Name: advanced compositional analysis of nanoparticle-polymer composites using direct fluorescence imaging
Uploaded: 2016-07-19T14:00:00
Description: Watch this Scientific Journal Video about Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging at JoVE.com

C.R.C. would like to acknowledge the Ramsay Memorial Trust for funding.

1. Preparation of CdSe/ZnS Core/Shell Quantum Dots
<ol>
	<li>Preparation of the trioctylphosphine (TOP)-Se solution
	<ol>
		<li>Prepare a 0.5 M solution of selenium in TOP by mixing the appropriate amount of Se into TOP in a Schlenk flask under nitrogen or in a glovebox (8 ml required per reaction, typically 0.4 g dissolved in 10 ml of TOP).</li>
		<li>Stir the mixture to dissolve the Se for 1 hr, resulting in a grey solution of the TOP-Se complex.</li>
		<li>Ensure the solution is then freeze-pump-tha...

<ol>
	<li>Pumera, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Graphene-based+nanomaterials+and+their+electrochemistry.">Graphene-based nanomaterials and their electrochemistry.</a> Chem. Soc. Rev. 39 (11), 4146-4157 (2010).</li><li>Zhang, Q., Uchaker, E., Candelaria, S. L., Cao, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanomaterials+for+energy+conversion+and+storage.">Nanomaterials for energy conversion and storage.</a> Chem. Soc. 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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superhydrophobic+Photocatalytic+Surfaces+through+Direct+Incorporation+of+Titania+Nanoparticles+into+a+Polymer+Matrix+by+Aerosol+Assisted+Chemical+Vapor+Deposition.">Superhydrophobic Photocatalytic Surfaces through Direct Incorporation of Titania Nanoparticles into a Polymer Matrix by Aerosol Assisted Chemical Vapor Deposition.</a> Adv. Mater. 24 (26), 3505-3508 (2012).</li><li>Crick, C. R., Bear, J. C., Southern, P., Parkin, I. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+general+method+for+the+incorporation+of+nanoparticles+into+superhydrophobic+films+by+aerosol+assisted+chemical+vapour+deposition.">A general method for the incorporation of nanoparticles into superhydrophobic films by aerosol assisted chemical vapour deposition.</a> J. Mater. 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Cluster Sci. 21 (3), 427-438 (2010).</li><li>Perni, 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+antimicrobial+properties+of+light-activated+polymers+containing+methylene+blue+and+gold+nanoparticles.">The antimicrobial properties of light-activated polymers containing methylene blue and gold nanoparticles.</a> Biomater. 30 (1), 89-93 (2009).</li><li>Noimark, 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=Dual-Mechanism+Antimicrobial+Polymer-ZnO+Nanoparticle+and+Crystal+Violet-Encapsulated+Silicone.">Dual-Mechanism Antimicrobial Polymer-ZnO Nanoparticle and Crystal Violet-Encapsulated Silicone.</a> Adv. Func. Mater. 25 (9), 1367-1373 (2015).</li><li>Gingery, D., B&#252;hlmann, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+gold+nanoparticles+on+multiwalled+carbon+nanotubes+by+thermal+evaporation.">Formation of gold nanoparticles on multiwalled carbon nanotubes by thermal evaporation.</a> Carbon. 46 (14), 1966-1972 (2008).</li><li>Abdelmoti, L. G., Zamborini, F. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potential-Controlled+Electrochemical+Seed-Mediated+Growth+of+Gold+Nanorods+Directly+on+Electrode+Surfaces.">Potential-Controlled Electrochemical Seed-Mediated Growth of Gold Nanorods Directly on Electrode Surfaces.</a> Langmuir. 26 (16), 13511-13521 (2010).</li><li>Crick, C. R., 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=Advanced+analysis+of+nanoparticle+composites+-+a+means+toward+increasing+the+efficiency+of+functional+materials.">Advanced analysis of nanoparticle composites - a means toward increasing the efficiency of functional materials.</a> RSC Adv. 5 (66), 53789-53795 (2015).</li><li>Solvas, X. C., Turek, V., Prodromakis, T., Edel, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+evaporator+for+on-chip+sample+concentration.">Microfluidic evaporator for on-chip sample concentration.</a> Lab Chip. 12 (20), 4049-4054 (2012).</li><li>Solvas, X. 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Cross-sectional fluorescence imaging allows for direct visualization of nanoparticles during swell encapsulation. The kinetics of encapsulation has been shown, with the drive toward a high nanoparticle surface concentration demonstrated. The extent of nanoparticle incorporation is shown to vary with swell encapsulation time (described in section 2.3), with the total amount of incorporated nanoparticles increasing as this time is extended, with the particle concentration localized at the surface if the polymer samples are...

The application of nanomaterials has long served as an area of increasing interest for novel technologies.1-3 This has included the growing use of nanoparticles in everyday items, including cosmetics, clothes, packaging and electronics.4-6 A major drive toward using nanoparticles in functional materials stems from their higher reactivity relative to the materials, in addition to the ability to tune properties by variation in particle size.7 One further advantage is the capability to easily form composite materials, introducing crucial properties to the host matrix, such as catalytic functionality, material strengthening and tuning of electrical properties.8-12
Nanoparticle-polymer composite materials can be achieved through a range of techniques, the simplest of which is direct integration of the desired nanoparticles during the fabrication of the host matrix.13,14 This results in a homogenous material with an even spacing of nanoparticulate material throughout. However, many applications only require the active material to be present at the external interfaces of the nanocomposites. As a result, direct incorporation does not result in efficient use of sometimes costly nanoparticle material as there is much nanoparticle waste through the bulk of the material.15,16 To achieve direct incorporation, the nanoparticles must also be compatible with host matrix formation. This may be challenging, especially in syntheses that require multifaceted reactions such as in the case of thermosetting polymers that are typically facilitated by metal complex catalysts mechanisms that may be affected by highly active nanoparticles.14
The considerable disadvantages associated with direct nanoparticle incorporation during the polymer synthesis, has led to the development of techniques aimed to limit nanoparticle incorporation to the surface layer.17-21 Swell encapsulation is one of the most successful strategies reported in the literature, to achieve high surface nanoparticle concentrations, with limited wastage in the polymer bulk.17-19 The technique utilizes the solvent driven swelling of polymer matrices, allowing for the incursion of molecular species and nanoparticles. Upon removal of the swelling solvent, the species within the matrix become fixed into place, with the highest concentration of species localized at the surface. To date, most of the reported uses of swell encapsulation are directed toward the fabrication of antimicrobial polymers, where it is key that the active agents are at the material surface. While many of these reports show enhanced antimicrobial activity, the precise surface nanoparticle composition is rarely probed in detail. Crick et al. recently demonstrated a method for the direct visualization of nanoparticle incursion, providing crucial insight into the kinetics and surface nanoparticle concentrations achieved by swell encapsulation.22
This work details the synthesis of cadmium selenide quantum dots (QD), their swell encapsulation into polydimethylsiloxane (PDMS) and the direct visualization of their incorporation using fluorescence imaging. The effect of varying swell encapsulation time and nanoparticle concentration in the swelling solution is explored. The fluorescence visualization technique allows for the direct imaging of nanoparticle incursion into the PDMS and demonstrates that the highest concentration of QDs is at the material surface.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polydimethylsiloxane sheets</td>
			<td style="width:71px;">NuSil</td>
			<td style="width:119px;">-</td>
			<td style="width:167px;">Medical Grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Oleylamine</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">O7805</td>
			<td>Technical Grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Trioctylphosphine</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">117854</td>
			<td>Technical Grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Trioctylphosphine oxide</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">346187</td>
			<td>Technical Grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">1-Octadecene</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">O806</td>
			<td>Technical Grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Zinc diethyldithiocarbamate</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">329703</td>
			<td>-</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Oleic acid</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">364525</td>
			<td>Technical Grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Triethylamine</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">471283</td>
			<td>-</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Cadmium oxide</td>
			<td style="width:71px;">Alfa Aesar</td>
			<td style="width:119px;">33235</td>
			<td>-</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hexadecylamine</td>
			<td style="width:71px;">Alfa Aesar</td>
			<td style="width:119px;">B22459</td>
			<td>Technical Grade</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">1-Dodecylphosphonic acid</td>
			<td style="width:71px;">Alfa Aesar</td>
			<td style="width:119px;">H26259</td>
			<td>-</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Selenium powder</td>
			<td style="width:71px;">Acros</td>
			<td style="width:119px;">19807</td>
			<td>-</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Chloroform</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">366919</td>
			<td>-</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">n-Hexane</td>
			<td style="width:71px;">Sigma Aldrich</td>
			<td style="width:119px;">208752</td>
			<td>-</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Microscope slides</td>
			<td style="width:71px;">VWR</td>
			<td style="width:119px;">631-0137</td>
			<td>Thickness No. 1</td>
		</tr>
	</tbody>
</table>

advanced compositional analysis of nanoparticle-polymer composites using direct fluorescence imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

The quantum dots exhibited red fluorescence, with a lambda max of approximately 600 nm.22,28 The red emission was due to the confinement of the exciton by the quantum rod whose size dimensions are within the strong confinement regime. Li et al. showed that for quantum rods, the emission shifts to lower energy with an increase in either width or length of the rod. They further showed that the emission mainly determined by the lateral confinement, which plays an importan...

Watch this Scientific Journal Video about Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging at JoVE.com

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise ...

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