems to these challenging environments, an encapsulation approach need to be implemented to contain the IVTT components and protect them from degradation.
The most common encapsulation approaches for IVTT systems include the use of lipid capsules, micelles, polymersomes, and other tightly enclosed microcontainers10,11,12. One disadvantage of this approach is the need to incorporate either passive or active mechanisms to transport materials in and out of the containers to allow communication with the external environment and provide sensing capabilities. To overcome some of these issues, the study here reports a method that provides a simple yet effective approach to encapsulate the encoding materials for different sensor designs to be expressed in IVTT systems. This approach is based on the use of Layer-by-Layer (LbL) deposition of a biopolymer in the presence of the plasmids of interest to create hollow microcapsules with high porosity, which allows the protected genetic material to interact with the different components of the IVTT of choice. The study demonstrated that encapsulated plasmids could direct transcription and translation when activated within this polymeric matrix, as shown with the response of a plasmid-encoded aptamer and a riboswitch to their corresponding targets. Additionally, this LbL coating protects the plasmids for months without any special storage conditions.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>(Z)-4-(3,5-difluoro-4-hydroxybenzylidene)-2-methyl-1-(2,2,2-trifluoroethyl)-1H-imidazol-5(4 H)-one (DFHBI-1T)</td>
			<td>Lucerna</td>
			<td>DFHBI-1T</td>
			<td></td>
		</tr>
		<tr>
			<td>5x T4 DNA Ligase Buffer</td>
			<td>ThermoFisher Scientific</td>
			<td>46300-018</td>
			<td></td>
		</tr>
		<tr>
			<td>6x Blue Gel Loading Dye</td>
			<td>New England BioLabs</td>
			<td>B7021S</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well plates, black circular</td>
			<td>Corning</td>
			<td>3601</td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>Sigma-Aldrich</td>
			<td>A9539</td>
			<td>BioReagent, for molecular biology, low EEO</td>
		</tr>
		<tr>
			<td>Ampicillin sodium salt</td>
			<td>Sigma-Aldrich</td>
			<td>A0166</td>
			<td>powder or crystals, BioReagent, suitable for cell culture</td>
		</tr>
		<tr>
			<td>BlpI restriction enzymes</td>
			<td>New England BioLabs</td>
			<td>R0585S</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning Disposable Vacuum Filter/Storage Systems</td>
			<td>FisherScientific</td>
			<td>09-761-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide, DMSO</td>
			<td>Sigma-Aldrich</td>
			<td>472301</td>
			<td>ACS reagent, &#8805;99.9%</td>
		</tr>
		<tr>
			<td>DNA Plasmid, pET28c-F30-2x Broccoli (5.4 kb), BrocApt.</td>
			<td>Addgene</td>
			<td>Plasmid #66788</td>
			<td></td>
		</tr>
		<tr>
			<td>DyLightTM550 Antibody Labeling kit (Invitrogen)</td>
			<td>ThermoFisher Scientific</td>
			<td>84530</td>
			<td></td>
		</tr>
		<tr>
			<td>E. coli S30 extract system for circular DNA</td>
			<td>Promega</td>
			<td>L1020</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon Conical centrifuge tubes, 15 mL</td>
			<td>FisherScientific</td>
			<td>14-959-53A</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon Conical centrifuge tubes, 50 mL</td>
			<td></td>
			<td>14-432-22</td>
			<td></td>
		</tr>
		<tr>
			<td>Fisherbrand Microcentrifuge tubes, 1.5 mL</td>
			<td>FisherScientific</td>
			<td>05-408-129</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrofluoric acid, HF</td>
			<td>Sigma-Aldrich</td>
			<td>695068</td>
			<td>ACS reagent, 48%</td>
		</tr>
		<tr>
			<td>Kanamycin sulfate</td>
			<td>Sigma-Aldrich</td>
			<td>60615</td>
			<td>mixture of Kanamycin A (main component) and Kanamycin B and C</td>
		</tr>
		<tr>
			<td>KpnI restriction enzymes</td>
			<td>New England BioLabs</td>
			<td>R0142S</td>
			<td></td>
		</tr>
		<tr>
			<td>LB agar plate supplemented with 100 &#181;g/mL ampicillin</td>
			<td>Sigma-Aldrich</td>
			<td>L5667</td>
			<td>pre-poured agar plates with 100 &#181;g/mL ampicillin</td>
		</tr>
		<tr>
			<td>LB agar plate supplemented with 50 &#181;g/mL kanamycin</td>
			<td>Sigma-Aldrich</td>
			<td>L0543</td>
			<td>pre-poured agar plates with 50 &#181;g/mL kanamycin</td>
		</tr>
		<tr>
			<td>LB broth (Lennox grade)</td>
			<td>Sigma-Aldrich</td>
			<td>L3022</td>
			<td></td>
		</tr>
		<tr>
			<td>Lithium bromide, LiBr</td>
			<td>Sigma-Aldrich</td>
			<td>213225</td>
			<td>ReagentPlus, &#8805;99%</td>
		</tr>
		<tr>
			<td>Max Efficiency DH5-&#945; competent E. coli strain</td>
			<td>ThermoFisher Scientific</td>
			<td>18258012</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>MilliporeSigma</td>
			<td>322415</td>
			<td>anhydrous, 99.8%</td>
		</tr>
		<tr>
			<td>MilliQ-water</td>
			<td>EMD MilliPore</td>
			<td></td>
			<td>Milli-Q Reference Water Purification System</td>
		</tr>
		<tr>
			<td>MinElute PCR Purification Kit</td>
			<td>Qiagen</td>
			<td>28004</td>
			<td></td>
		</tr>
		<tr>
			<td>N-(3-Dimethylaminopropyl)-N&#8242;-ethylcarbodiimide hydrochloride, EDC</td>
			<td>Sigma-Aldrich</td>
			<td>E1769</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS (phosphate buffered saline)</td>
			<td>ThermoFisher Scientific</td>
			<td>10010023</td>
			<td>1x PBS, pH 7.4</td>
		</tr>
		<tr>
			<td>Phusion High-Fidelity DNA Polymerase</td>
			<td>New England Biolabs</td>
			<td>M0530S</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylenimine, branched</td>
			<td>Sigma-Aldrich</td>
			<td>408727</td>
			<td>average Mw ~25,000</td>
		</tr>
		<tr>
			<td>PURExpress In Vitro Protein Synthesis Kit</td>
			<td>New England BioLabs</td>
			<td>E6800S</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAEX II Gel Extraction Kit</td>
			<td>Qiagen</td>
			<td>20021</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAprep Spin Miniprep Kit</td>
			<td>Qiagen</td>
			<td>&#160;27104</td>
			<td></td>
		</tr>
		<tr>
			<td>Quick-Load 2-Log DNA Ladder (0.1-10.0 kb)</td>
			<td>New England BioLabs</td>
			<td>N0469S</td>
			<td></td>
		</tr>
		<tr>
			<td>SiO&#8322; silica microspheres, 4.0 &#181;m</td>
			<td>Polysciences, Inc.</td>
			<td>24331-15</td>
			<td>10% aqueous solution</td>
		</tr>
		<tr>
			<td>Slide-A-Lyzer G2 Dialysis Cassettes, 3.5K MWCO, 15 mL</td>
			<td>ThermoFisher Scientific</td>
			<td>87724</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium carbonate, Na&#8322;CO&#8323;</td>
			<td>Sigma-Aldrich</td>
			<td>222321</td>
			<td>ACS reagent, anhydrous, &#8805;99.5%, powder</td>
		</tr>
		<tr>
			<td>Spectrum Spectra/Por Float-A-Lyzer G2 Dialysis Devices</td>
			<td>FisherScientific</td>
			<td>08-607-008</td>
			<td>Spectrum G235058</td>
		</tr>
		<tr>
			<td>SYBR Safe DNA gel stain</td>
			<td>ThermoFisher Scientific</td>
			<td>S33102</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA Ligase (5 U/&#181;L)</td>
			<td>ThermoFisher Scientific</td>
			<td>EL0011</td>
			<td></td>
		</tr>
		<tr>
			<td>Theophylline</td>
			<td>Sigma-Aldrich</td>
			<td>T1633</td>
			<td>anhydrous, &#8805;99%, powder</td>
		</tr>
		<tr>
			<td>Tris Acetate-EDTA buffer (TAE buffer)</td>
			<td>Sigma-Aldrich</td>
			<td>T6025</td>
			<td>Contains 40 mM Tris-acetate and 1 mM EDTA, pH 8.3.</td>
		</tr>
		<tr>
			<td>UltraPure DNase/RNase-Free Distilled Water</td>
			<td>FisherScientific</td>
			<td>10-977-023</td>
			<td></td>
		</tr>
		<tr>
			<td>ZymoPURE II Plasmid MaxiPrep kit</td>
			<td>ZymoResearch</td>
			<td>D4202</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of multifunctional silk-based microcapsules loaded with dna plasmids encoding rna aptamers and riboswitches

We introduce a protocol for the preparation of DNA-laden silk fibroin microcapsules via the Layer-by-Layer (LbL) assembly method on sacrificial spherical cores. Following adsorption of a prime layer and DNA plasmids, the formation of robust microcapsules was facilitated by inducing &#946;-sheets in silk secondary structure during acute dehydration of a single silk layer. Hence, the layering occurred via multiple hydrogen bonding and hydrophobic interactions. Upon adsorption of multilayered shells, the core-shell structures can be further functionalized with gold nanoparticles (AuNPs) and/or antibodies (IgG) to be used for remote sensing and/or targeted delivery. Adjusting several key parameters during sequential deposition of key macromolecules on silica cores such as the presence of a polymer primer, the concentration of DNA and silk protein, as well as a number of adsorbed layers resulted in biocompatible, DNA-laden microcapsules with variable permeability and DNA loadings. Upon dissolution of silica cores, the protocol demonstrated the formation of hollow and robust microcapsules with DNA plasmids immobilized to the inner surface of the capsule membrane. Creating a selectively permeable biocompatible membrane between the DNA plasmids and the external environment preserved the DNA during long-term storage and played an important role in the improved output response from spatially confined plasmids. The activity of DNA templates and their accessibility were tested during in vitro transcription and translation reactions (cell-free systems). DNA plasmids encoding RNA light-up aptamers and riboswitches were successfully activated with corresponding analytes, as was visualized during localization of fluorescently labeled RNA transcripts or GFPa1 protein in the shell membranes.

Here, the study addresses the functionality of DNA templates encoding different sensor designs (two types of RNA-regulated transcription/translation elements) after encapsulation in silk protein capsules. Microcapsules were prepared via templated Layer-by-Layer (LbL) assembly of the key components: A prime layer, DNA plasmids encoding sensor designs, and silk fibroin biopolymer (Figure 2). Deposition of macromolecules in a layered fashion allows controlling the permeability of the capsule me...

Watch this Scientific Journal Video about Preparation of Multifunctional Silk-Based Microcapsules Loaded with DNA Plasmids Encoding RNA Aptamers and Riboswitches at JoVE.com

Preparation of Multifunctional Silk-Based Microcapsules Loaded with DNA Plasmids Encoding RNA Aptamers and Riboswitches

The protocol describes the formation of robust and biocompatible DNA-laden microcapsules as multiplexed in vitro biosensors capable of tracking several ligands.

We introduce a protocol for the preparation of DNA-laden silk fibroin microcapsules via the Layer-by-Layer (LbL) assembly method on sacrificial spherical ...

Research

JoVE Journal

Biology

Homemade Site Directed Mutagenesis of Whole Plasmids

Site directed mutagenesis of whole plasmids is a simple way to create slightly different variations of an original plasmid. With this method the cloned ...

Visualizing Single-molecule DNA Replication with Fluorescence Microscopy

We describe a simple fluorescence microscopy-based real-time method for observing DNA replication at the single-molecule level. A circular, forked DNA ...

Generation of RNA/DNA Hybrids in Genomic DNA by Transformation using RNA-containing Oligonucleotides

Synthetic short nucleic acid polymers, oligonucleotides (oligos), are the most functional and widespread tools of molecular biology. Oligos can be ...

iCLIP - Transcriptome-wide Mapping of Protein-RNA Interactions with Individual Nucleotide Resolution

The unique composition and spatial arrangement of RNA-binding proteins (RBPs) on a transcript guide the diverse aspects of post-transcriptional ...

In vitro Transcription and Capping of Gaussia Luciferase mRNA Followed by HeLa Cell Transfection

In vitro Transcription and Capping of Gaussia Luciferase mRNA Followed by HeLa Cell Transfection

In vitro transcription is the synthesis of RNA transcripts by RNA polymerase from a linear DNA template containing the corresponding promoter sequence ...

Preparation of DNA-crosslinked Polyacrylamide Hydrogels

Mechanobiology is an emerging scientific area that addresses the critical role of physical cues in directing cell morphology and function. For example, ...

Real-time Imaging of Single Engineered RNA Transcripts in Living Cells Using Ratiometric Bimolecular Beacons

The growing realization that both the temporal and spatial regulation of gene expression can have important consequences on cell function has led to the ...

Amplification, Next-generation Sequencing, and Genomic DNA Mapping of Retroviral Integration Sites

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of ...

Visualization of Surface-tethered Large DNA Molecules with a Fluorescent Protein DNA Binding Peptide

Large DNA molecules tethered on the functionalized glass surface have been utilized in polymer physics and biochemistry particularly for investigating ...

Preparation of Formalin-fixed Paraffin-embedded Tissue Cores for both RNA and DNA Extraction

Formalin-fixed paraffin embedded tissue (FFPET) represents a valuable, well-annotated substrate for molecular investigations. The utility of FFPET in ...