The authors thank the funding of the National Natural Science Foundation of China (82001945), the Shanghai Pujiang Program (20PJ1410700), and the starting grant of ShanghaiTech University. The authors thank the Centre for High-resolution Electron Microscopy (ChEM), School of Physical Science and Technology, ShanghaiTech University (No. EM02161943) for the material characterization support. The authors thank the Analytical Instrumentation Center (#SPST-AIC10112914), School of Physical Science and Technology, ShanghaiTech University for the spectral test support and XRD test support. The authors also thank Prof. Jianfeng Li for the help with the material characterizations.

1. Synthesis of Zn2GeO4: Mn PLNPs
<ol>
	<li>Prepare 2 M/L sodium hydroxide solution by dissolving 10 mM sodium hydroxide in 5 mL of deionized water.</li>
	<li>Prepare 0.4 M/L sodium germanate solution by adding 2 mM of germanium oxide into 5 mL of sodium hydroxide solution, and then stir at room temperature for about 30 min.</li>
	<li>Add 4 mM of zinc chloride, 0.01 mM of manganese nitrate and 600 &#181;L of nitric acid (65%-68%, wt) to a 100 mL small beaker containing 22 mL of deionized water. 
	CAUTION: The addition of nitric acid should be strictly carried out in a fume hood and ensure that there are no open flames or heating around.</li>
	<li>Stir vigorously until the solution of step 1.3 is completely dissolved.</li>
	<li>Slowly add 2 mM sodium germanate solution to the solution of step 1.4. Add 1 mL of polyethylene glycol (PEG; 300, Mw) to the solution.</li>
	<li>Put the calibrated pH meter probe into the solution to monitor the pH value of the reaction system. Set a relatively gentle stirring to avoid splashing of the solution and collision between the stirring bar and the probe.</li>
	<li>Add ammonium hydroxide with a mass fraction of 25%-28% to the solution drop by drop, and adjust the pH of the solution to 6.0, 8.0 or 9.4 depending on the luminescence property to be studied. Be sure to add ammonium hydroxide slowly and monitor the pH changes of the solution at all times to prevent the system from being too acidic or too alkaline, so as not to affect the morphology and luminescent properties of nanomaterials.</li>
	<li>Cover the beaker with sealing film and stir the solution at room temperature for 1 h. Try not to expose the system to air to prevent dust from entering and causing solvent volatilization, while stirring at a constant speed so that the liquid level of the system will not splash when the system is fully mixed.</li>
	<li>Transfer the solution to a Teflon-lined autoclave and place it in an electric thermostatic drying oven at 220 &#176;C for 4 h. 
	NOTE: The appropriate Teflon-lined autoclave should be selected according to the volume of the system, and the reactor should be kept clean. The volume of the added raw materials should not exceed 1/3rd of the volume of the autoclave. At the same time, make sure the autoclave is completely closed before placing it into the electric thermostatic drying oven.</li>
	<li>Turn OFF the electric thermostatic drying oven when the reaction is completed and wait for the system to cool down to room temperature to take out the reactor. Be sure to wait until the reactor is completely cooled and the pressure is reduced to a safe range before proceeding to the next step to avoid direct contact between high temperature and skin.</li>
	<li>Slowly open the reactor and transfer the reaction solution to two 50 mL centrifuge tubes. Rinse the reactor with 40 mL of ethanol, and subsequently transfer the ethanol solution to the same centrifuge tubes.</li>
	<li>Vortex for 30 s so that the solution can be mixed evenly, then centrifuge the sample at 4000 x g for 15 min at room temperature and remove the supernatant.</li>
	<li>Add 10 mL of deionized water to each centrifuge tube and sonicate for 5 min (240 W, 40 kHz) to redisperse the product.</li>
	<li>Add 20 mL of ethanol into each centrifuge tube and vortex for 30 s to mix the solution evenly.</li>
	<li>Continue to centrifuge the product according to the setting mentioned before (4000 x g, 15 min) at room temperature and discard the supernatant.</li>
	<li>Ultrasonicate for 5 min to disperse the product in 2 mL of methanol solution, seal the sample with sealing film and store it in a 4 &#176;C refrigerator to prevent sample contamination and solvent evaporation for future illumination applications.</li>
</ol>
2. Synthesis of ZnGa2O4: Cr PLNPs
<ol>
	<li>Dissolve 12 mM Ga(NO3)3.xH2O, 7.2 mM ZnCl2 and 0.024 mM Cr(NO3)3.9H2O in 30 mL of deionized water.</li>
	<li>Add 1 mL of PEG (300, Mw) to the solution. Add ammonium hydroxide (25%-28% wt) to the solution, stir gently to reach a pH of 9.0-9.4. Be sure to control the stirring speed so that the solution can mix thoroughly without splashing onto the pH meter.</li>
	<li>Cover the beaker with a sealing film and stir the solution at room temperature for 1 h. Try to minimize the exposure of the system to air to prevent dust from entering and solvent evaporation. At the same time, control the stirring speed so that the system does not splash while mixing thoroughly.</li>
	<li>Transfer the solution to a Teflon-lined autoclave and run at 220 &#176;C for 6 h. Take out the container after the temperature drops to room temperature. Ensure that the reaction vessel has fully cooled down, and the pressure has dropped to a safe range before proceeding with subsequent operations, as well as avoid direct contact of high temperatures with the skin.</li>
	<li>Transfer the reaction solution to two 50 mL centrifuge tubes. Rinse the reactor with 40 mL of ethanol, and then transfer the ethanol solution to the same centrifuge tubes.</li>
	<li>Vortex for 30 s to mix the solution and then centrifuge the sample at 4000 x g for 15 min at room temperature and remove the supernatant.</li>
	<li>Add 10 mL of deionized water to each centrifuge tube and sonicate for 5 min to redisperse the product.</li>
	<li>Add 20 mL of ethanol into each centrifuge tube and vortex for 30 s to mix the solution evenly. Continue centrifuging the product at room temperature as previously mentioned (4000 x g, 15 min) and discard the supernatant.</li>
	<li>Ultrasonicate for 5 min to disperse the product in 2 mL of deionized water and seal the sample with a sealing film for storage.</li>
</ol>
3. Purification for raw materials
<ol>
	<li>Purify methyl methacrylate (MMA) by column chromatography as described below.
	<ol>
		<li>Fill half of the column with alkaline aluminum oxide (100-200 mesh) and compact lightly with a glass rod. When filling the column with aluminum oxide, pay attention to even distribution and uniform compaction of the filler to improve separation efficiency.</li>
		<li>Add a small amount of MMA and open the PTFE throttle piston below. Once the solvent layer wets the entire aluminum oxide and liquid flows out, add more MMA and repeat this process multiple times. The time when mass ratio of the entire MMA added to the basic aluminum oxide is: 1:50 represents the end of the process.</li>
		<li>Place the final collected MMA sample into a glass bottle, seal it with a sealing film and store at 4 &#176;C. 
		CAUTION: The entire process should be carried out in a fume hood due to the strong volatility of MMA. At the same time, operators should wear masks and lab coats.</li>
	</ol>
	</li>
	<li>Purify azobisisobutyronitrile (AIBN) by recrystallization as described below.
	<ol>
		<li>Prepare a 50 mL of mixed solution with a volume ratio of 7:3 of ethanol and distilled water and heat the solution.</li>
		<li>Add 5 g of AIBN when the solution is boiling and stir to mix the solution evenly.</li>
		<li>Remove insoluble impurities by hot filtration as described below.
		<ol>
			<li>Place the filter paper snugly against the inner wall of the triangular funnel and ensure that the filter paper is below the edge of the funnel.</li>
			<li>Place the glass rod against the three-layer section of the filter paper. If the glass rod is not placed against the three-layer section of the filter paper, it may puncture the filter paper, leading to inefficient filtration.</li>
			<li>Place the tip of the beaker containing the solution close to the glass rod and pour it while it is hot. The purpose of this step is to prevent splashing liquid droplets.</li>
			<li>Rinse the beaker with 10 mL of cold distilled water, and again perform the above filtration process; repeat 3x.</li>
		</ol>
		</li>
		<li>The solution becomes supersaturated due to the decrease in solubility during cooling, resulting in the precipitation of crystals. Put the collected solution in a refrigerator at 4 &#176;C for cooling and crystallization. The sample will appear in the state of white needle-like crystals.</li>
		<li>Seal the sample with aluminum foil and store at 4 &#176;C. 
		CAUTION Protective measures should be taken during the operation due to the toxicity of AIBN, while also avoiding contact with open flames, high temperatures, and oxidizing agents.</li>
	</ol>
	</li>
</ol>
4. Copolymerization of methyl methacrylate (MMA)
<ol>
	<li>Set the water bath temperature to 80 &#176;C. 
	NOTE: The temperature of the water has a severe influence on the rate of polymerization and thus affects the final product formation. Therefore, the temperature of the water bath should be strictly guaranteed not to be too high.</li>
	<li>Weigh 20 g of MMA into a 100 mL eggplant-shaped bottle. Keep the container dry before the experiment. 
	NOTE: The eggplant-shaped bottle is chosen to facilitate the water bath heating and the replacement of air with nitrogen in the system. Try to weigh the sample in a well-ventilated environment while wearing a mask.</li>
	<li>Add the pre-prepared methanol solution of Zn2GeO4: Mn into the reaction vessel.</li>
	<li>Thoroughly dissolve the sample in MMA with the help of ultrasound for about 10 min (240 W, 40 kHz) at room temperature. Keep the reaction vessel sealed to prevent solvent evaporation and avoid excessively high temperatures during the ultrasonication process.</li>
	<li>Add 0.012 g of AIBN to the solution and mix the solution completely. 
	NOTE: AIBN should be used under anhydrous conditions and ensure that there is no open flame around the experimental operation. Be sure to wear protective gear.</li>
	<li>Place the flask in an 80 &#176;C water bath and purge the air from the reaction system with N2 for approximately 35 min. When the reaction is about to end, gently shake the reaction container. If the solution does not shake vigorously, it proves that the reaction is successful. 
	NOTE: The reaction time will change with the temperature of the water bath. Make sure that the temperature of the water bath reaches 80 &#176;C and start timing for 35 min.</li>
	<li>After the reaction is over, quickly transfer the reaction vessel to an ice bath to cool it down quickly. 
	NOTE: This process should be as fast as possible to avoid excessive pre-polymerization of MMA, and the ice bath can be prepared in advance during the reaction interval.</li>
	<li>Slowly pour the solution into a two-dimensional or three-dimensional mold, put the mold into an electric thermostatic drying oven at 40 &#176;C for 10 h, 70 &#176;C for 8 h, and 100 &#176;C for another 2 h to obtain target material.</li>
	<li>Close the electric thermostatic drying oven after the reaction stops, and let it cool down to room temperature. Open the electric thermostatic drying oven to take out the mold after the reaction system is sufficiently cooled to avoid skin burns caused by direct contact between high temperature and body.</li>
	<li>Carefully remove the mold and expose the polymerized PMMA sample (ZGO: Mn-PMMA) to a UV lamp for about 3 min. For example, when exposing a transparent ZGO: Mn-PMMA film to ultraviolet light through a black cardboard cutout in the shape of the letter H, a corresponding pattern of green phosphorescent emission is obtained. The pattern can be erased after 5 min. Subsequently, the process can be repeated by using another black cardboard cutout in the shape of different letters, generating new luminescent patterns.</li>
</ol>

Hydrothermal Synthesis of Persistent Luminescent Nanoparticles

There is nothing to disclose.

This article introduces a synthesis method for persistent luminescent nanomaterials and polymerization for color rendering applications. The materials showed extremely stable optical properties and a visible afterglow after ceasing excitation of ultraviolet light. A persistent luminescent nanomaterial (Zn2GeO4: Mn) was prepared using a hydrothermal method with different pH (Figure 1A). The TEM image showed that ZGO: Mn PLNPs whose pH is 9.4 were rod-shaped with an avera...

Persistent luminescence (PL) is a unique optical process that can store energy from ultraviolet light, visible light, X-rays, or other excitation sources and then release it in the form of photon emission for seconds, minutes, hours, or even for days1. The discovery of continuous luminous phenomenon originated from the Song dynasty in ancient China 1000 years ago when a painter accidentally discovered a painting that glowed in the dark. It was later found that some natural raw materials and minerals could absorb sunlight and then glow in the dark and can even be made into fascinating glowing pearls2. However, the first adequate record of persistent phosphors needed to be traced back to the discovery of PL emission from Bologna stone in the early 17th century, which gave off a yellow to orange afterglow in the dark1,2,3,4. Later, it was discovered that the natural impurities of Cu+ in BaS played an important role in this persistent luminescence phenomenon1,4. Until the mid-1990s, the production of persistent phosphors was largely limited to sulfides5. In 1996, Matsuzawa et al. reported a new metal oxide (SrAl2O4:Eu2+, Dy3+) phosphor showing extremely bright afterglow, which greatly stimulated the expansion of persistent luminescence research6.
The unique properties of persistent luminescent materials are mainly derived from two kinds of active centers: emission centers and trap centers1,7,8. Among them, the former determines the emission wavelength, while the sustained intensity and time are mainly determined by the trap centers. Therefore, the design of PL materials should take both aspects into consideration in order to achieve the desired emission wavelength and long-lasting luminescence9,10. The emission centers can be lanthanide ions with 5d to 4f or 4f to 4f transitions, transition metal ions with d to d transitions, or post-transition metal ions with p to s transitions1,11,12,13. On the other hand, trap centers are formed by lattice defects or various co-dopants14,15, which usually do not emit radiation but instead store the excitation energy for a while and then gradually release it to the emitting center through thermal or other physical activation16,17. Many phosphors with different hosts and dopant ions have been reported. So far, inorganic metal compounds18, metal-organic frameworks8, certain organic composites19, and polymers20 have been found to have PL properties. In recent years, deep trap persistent luminescent materials with controllable energy storage and photon release properties have shown great potential applications in information storage21, multi-layer anti-counterfeiting22, and advanced displays23.
Based on the above composition, PLNPs with various matrices have been successfully designed and synthesized, such as BaZrSi3O97, Y2O2S24, Ca14Mg2(SiO4)825, CaAl2O426, SrAl2O426,27 , and Sr2MgSi2O728 with multi-doped luminescent centers, in which the luminescence centers strongly depend on the crystal field effect of the host lattice, while the defects generated or improved by different doping serve as auxiliary centers to control the afterglow intensity and duration. In addition to co-doping, long-lasting emission can also be observed in the case of only one activator, such as heterogeneous PLNPs with the matrix of Y3Al2Ga3O1229, BaGa2O430, Ca2SnO431, CdSiO332 , and Zn3Ga2Ge2O1033. Germanate-based ternary oxides include Ca2Ge7O16, Zn2GeO4, BaGe4O9, etc., which are typical wide-bandgap semiconductor materials with tunable emission, reproducible and stable luminescence, high quantum yield, environmental friendliness and wide availability34,35,36. These advantages make it a good activator-type photoluminescent carrier. In the past few years, germanates with various microstructures35,37, have been prepared by conventional solid-state reactions or chemical solution methods, and these characteristics make Zn2GeO4 useful in sterilize38, anti-counterfeiting39, catalysis40, light diodes41 , biosensing42, battery anodes43, detectors44,45, etc.
In order to expand the application of PL materials, the controllable synthesis of uniform and persistent luminescent nanoparticles has been developed. A decade ago, persistent phosphors were synthesized by solid-state synthesis46. However, the long reaction time and high annealing temperature during the synthesis process resulted in large and irregular phosphors, which limited their application in other fields such as biomedicine. In 2007, Chermont et al. used sol-gel approach to synthesize nanoparticles for the first time and prepared Ca0.2Zn0.9Mg0.9Si2O6: Eu2+, Dy3+, Mn2+, which opened the era of PLNPs47. However, the top-down synthesis strategy is accompanied by problems such as uncontrollable size and morphology, so researchers have done a lot of work in the development of controllable bottom-up synthesis of PLNPs. Since 2015, various synthesis methods have emerged one after another, such as the template synthesis method, hydrothermal/solvent thermal method, sol-gel method and other wet chemical synthesis methods for the synthesis of uniform and controllable PLNPs47,48,49,50. Among them, hydrothermal synthesis is one of the most commonly used methods for preparing nanomaterials, which can provide an adjustable and mild synthetic method to prepare compounds or materials with special structures and properties51.
Here, we present a detailed experimental procedure for synthesizing Zn2GeO4: Mn PLNPs with 1D nanorods morphology via the hydrothermal method and providing them with a rigid environment for further illumination applications. It was found that the luminescence properties of PLNPs, including emission wavelength and afterglow decay curve, can be changed by adjusting the pH value of the precursor. On the other hand, to emphasize the versatility of this method, we also synthesize PLNPs with Cr as the luminescent center using ZnGa2O4 as the matrix (ZnGa2O4: Cr), which exhibits afterglow emission (697 nm) in the near-infrared region after being excited by ultraviolet light (365 nm). This article mainly focuses on Zn2GeO4: Mn whose pH value of precursor solution is 9.4 for two-dimensional and three-dimensional artworks production and visualization. Zn2GeO4: Mn is a type of nanomaterial with Mn ions as the luminescent center which obtains strong green light emission (~ 537 nm) under the excitation of 365 nm ultraviolet light. At the same time, the continuous green light can still be seen after stopping excitation. In order to promote the polymerization of PLNPs in methyl methacrylate, ligands (Poly-ethylene glycol) were added during the hydrothermal synthesis process, and then PLNPs were polymerized with methyl methacrylate (MMA) in a two-dimensional or three-dimensional mold so that it can form glowing artwork while smoothly demolding.
This protocol provides a feasible method for the hydrothermal synthesis, polymerization reactions, and luminescent applications of PLNPs in advanced color rendering. Any differences in pH, temperature, and chemical reagents during nanocrystal growth will affect the size and optical properties of PLNP nanostructures. This detailed protocol aims to help new researchers in the field to improve the reproducibility of PLNPs using a hydrothermal method for further wider applications.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>azobisisobutyronitrile (99%)</td>
			<td>Macklin</td>
			<td>A800354</td>
			<td>Further purification required</td>
		</tr>
		<tr>
			<td>methyl methacrylate(99%)</td>
			<td>Sigma-Aldrich</td>
			<td>M55909</td>
			<td>Further purification required</td>
		</tr>
		<tr>
			<td>deionized water</td>
			<td>Merck</td>
			<td>ZEQ7016T0C</td>
			<td>Milli-Q&#160;Direct Water Purification System</td>
		</tr>
		<tr>
			<td>alkaline aluminum oxide (100-200 mesh)</td>
			<td>Macklin</td>
			<td>A800033</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;ammonium hydroxide&#160; (25%-28%, wt)</td>
			<td>Macklin</td>
			<td>A801005</td>
			<td></td>
		</tr>
		<tr>
			<td>beaker&#160;</td>
			<td>Synthware</td>
			<td>B220100</td>
			<td></td>
		</tr>
		<tr>
			<td>chromium(III) nitrate nonahydrate (99.95%)</td>
			<td>Aladdin</td>
			<td>C116448</td>
			<td></td>
		</tr>
		<tr>
			<td>centrifuge</td>
			<td>ThermoFisher Scientific</td>
			<td>75004250</td>
			<td></td>
		</tr>
		<tr>
			<td>column</td>
			<td>Synthware</td>
			<td>C184464CR</td>
			<td></td>
		</tr>
		<tr>
			<td>digital camera</td>
			<td>&#160;Canon</td>
			<td>EOS M50 Mark II</td>
			<td></td>
		</tr>
		<tr>
			<td>electric thermostaticdrying oven</td>
			<td>Longyue</td>
			<td>LDO-9036A</td>
			<td></td>
		</tr>
		<tr>
			<td>ethanol (99.7%)</td>
			<td>Greagent</td>
			<td>1158566</td>
			<td></td>
		</tr>
		<tr>
			<td>gallium nitrate hydrate(99.9%)</td>
			<td>Aladdin</td>
			<td>G109501</td>
			<td></td>
		</tr>
		<tr>
			<td>germanium oxide (99.99%)</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>51009860</td>
			<td></td>
		</tr>
		<tr>
			<td>glass rod</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>91229401</td>
			<td></td>
		</tr>
		<tr>
			<td>powder X-Ray Diffractometer</td>
			<td>D2 PHASER DESKTOP XRD</td>
			<td>BRUKER</td>
			<td></td>
		</tr>
		<tr>
			<td>manganese nitrate (98%)</td>
			<td>Macklin</td>
			<td>M828399</td>
			<td></td>
		</tr>
		<tr>
			<td>methanol (99.5%)</td>
			<td>Greagent</td>
			<td>1226426</td>
			<td></td>
		</tr>
		<tr>
			<td>nitric acid (65.0-68.0%, wt)</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10014508</td>
			<td></td>
		</tr>
		<tr>
			<td>pH meter</td>
			<td>Shanghai Leici Sensor Technology Co., Ltd</td>
			<td>PHS-3C</td>
			<td></td>
		</tr>
		<tr>
			<td>polyethylene glycol (300, Mw)</td>
			<td>Adamas</td>
			<td>01050882(41713A)</td>
			<td></td>
		</tr>
		<tr>
			<td>sealing film</td>
			<td>Parafilm</td>
			<td>2025722</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium hydroxide (GR)</td>
			<td>Sinopharm Chemical ReagentCo., Ltd</td>
			<td>10019764</td>
			<td></td>
		</tr>
		<tr>
			<td>spectrometer</td>
			<td>Horiba</td>
			<td>Fluorolog-3&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>transmission electron microscope</td>
			<td>JEOL&#160;</td>
			<td>JEM-1400 Plus</td>
			<td></td>
		</tr>
		<tr>
			<td>transmission electron microscope</td>
			<td>JEOL</td>
			<td>2100 Plus&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>triangular funnel</td>
			<td>Synthware</td>
			<td>F181975</td>
			<td></td>
		</tr>
		<tr>
			<td>ultrasound machine</td>
			<td>centrifuge</td>
			<td>JP-040S</td>
			<td></td>
		</tr>
		<tr>
			<td>zinc chloride (98%)</td>
			<td>Greagent</td>
			<td>01113266/G81783A</td>
			<td></td>
		</tr>
	</tbody>
</table>

synthesis of persistent luminescent nanoparticles for rewritable displays and illumination applications

Persistent luminescent nanoparticles (PLNPs) possess the capabilities to maintain extended longevity and robust emission even after the excitation has ceased. PLNPs have been widely used across various domains, including information displays, data encryption, biological imaging, and artistic decoration with sustained and vivid luminosity, providing boundless possibilities for a variety of innovative technology and artistic projects. This protocol focuses on an experimental procedure for the hydrothermal synthesis of PLNPs. The successful synthesis of enduring luminescent nanomaterials with Mn2+ or Cr3+ serving as a luminescent center in Zn2GeO4: Mn (ZGO: Mn) or ZnGa2O4: Cr highlights the universality of this synthetic method. On the other hand, the optical properties of ZGO: Mn can be changed by adjusting the pH of precursor solutions, demonstrating the tunability of the protocol. When charged with ultraviolet (UV) at a wavelength of 365 nm for 3 min and then stopped, PLNPs exhibit the remarkable capacity to generate afterglow efficiently and consistently, which makes them ideal for making two-dimensional rewritable displays and three-dimensional transparent, luminous artworks. This protocol outlined in this paper provides a feasible method for the synthesis of persistent luminescent nanoparticles for further illumination and imaging applications, opening up novel prospects for the fields of science and art.

The synthesis diagram of Zn2GeO4: Mn (ZGO: Mn) PLNPs is shown in Figure 1. The amphiphilic polymer Poly-ethylene glycol (PEG) is added to modify the ligand-free Zn2GeO4: Mn (ZGO: Mn) nanorods to better dissolve in MMA medium. First, the transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) images of ZGO: Mn whose pH is 9.4 are collected (Figure 1), and then dynamic light scatt...

Author Spotlight: Advancing Bioimaging and Therapy with Functional Nanomaterials

A protocol is presented for the synthesis of persistent luminescent nanomaterials (PLNPs) and their potential applications in rewritable displays and artistic processing utilizing the afterglow effect under ultraviolet light (365 nm) irradiation.

Synthesis of Persistent Luminescent Nanoparticles for Rewritable Displays and Illumination Applications

Persistent luminescent nanoparticles (PLNPs) possess the capabilities to maintain extended longevity and robust emission even after the excitation has ...

synthesis-persistent-luminescent-nanoparticles-for-rewritable

Research

JoVE Journal

Chemistry

1.8K Views.  Shanghai Tech University. A protocol is presented for the synthesis of persistent luminescent nanomaterials (PLNPs) and their potential applications in rewritable displays and artistic processing utilizing the afterglow effect under ultraviolet light (365 nm) irradiation. 

Video: Author Spotlight: Advancing Bioimaging and Therapy with Functional Nanomaterials

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

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 oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

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

Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, quantum dots should be highly fluorescent and small/monodisperse in size. While commonly used cadmium-based quantum dots possess these qualities, they are potentially toxic due to the possible release of Cd2+ ions through nanoparticle degradation. Indium-based quantum dots, specifically InP/ZnS, have recently been explored as a viable alternative to cadmium-based quantum dots due to their relatively similar fluorescence characteristics and size. The synthesis presented here uses standard hot-injection techniques for effective nanoparticle growth; however, nanoparticle properties such as size, emission wavelength, and emission intensity can drastically change due to small changes in the reaction conditions. Therefore, reaction conditions such temperature, reaction duration, and precursor concentration should be maintained precisely to yield reproducible products. Because quantum dots are not inherently soluble in aqueous solutions, they must also undergo surface modification to impart solubility in water. In this protocol, an amphiphilic polymer is used to interact with both hydrophobic ligands on the quantum dot surface and bulk solvent water molecules. Here, a detailed protocol is provided for the synthesis of highly fluorescent InP/ZnS quantum dots that are suitable for use in biomedical applications.

In this protocol, the synthesis of Cd-free InP/ZnS quantum dots (QDs) is detailed. InP-based QDs are gaining popularity due to the toxicity of Cd2+ ions that may be released through nanoparticle degradation. After synthesis, QDs are solubilized in water using an amphiphilic polymer for use in biomedical applications.

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, ...

Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide (CdS) nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal-sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired.

Herein we present a method to synthesize ligand-free cadmium sulfide (CdS) nanoparticles based on a unique sulfur copolymer. The sulfur copolymer operates as a high temperature solvent and a sulfur source during the nanoparticle synthesis and stabilizes the nanoparticles after the reaction.

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature ...

Synthesis of Core-shell Lanthanide-doped Upconversion Nanocrystals for Cellular Applications

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical properties, which allow for the absorption of near-infrared (NIR) light and can subsequently convert it into multiplexed emissions that span over a broad range of regions from the UV to the visible to the NIR. This article presents detailed experimental procedures for high-temperature co-precipitation synthesis of core-shell UCNs that incorporate different lanthanide ions into nanocrystals for efficiently converting deep-tissue penetrable NIR excitation (808 nm) into a strong blue emission at 480 nm. By controlling the surface modification with biocompatible polymer (polyacrylic acid, PAA), the as-prepared UCNs acquires great solubility in buffer solutions. The hydrophilic nanocrystals are further functionalized with specific ligands (dibenzyl cyclooctyne, DBCO) for localization on the cell membrane. Upon NIR light (808 nm) irradiation, the upconverted blue emission can effectively activate the light-gated channel protein on the cell membrane and specifically regulate the cation (e.g., Ca2+) influx in the cytoplasm. This protocol provides a feasible methodology for the synthesis of core-shell lanthanide-doped UCNs and subsequent biocompatible surface modification for further cellular applications.

A protocol is presented for the synthesis of core-shell lanthanide-doped upconversion nanocrystals (UCNs) and their cellular applications for channel protein regulation upon near-infrared (NIR) light illumination.

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical ...

Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. Here, we introduce the molten-salt synthesis (MSS) method for making metal oxide nanomaterials. Advantages over other methods include its simplicity, greenness, reliability, scalability, and generalizability. Using pyrochlore lanthanum hafnium oxide (La2Hf2O7) as a representative, we describe the MSS protocol for the successful synthesis of complex metal oxide nanoparticles (NPs). Furthermore, this method has the unique ability to produce NPs with different material features by changing various synthesis parameters such as pH, temperature, duration, and post-annealing. By fine-tuning these parameters, we are able to synthesize highly uniform, non-agglomerated, and highly crystalline NPs. As a specific example, we vary the particle size of the La2Hf2O7&#160;NPs by changing the concentration of the ammonium hydroxide solution used in the MSS process, which allows us to further explore the effect of particle size on various properties. It is expected that the MSS method will become a more popular synthesis method for nanomaterials and more widely employed in the nanoscience and nanotechnology community in the upcoming years.

Here, we demonstrate a unique, relatively low-temperature, molten-salt synthesis method for preparing uniform complex metal oxide lanthanum hafnate nanoparticles.

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. ...

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...

Escherichia coli-Based Cell-Free Protein Synthesis: Protocols for a robust, flexible, and accessible platform technology

Over the last 50 years, Cell-Free Protein Synthesis (CFPS) has emerged as a powerful technology to harness the transcriptional and translational capacity of cells within a test tube. By obviating the need to maintain the viability of the cell, and by eliminating the cellular barrier, CFPS has been foundational to emerging applications in biomanufacturing of traditionally challenging proteins, as well as applications in rapid prototyping for metabolic engineering, and functional genomics. Our methods for implementing an E. coli-based CFPS platform allow new users to access many of these applications. Here, we describe methods to prepare extract through the use of enriched media, baffled flasks, and a reproducible method of tunable sonication-based cell lysis. This extract can then be used for protein expression capable of producing 900 &#181;g/mL or more of super folder green fluorescent protein (sfGFP) in just 5 h from experimental setup to data analysis, given that appropriate reagent stocks have been prepared beforehand. The estimated startup cost of obtaining reagents is $4,500 which will sustain thousands of reactions at an estimated cost of $0.021 per &#181;g of protein produced or $0.019 per &#181;L of reaction. Additionally, the protein expression methods mirror the ease of the reaction setup seen in commercially available systems due to optimization of reagent pre-mixes, at a fraction of the cost. In order to enable the user to leverage the flexible nature of the CFPS platform for broad applications, we have identified a variety of aspects of the platform that can be tuned and optimized depending on the resources available and the protein expression outcomes desired.

Escherichia coli-Based Cell-Free Protein Synthesis: Protocols for a robust, flexible, and accessible platform technology

This protocol details the steps, costs, and equipment necessary to generate E. coli-based cell extracts and implement in vitro protein synthesis reactions within 4 days or less. To leverage the flexible nature of this platform for broad applications, we discuss reaction conditions that can be adapted and optimized.

Over the last 50 years, Cell-Free Protein Synthesis (CFPS) has emerged as a powerful technology to harness the transcriptional and translational capacity ...

Synthesis of Aptamer-PEI-g-PEG Modified Gold Nanoparticles Loaded with Doxorubicin for Targeted Drug Delivery

Due to drug resistance and toxicity in healthy cells, use of doxorubicin (DOX) has been limited in clinical cancer therapy. This protocol describes the designing of poly(ethylenimine) grafted with polyethylene glycol (PEI-g-PEG) copolymer functionalized gold nanoparticles (AuNPs) with loaded aptamer (AS1411) and DOX through amide reactions. AS1411 is specifically bonded with targeted nucleolin receptors on cancer cells so that DOX targets cancer cells instead of healthy cells. First, PEG is carboxylated, then grafted to branched PEI to obtain a PEI-g-PEG copolymer, which is confirmed by 1H NMR analysis. Next, PEI-g-PEG copolymer coated gold nanoparticles (PEI-g-PEG@AuNPs) are synthesized, and DOX and AS1411 are covalently bonded to AuNPs gradually via amide reactions. The diameter of the prepared AS1411-g-DOX-g-PEI-g-PEG@AuNPs is ~39.9 nm, with a zeta potential of -29.3 mV, indicating that the nanoparticles are stable in water and cell medium. Cell cytotoxicity assays show that the newly designed DOX loaded AuNPs are able to kill cancer cells (A549). This synthesis demonstrates the delicate arrangement of PEI-g-PEG copolymers, aptamers, and DOX on AuNPs that are achieved by sequential amide reactions. Such aptamer-PEI-g-PEG functionalized AuNPs provide a promising platform for targeted drug delivery in cancer therapy.

In this protocol, doxorubicin-loaded AS1411-g-PEI-g-PEG modified gold nanoparticles are synthesized via three-step amide reactions. Then, doxorubicin is loaded and delivered to target cancer cells for cancer therapy.

Due to drug resistance and toxicity in healthy cells, use of doxorubicin (DOX) has been limited in clinical cancer therapy. This protocol describes the ...

Preparation of Silver-Palladium Alloyed Nanoparticles for Plasmonic Catalysis under Visible-Light Illumination

Localized surface plasmon resonance (LSPR) in plasmonic nanoparticles (NPs) can accelerate and control the selectivity of a variety of molecular transformations. This opens possibilities for the use of visible or near-IR light as a sustainable input to drive and control reactions when plasmonic nanoparticles supporting LSPR excitation in these ranges are employed as catalysts. Unfortunately, this is not the case for several catalytic metals such as palladium (Pd). One strategy to overcome this limitation is to employ bimetallic NPs containing plasmonic and catalytic metals. In this case, the LSPR excitation in the plasmonic metal can contribute to accelerate and control transformations driven by the catalytic component. The method reported herein focuses on the synthesis of bimetallic silver-palladium (Ag-Pd) NPs supported on ZrO2 (Ag-Pd/ZrO2) that acts as a plasmonic-catalytic system. The NPs were prepared by co-impregnation of corresponding metal precursors on the ZrO2 support followed by simultaneous reduction leading to the formation of bimetallic NPs directly on the ZrO2 support. The Ag-Pd/ZrO2 NPs were then used as plasmonic catalysts for the reduction of nitrobenzene under 425 nm illumination by LED lamps. Using gas chromatography (GC), the conversion and selectivity of the reduction reaction under the dark and light irradiation conditions can be monitored, demonstrating the enhanced catalytic performance and control over selectivity under LSPR excitation after alloying non-plasmonic Pd with plasmonic metal Ag. This technique can be adapted to a wide range of molecular transformations and NPs compositions, making it useful for the characterization of the plasmonic catalytic activity of different types of catalysis in terms of conversion and selectivity.

Presented here is a protocol for the synthesis of silver-palladium (Ag-Pd) alloy nanoparticles (NPs) supported on ZrO2 (Ag-Pd/ZrO2). This system allows for harvesting energy from visible light irradiation to accelerate and control molecular transformations. This is illustrated by nitrobenzene reduction under light irradiation catalyzed by Ag-Pd/ZrO2 NPs.