This work was funded in part by the Texas Emerging Technology Fund (Startup to TB), the Texas State University Research Enhancement Program, the Texas State University Doctoral Research Fellowship (to TC), the NSF Partnership for Research and Education in Materials (PREM, DMR-1205670), The Welch Foundation (AI-0045), and National Institutes of Health (R01CA032132).

<ol>
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The authors have nothing to disclose.

In this work, electroactive polymer NPs have been synthesized as potential PTT agents for cancer treatment. The preparation of the NPs is described, starting with the synthesis of the monomers followed by emulsion polymerization. While the preparation of NPs using electroactive polymers such as EDOT and pyrrole has been described before, this paper describes the preparation of polymeric NPs starting with unique extended conjugation monomers, demonstrating that this process can be extended to larger, more complex monomers...

Electroactive polymers change their properties (color, conductivity, reactivity, volume, etc.) in the presence of an electric field. The rapid switching times, tunability, durability, and lightweight characteristics of electroactive polymers have led to many proposed applications, including alternative energy, sensors, electrochromics, and biomedical devices. Electroactive polymers are potentially useful as flexible, light-weight battery and capacitor electrodes.1 Applications of electroactive polymers in electrochromic devices include glare-reduction systems for buildings and automobiles, sunglasses, protective eyewear, optical storage devices, and smart textiles.2-5 Smart windows can reduce energy requirements by blocking specific wavelengths of light on-demand and protecting interiors of homes and automobiles. Smart textiles can be used in clothing to help protect against UV radiation.6 Electroactive polymers have also begun to be used in medical devices. Among electroactive polymers used in biomedical devices, polypyrrole (PPy), polyaniline (PANI), and poly(3,4-ethylenedioxythiophene) (PEDOT) are among the most common. For example, these types of polymers are commonly used as transducers in biosensor devices.7 Applications in therapeutic delivery have also shown promise; studies have demonstrated the release of drugs and therapeutic proteins from devices prepared from electroactive polymers.8-12 More recently, electroactive polymers have been used as therapeutic agents in photothermal therapy.13-15 In photothermal therapy, photothermal agents must absorb light in the near-infrared (NIR) region (~ 700&#8722;900 nm), also known as the therapeutic window, where light has the maximum depth of penetration in tissue, typically up to 1 cm.16,17 In this range, biological chromophores such as hemoglobin, oxygenated hemoglobin, lipids, and water have little-to-no absorbance, which enables light to penetrate easily. When photothermal agents absorb light in this therapeutic window, the photoenergy is converted to photothermal energy.
Irvin and co-workers have previously reported alkoxy-substituted bis-EDOT benzene monomers that were synthesized using Negishi coupling.18 Negishi coupling is a preferred method for carbon-carbon bond formation. This process has many advantages, including the use of organozinc intermediates, which are less toxic and tend to have higher reactivity than other organometallics used.19,20 Organozinc compounds are also compatible with a wide range of functional groups on the organohalides.20 In the Negishi coupling reaction, an organohalide and organometal are coupled through the use of a palladium(0) catalyst.20 In the work presented herein, this cross coupling method is utilized in the synthesis of 1,4-dialkoxy-2,5-bis(3,4-ethylenedioxythienyl) benzene (BEDOT-B(OR)2) monomers. These monomers can then be easily polymerized electrochemically or chemically to yield polymers that are promising candidates for use in biomedical applications.
Conventional methods for preparation of colloidal polymeric suspensions in aqueous solutions for biomedical applications typically involve the dissolution of bulk polymers followed by nanoprecipitation or emulsion-solvent evaporation techniques.21,22 In order to produce NPs of poly(BEDOT-B(OR)2), a bottom-up approach is demonstrated here where the NPs are synthesized via in situ emulsion polymerization. Emulsion polymerization is a process that is easily scalable and is a relatively fast method for NP preparation.22 Studies using emulsion polymerization to produce NPs of other electroactive polymers have been reported for PPy and PEDOT.15,23,24 PEDOT NPs, for example, have been prepared using spray emulsion polymerization.24 This method is difficult to reproduce, and typically yields larger, micron-sized particles. The protocol described in this article explores the use of a drop-sonication method to reproducibly prepare 100-nm polymer NPs.
In this protocol, electroactive polymers tailored to absorb light in the NIR region similar to previously reported poly(BEDOT-B(OR)2) are synthesized and characterized to demonstrate their potential in electrochromic devices and as PTT agents. First, the protocol for the synthesis of the monomers via Negishi coupling is described. The monomers are characterized using NMR and UV-Vis-NIR spectroscopy. The preparation of NP colloid suspensions via oxidative emulsion polymerization in aqueous media is also described. The procedure is based on a two-step emulsion polymerization process previously described by Han et al. that is applied to the different monomers. A two-surfactant system is used to control the NP monodispersity. A cell viability assay is used to evaluate cytocompatibility of the NPs. Lastly, the potential of these NPs to act as PTT transducers is demonstrated by irradiation with a NIR laser.

<table border="0" cellpadding="0" cellspacing="0" width="747">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:291px;">2 mm diameter platinum working electrode</td>
			<td style="width:171px;">CH Instruments</td>
			<td style="width:119px;">CH102</td>
			<td style="width:167px;">Polished using very fine sandpaper</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:291px;">3,4-ethylenedioxythiophene</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">483028</td>
			<td style="width:167px;">Purified by vacuum distillation</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:291px;">3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) 98%</td>
			<td>Alfa Aesar</td>
			<td style="width:119px;">L11939</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">505 Sonic Dismembrator</td>
			<td>Fisher Scientific&#8482;&#160;</td>
			<td style="width:119px;">FB505110</td>
			<td style="width:167px;">1/8 &#8220; tip and rated at 500 watts</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">808 nm laser diode</td>
			<td>ThorLabs</td>
			<td style="width:119px;">L808P1WJ</td>
			<td style="width:167px;">Rated at 1 W</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Acetonitrile anhydrous 99%</td>
			<td>Acros</td>
			<td style="width:119px;">61022-0010</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Avanti J-26 XPI</td>
			<td>Beckman Coulter</td>
			<td style="width:119px;">393127</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Bromohexane 98%</td>
			<td>MP Biomedicals</td>
			<td style="width:119px;">202323</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Dialysis (100,000) MWCO</td>
			<td>SpectrumLabs</td>
			<td style="width:119px;">G235071</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Dimethyl sulfoxide 99% (DMSO)</td>
			<td>BDH</td>
			<td style="width:119px;">BDH1115</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Dimethylformamide anhydrous (DMF) 99%</td>
			<td>Acros</td>
			<td style="width:119px;">326870010</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Dodecyl benzenesulfonate (DBSA)&#160;</td>
			<td>TCI</td>
			<td style="width:119px;">D0989</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dulbecco&#8217;s modified eagle medium (DMEM)&#160;</td>
			<td>Corning</td>
			<td style="width:119px;">10-013 CV</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">EMS 150 TES sputter coater</td>
			<td style="width:171px;">Electron Microscopy Sciences</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Ethanol (EtOH) 100%</td>
			<td>BDH</td>
			<td style="width:119px;">BDH1156</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">ethyl 4-bromobutyrate (98%)</td>
			<td>Acros</td>
			<td style="width:119px;">173551000</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Ethyl acetate 99%</td>
			<td>Fisher</td>
			<td style="width:119px;">UN1173</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal bovine serum (FBS)</td>
			<td>Corning</td>
			<td style="width:119px;">35-010-CV</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Helios NanoLab 400</td>
			<td>FEI</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Hexane</td>
			<td>Fisher</td>
			<td style="width:119px;">H306-4</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Hydrochloric acid (HCl)</td>
			<td>Fisher</td>
			<td style="width:119px;">A142-212</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Hydroquinone 99.5%</td>
			<td>Acros</td>
			<td style="width:119px;">120915000</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Hydrozine anhydrous 98%</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">215155</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Indium tin oxide (ITO) coated galss</td>
			<td>Delta Technologies</td>
			<td style="width:119px;">CG-41IN-CUV</td>
			<td style="width:167px;">4-8 &#937;/sq</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:291px;">Iron chloride 97% FeCl3</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">157740</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:291px;">Magnesium sulfate (MgSO4)</td>
			<td>Fisher</td>
			<td style="width:119px;">593295</td>
			<td style="width:167px;">Dried at 100 oC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">SKOV-3</td>
			<td>ATCC</td>
			<td style="width:119px;">HTB-26</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Methanol</td>
			<td>BDH</td>
			<td style="width:119px;">BHD1135</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">n-Butlithium (2.5 M)&#160;</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">230707</td>
			<td style="width:167px;">Pyrophoric</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:291px;">Poly(styrenesulfonate-co-malic acid) (PSS-co-MA) 20,000 MW</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">434566</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:291px;">Potassium carbonate</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">209619</td>
			<td style="width:167px;">Dried at 100 oC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Potassium hydroxide</td>
			<td>Alfa Aesar</td>
			<td style="width:119px;">A18854</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Potassium iodide</td>
			<td>Fisher</td>
			<td style="width:119px;">P410-100</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">RO-5 stirplate</td>
			<td>IKA-Werke</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">SC4000 IR camera</td>
			<td>FLIR</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Synergy H4 Hybrid Reader</td>
			<td>Biotek</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:291px;">Tetrabutylammonium perchlorate (TBAP) 99%</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">3579274</td>
			<td style="width:167px;">Purified by recrystallization in ethyl acetate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Tetrahydrofuran anhydrous (THF) 99%</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">401757</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">tetrakis(triphenylphosphine) 
			palladium(0)</td>
			<td>Sigma-Aldrich</td>
			<td style="width:119px;">216666</td>
			<td style="width:167px;">Moisture sensitive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Thermomixer</td>
			<td>Eppendorf</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">USB potentiostat/galvanostat</td>
			<td>WaveNow</td>
			<td style="width:119px;">AFTP1</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:291px;">Zetasizer Nano Zs</td>
			<td>Malvern</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Optical Arrangment 175o</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:291px;">Zinc chloride (1 M) ZnCl2</td>
			<td>Acros</td>
			<td style="width:119px;">370057000</td>
			<td style="width:167px;"></td>
		</tr>
	</tbody>
</table>

electroactive polymer nanoparticles exhibiting photothermal properties

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT).

The reaction protocol yielding M1 and M2 is shown in Figure 1. The monomers can be characterized by 1H and 13C NMR spectroscopy, melting point, and elemental analysis. The 1H NMR spectrum provides information regarding the connectivity of atoms and their electronic environments; thus, it is routinely used to verify that reactions have been completed successfully. Negishi coupling reactions involve coupling of the phenyl ring to the EDOT, c...

Watch this Scientific Journal Video about Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties at JoVE.com

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

A protocol is presented for the synthesis and preparation of nanoparticles consisting of electroactive polymers.

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step ...

electroactive-polymer-nanoparticles-exhibiting-photothermal-properties

Research

JoVE Journal

Engineering

13.7K Views.  Texas State University. A protocol is presented for the synthesis and preparation of nanoparticles consisting of electroactive polymers. 

Video: Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

Micropunching Lithography for Generating Micro- and Submicron-patterns on Polymer Substrates

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of low weight, easy tailoring of properties and a wide spectrum of applications2,3. Due to sensitivity of conducting polymers to environmental conditions (e.g., air, oxygen, moisture, high temperature and chemical solutions), lithographic techniques present significant technical challenges when working with these materials4. For example, current photolithographic methods, such as ultra-violet (UV), are unsuitable for patterning the conducting polymers due to the involvement of wet and/or dry etching processes in these methods. In addition, current micro/nanosystems mainly have a planar form5,6. One layer of structures is built on the top surfaces of another layer of fabricated features. Multiple layers of these structures are stacked together to form numerous devices on a common substrate. The sidewall surfaces of the microstructures have not been used in constructing devices. On the other hand, sidewall patterns could be used, for example, to build 3-D circuits, modify fluidic channels and direct horizontal growth of nanowires and nanotubes.
A macropunching method has been applied in the manufacturing industry to create macropatterns in a sheet metal for over a hundred years. Motivated by this approach, we have developed a micropunching lithography method (MPL) to overcome the obstacles of patterning conducting polymers and generating sidewall patterns. Like the macropunching method, the MPL also includes two operations (Fig. 1): (i) cutting; and (ii) drawing. The "cutting" operation was applied to pattern three conducting polymers4, polypyrrole (PPy), Poly(3,4-ethylenedioxythiophen)-poly(4-styrenesulphonate) (PEDOT) and polyaniline (PANI). It was also employed to create Al microstructures7. The fabricated microstructures of conducting polymers have been used as humidity8, chemical8, and glucose sensors9. Combined microstructures of Al and conducting polymers have been employed to fabricate capacitors and various heterojunctions9,10,11. The "cutting" operation was also applied to generate submicron-patterns, such as 100- and 500-nm-wide PPy lines as well as 100-nm-wide Au wires. The "drawing" operation was employed for two applications: (i) produce Au sidewall patterns on high density polyethylene (HDPE) channels which could be used for building 3D microsystems12,13,14, and (ii) fabricate polydimethylsiloxane (PDMS) micropillars on HDPE substrates to increase the contact angle of the channel15.

A micropunching lithography approach is developed to generate micro- and submicron-patterns on top, sidewall and bottom surfaces of polymer substrates. It overcomes the obstacles of patterning conducting polymers and generating sidewall patterns. This method allows rapid fabrication of multiple features and is free of aggressive chemistry.

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of ...

Optical Trapping of Nanoparticles

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3.
A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure.
The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm hydrodynamic radius bovine serum albumin proteins8. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres.

The following setup approach details low power optical trapping of dielectric nanoparticles using a double-nanohole in metal film.

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping ...

Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication, we have shown via molecular dynamics simulations and atomic force microscopy experiments, that using an immiscible polymer brush system terminating the substrate and the slider surfaces, respectively, can eliminate such interdigitation. As a consequence, wear in the contacts is reduced. Moreover, the friction force is two orders of magnitude lower compared to traditional miscible polymer brush systems. This newly proposed system therefore holds great potential for application in industry. Here, the methodology to construct an immiscible polymer brush system of two different brushes each solvated by their own preferred solvent is presented. The procedure how to graft poly(N-isopropylacrylamide) (PNIPAM) from a flat surface and poly(methyl methacrylate) (PMMA) from an atomic force microscopy (AFM) colloidal probe is described. PNIPAM is solvated in water and PMMA in acetophenone. Via friction force AFM measurements, it is shown that the friction for this system is indeed reduced by two orders of magnitude compared to the miscible system of PMMA on PMMA solvated in acetophenone.

The methodology to perform friction force microscopy experiments for contacting brushes is presented: Two polymer brushes that are grafted from (a) substrates and (b) colloidal probes are slid to show that, by using two contacting immiscible brush systems, friction in sliding contacts is reduced compared to miscible brush systems.

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low ...

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

We describe the synthesis and properties of multifunctional Fe2O3-Au nanoparticles produced by a wet chemical approach and investigate their photothermal properties using laser irradiation. The composite Fe2O3-Au nanoparticles retain the properties of both materials, creating a multifunctional structure with excellent magnetic and plasmonic properties.

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to ...

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

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.

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 ...

Inkjet-printed Polyvinyl Alcohol Multilayers

Inkjet printing is a modern method for polymer processing, and in this work, we demonstrate that this technology is capable of producing polyvinyl alcohol (PVOH) multilayer structures. A polyvinyl alcohol aqueous solution was formulated. The intrinsic properties of the ink, such as surface tension, viscosity, pH, and time stability, were investigated. The PVOH-based ink was a neutral solution (pH 6.7) with a surface tension of 39.3 mN/m and a viscosity of 7.5 cP. The ink displayed pseudoplastic (non-Newtonian shear thinning) behavior at low shear rates, and overall, it demonstrated good time stability. The wettability of the ink on different substrates was investigated, and glass was identified as the most suitable substrate in this particular case. A proprietary 3D inkjet printer was employed to manufacture polymer multilayer structures. The morphology, surface profile, and thickness uniformity of inkjet-printed multilayers were evaluated via optical microscopy.

An inkjet printer was used to manufacture polyvinyl alcohol multilayers. Polyvinyl alcohol water-based ink was formulated, and the main physical properties were investigated.

Inkjet printing is a modern method for polymer processing, and in this work, we demonstrate that this technology is capable of producing polyvinyl alcohol ...

Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering thermal wave fields that are disturbed by the defect. This effect is measured and used to locate the defect. We form the destructively interfering wave fields by using a modified projector. The original light engine of the projector is replaced with a fiber-coupled high-power diode laser. Its beam is shaped and aligned to the projector&#39;s spatial light modulator and optimized for optimal optical throughput and homogeneous projection by first characterizing the beam profile, and, second, correcting it mechanically and numerically. A high-performance infrared (IR) camera is set up according to the tight geometrical situation (including corrections of the geometrical image distortions) and the requirement to detect weak temperature oscillations at the sample surface. Data acquisition can be performed once a synchronization between the individual thermal wave field sources, the scanning stage, and the IR camera is established by using a dedicated experimental setup which needs to be tuned to the specific material being investigated. During data post-processing, the relevant information on the presence of a defect below the surface of the sample is extracted. It is retrieved from the oscillating part of the acquired thermal radiation coming from the so-called depletion line of the sample surface. The exact location of the defect is deduced from the analysis of the spatial-temporal shape of these oscillations in a final step. The method is reference-free and very sensitive to changes within the thermal wave field. So far, the method has been tested with steel samples but is applicable to different materials as well, in particular to temperature sensitive materials.

This method aims at locating vertical subsurface defects. Here, we couple a laser with a spatial light modulator and trigger its video input to heat a sample surface deterministically with two anti-phased modulated lines while acquiring highly resolved thermal images. The defect position is retrieved from evaluating thermal wave interference minima.

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Production and Characterization of Vacuum Deposited Organic Light Emitting Diodes

A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex donor-acceptor emitters is presented. With a step-by-step procedure, readers will be able to repeat and produce OLED devices based on simple organic emitters. A patterning procedure allowing the creation of personalized indium tin oxide (ITO) shape is shown. This is followed by the evaporation of all layers, encapsulation and characterization of each individual device. The end goal is to present a procedure that will give the opportunity to repeat the information presented in cited publication but also using different compounds and structures in order to prepare efficient OLEDs.

A protocol for the production of simple structured organic light-emitting diodes (OLEDs) is presented.

A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex ...