This research was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Research Chairs Program, and Simon Fraser University. This work made use of 4D LABS shared facilities supported by the Canada Foundation for Innovation (CFI), British Columbia Knowledge Development Fund (BCKDF) and Simon Fraser University.

1. Synthesis of the NaYF4/Yb3+/Er3+ Upconverting Nanoparticles (UCNP)
<ol>
	<li>Set up the apparatus as followed:
	<ol>
		<li>Place a 250 ml heating mantle on a regular stirring plate and plug the mantle onto the thermal couple.</li>
		<li>Place a 250 ml round bottom flask equipped with a magnetic stir bar onto the heating mantle with proper clamping.</li>
		<li>Attach an air adapter to the left neck of the round bottom flask and connect this air adapter to the Schlenk line with plastic...

<ol>
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The nanoparticles synthesized according to this protocol have a size distribution from 20 to 25 nm centered at around 22.5 nm.26,27 They can be classified as spherical particles with a &#945;-NaYF4 host lattice structure. There are two critical steps in this protocol. In the UCNP synthesis, it is crucial to maintain the heating temperature and time as precise as possible to assure a narrow distribution of particle size. Simultaneous addition of NaOH and NH4F along with the addition of lan...

Today there is still an urgent need to develop new types of bio-imaging agents. Many novel fluorescent probes have been well documented.1-6 However, substantial improvements in the image resolution remains a challenge.7 One practical method is to directly modulate the fluorescence probes between a &#8216;light&#8217; emissive state and a &#8216;dark&#8217; quenched state.8-12 This particular method has been applied to develop technologies such as stimulated emission depletion (STED) microscopy13 and stochastic optical reconstruction microscopy (STORM).14
Another approach to modulate fluorescence is to couple photoresponsive chromophores together with fluorescent probes.15,16 Toggling the photoresponsive chromophore between two isomers where only one of the isomers can act as an efficient energy-transfer acceptor, allows control over quenching of the fluorescence from the probe through F&#246;rster Resonance Energy Transfer (FRET) and other mechanisms. The result is the creation of an emissive state and a quenched state that can be alternated by exposure of the photoresponsive chromophore to different wavelengths of light.
Photoresponsive diarylethene chromophores can be reversibly toggled between a colorless ring-open isomer and a colored ring-closed isomer upon irradiation with UV and visible light.17-19 The thermal stability of the two isomers and tunable absorption spectra of the ring-closed isomer make diarylethenes very good candidates as controllable FRET acceptors.20-23 Lanthanide-doped NaYF4 upconverting nanoparticles are useful for bio-imaging.24 These nanoparticles absorb near-infrared light and emit light in several regions of the visible spectrum. Examples of fluorescence modulation by combining photoresponsive diarylethene chromophores and nanoparticles have been previously reported by our group.25-27 However, the systems described in each example required an additional synthetic modification to attach the diarylethenes to the surface of the nanoparticles, which complicates the development of more diverse systems.
Herein we demonstrate a simple &#8216;plug-and-play&#8217; method to prepare water-dispersible organic dye molecules and photoresponsive upconverting nanoparticles using a self-assembly strategy. The choice of polymers; poly(styrene-alt-maleic anhydride) and polyether amine 2070 provide both a hydrophobic and hydrophilic environment. The hydrophobic sections of the polymer help to hold the normally water insoluble organic molecules and upconverting nanoparticles together, whereas the hydrophilic region of the polymer is critical for maintaining the water-solubility. We will first demonstrate synthesis of the upconverting nanoparticles by the thermal nucleation method. Then, we will prove how the organic molecules and upconverting nanoparticles are encapsulated within hydrophobic regions of the polymer shell and remain stable in aqueous media by simply co-stirring a solution of the upconverting nanoparticles, polymer and different organic dye molecules, followed by a convenient work-up procedure. We also demonstrate how to modulate fluorescence emission of the assemblies using external light irradiation. We anticipate the scope of using this &#8216;plug-and-play&#8217; method to make water-dispersible nanoassemblies will continue to expand.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>yttrium acetate</td>
			<td>sigma</td>
			<td>326046</td>
			<td>Yttrium(III) acetate hydrate</td>
		</tr>
		<tr>
			<td>ytterbium acetate</td>
			<td>sigma</td>
			<td>544973</td>
			<td>&#160;Ytterbium(III) acetate hydrate&#160;</td>
		</tr>
		<tr>
			<td>erbium acetate</td>
			<td>sigma</td>
			<td>325570</td>
			<td>Erbium(III) acetate hydrate</td>
		</tr>
		<tr>
			<td>oleic acid</td>
			<td>sigma</td>
			<td>75096</td>
			<td>analytical standard</td>
		</tr>
		<tr>
			<td>octadecene</td>
			<td>sigma</td>
			<td>O806&#160;</td>
			<td>Technical grade&#160;</td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td></td>
			<td>S5881&#160;</td>
			<td>reagent grade</td>
		</tr>
		<tr>
			<td>NH4F</td>
			<td></td>
			<td>216011</td>
			<td>ACS reagent</td>
		</tr>
		<tr>
			<td>poly(styrene-alt-maleic anhydride)</td>
			<td>sigma</td>
			<td>4422699</td>
			<td>Average Mn= 1700</td>
		</tr>
		<tr>
			<td>JeffAmine 2070</td>
			<td>Huntsman</td>
			<td>M-2070</td>
			<td></td>
		</tr>
		<tr>
			<td>Varian Carry 300</td>
			<td>Agilent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>JDSU NIR laser</td>
			<td>JSDU</td>
			<td>L4-9897510-100M</td>
			<td>980 nm diode laser</td>
		</tr>
	</tbody>
</table>

a 'plug and play' method to create water-dispersible nanoassemblies containing an amphiphilic polymer, organic dyes and upconverting nanoparticles

In this protocol, we first describe a procedure to synthesize lanthanide doped upconverting nanoparticles (UCNPs). We then demonstrate how to generate amphiphilic polymers in situ, and describe a protocol to encapsulate the prepared UCNPs and different organic dye molecules (porphyrins and diarylethenes) using polymer shells to form stable water-dispersible nanoassemblies. The nanoassembly samples containing both the UCNPs and the diarylethene organic dyes have interesting photochemical and photophysical properties. Upon 365 nm UV irradiation, the diarylethene group undergoes a visual color change. When the samples are irradiated with visible light of another specific wavelength, the color fades and the samples return to the initial colorless state. The samples also emit visible light from the UCNPs upon irradiation with 980 nm near-infrared light. The emission intensity of the samples can be tuned through alternate irradiation with UV and visible light. Modulation of fluorescence can be performed for many cycles without observable degradation of the samples. This versatile encapsulation procedure allows for the transfer of hydrophobic molecules and nanoparticles from an organic solvent to an aqueous medium. The polymer helps to maintain a lipid-like microenvironment for the organic molecules to aid in preservation of their photochemical behavior in water. Thus this method is ideal to prepare water-dispersible photoresponsive systems. The use of near-infrared light to activate upconverting nanoparticles allows for lower energy light to be used to activate photoreactions instead of more harmful ultraviolet light.

Absorption spectra and photoluminescence spectra were collected for sample DAE-UCNP. The absorption spectra are used for comparing the spectral overlap between the closed diarylethene chromophores and the upconverting nanoparticles. Photographs of the samples (both TPP-UCNP and DAE-UCNP) were also included to demonstrate successful encapsulation of organic dye molecules and upconverting nanoparticles, which are located within the amphiphilic polymer shells in the aqueous phase. The modulation of photochemistry and fluore...

Watch this Scientific Journal Video about A 'Plug and Play' Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles at JoVE.com

A &#039;Plug and Play&#039; Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles

Organic dye molecules and oleic acid coated upconverting nanoparticles are not water-soluble. This protocol describes a &#8216;plug and play&#8217; method that enables the transfer of organic dye molecules and upconverting particles from their initial hydrophobic solvent to water.

A 'Plug and Play' Method to Create Water-dispersible Nanoassemblies Containing an Amphiphilic Polymer, Organic Dyes and Upconverting Nanoparticles

In this protocol, we first describe a procedure to synthesize lanthanide doped upconverting nanoparticles (UCNPs). We then demonstrate how to generate ...

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9.7K 次观看.  Simon Fraser University. Organic dye molecules and oleic acid coated upconverting nanoparticles are not water-soluble. This protocol describes a ‘plug and play’ method that enables the transfer of organic dye molecules and upconverting particles from their initial hydrophobic solvent to water. 