Name: generation of scalable, metallic high-aspect ratio nanocomposites in a biological liquid medium
Uploaded: 2015-07-08T15:00:00
Description: Watch this Scientific Journal Video about Generation of Scalable, Metallic High-Aspect Ratio Nanocomposites in a Biological Liquid Medium at JoVE.com

The authors would like to acknowledge the technical assistance of Alfred Gunasekaran in electron microscopy studies at the Institute of Micromanufacturing at Louisiana Tech University, and Dr. Jim McNamara for assistance with additional microscopy studies. The work described was supported in part by Louisiana board of Regents PKSFI Contract No. LEQSF (2007-12)-ENH-PKSFI-PRS-04 and the James E. Wyche III Endowed Professorship from Louisiana Tech University (to M.D.).

1. Planning of Experiments
<ol>
	<li>Determine the volume of copper nanocomposites needed for synthesis. On that basis, choose a number of small volume flasks (25 cm2), or larger flasks as indicated below in preparation of materials.</li>
	<li>For this synthesis, use a 37 &#176;C incubator with 5% CO2 and at least 40% humidity. Ensure that such an incubator is available and that it will not be repeatedly disturbed over the period of synthesis (approximately 24 hr). 
	CAUTION: Repeated opening...

<ol>
	<li>Klinman, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+copper-enzyme+family+of+dopamine+beta-monooxygenase+and+peptidylglycine+alpha-hydroxylating+monooxygenase:+resolving+the+chemical+pathway+for+substrate+hydroxylation.">The copper-enzyme family of dopamine beta-monooxygenase and peptidylglycine alpha-hydroxylating monooxygenase: resolving the chemical pathway for substrate hydroxylation.</a> The Journal of biological chemistry. 281, 3013-3016 (2006).</li><li>Uauy, R., Olivares, M., Gonzalez, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Essentiality+of+copper+in+humans.">Essentiality of copper in humans.</a> The American journal of clinical nutrition. 67, 952S-959S (1998).</li><li>Karlsson, H. L., Cronholm, P., Gustafsson, J., Copper Moller, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=oxide+nanoparticles+are+highly+toxic:+a+comparison+between+metal+oxide+nanoparticles+and+carbon+nanotubes.">oxide nanoparticles are highly toxic: a comparison between metal oxide nanoparticles and carbon nanotubes.</a> Chemical research in toxicology. 21, 1726-1732 (2008).</li><li>Parekh, G., 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=Layer-by-layer+nanoencapsulation+of+camptothecin+with+improved+activity.">Layer-by-layer nanoencapsulation of camptothecin with improved activity.</a> International journal of pharmaceutics. 465, 218-227 (2014).</li><li>Harrington, M. J., Masic, A., Holten-Andersen, N., Waite, J. H., Fratzl, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron-clad+fibers:+a+metal-based+biological+strategy+for+hard+flexible+coatings.">Iron-clad fibers: a metal-based biological strategy for hard flexible coatings.</a> Science. 328, 216-220 (2010).</li><li>Keyson, 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=CuO+urchin-nanostructures+synthesized+from+a+domestic+hydrothermal+microwave+method.">CuO urchin-nanostructures synthesized from a domestic hydrothermal microwave method.</a> Materials Research Bulletin. 43, 771-775 (2008).</li><li>Liu, B., Zeng, H. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesoscale+organization+of+CuO+nanoribbons:+formation+of+'dandelions'.">Mesoscale organization of CuO nanoribbons: formation of 'dandelions'.</a> J Am Chem Soc. 126, 8124-8125 (2004).</li><li>Peng, M., 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=Controllable+synthesis+of+self-assembled+Cu2S+nanostructures+through+a+template-free+polyol+process+for+the+degradation+of+organic+pollutant+under+visible+light.">Controllable synthesis of self-assembled Cu2S nanostructures through a template-free polyol process for the degradation of organic pollutant under visible light.</a> Materials Research Bulletin. 44, 1834-1841 (2009).</li><li>Deodhar, S., Huckaby, J., Delahoussaye, M., DeCoster, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-Aspect+Ratio+Bio-Metallic+Nanocomposites+for+Cellular+Interactions.">High-Aspect Ratio Bio-Metallic Nanocomposites for Cellular Interactions.</a> IOP Conference Series: Materials Science and Engineering. 64, 012014 (2014).</li><li>Montes-Burgos, 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=Characterisation+of+nanoparticle+size+and+state+prior+to+nanotoxicological+studies.">Characterisation of nanoparticle size and state prior to nanotoxicological studies.</a> Journal of Nanoparticle Research. 12, 47-53 (2010).</li><li>Wiogo, H. T., Lim, M., Bulmus, V., Yun, J., Amal, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stabilization+of+magnetic+iron+oxide+nanoparticles+in+biological+media+by+fetal+bovine+serum+(FBS).">Stabilization of magnetic iron oxide nanoparticles in biological media by fetal bovine serum (FBS).</a> Langmuir. 27, 843-850 (2011).</li><li>Yunker, P. J., Still, T., Lohr, M. A., Yodh, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suppression+of+the+coffee-ring+effect+by+shape-dependent+capillary+interactions.">Suppression of the coffee-ring effect by shape-dependent capillary interactions.</a> Nature. 476, 308-311 (2011).</li><li>Kahler, H., Lloyd Jr, B., Eden, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+Microscopic+and+Other+Studies+on+a+Copper&#8211;Cystine+Complex.">Electron Microscopic and Other Studies on a Copper&#8211;Cystine Complex.</a> The Journal of Physical Chemistry. 56, 768-770 (1952).</li><li>Furia, E., Sindona, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complexation+of+L-cystine+with+metal+cations.">Complexation of L-cystine with metal cations.</a> Journal of Chemical &amp; Engineering Data. 55, 2985-2989 (2010).</li><li>Hawkins, C., Perrin, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polynuclear+Complex+Formation.+II.+Copper+(II)+with+Cystine+and+Related+Ligands.">Polynuclear Complex Formation. II. Copper (II) with Cystine and Related Ligands.</a> Inorganic Chemistry. 2, 843-849 (1963).</li><li>Hallman, P., Perrin, D., Watt, A. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+computed+distribution+of+copper+(II)+and+zinc+(II)+ions+among+seventeen+amino+acids+present+in+human+blood+plasma.">The computed distribution of copper (II) and zinc (II) ions among seventeen amino acids present in human blood plasma.</a> Biochem. J. 121, 549-555 (1971).</li><li>Jensen, L. S., Maurice, D. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+sulfur+amino+acids+on+copper+toxicity+in+chicks.">Influence of sulfur amino acids on copper toxicity in chicks.</a> The Journal of nutrition. 109, 91-97 (1979).</li><li>Lee, Y., Choi, J. R., Lee, K. J., Stott, N. E., Kim, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-scale+synthesis+of+copper+nanoparticles+by+chemically+controlled+reduction+for+applications+of+inkjet-printed+electronics.">Large-scale synthesis of copper nanoparticles by chemically controlled reduction for applications of inkjet-printed electronics.</a> Nanotechnology. 19, 415604 (2008).</li><li>Hume, J., 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=Engineered+coiled-coil+protein+microfibers.">Engineered coiled-coil protein microfibers.</a> Biomacromolecules. 15, 3503-3510 (2014).</li></ol>

While evaluating potential toxic effects of nanomaterials including CNPs, it was observed that over the long-term, CNPs were transformed from an initially more dispersed particulate distribution to a larger, aggregated form (Figure 2). In some cases, these highly aggregated formations which were produced in the cell culture dish, under biological conditions, formed highly linear projections from the central aggregate, reminiscent of previously described copper- containing &#8220;urchins&#8221; 6</su...

Copper is a highly reactive metal that in the biological world is essential in some enzyme functions 1,2, but in higher concentrations is potently toxic including in the nanoparticulate form 3,4. Concern over copper toxicity has become more relevant as CNPs and other copper-based nanomaterials are utilized, due to the increased surface area/mass for nanostructures. Thus, even a small mass of copper, in nanoparticle form, could cause local toxicity due to its ability to penetrate the cell and be broken down into reactive forms. Some biological species can complex with and chelate metal ions, and even incorporate them into biological structures as has been described in marine mussels 5. In studying the potential toxic effects of nanomaterials 4, it was discovered that over time, and under biological conditions used for typical cell culturing (37 &#176;C and 5% CO2), stable copper biocomposites could be formed with a high-aspect ratio (linear) structure.
By a process of elimination, the initial discovery of these linear biocomposites, which occurred in complete cell culture media, was simplified to a defined protocol of essential elements needed for the biocomposites to self-assemble. Self-assembly of two types of highly linear biocomposites was discovered to be possible with two starting metal components: 1) CNPs and 2) copper sulfate, with the common biological component being cystine. Although more complex, so called &#8220;urchin&#8221; and &#8220;nanoflower&#8221; type copper-containing structures with nanoscale and microscale features have been previously reported, these were produced under non-biological conditions, such as temperatures of 100 &#176;C or greater 6-8. To our knowledge, synthesis of individual, linear copper-containing nanostructures that are scalable in liquid phase under biological conditions has not been previously described. 
One of the starting materials utilized for synthesis of nanocomposites, namely CNPs, has been reported previously to be very toxic to cells 4. It has recently been reported that after the nanocomposites are formed, these structures are less toxic on a per mass basis than the starting NPs 9. Thus, the synthesis described here may be derived from a biological and biochemical reaction that has utility in stabilizing reactive copper species, both in the sense of transforming the NP form into larger structures and in producing composites less toxic to cells. 
In contrast to many other nanomaterial forms which are known to aggregate or clump upon interaction with biological liquid media 10,11, once formed, the highly linear composites described here avoid aggregation, possibly due to a redistribution of charge which has been previously reported 9. As detailed in the current work, this avoidance of aggregation is convenient for the purposes of working with the structures once formed for at least 3 reasons: 1) composite structures once formed may be concentrated using centrifugation and then easily dispersed again using vortex mixing; 2) formed structures can be decreased in average size by sonication for different periods of time; and 3) the formed linear structures may provide an additional tool for avoiding the recently described &#8220;coffee ring effect&#8221; 12 and thus provide a dopant for creating more evenly distributed coatings of materials, especially those containing spherical particulates.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Mini Vortexer</td>
			<td>VWR (https://us.vwr.com)</td>
			<td>58816-121</td>
			<td></td>
		</tr>
		<tr>
			<td>CO2 Incubator Model # 2425-2</td>
			<td>VWR (https://us.vwr.com)</td>
			<td>Contact vendor</td>
			<td>Current model calalog # 98000-360</td>
		</tr>
		<tr>
			<td>Eppendorf Centrifuge (Refrigerated Microcentrifuge)</td>
			<td>Labnet (http://labnetinternational.com/)</td>
			<td>C2500-R</td>
			<td>Model Prism R</td>
		</tr>
		<tr>
			<td>Cell Culture Centrifuge Model Z323K</td>
			<td>Labnet (http://labnetinternational.com/)</td>
			<td>Contact vendor</td>
			<td>Current model Z206A catalog # C0206-A</td>
		</tr>
		<tr>
			<td>Sonicator (Ultrasonic Cleaner)</td>
			<td>Branson Ultrasonics Corporation (http://www.bransonic.com/)</td>
			<td>1510R-MTH</td>
			<td></td>
		</tr>
		<tr>
			<td>Balance</td>
			<td>Sartorius (http://dataweigh.com)</td>
			<td></td>
			<td>Model CP225D similar model CPA225D</td>
		</tr>
		<tr>
			<td>Olympus IX51 Inverted Light Microscope</td>
			<td>Olympus (http://olympusamerica.com</td>
			<td>Contact vendor</td>
			<td></td>
		</tr>
		<tr>
			<td>Olympus DP71 microscope digital camera</td>
			<td>Olympus (http://olympusamerica.com</td>
			<td>Contact vendor</td>
			<td></td>
		</tr>
		<tr>
			<td>external power supply unit- white light for Olympus microscope</td>
			<td>Olympus (http://olympusamerica.com</td>
			<td>TH4-100</td>
			<td></td>
		</tr>
		<tr>
			<td>10x, 20, and 40x microscope objectives</td>
			<td>Olympus (http://olympusamerica.com</td>
			<td>Contact vendor</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning Electron Microscope</td>
			<td>Hitachi (http://hitachi-hitec.com/global/em/sem/sem_index.html)</td>
			<td>model S-4800</td>
			<td></td>
		</tr>
		<tr>
			<td>Transmission Electron Microscope</td>
			<td>Zeiss (http://zeiss.com/microscopy/en_de/products.html)</td>
			<td>model Libra 120</td>
			<td></td>
		</tr>
		<tr>
			<td>Table Top Work Station Unidirectional Flow Clean Bench</td>
			<td>Envirco (http://envirco-hvac.com)</td>
			<td>model PNG62675</td>
			<td>Used for sterile cell culture technique</td>
		</tr>
	</tbody>
</table>

generation of scalable, metallic high-aspect ratio nanocomposites in a biological liquid medium

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper and cystine, with either copper nanoparticles (CNPs) or copper sulfate contributing the metallic component. Synthesis is carried out in liquid under biological conditions (37 &#176;C) and the self-assembled composites form after 24 hr. Once formed, these composites are highly stable in both liquid media and in a dried form. The composites scale from the nano- to micro- range in length, and from a few microns to 25 nm in diameter. Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) demonstrated that sulfur was present in the NP-derived linear structures, while it was absent from the starting CNP material, thus confirming cystine as the source of sulfur in the final nanocomposites. During synthesis of these linear nano- and micro-composites, a diverse range of lengths of structures is formed in the synthesis vessel. Sonication of the liquid mixture after synthesis was demonstrated to assist in controlling average size of the structures by diminishing the average length with increased time of sonication. Since the formed structures are highly stable, do not agglomerate, and are formed in liquid phase, centrifugation may also be used to assist in concentrating and segregating formed composites.

Figure 1 shows a flow-chart schematic of the synthesis steps to form the linear biocomposites described in this work. CNPs or copper sulfate as starting materials are combined with sterile water to form a 2 mg/ml solution, this solution is mixed and sonicated to provide an even mixture, and this copper solution is then mixed in the following ratio for synthesis: 949 parts sterile water: 50 parts copper mixture: 1 part cystine stock solution. The actual volumes may be increased or decreased according to t...

Watch this Scientific Journal Video about Generation of Scalable, Metallic High-Aspect Ratio Nanocomposites in a Biological Liquid Medium at JoVE.com

Generation of Scalable, Metallic High-Aspect Ratio Nanocomposites in a Biological Liquid Medium

Here we present a protocol to synthesize novel, high-aspect ratio biocomposites under biological conditions and in liquid media. The biocomposites scale from nanometers to micrometers in diameter and length, respectively. Copper nanoparticles (CNPs) and copper sulfate combined with cystine are the key components for the synthesis.

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper ...

generation-scalable-metallic-high-aspect-ratio-nanocomposites

Research

JoVE Journal

Bioengineering

Cellular Lipid Extraction for Targeted Stable Isotope Dilution Liquid Chromatography-Mass Spectrometry Analysis

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including numerous stereoisomers1,2. These metabolites can be formed from free or esterified fatty acids. Many of these oxidized metabolites have biological activity and have been implicated in various diseases including cardiovascular and neurodegenerative diseases, asthma, and cancer3-7. Oxidized bioactive lipids can be formed enzymatically or by reactive oxygen species (ROS). Enzymes that metabolize fatty acids include cyclooxygenase (COX), lipoxygenase (LO), and cytochromes P450 (CYPs)1,8. Enzymatic metabolism results in enantioselective formation whereas ROS oxidation results in the racemic formation of products.
While this protocol focuses primarily on the analysis of AA- and some LA-derived bioactive metabolites; it could be easily applied to metabolites of other fatty acids. Bioactive lipids are extracted from cell lysate or media using liquid-liquid (l-l) extraction. At the beginning of the l-l extraction process, stable isotope internal standards are added to account for errors during sample preparation. Stable isotope dilution (SID) also accounts for any differences, such as ion suppression, that metabolites may experience during the mass spectrometry (MS) analysis9. After the extraction, derivatization with an electron capture (EC) reagent, pentafluorylbenzyl bromide (PFB) is employed to increase detection sensitivity10,11. Multiple reaction monitoring (MRM) is used to increase the selectivity of the MS analysis. Before MS analysis, lipids are separated using chiral normal phase high performance liquid chromatography (HPLC). The HPLC conditions are optimized to separate the enantiomers and various stereoisomers of the monitored lipids12. This specific LC-MS method monitors prostaglandins (PGs), isoprostanes (isoPs), hydroxyeicosatetraenoic acids (HETEs), hydroxyoctadecadienoic acids (HODEs), oxoeicosatetraenoic acids (oxoETEs) and oxooctadecadienoic acids (oxoODEs); however, the HPLC and MS parameters can be optimized to include any fatty acid metabolites13.
Most of the currently available bioanalytical methods do not take into account the separate quantification of enantiomers. This is extremely important when trying to deduce whether or not the metabolites were formed enzymatically or by ROS. Additionally, the ratios of the enantiomers may provide evidence for a specific enzymatic pathway of formation. The use of SID allows for accurate quantification of metabolites and accounts for any sample loss during preparation as well as the differences experienced during ionization. Using the PFB electron capture reagent increases the sensitivity of detection by two orders of magnitude over conventional APCI methods. Overall, this method, SID-LC-EC-atmospheric pressure chemical ionization APCI-MRM/MS, is one of the most sensitive, selective, and accurate methods of quantification for bioactive lipids.

This protocol will demonstrate the extraction and analysis of free and esterified bioactive fatty acids from cells. Fatty acids are accurately quantified using stable isotope dilution, chiral liquid chromatography, electron capture atmospheric chemical ionization multiple reaction monitoring mass spectrometry (SID-LC-ECAPCI-MRM/MS).

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including ...

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. 
To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.
The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

A method is discussed by which the in vivo mechanical behavior of stimuli-responsive materials is monitored as a function of time. Samples are tested ex vivo using a microtensile tester with environmental controls to simulate the physiological environment. This work further promotes understanding the in vivo behavior of our material.

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, ...

In situ TEM of Biological Assemblies in Liquid

Researchers regularly use Transmission Electron Microscopes (TEMs) to examine biological entities and to assess new materials. Here, we describe an additional application for these instruments- viewing viral assemblies in a liquid environment. This exciting and novel method of visualizing biological structures utilizes a recently developed microfluidic-based specimen holder. Our video article demonstrates how to assemble and use a microfluidic holder to image liquid specimens within a TEM. In particular, we use simian rotavirus double-layered particles (DLPs) as our model system. We also describe steps to coat the surface of the liquid chamber with affinity biofilms that tether DLPs to the viewing window. This permits us to image assemblies in a manner that is suitable for 3D structure determination. Thus, we present a first glimpse of subviral particles in a native liquid environment.

In situ TEM of Biological Assemblies in Liquid

Here we describe a procedure to image viral complexes in liquid at nanometer resolution using a transmission electron microscope.

Researchers regularly use Transmission Electron Microscopes (TEMs) to examine biological entities and to assess new materials. Here, we describe an ...

Synthesis of Keratin-based Nanofiber for Biomedical Engineering

Electrospinning, due to its versatility and potential for applications in various fields, is being frequently used to fabricate nanofibers. Production of these porous nanofibers is of great interest due to their unique physiochemical properties. Here we elaborate on the fabrication of keratin containing poly (&#949;-caprolactone) (PCL) nanofibers (i.e., PCL/keratin composite fiber). Water soluble keratin was first extracted from human hair and mixed with PCL in different ratios. The blended solution of PCL/keratin was transformed into nanofibrous membranes using a laboratory designed electrospinning set up. Fiber morphology and mechanical properties of the obtained nanofiber were observed and measured using scanning electron microscopy and tensile tester. Furthermore, degradability and chemical properties of the nanofiber were studied by FTIR. SEM images showed uniform surface morphology for PCL/keratin fibers of different compositions. These PCL/keratin fibers also showed excellent mechanical properties such as Young&#39;s modulus and failure point. Fibroblast cells were able to attach and proliferate thus proving good cell viability. Based on the characteristics discussed above, we can strongly argue that the blended nanofibers of natural and synthetic polymers can represent an excellent development of composite materials that can be used for different biomedical applications.

Electrospun nanofibers have a high surface area to weight ratio, excellent mechanical integrity, and support cell growth and proliferation. These nanofibers have a wide range of biomedical applications. Here we fabricate keratin/ PCL nanofibers, using the electrospinning technique, and characterize the fibers for possible applications in tissue engineering.

Electrospinning, due to its versatility and potential for applications in various fields, is being frequently used to fabricate nanofibers. Production of ...

Alternating Magnetic Field-Responsive Hybrid Gelatin Microgels for Controlled Drug Release

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of smart soft devices for biomedical applications. Although a number of magnetically-responsive drug delivery systems have demonstrated efficacies through either in vitro proof of concept studies or in vivo preclinical applications, their use in clinical settings is still limited by their insufficient biocompatibility or biodegradability. Additionally, many of the existing platforms rely on sophisticated techniques for their fabrications. We recently demonstrated the fabrication of biodegradable, gelatin-based thermo-responsive microgel by physically entrapping poly(N-isopropylacrylamide-co-acrylamide) chains as a minor component within a three-dimensional gelatin network. In this study, we present a facile method to fabricate a biodegradable drug release platform that enables a magneto-thermally triggered drug release. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and thermo-responsive polymers within gelatin-based colloidal microgels, in conjunction with an alternating magnetic field application system.

We present a facile method to fabricate a biodegradable gelatin-based drug release platform that is magneto-thermally responsive. This was achieved by incorporating superparamagnetic iron oxide nanoparticles and poly(N-isopropylacrylamide-co-acrylamide) within a spherical gelatin micro-network crosslinked by genipin, in conjunction with an alternating magnetic field application system.

Magnetically-responsive nano/micro-engineered biomaterials that enable a tightly controlled, on-demand drug delivery have been developed as new types of ...

Preparation of Monodomain Liquid Crystal Elastomers and Liquid Crystal Elastomer Nanocomposites

LCEs are shape-responsive materials with fully reversible shape change and potential applications in medicine, tissue engineering, artificial muscles, and as soft robots. Here, we demonstrate the preparation of shape-responsive liquid crystal elastomers (LCEs) and LCE nanocomposites along with characterization of their shape-responsiveness, mechanical properties, and microstructure. Two types of LCEs &#8212; polysiloxane-based and epoxy-based &#8212; are synthesized, aligned, and characterized. Polysiloxane-based LCEs are prepared through two crosslinking steps, the second under an applied load, resulting in monodomain LCEs. Polysiloxane LCE nanocomposites are prepared through the addition of conductive carbon black nanoparticles, both throughout the bulk of the LCE and to the LCE surface. Epoxy-based LCEs are prepared through a reversible esterification reaction. Epoxy-based LCEs are aligned through the application of a uniaxial load at elevated (160 &#176;C) temperatures. Aligned LCEs and LCE nanocomposites are characterized with respect to reversible strain, mechanical stiffness, and liquid crystal ordering using a combination of imaging, two-dimensional X-ray diffraction measurements, differential scanning calorimetry, and dynamic mechanical analysis. LCEs and LCE nanocomposites can be stimulated with heat and/or electrical potential to controllably generate strains in cell culture media, and we demonstrate the application of LCEs as shape-responsive substrates for cell culture using a custom-made apparatus.

We demonstrate the preparation of siloxane-based and epoxy-based liquid crystal elastomers (LCEs) and LCE nanocomposites. The LCEs are characterized with respect to reversible strain, liquid crystal ordering, and stiffness. As a potential application, we demonstrate their use as shape-responsive substrates in a custom device for active cell culture.

LCEs are shape-responsive materials with fully reversible shape change and potential applications in medicine, tissue engineering, artificial muscles, and ...

A Novel Technique for Generating and Observing Chemiluminescence in a Biological Setting

Intraoperative imaging techniques have the potential to make surgical interventions safer and more effective; for these reasons, such techniques are quickly moving into the operating room. Here, we present a new approach that utilizes a technique not yet explored for intraoperative imaging: chemiluminescent imaging. This method employs a ruthenium-based chemiluminescent reporter along with a custom-built nebulizing system to produce ex vivo or in vivo images with high signal-to-noise ratios. The ruthenium-based reporter produces light following exposure to an aqueous oxidizing solution and re-reduction within the surrounding tissue. This method has allowed us to detect reporter concentrations as low as 6.9 pmol/cm2. In this work, we present a visual guide to our proof-of-concept in vivo studies involving subdermal and intravenous injections in mice. The results suggest that this technology is a promising candidate for further preclinical research and might ultimately become a useful tool in the operating room.

This protocol describes a new intraoperative imaging technique that uses a ruthenium complex as a source of chemiluminescent light emission, thereby producing high signal-to-noise ratios during in vivo imaging. Intraoperative imaging is an expanding field that could revolutionize the way that surgical procedures are performed.

Intraoperative imaging techniques have the potential to make surgical interventions safer and more effective; for these reasons, such techniques are ...

Automated Robotic Liquid Handling Assembly of Modular DNA Devices

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; represented by &#34;devices&#34; created as combinations of individual genetic components. However, manual assembly of such large numbers of devices is time-intensive, error-prone, and costly. The increasing sophistication and scale of synthetic biology research necessitates an efficient, reproducible way to accommodate large-scale, complex, and high throughput device construction.
Here, a DNA assembly protocol using the Type-IIS restriction endonuclease based Modular Cloning (MoClo) technique is automated on two liquid-handling robotic platforms. Automated liquid-handling robots require careful, often times tedious optimization of pipetting parameters for liquids of different viscosities (e.g. enzymes, DNA, water, buffers), as well as explicit programming to ensure correct aspiration and dispensing of DNA parts and reagents. This makes manual script writing for complex assemblies just as problematic as manual DNA assembly, and necessitates a software tool that can automate script generation. To this end, we have developed a web-based software tool, http://mocloassembly.com, for generating combinatorial DNA device libraries from basic DNA parts uploaded as Genbank files. We provide access to the tool, and an export file from our liquid handler software which includes optimized liquid classes, labware parameters, and deck layout. All DNA parts used are available through Addgene, and their digital maps can be accessed via the Boston University BDC ICE Registry. Together, these elements provide a foundation for other organizations to automate modular cloning experiments and similar protocols.
The automated DNA assembly workflow presented here enables the repeatable, automated, high-throughput production of DNA devices, and reduces the risk of human error arising from repetitive manual pipetting. Sequencing data show the automated DNA assembly reactions generated from this workflow are ~95% correct and require as little as 4% as much hands-on time, compared to manual reaction preparation.

Here, an automated workflow to perform modular DNA &#34;device&#34; assembly using a modular cloning DNA assembly method on liquid-handling robots is presented. The protocol uses an intuitive software tool for generating liquid handler picklists for combinatorial DNA device library generation, which we demonstrate using two liquid handling platforms.

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; ...

Synthesis of Biocompatible Liquid Crystal Elastomer Foams as Cell Scaffolds for 3D Spatial Cell Cultures

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block co-polymers featuring cholesterol units as side-chain pendant groups, resulting in smectic-A (SmA) liquid crystal elastomers (LCEs). Foam-like scaffolds, prepared using metal templates, feature interconnected microchannels, making them suitable as 3D cell culture scaffolds. The combined properties of the regular structure of the metal foam and of the elastomer result in a 3D cell scaffold that promotes not only higher cell proliferation compared to conventional porous templated films, but also better management of mass transport (i.e., nutrients, gases, waste, etc.). The nature of the metal template allows for the easy manipulation of foam shapes (i.e., rolls or films) and for the preparation of scaffolds of different pore sizes for different cell studies while preserving the interconnected porous nature of the template. The etching process does not affect the chemistry of the elastomers, preserving their biocompatible and biodegradable nature. We show that these smectic LCEs, when grown for extensive time periods, enable the study of clinically relevant and complex tissue constructs while promoting the growth and proliferation of cells.

This study presents a methodology to prepare 3D, biodegradable, foam-like cell scaffolds based on biocompatible side-chain liquid crystal elastomers (LCEs). Confocal microscopy experiments show that foam-like LCEs allow for cell attachment, proliferation, and the spontaneous alignment of C2C12s myoblasts.

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block ...

Rapid, Scalable Assembly and Loading of Bioactive Proteins and Immunostimulants into Diverse Synthetic Nanocarriers Via Flash Nanoprecipitation

Nanomaterials present a wide range of options to customize the controlled delivery of single and combined molecular payloads for therapeutic and imaging applications. This increased specificity can have significant clinical implications, including decreased side effects and lower dosages with higher potency. Furthermore, the in situ targeting and controlled modulation of specific cell subsets can enhance in vitro and in vivo investigations of basic biological phenomena and probe cell function. Unfortunately, the required expertise in nanoscale science, chemistry and engineering often prohibit laboratories without experience in these fields from fabricating and customizing nanomaterials as tools for their investigations or vehicles for their therapeutic strategies. Here, we provide protocols for the synthesis and scalable assembly of a versatile non-toxic block copolymer system amenable to the facile formation and loading of nanoscale vehicles for biomedical applications. Flash nanoprecipitation is presented as a methodology for rapid fabrication of diverse nanocarriers from poly(ethylene glycol)-bl-poly(propylene sulfide) copolymers. These protocols will allow laboratories with a wide range of expertise and resources to easily and reproducibly fabricate advanced nanocarrier delivery systems for their applications. The design and construction of an automated instrument that employs a high-speed syringe pump to facilitate the flash nanoprecipitation process and to allow enhanced control over the homogeneity, size, morphology and loading of polymersome nanocarriers is described.

Nanomaterials provide versatile mechanisms of controlled therapeutic delivery for both basic science and translational applications, but their fabrication often requires expertise that is unavailable in most biomedical laboratories. Here, we present protocols for the scalable fabrication and therapeutic loading of diverse self-assembled nanocarriers using flash nanoprecipitation.

Nanomaterials present a wide range of options to customize the controlled delivery of single and combined molecular payloads for therapeutic and imaging ...