Name: controlled synthesis and fluorescence tracking of highly uniform poly(n-isopropylacrylamide) microgels
Uploaded: 2016-09-08T14:00:00
Description: Watch this Scientific Journal Video about Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels at JoVE.com

The Deutsche Forschungsgemeinschaft (DFG) is acknowledged for financial support within the Sonderforschungsbereich SFB 985 "Functional Microgels and Microgel Systems".

1. Microgel Synthesis
NOTE: N-isopropylacrylamide (NIPAM) was recrystallized from n-hexane. Other reagents were used as received.
<ol>
	<li>Conventional Batch Synthesis of Poly(NIPAM) Matrix Microgels
	<ol>
		<li>Dissolve 1.8 g NIPAM and 24 mg N,N&#39;-bisacrylamide (BIS) in 245 ml filtered (0.2 &#181;m regenerated cellulose (RC) membrane filter) double distilled water in a 500 ml three-neck round bottom flask equipped with a reflux condenser, a stirrer and a rubber septum....

<ol>
	<li>Pelton, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature-sensitive+aqueous+microgels.">Temperature-sensitive aqueous microgels.</a> Adv. Colloid Interfac. 85, 1-33 (2000).</li><li>Pich, A., Richtering, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microgels+by+Precipitation+Polymerization:+Synthesis,+Characterization+and+Functionalization.">Microgels by Precipitation Polymerization: Synthesis, Characterization and Functionalization.</a> Adv. Polym. Sci. 234, 1-37 (2010).</li><li>Richtering, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Responsive+Emulsions+Stabilized+by+Stimuli-Sensitive+Microgels:+Emulsions+with+Special+Non-Pickering+Properties.">Responsive Emulsions Stabilized by Stimuli-Sensitive Microgels: Emulsions with Special Non-Pickering Properties.</a> Langmuir. 28 (50), 17218-17229 (2012).</li><li>Wiese, S., Spiess, A. C., Richtering, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microgel-Stabilized+Smart+Emulsions+for+Biocatalysis.">Microgel-Stabilized Smart Emulsions for Biocatalysis.</a> Angew. Chem. Int. Edit. 52 (2), 576-579 (2012).</li><li>Schmitt, V., Ravaine, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+compaction+versus+stretching+in+Pickering+emulsions+stabilised+by+microgels.">Surface compaction versus stretching in Pickering emulsions stabilised by microgels.</a> Curr. Opin. Colloid In. 18 (6), 532-541 (2013).</li><li>Wellert, S., Richter, M., Hellweg, T., von Klitzing, ., R, Y., Hertle, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Responsive+Microgels+at+Surfaces+and+Interfaces.">Responsive Microgels at Surfaces and Interfaces.</a> Z. Phys. Chem. 229 (7-8), 1-26 (2015).</li><li>Li, Z., Harbottle, D., Pensini, E., Ngai, T., Richtering, W., Xu, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fundamental+Study+of+Emulsions+Stabilized+by+Soft+and+Rigid+Particles.">Fundamental Study of Emulsions Stabilized by Soft and Rigid Particles.</a> Langmuir. 31 (23), 6282-6288 (2015).</li><li>Deshmukh, O. S., van den Ende, D., Stuart, M. C., Mugele, F., Duits, M. H. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hard+and+soft+colloids+at+fluid+interfaces:+Adsorption,+interactions,+assembly+&amp;+rheology.">Hard and soft colloids at fluid interfaces: Adsorption, interactions, assembly &amp; rheology.</a> Adv. Colloid Interfac. 222, 215-227 (2015).</li><li>Serpe, M. J., Kim, J., Lyon, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colloidal+Hydrogel+Microlenses.">Colloidal Hydrogel Microlenses.</a> Adv. Mater. 16 (2), 184-187 (2004).</li><li>Schmidt, S., Zeiser, M., Hellweg, T., Duschl, C., Fery, A., M&#246;hwald, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adhesion+and+Mechanical+Properties+of+PNIPAM+Microgel+Films+and+Their+Potential+Use+as+Switchable+Cell+Culture+Substrates.">Adhesion and Mechanical Properties of PNIPAM Microgel Films and Their Potential Use as Switchable Cell Culture Substrates.</a> Adv. Func. Mater. 20 (19), 3235-3243 (2010).</li><li>Xia, Y., He, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoresponsive+Microgel+Films+for+Harvesting+Cells+and+Cell+Sheets.">Thermoresponsive Microgel Films for Harvesting Cells and Cell Sheets.</a> Biomacromolecules. 14 (10), 3615-3625 (2013).</li><li>Guan, Y., Zhang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PNIPAM+microgels+for+biomedical+applications:+from+dispersed+particles+to+3D+assemblies.">PNIPAM microgels for biomedical applications: from dispersed particles to 3D assemblies.</a> Soft Matter. 7 (14), 6375 (2011).</li><li>Yunker, P. J., Chen, K., Gratale, M. D., Lohr, M. A., Still, T., 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=Physics+in+ordered+and+disordered+colloidal+matter+composed+of+poly(N-isopropylacrylamide)+microgel+particles.">Physics in ordered and disordered colloidal matter composed of poly(N-isopropylacrylamide) microgel particles.</a> Rep. Prog. Phys. 77 (5), 056601-056629 (2014).</li><li>Lohr, M. A., Still, T., 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=Vibrational+and+structural+signatures+of+the+crossover+between+dense+glassy+and+sparse+gel-like+attractive+colloidal+packings.">Vibrational and structural signatures of the crossover between dense glassy and sparse gel-like attractive colloidal packings.</a> Phys. Rev. E. 90 (6), 062305 (2014).</li><li>Dreyfus, R., Xu, Y., Still, T., Hough, L. A., Yodh, A. G., Torquato, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosing+hyperuniformity+in+two-dimensional,+disordered,+jammed+packings+of+soft+spheres.">Diagnosing hyperuniformity in two-dimensional, disordered, jammed packings of soft spheres.</a> Phys. Rev. E. 91 (1), 012302-012312 (2015).</li><li>Kojima, H., Tanaka, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reentrant+volume+phase+transition+of+cross-linked+poly(N-isopropylacrylamide)+gels+in+mixed+solvents+of+water/methanol.">Reentrant volume phase transition of cross-linked poly(N-isopropylacrylamide) gels in mixed solvents of water/methanol.</a> Soft Matter. 8 (10), 3010-3011 (2012).</li><li>Hofmann, C. H., Plamper, F. A., Scherzinger, C., Hietala, S., Richtering, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cononsolvency+Revisited:+Solvent+Entrapment+by+N-Isopropylacrylamide+and+N,+N-Diethylacrylamide+Microgels+in+Different+Water/Methanol+Mixtures.">Cononsolvency Revisited: Solvent Entrapment by N-Isopropylacrylamide and N, N-Diethylacrylamide Microgels in Different Water/Methanol Mixtures.</a> Macromolecules. 46 (2), 523-532 (2013).</li><li>Bischofberger, I., Calzolari, D. C. E., Trappe, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Co-nonsolvency+of+PNiPAM+at+the+transition+between+solvation+mechanisms.">Co-nonsolvency of PNiPAM at the transition between solvation mechanisms.</a> Soft Matter. 10 (41), 8288-8295 (2014).</li><li>Virtanen, O. L. J., Richtering, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetics+and+particle+size+control+in+non-stirred+precipitation+polymerization+of+N-isopropylacrylamide.">Kinetics and particle size control in non-stirred precipitation polymerization of N-isopropylacrylamide.</a> Colloid Polym. Sci. 292 (8), 1743-1756 (2014).</li><li>Virtanen, O. L. J., Ala-Mutka, H. M., Richtering, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Can+the+Reaction+Mechanism+of+Radical+Solution+Polymerization+Explain+the+Microgel+Final+Particle+Volume+in+Precipitation+Polymerization+of+N-Isopropylacrylamide?.">Can the Reaction Mechanism of Radical Solution Polymerization Explain the Microgel Final Particle Volume in Precipitation Polymerization of N-Isopropylacrylamide?.</a> Macromol. Chem. Phys. 216 (13), 1431-1440 (2015).</li><li>Glatter, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+method+for+the+evaluation+of+small-angle+scattering+data.">A new method for the evaluation of small-angle scattering data.</a> J. Appl. Crystallogr. 10 (5), 415-421 (1977).</li><li>Svergun, D. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+the+regularization+parameter+in+indirect-transform+methods+using+perceptual+criteria.">Determination of the regularization parameter in indirect-transform methods using perceptual criteria.</a> J. Appl. Crystallogr. 25 (4), 495-503 (1992).</li><li>Glatter, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Convolution+Square+Root+of+Band-Limited+Symmetrical+Functions+and+Its+Application+to+Small-Angle+Scattering+Data.">Convolution Square Root of Band-Limited Symmetrical Functions and Its Application to Small-Angle Scattering Data.</a> J. Appl. Crystallogr. 14, 101-108 (1981).</li><li>Glatter, O., Hainisch, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improvements+in+Real-Space+Deconvolution+of+Small-Angle+Scattering+Data.">Improvements in Real-Space Deconvolution of Small-Angle Scattering Data.</a> J. Appl. Crystallogr. 17, 435-441 (1984).</li><li>Cheezum, M. K., Walker, W. F., Guilford, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+Comparison+of+Algorithms+for+Tracking+Single+Fluorescent+Particles.">Quantitative Comparison of Algorithms for Tracking Single Fluorescent Particles.</a> Biophys. J. 81 (4), 2378-2388 (2001).</li><li>W&#246;ll, D., K&#246;lbl, C., Stempfle, B., Karrenbauer, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+method+for+automatic+single+molecule+tracking+of+blinking+molecules+at+low+intensities.">A novel method for automatic single molecule tracking of blinking molecules at low intensities.</a> Phys. Chem. Chem. Phys. 15 (17), 6196-6205 (2013).</li><li>Saxton, M. J., Jacobson, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-particle+tracking:+Applications+to+membrane+dynamics.">Single-particle tracking: Applications to membrane dynamics.</a> Annu. Rev. Bioph. Biom. 26, 373-399 (1997).</li><li>Pusey, P. N., van Megen, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+small+polydispersities+by+photon+correlation+spectroscopy.">Detection of small polydispersities by photon correlation spectroscopy.</a> J. Chem. Phys. 80 (8), 3513 (1984).</li><li>Stieger, M., Pedersen, J. S., Richtering, W., Lindner, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small-angle+neutron+scattering+study+of+structural+changes+in+temperature+sensitive+microgel+colloids.">Small-angle neutron scattering study of structural changes in temperature sensitive microgel colloids.</a> J. Chem. Phys. 120 (13), 6197-6206 (2004).</li><li>Wu, X., Pelton, R. H., Hamielec, A. E., Woods, D. R., McPhee, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+kinetics+of+poly(N-isopropylacrylamide)+microgel+latex+formation.">The kinetics of poly(N-isopropylacrylamide) microgel latex formation.</a> Colloid Polym. Sci. 272, 467-477 (1994).</li><li>Weeks, E. R., Weitz, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subdiffusion+and+the+cage+effect+studied+near+the+colloidal+glass+transition.">Subdiffusion and the cage effect studied near the colloidal glass transition.</a> Chem. Phys. 284 (1-2), 361-367 (2002).</li><li>Ernst, D., K&#246;hler, J., Weiss, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+the+type+of+anomalous+diffusion+with+single-particle+tracking.">Probing the type of anomalous diffusion with single-particle tracking.</a> Phys. Chem. Chem. Phys. 16 (17), 7686-7691 (2014).</li><li>. FitIt! (Version 1.1.4) Available from: <a target="_blank" href="https://www.github.com/ovirtanen/fitit">https://www.github.com/ovirtanen/fitit</a> (2015)</li><li>Provencher, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Constrained+Regularization+Method+For+Inverting+Data+Represented+By+A+Linear+Algebraic+or+Integral+Equations.">A Constrained Regularization Method For Inverting Data Represented By A Linear Algebraic or Integral Equations.</a> Comput. Phys. Commun. 27 (3), 213-227 (1982).</li><li>Holtzer, L., Meckel, T., Schmidt, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanometric+three-dimensional+tracking+of+individual+quantum+dots+in+cells.">Nanometric three-dimensional tracking of individual quantum dots in cells.</a> Appl. Phys. Lett. 90 (5), 053902-053904 (2007).</li><li>Diezmann, A. V., Lee, M. Y., Lew, M. D., Moerner, W. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correcting+field-dependent+aberrations+with+nanoscale+accuracy+in+three-dimensional+single-molecule+localization+microscopy.">Correcting field-dependent aberrations with nanoscale accuracy in three-dimensional single-molecule localization microscopy.</a> Optica. 2 (11), 985-989 (2015).</li><li>Lindner, P., Zemb, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Neutrons, X-rays and Light: Scattering Methods Applied to Soft Condensed Matter. , (2002).</li></ol>

Addition of small amounts of functional comonomer can have a significant effect on the particle size and structure of the PNIPAM derived microgels. Simultaneous small-scale test tube polymerization is a good method to account for such changes, and helps to rapidly find the right reactant compositions for target particle size for upscaling the reaction as needed. The mass of the particles is approximately exponentially dependent on the ...

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels 1,2 have attracted continuous interest over the past two decades due to their potential in various smart applications. Demonstrated use cases include switchable emulsion stabilizers 3-8, microlenses 9, cell culture substrates for easy cell harvesting 10,11, and smart carriers for low molecular weight compounds and other biomedical uses 12. From a fundamental research point of view these particles have been proven to be useful for investigating subjects such as colloidal interactions 13-15 and polymer-solvent interactions 16-18.
Successful use of PNIPAM microgels and their derivatives in any given application typically requires knowledge on the mean particle size and width of the particle size distribution. For the correct interpretation of the experimental results involving PNIPAM microgels, the particle structure, which can be affected by functional comonomers, has to be known. Dynamic and static light scattering (DLS and SLS, respectively) are uniquely suited for acquiring this information because these methods are fast and relatively easy to use; and they probe the particle properties non-invasively in their native environment (dispersion). DLS and SLS also collect data from vast number of particles avoiding the bias arising from small sample sizes, typical for microscopy methods. Therefore, the first aim of this work is to introduce good practice regarding light scattering for practitioners new to colloidal characterization.
Typically, precipitation polymerization is carried out in laboratory scale and finding the right reaction conditions for specific particle properties can be laborious and require many repetitions of the synthesis. In contrast to large batch synthesis, non-stirred precipitation polymerization 19,20 is a rapid procedure in which batches of different reactant composition can be polymerized simultaneously yielding particles of narrow size distribution. Simultaneous polymerization minimizes experimental variation and large output means that right reaction conditions can be found fast for upscaling the reaction. Hence, our second aim is to demonstrate the usefulness of non-stirred precipitation polymerization in prototyping and in applications that do not require a large amount of product.
Different aspects of synthesis and characterization come together in the example of application of fluorescent labeled PNIPAM microgels in colloidal interaction research. Here we use highly accurate single particle tracking to investigate the diffusion of labeled tracer microgels in dispersion of unlabeled matrix microgels over a wide matrix concentration range and resolve the cage effect in concentrated colloidal dispersion. Wide-field fluorescence microscopy is well suited for this purpose as it can characterize the specific behavior of a few tracer molecules among a large number of potentially different matrix species. This is in contrast to techniques such as DLS, SLS and rheology, which measure the ensemble average properties of systems and therefore cannot resolve behavior of small number of probe particles in a large system. Furthermore, in this specific example conventional light scattering methods cannot be utilized also due to high particle concentration, which leads to strong multiple scattering invalidating any standard analysis. Use of automated data processing and statistical methods enable analysis of overall system behavior also for single particle tracking, when averaged over large sample sizes.

<table border="0" cellpadding="0" cellspacing="0" width="741">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:259px;">Acetone</td>
			<td style="width:199px;">VWR Chemicals</td>
			<td style="width:155px;">KRAF13455</td>
			<td style="width:129px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:259px;">Bisacrylamid</td>
			<td style="width:199px;">AppliChem</td>
			<td style="width:155px;">A3636</td>
			<td style="width:129px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:259px;">n-Hexane</td>
			<td style="width:199px;">Merck</td>
			<td style="width:155px;">104374</td>
			<td style="width:129px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:259px;">N-Isopropylacrylamide</td>
			<td style="width:199px;">Fisher Scientific</td>
			<td style="width:155px;">AC412785000</td>
			<td>recrystallized from n-hexane</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:259px;">Methacryloxyethyl thiocarbamoyl rhodamine B</td>
			<td style="width:199px;">Polysciences</td>
			<td style="width:155px;">23591</td>
			<td style="width:129px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:259px;">Potassium peroxodisulfate</td>
			<td style="width:199px;">Merck</td>
			<td style="width:155px;">105091</td>
			<td style="width:129px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:259px;">Silicone oil 47 V 350</td>
			<td style="width:199px;">VWR Chemicals</td>
			<td style="width:155px;">83851</td>
			<td style="width:129px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:259px;">Toluene</td>
			<td style="width:199px;">Sigma Aldrich</td>
			<td style="width:155px;">244511</td>
			<td style="width:129px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">F12 Refrigerated/heating circulator</td>
			<td style="width:199px;">Julabo</td>
			<td>9116612</td>
			<td style="width:129px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microscope</td>
			<td>Olympus</td>
			<td>IX83</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">XY(Z) Piezo System</td>
			<td>Physik Instrumente</td>
			<td>P-545.3R7</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">100x Oil immersion objective</td>
			<td>Olympus</td>
			<td>UPLSAPO</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">QuadLine Beamsplitter</td>
			<td>AHF Analysentechnik</td>
			<td>F68-556T</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">&#160;Cobolt Jive 150 laser</td>
			<td>Cobolt</td>
			<td>0561-04-01-0150-300</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Multimode Fiber</td>
			<td>Thorlabs</td>
			<td>UM22-600</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">iXON Ultra 897 EMCCD camera</td>
			<td>Andor</td>
			<td>DU-897U-CS0-BV</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Laser goniometer</td>
			<td>SLS Systemtechnik</td>
			<td>Mark III</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">CF40 Cryo-compact circulator</td>
			<td>Julabo</td>
			<td>9400340</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Laser goniometer system&#160;</td>
			<td>ALV GmbH</td>
			<td>ALV / CGS-8F</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Multi-tau corretator</td>
			<td>ALV GmbH</td>
			<td>ALV-7004</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Light scattering electronics</td>
			<td>ALV GmbH</td>
			<td>ALV / LSE 5004</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Photon counting module</td>
			<td>PerkinElmer</td>
			<td>SPCM-CD2969</td>
			<td>2 units in pseudo cross-correlation mode</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">633 nm HeNe Laser</td>
			<td>JDS Uniphase</td>
			<td>1145P</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">F32 Refrigerated/heating circulator</td>
			<td>Julabo</td>
			<td>9312632</td>
			<td></td>
		</tr>
	</tbody>
</table>

controlled synthesis and fluorescence tracking of highly uniform poly(n-isopropylacrylamide) microgels

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.

The number of PNIPAM microgel particles in the batch, and thus the final particle volume, is determined early in the reaction during the nucleation phase 20 Hydrophobic co-monomer dye methacryloxyethyl thiocarbamoyl rhodamine B influences the nucleation by reducing the particle number density in the batch. The decrease in particle concentration for two different initial NIPAM concentrations can be seen as increase in...

Watch this Scientific Journal Video about Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels at JoVE.com

Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels

Non-stirred precipitation polymerization provides a rapid, reproducible prototyping approach to the synthesis of stimuli-sensitive poly(N-isopropylacrylamide) microgels of narrow size distribution. In this protocol synthesis, light scattering characterization and single particle fluorescence tracking of these microgels in a wide-field microscopy setup are demonstrated.

Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this ...

Research

JoVE Journal

Chemistry

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Synthesis of Poly(N-isopropylacrylamide) Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability

Synthesis of PolyN-isopropylacrylamide Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability

Janus microparticles are compartmentalized particles with differing molecular structures and/or functionality on each of their two sides. Because of this ...

Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form ...

Synthesis and Reaction Chemistry of Nanosize Monosodium Titanate

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the ...

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Scale-up Chemical Synthesis of Thermally-activated Delayed Fluorescence Emitters Based on the Dibenzothiophene-S,S-Dioxide Core

We report a procedure to linearly scale-up the synthesis of 2,8-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)dibenzothiophene-S,S-dioxide (compound 4) and ...

Synthesis and Mass Spectrometry Analysis of Oligo-peptoids

Peptoids are sequence-controlled peptide-mimicking oligomers consisting of N-alkylated glycine units. Among many potential applications, peptoids have ...