This work was supported by JSPS KAKENHI grant number JP16H01282 (TF), a Grant-in-Aid for Scientific Research on Innovative Areas &#34;Memory Dynamism,&#34; and JP19H05778 (TF), &#34;MolMovies.&#34;

1. Synthesis of the modular caging paBhc group for clickable caged compounds28,41
<ol>
	<li>Preparation of (6-bromo-7-hydroxycoumarin-4-yl)methyl chloride (Bhc-CH2Cl)
	<ol>
		<li>Place 4-bromoresorcinol (9.742 g, 51.5 mmol) in a 100 mL round-bottomed flask equipped with a stirrer bar.</li>
		<li>Add conc. H2SO4 (98%, 30 mL) to the flask and stir the mixture to dissolve.</li>
		<li>Add ethyl 4-chloroacetoacetate (10 mL, 74 mmol) dropwise.</li>
		<li>Continue stirring the mixture at ambient temperature for 5 days.</li>
		<li>Separately, place crushed ice cubes (~200 mL) in a 500 mL Erlenmeyer flask.</li>
		<li>Pour the reaction mixture into the ice and stir vigorously for 30 min until a finely powdered precipitate is obtained.</li>
		<li>Collect the precipitate via vacuum filtration. Wash the light brown precipitate with water five times.</li>
		<li>Dry the precipitate under vacuum overnight to yield BhcCH2Cl as a light brown powder (13.57 g, 46.9 mmol).</li>
	</ol>
	</li>
	<li>Preparation of (6-bromo-7-hydroxycoumarin-4-yl)methanol (BhcCH2OH)
	<ol>
		<li>Place the prepared BhcCH2Cl (1.1440 g, 3.95 mmol) and 1 M HCl (300 mL) in a 1 L round-bottomed flask equipped with a Dimroth condenser. Stir the mixture at 140 &#176;C for 5 days. After this time, cool the mixture to ambient temperature.</li>
		<li>Remove the water from the reaction by rotary evaporation under vacuum to yield BhcCH2OH (1) as a light brown powder (1.0359 g, 3.82 mmol, 97% yield). 
		NOTE: The use of 250 mL of 1 M HCl per 1 g of BhcCH2Cl gives a satisfactory result.</li>
	</ol>
	</li>
	<li>Preparation of paBhcCH2OH (2) via the Mannich reaction
	<ol>
		<li>Place paraformaldehyde (446.4 mg, 14.9 mmol) in a 50 mL round-bottomed flask. Add anhydrous ethanol (5 mL) and N-methylpropargylamine (1.25 mL, 14.8 mmol) to the flask.</li>
		<li>Stir the mixture at ambient temperature for 1 h under an Ar atmosphere.</li>
		<li>Add BhcCH2OH (1) (1.367 g, 5.04 mmol) to the flask. Heat the mixture to 80 &#176;C with a block heater apparatus, and continue stirring the mixture at 80 &#176;C for 2 h under an Ar atmosphere.</li>
		<li>Stop the block heater and cool the reaction mixture to room temperature.</li>
		<li>Collect the resulting light brown-yellow precipitate by vacuum filtration. Wash the precipitate twice with a small amount of anhydrous ethanol (1 mL each time).</li>
		<li>Remove the excess ethanol under vacuum to yield paBhcCH2OH (2) (1.393 g, 3.96 mmol).</li>
	</ol>
	</li>
</ol>
2. Preparation of clickable caged compounds
NOTE: The following procedures can be applied to the preparation of other clickable caged compounds containing hydroxyl, amino, and carboxylate functional groups.
<ol>
	<li>General Procedure 1: Preparation of a clickable caged amine
	<ol>
		<li>Place paBhcCH2OH (2) (709.6 mg, 2.02 mmol) and N,N&#8217;-carbonyl diimidazole (CDI, 397.6 mg, 2.45 mmol) in a 30 mL round-bottomed flask. Add dry CH2Cl2 (6 mL) and stir the solution at ambient temperature for 1 h.</li>
		<li>Add 4-dimethylaminopyridine (4-DMAP, 324.8 mg, 2.66 mmol) and tert-butyl (6-aminohexyl)carbamate (533.1 mg, 2.46 mmol). Stir the solution at ambient temperature for 3 h.</li>
		<li>Remove the solvent and other volatile materials using a rotary evaporator under vacuum. Purify the residue directly using silica gel flash column chromatography.</li>
	</ol>
	</li>
	<li>General Procedure 2: Preparation of a clickable caged alcohol
	<ol>
		<li>Place paclitaxel (PTX, 48.7 mg, 0.057 mmol) in a 30 mL round-bottomed flask equipped with a three-way stopcock and an Ar balloon. Add dry CH2Cl2 (1 mL), 4-DMAP (17.1 mg, 0.14 mmol), and 4-nitrophenyl chloroformate (26.0 mg, 0.13 mmol).</li>
		<li>Stir the solution at ambient temperature for 2.5 h under an Ar atmosphere.</li>
		<li>Add 4-DMAP (15.7 mg, 0.13 mmol) and paBhcCH2OH (2) (39.1 mg, 0.111 mmol) to the solution. Continue stirring the mixture at ambient temperature for 17 h.</li>
		<li>Add CHCl3 (10 mL) and 15% aqueous NaHCO3 (5 mL) to the mixture. Stir the mixture vigorously for approximately 3 min. Remove the aqueous layer with a pipette.</li>
		<li>Add 0.5 M citric acid (5 mL) to the flask containing the organic layer. Stir the mixture and remove the aqueous layer as above.</li>
		<li>Separate the organic layer using a phase separation column. Remove the solvents with a rotary evaporator under vacuum. Purify the product using standard silica gel flash column chromatography.</li>
	</ol>
	</li>
	<li>General Procedure 3: Preparation of a clickable caged carboxylic acid
	<ol>
		<li>Dissolve arachidonic acid (33.0 &#956;L, 0.100 mmol), paBhcCH2OH (2) (39.6 mg, 0.112 mmol), and 4-DMAP (14.1 mg, 0.115 mmol) in dry CH2Cl2 (2 mL). Add N,N&#697;-diisopropylcarbodiimide (DIPC, 17.0 &#956;L, 0.110 mmol) and stir the solution at ambient temperature for 140 min.</li>
		<li>Remove the solvent under vacuum. Purify the residue directly using silica gel flash column chromatography.</li>
	</ol>
	</li>
</ol>
3. Installation of a functional unit into the clickable caged compounds
<ol>
	<li>Dissolve copper(II) sulfate pentahydrate (249 mg) in ion-exchanged water (IEW, 10 mL) to give a 0.1 M CuSO4 solution.</li>
	<li>Dissolve 2&#697;-paBhcmoc-PTX (8.0 mg, 6.5 &#956;mol), tris(3-hydroxypropyltriazolylmethyl)amine (THPTA, 17.5 mg, 40.3 &#956;mol), sodium l-ascorbate (162.4 mg, 0.825 mmol), and 15-chloro-3,6,9-trioxapentadecyl azide (3.1 mg, 11 &#956;mol) in a mixed solvent of 0.1 M phosphate buffer (2.5 mL, pH 7.2) and dimethyl sulfoxide (DMSO, 0.5 mL).</li>
	<li>Add the 0.1 M CuSO4 solution (81.2 &#956;L, 8.1 &#956;mol) to the reaction mixture. Stir the mixture at ambient temperature for 80 min. Monitor the progress of the reaction using high-performance liquid chromatography (HPLC).</li>
	<li>Dissolve the precipitates by adding a 75% acetonitrile/water solution (3.5 mL). Apply the resulting solution directly to the semi-preparative HPLC system to purify the desired product. 
	NOTE: Solubilization of the reaction mixture by the addition of tert-butanol can accelerate the progression of the reaction.</li>
</ol>
4. Photolytic uncaging reaction of the caged compounds
<ol>
	<li>Preparation of the stock solutions
	<ol>
		<li>Dissolve the desired caged compound (5 &#956;mol) in DMSO (500 &#956;L) to prepare a 10 mM stock solution. Dispense an aliquot of each solution (10 &#956;L) into a 1.5 mL microcentrifuge tube and store in a freezer (&#8722;20 &#176;C) until just before use.</li>
		<li>6 mM K3[Fe(C2O4)3] (100 mL): Dissolve recrystallized potassium ferrioxalate (0.295 g, 0.675 mmol) in 80 mL of water. Add 0.5 M H2SO4 (10 mL) and an appropriate amount of IEW to make up the volume to 100 mL. 
		NOTE: Potassium ferrioxalate should be purified via recrystallization from hot water and stored in the dark. Recrystallized potassium ferrioxalate is obtained as the trihydrate; therefore, its formula is K3[Fe(C2O4)3]&#183;3H2O and a formula weight of 491.24 should be considered during preparation of the stock solution. Check the purity of the 6 mM solution by measuring its absorption at 510 nm. If the absorbance is &#60;0.02, it is suitable for use in the experiment.</li>
		<li>0.1% Buffer-phen (30 mL): Dissolve NaOAc&#183;3H2O (7.35 g), 1,10-phenanthroline (phen)&#183;H2O (30 mg), and conc. H2SO4 (0.9 mL) in IEW (20 mL). Add IEW to make up the volume to 30 mL. 
		NOTE: The solution contains 1.8 M NaOAc, 0.54 M H2SO4, and 0.1% 1,10-phenanthroline.</li>
	</ol>
	</li>
	<li>Measurement of the number of photons using ferrioxalate actinometry
	<ol>
		<li>Place 6 mM K3[Fe(C2O4)3] (V1 L) in a quartz cuvette. Irradiate the solution with 350 nm light for 5 s.</li>
		<li>Transfer the irradiated solution to a Pyrex cuvette with an l [cm] path length.</li>
		<li>Add 0.1% Buffer-phen (V2 L) to the irradiated sample solution and mix well by pipetting. Measure the absorbance of the sample at 510 nm. Calculate the average absorption change per unit time (&#916;A510 [s&#8722;1]).</li>
		<li>Calculate the number of moles of generated Fe2+ ions per unit time according to the following equation: 
		nFe2+ [mol s&#8722;1] = ((V1 + V2) [L] &#215; &#916;A510 [s&#8722;1])/(l [cm] &#215; &#949;510 [L mol&#8722;1 cm&#8722;1]), 
		where (V1 + V2) is the volume of the sample for the absorption measurement, l is the optical path length of the cuvette, and &#949;510 is the molar absorptivity of the Fe2+-phen complex at 510 nm. 
		NOTE: In the typical experimental conditions, values of V1 = 2.0 &#215; 10&#8722;3 L, V2 = 0.33 &#215; 10&#8722;3 L, l = 1.0 cm, and &#949;510 = 1.1 &#215; 104 L mol&#8722;1 cm&#8722;1 were used.</li>
		<li>Calculate the number of moles of photons that reach the sample (I0) using the following formula: 
		I0 [einstein cm&#8722;2 s&#8722;1] = nFe2+/&#934;350 
		where &#934; 350 is the quantum efficiency of photoreduction of the ferrioxalate at 350 nm. 
		NOTE: Although the quantum efficiency of the potassium ferrioxalate actinometer at 350 nm is not reported, the reported value of 1.2542 at 358 nm was employed.</li>
	</ol>
	</li>
	<li>Quantum efficiency measurements at 350 nm
	<ol>
		<li>Dilute the sample stock solution (in DMSO, 10 &#956;L) with K-MOPS buffer (pH 7.2, 10 mL) to give a 10 &#956;M solution in K-MOPS containing 0.1% DMSO. 
		NOTE: K-MOPS buffer consisted of 100 mM KCl and 10 mM 3-(N-morpholino)propanesulfonic acid (Mops) titrated to pH 7.2 with KOH.</li>
		<li>Transfer an aliquot of the solution (V1 L) into the same cuvette used in the photoreaction of the chemical actinometer. Irradiate the sample solution using the same setup as described in step 4.2.1.</li>
		<li>Remove an aliquot (50 &#956;L) from the irradiated solution periodically and analyze using HPLC.</li>
		<li>Determine the irradiation time, in seconds, in which 90% of the starting material reacted (t90%) by fitting plots of the time-dependent disappearance of the starting material. 
		NOTE: The absorbance of the irradiated sample must be maintained at &#60;0.1 so that the inner filtering of the radiation can be neglected. It is desirable that the photolytic consumption of the starting material can be approximated by single-exponential decay so that there is no undesired secondary effect that interferes with the photolysis process.</li>
		<li>Calculate the quantum yield of disappearance (&#934;dis) using the following equation28: 
		&#934;dis = 1/(t90% &#215; I0 &#215; &#963;350) 
		where t90% [s] is the irradiation time in which 90% of the starting material was consumed, I0 [einstein cm&#8722;2 s&#8722;1] is the number of moles of photons, and &#963;350 [cm2 mol&#8722;1] is the decadic extinction coefficient of the sample at 350 nm. 
		NOTE: &#963;350 [cm2 mol&#8722;1] = 103&#949;350 [M&#8722;1 cm&#8722;1].</li>
	</ol>
	</li>
</ol>
5. Targeting of a clickable caged compound with a HaloTag ligand
NOTE: Prior to use, maintain the HeLa cells in Dulbecco&#8217;s modified Eagle medium (DMEM, low glucose, sodium pyruvate, l-glutamine) supplemented with 10% fetal bovine serum (FBS) containing 1% antibiotics (streptomycin sulfate, penicillin G, and amphotericin) at 37 &#176;C and 5% CO2.
<ol>
	<li>Remove the medium and trypsinize the cells by treating with trypsin-ethylenediaminetetraacetic acid (EDTA, 1 mL) at 37 &#176;C for 1 min. Add DMEM (4 mL) to the cells and re-suspend the cells by pipetting gently. Seed approximately 5 &#215; 105 cells per dish into 35 mm glass bottom dishes in DMEM (2 mL) 24 h before transfection.</li>
	<li>For four dishes, in a 1.5 mL microcentrifuge tube, dilute the plasmid DNA (pcDNA3-Halo-EGFR, 14 &#956;g) in the reduced serum medium (700 &#956;L). Separately, dilute the lipofection reagent (5 &#956;L) in the reduced serum medium (150 &#956;L) into each of four tubes and allow them stand at ambient temperature for 5 min.</li>
	<li>Add a portion of the diluted plasmid DNA (150 &#956;L) to each of the diluted lipofection reagent samples. Incubate at ambient temperature for 5 min.</li>
	<li>After maintaining the cells at 37 &#176;C and 5% CO2 for 24 h, aspirate the DMEM and rinse the cells with phosphate-buffered saline (PBS, 2 mL). Add the reduced serum medium (1.5 mL).</li>
	<li>Add the plasmid-lipofection reagent (150 &#956;L) complex to each dish. Maintain the cells at 37 &#176;C and 5% CO2 for 48 h.</li>
	<li>Aspirate the medium, add a portion of freshly prepared DMEM (1 mL) containing 2 &#956;M paBhc-hex-FITC/Halo, and incubate the cells at 37 &#176;C and 5% CO2 for 30 min.</li>
	<li>Aspirate the medium containing the caged compound and rinse the cells twice with PBS+ (1 mL per rinse) to remove any unbound compounds. Add the reduced serum medium (500 &#956;L) and incubate the cells at 37 &#176;C and 5% CO2 for 30 min to remove the compounds that entered the cells. 
	NOTE: PBS+ is phosphate-buffered saline supplemented with 2 mM CaCl2 and 1 mM MgCl2.</li>
	<li>Remove the medium and rinse the cells twice with PBS+ (1 mL). Add a portion of a medium (1 mL) that does not contain phenol red. Record fluorescence images by laser scanning confocal fluorescence microscopy.</li>
</ol>
6. Photomediated modulation of a kinase localization using a clickable caged compound
NOTE: Prior to use, maintain the CHO-K1 cells in Ham&#8217;s F-12 medium supplemented with 10% FBS at 37 &#176;C and 5% CO2.
<ol>
	<li>Prepare a 100&#215; working solution (1 mM)of paBhc-AA (5) in DMSO. 
	NOTE: A 10 mM stock solution of the compound is prepared and stored in a freezer (-20 &#176;C).</li>
	<li>Seed approximately 5 &#215; 105 cells per dish into 35 mm glass bottom dishes in DMEM (2 mL) 24 h before transfection.</li>
	<li>Transfect CHO-K1 cells with a plasmid coding for GFP-DGK&#947; 48 h before the uncaging experiments. 
	NOTE: Transfection is performed according to steps 5.2&#8211;5.5.</li>
	<li>Replace the medium with a reduced serum medium (2 mL). Add the 100&#215; paBhc-AA working solution (20 &#956;L) and incubate the cells at 37 &#176;C and 5% CO2 for between 5 min and 1 h. 
	NOTE: The loading time depends on the compound employed.</li>
	<li>Place the cells on the objective stage of an inverted fluorescent microscope equipped with a dual light source fluorescence illuminator.</li>
	<li>Take a fluorescent image every 10 s. Irradiate the cells with 330&#8211;385 nm light through a microscope objective for an appropriate time. Alternatively, irradiate the cells with 405 nm light using a Xe lamp through flexible quartz fibers.</li>
	<li>Continue to record fluorescent images for 10 min.</li>
</ol>

We have nothing to disclose.

We previously developed Bhc caged compounds of various biologically active molecules that exhibit high photolytic efficiencies28,45,46,47. With the aim of expanding the repertoire of Bhc caging groups, we also reported platforms of modular caged compounds that can be modified easily by the introduction of various functional units32,40,41. The present protocol therefore represents a method for the synthesis of a clickable precursor of Bhc caging groups that can be modified via the copper(I)-catalyzed Huisgen cyclization. The synthesis of the clickable precursor, paBhcCH2OH (2), was achieved via a four-step reaction sequence starting from the commercially available 4-bromoresorcinol (Figure 1A). The advantage of the present protocol is that no laborious purification steps (e.g., column chromatographic separations) are required.
As clickable precursor paBhcCH2OH (2) can be used to mask various functional groups, clickable caged compounds of amines, alcohols, and carboxylic acids were synthesized using 2 as the precursor (Figure 1B). Amines were modified as their carbamates while alcohols were modified as their carbonates. In general procedures 1 and 2, CDI was used for the preparation of clickable carbamates, while 4-nitrophenyl chloroformate was used for the preparation of carbonates. As indicated by the reaction mechanism, both reagents can be used for the preparation of carbamates and carbonates. It should also be noted that the yield of the desired caged compound depends on the chemical structure of the molecule to be caged. Other examples can be seen in our previous reports28,30,33,48.
Click modification was then performed using a slight modification of the reported procedure49. The addition of tris(triazolylmethyl)amine-based ligands is necessary to obtain the desired products in good to high yields. Since a variety of azides are readily available both from commercial sources and from literature procedures, we can prepare various modular caged compounds with additional properties such as water solubility and cellular targeting ability (Figure 2).
The quantum yield of photolysis was then measured according to a reported procedure28,50. Figure 3 shows that the photolytic consumption of 2&#697;-glc-paBhcmoc-PTX and the release of PTX were approximated by single-exponential decay and rise, respectively, suggesting no inner filtering of the radiation or undesired secondary effects. Improved photolysis quantum yields (&#934;) and photolysis efficiencies (&#949;&#934;) were observed for the clickable paBhc caged compounds compared to those of the previously reported Bhc caged compounds (Table 1)41,43. Since the photolysis efficiencies (&#949;&#934;) of Bhc caged compounds are more than one hundred times higher than those of 2-nitrobenzyl-type caged compounds48, the marked improvement due to the presence of paBhc caging groups is clearly an advantage for this system.
As a proof-of-concept experiment, a hydrophilic moiety was introduced into 2&#697;-paBhcmoc-PTX (4) and a cellular targeting ligand was introduced into compound 3 (Figure 2). The water solubility of 2&#697;-glc-paBhcmoc-PTX was 650 times higher than that of the parent PTX (Table 1). Selective cellular targeting was achieved using a tag-probe system, and paBhcmoc-hex-FITC/Halo (8) bearing the HaloTag ligand was successfully targeted to the cell membrane of cultured mammalian cells expressing the HaloTag/EGFR fusion protein (Figure 4). Photo-mediated modulation of the subcellular localization of a kinase was also achieved using a clickable caged compound 5 (Figure 5).
In conclusion, we successfully demonstrated a method for the preparation of clickable platforms for photo-caged compounds of biologically interesting molecules that can be modified easily with additional properties, such as water solubility and a cellular targeting ability. Since the paBhc caging group can be used to prepare any molecules with modifiable functional groups, the application of the present protocol is not limited to the molecules described herein. Using a modular platform, namely the paBhc caging group, the desired caged compounds can be easily prepared, and their physical and chemical properties can be modulated via click modification.

Caged compounds are designed synthetic molecules whose original functions are temporally masked by covalently attached photo-removable protecting groups. Interestingly, caged compounds of biologically relevant molecules provide an indispensable method for the spatiotemporal control of the cellular physiology1,2,3,4,5,6. In 1977, Engels and Schlaeger reported the 2-nitrobenzyl ester of cAMP as a membrane permeable and photolabile derivative of cAMP7. The following year, Kaplan reported the 1-(2-nitrophenyl)ethyl ester of ATP (NPE-ATP) and named this compound &#8220;caged&#8221; ATP8. Since then, a range of photochemically removable protecting groups such as 2-nitrobenzyls, p-hydroxyphenacyls9, 2-(2-nitrophenyl)ethyls10,11, 7-nitroindolin-1-yls12,13, and (coumarin-4-yl)methyls14,15,16 have been used for the preparation of caged compounds.
The synthesis of caged compounds with desirable additional properties such as membrane permeability, water solubility, and cellular targeting ability would be expected to facilitate cell biological applications. Since the physical and photochemical properties of these molecules depend primarily on the chemical structure of the photochemically removable protecting groups used to prepare them, a diverse repertoire of photo-caging groups is required. However, the structural diversity of currently available caging groups that exhibit high photolysis efficiencies is limited. This could be an obstacle to increasing the use of caged compounds.
To address this issue, the repertoire of photo-caging groups has been expanded by the chemical modification of existing photoremovable protecting groups or the design of new photolabile chromophores with superior photophysical and photochemical properties. Examples include nitrodibenzofuran (NDBF)17, [3-(4,5-dimethoxy-2-nitrophenyl)-2-butyl] (DMNPB)18,19, a calcium-sensitive 2-nitrobenzyl photocage20, substituted coumarinylmethyls (DEAC45021, DEAdcCM22, 7-azetidinyl-4-methylcoumarin23, and styryl coumarins24), cyanine derivatives (CyEt-pan)25, and BODIPY derivatives26,27.
In addition, we previously developed the (6-bromo-7-hydroxycoumarin-4-yl)methyl (Bhc) group and successfully synthesized various caged compounds of neurotransmitters28, second messengers29,30, and oligonucleotides31,32,33 exhibiting large one- and two-photon excitation cross-sections. If additional properties can be installed easily into the caging groups without compromising their photosensitivity, then the repertoire of caged compounds can be expanded34,35,36,37,38,39. We therefore designed modular caged compounds that comprise three parts, namely the Bhc group as a photo-responsive core, chemical handles for the installation of additional functionalities, and the molecules that are to be masked40,41.
Thus, this article provides a practical method for the preparation of caged compounds of biologically relevant molecules. The present protocol describes methods for the preparation of a clickable platform for photo-caging groups, the introduction of additional functionalities to expand the repertoire of caged compounds, the measurement of their physical and photochemical properties, and the cell-type selective targeting of a clickable caged compound for further cellular application.

<table>
	<tbody>
		<tr>
			<td>acetonitrile, EP</td>
			<td>Nacalai</td>
			<td>00404-75</td>
			<td></td>
		</tr>
		<tr>
			<td>acetonitrile, super dehydrated</td>
			<td>FUJIFILM Wako</td>
			<td>010-22905</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic, 100X</td>
			<td>Thermo Fisher</td>
			<td>15240062</td>
			<td></td>
		</tr>
		<tr>
			<td>4-bromoresorcinol</td>
			<td>TCI Chemicals</td>
			<td>B0654</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N&#8217;-carbonyldiimidazole</td>
			<td>FUJIFILM Wako</td>
			<td>034-10491</td>
			<td></td>
		</tr>
		<tr>
			<td>chloroform</td>
			<td>Kanto</td>
			<td>07278-71</td>
			<td></td>
		</tr>
		<tr>
			<td>Copper (II) Sulfate Pentahydrate, 99.9%</td>
			<td>FUJIFILM Wako</td>
			<td>032-12511</td>
			<td></td>
		</tr>
		<tr>
			<td>dichloromethane, dehydrated</td>
			<td>Kanto</td>
			<td>11338-05</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N&#39;-Diisopropylcarbodiimide (DIPC)</td>
			<td>TCI Chemicals</td>
			<td>D0254</td>
			<td></td>
		</tr>
		<tr>
			<td>4-dimethylaminopyridine</td>
			<td>TCI Chemicals</td>
			<td>D1450</td>
			<td></td>
		</tr>
		<tr>
			<td>dimethylsulfoxide, dehydrated -super-</td>
			<td>Kanto</td>
			<td>10380-05</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM - Dulbecco&#39;s Modified Eagle Medium</td>
			<td>Sigma</td>
			<td>D6046-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>dual light source fluorescence illuminator, IX2-RFAW</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol (99.5)</td>
			<td>FUJIFILM Wako</td>
			<td>054-07225</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl 4-Chloroacetoacetate</td>
			<td>TCI Chemicals</td>
			<td>C0911</td>
			<td></td>
		</tr>
		<tr>
			<td>Ham&#39;s F-12 with L-Glutamine and Phenol Red</td>
			<td>FUJIFILM Wako</td>
			<td>087-08335</td>
			<td></td>
		</tr>
		<tr>
			<td>hydrochloric acid</td>
			<td>FUJIFILM Wako</td>
			<td>087-01076</td>
			<td></td>
		</tr>
		<tr>
			<td>inverted fluorescent microscope IX-71</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ISOLUTE Phase Separator, 15 mL</td>
			<td>Biotage</td>
			<td>120-1906-D</td>
			<td></td>
		</tr>
		<tr>
			<td>L-(+)-Ascorbic Acid Sodium Salt</td>
			<td>FUJIFILM Wako</td>
			<td>196-01252</td>
			<td></td>
		</tr>
		<tr>
			<td>laser scanning fluorescence confocal microscopy, FLUOVIEW FV1200/IX-81</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lipofectamine 2000 Transfection Reagent</td>
			<td>Thermo Fisher</td>
			<td>11668027</td>
			<td>lipofection reagent</td>
		</tr>
		<tr>
			<td>3-(N-morpholino)propanesulfonic acid</td>
			<td>Dojindo</td>
			<td>345-01804</td>
			<td>MOPS</td>
		</tr>
		<tr>
			<td>4-nitrophenylchloroformate (4-NPC)</td>
			<td>TCI Chemicals</td>
			<td>C1400</td>
			<td></td>
		</tr>
		<tr>
			<td>Opti-MEM I Reduced Serum Medium, no phenol red</td>
			<td>Thermo Fisher</td>
			<td>11058021</td>
			<td>reduced serum medium contains no phenol red</td>
		</tr>
		<tr>
			<td>1,10&#8208;Phenanthroline Monohydrate</td>
			<td>Nacalai</td>
			<td>26707-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Photochemical reactor with RPR 350 nm lamps</td>
			<td>Rayonet</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium Trioxalatoferrate (III) trihydrate</td>
			<td>FUJIFILM Wako</td>
			<td>W01SRM19-5000</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Acetate Trihydrate</td>
			<td>Nacalai</td>
			<td>31115-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Bicarbonate</td>
			<td>FUJIFILM Wako</td>
			<td>199-05985</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfuric Acid, 96-98%</td>
			<td>FUJIFILM Wako</td>
			<td>190-04675</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris(3-hydroxypropyltriazolylmethyl)amine (THPTA)</td>
			<td>ALDRICH</td>
			<td>762342-100MG</td>
			<td></td>
		</tr>
		<tr>
			<td>tri&#8208;Sodium Citrate Dihydrate</td>
			<td>Nacalai</td>
			<td>31404-15</td>
			<td></td>
		</tr>
		<tr>
			<td>Xenon light source, MAX-303</td>
			<td>Asahi Spectra</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

design, synthesis, and photochemical properties of clickable caged compounds

Caged compounds enable the photo-mediated manipulation of the cell physiology with high spatiotemporal resolution. However, the limited structural diversity of currently available caging groups and the difficulties in synthetic modification without sacrificing their photolysis efficiencies are obstacles to expanding the repertoire of caged compounds for live cell applications. As the chemical modification of coumarin-type photo-caging groups is a promising approach for the preparation of caged compounds with diverse physical and chemical properties, we report a method for the synthesis of clickable caged compounds that can be modified easily with various functional units via the copper(I)-catalyzed Huisgen cyclization. The modular platform molecule contains a (6-bromo-7-hydroxycoumarin-4-yl)methyl (Bhc) group as a photo-caging group, which exhibits a high photolysis efficiency compared to those of the conventional 2-nitrobenzyls. General procedures for the preparation of clickable caged compounds containing amines, alcohols, and carboxylates are presented. Additional properties such as the water solubility and cell targeting ability can be readily incorporated into clickable caged compounds. Furthermore, the physical and photochemical properties, including the photolysis quantum yield, were measured and were found to be superior to those of the corresponding Bhc caged compounds. The described protocol could therefore be considered a potential solution for the lack of structural diversity in the available caged compounds.

Clickable caged compounds of some biologically interesting molecules, including arachidonic acid and paclitaxel, were successfully synthesized (Figure 1)28,41. Additional properties such as the water solubility and cellular targeting ability were introduced into paBhcmoc-PTX via the copper(I)-catalyzed Huisgen cyclization (&#8220;Click&#8221; reaction) (Figure 2). These clickable caged PTXs were then photolyzed to produce their parent PTXs upon irradiation at 350 nm (Figure 3), and the physical and photochemical properties of the clickable caged compounds are summarized in Table 1. The quantum yields of clickable caged compounds 2&#697;-glc-paBhcmoc-PTX (&#934;dis 0.14) and paBhc-AA (&#934;dis 0.083) were more than twice those of conventional Bhc caged compounds 2&#697;-Bhcmoc-PTX (&#934;dis 0.040) and Bhc-AA (&#934;dis 0.038)43. In addition, an improved water solubility was observed for 2&#697;-glc-paBhcmoc-PTX, which contains a glucose moiety.
In live cell experiments, the targeting of paBhc-hex-FITC/Halo to the cultured mammalian cells transiently expressing a fusion protein of a HaloTag protein and epidermal growth factor receptor (EGFR) was achieved successfully. Green fluorescence of the fluorescein moiety of paBhc-hex-FITC/Halo was observed on the cell membrane (Figure 4). Photo-mediated modulation of the subcellular localization of a kinase was achieved using a paBhc caged compound. The translocation of diacylglycerol kinase &#947; (DGK&#947;) has been reported to be activated in the presence of arachidonic acid (AA)44. CHO-K1 cells transiently expressing GFP-DGK&#947; were treated with either AA or paBhc-AA (5). Addition of AA caused the modulation of the subcellular localization of DGK&#947; (Figure 5A,B). Similar changes in the localization of DGK&#947; were observed for the paBhc-AA-treated cells after exposure to UV light (Figure 5C,D).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/60021/60021fig01.jpg" /> 
Figure 1: Preparation of the clickable caged compounds. 
(A) Reagents and conditions: a. ethyl 4-chloroacetoacetate/conc. H2SO4/rt/7 days/91% yield, b. 1 M HCl/reflux/3 days/97% yield. c. N-methylpropargylamine /HCHO/EtOH, then add (1) and heat at reflux for 17 h/79% yield. (B) Syntheses of the clickable caged amine, PTX, and arachidonic acid. <a href="https://www.jove.com/files/ftp_upload/60021/60021fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/60021/60021fig02.jpg" /> 
Figure 2: Installation of functional units into clickable caged compounds. 
(A) Synthesis of a water-soluble caged PTX via the copper(I)-catalyzed Huisgen cyclization. (B) Structures of clickable caged compounds containing the HaloTag ligand for cellular targeting. <a href="https://www.jove.com/files/ftp_upload/60021/60021fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/60021/60021fig03.jpg" /> 
Figure 3: Photolysis of 2&#697;-glc-paBhcmoc-PTX (6). 
Samples (10 &#956;M) in K-MOPS solution (pH 7.2) were irradiated at 350 nm. (A) Typical HPLC traces for the photolysis of 6 (measured at 254 nm). Samples were analyzed at the specified irradiation time. (B) Time course for the photolysis of 6. Blue circles show the consumption of 6. The solid line shows the least-squares curve fit for a simple decaying exponential for 6. Red squares show the yield of PTX. The error bars represent the standard deviation (&#177;SD). <a href="https://www.jove.com/files/ftp_upload/60021/60021fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/60021/60021fig04.jpg" /> 
Figure 4: Fluorescence images of cultured mammalian cells incubated with paBhc-hex-FITC/Halo (8). 
Cells transfected with pcDNA3-Halo-EGFR were incubated with a 2 &#956;M solution of compound 8 at 37 &#176;C for 30 min. The images were obtained after repeated washing with PBS+. Mock-treated HEK293T cells (A: differential interference contrast (DIC) image and D: fluorescence image). HEK293T cells (B and E) and HeLa cells (C and F) transiently expressing Halo-EGFR (B and C: DIC images and E and F: fluorescence images). <a href="https://www.jove.com/files/ftp_upload/60021/60021fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/60021/60021fig05.jpg" /> 
Figure 5: Fluorescence images after UV irradiation of the CHO-K1 cells incubated with Bhc caged arachidonic acid. CHO-K1 cells were transfected with a fusion protein DGK&#947;-EGFP. 
(A) A fluorescence image of the transfected cells. (B) 100 s after the addition of a 10 &#956;M solution of arachidonic acid. (C) Cells were incubated with a 10 &#956;M solution of paBhc-AA (5) at 37 &#176;C for 5 min. (D) 100 s after 20-s UV irradiation (330&#8211;385 nm). <a href="https://www.jove.com/files/ftp_upload/60021/60021fig05large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>compounds</td>
			<td>&#955;max (nm)a</td>
			<td>&#949;max (M-1 cm-1)b</td>
			<td>&#981;disc</td>
			<td>&#949;&#981;disd</td>
			<td>Solubility (&#956;M)e</td>
		</tr>
		<tr>
			<td>PTX</td>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
			<td>1.0</td>
		</tr>
		<tr>
			<td>2&#39;-Bhcmoc-PTX</td>
			<td>340</td>
			<td>10500</td>
			<td>0.040</td>
			<td>400</td>
			<td>55</td>
		</tr>
		<tr>
			<td>2&#39;-paBhcmoc-PTX</td>
			<td>359</td>
			<td>9300</td>
			<td>0.059</td>
			<td>670</td>
			<td>8.3</td>
		</tr>
		<tr>
			<td>2&#39;-glc-Bhcmoc-PTX</td>
			<td>373</td>
			<td>12300</td>
			<td>0.14</td>
			<td>1280</td>
			<td>650</td>
		</tr>
		<tr>
			<td>Bhc-AA</td>
			<td>341</td>
			<td>10800</td>
			<td>0.038</td>
			<td>390</td>
			<td></td>
		</tr>
		<tr>
			<td>paBhc-AA</td>
			<td>366</td>
			<td>10300</td>
			<td>0.083</td>
			<td>750</td>
			<td></td>
		</tr>
	</tbody>
</table>
Table 1: Physical and photochemical properties of the clickable caged compounds. 
a. Absorption maximum (nm), b. Molar absorptivity at &#955;max (M&#8722;1 cm&#8722;1), c. Quantum yield of the disappearance of the starting materials at 350 nm, d. The product of molar absorptivity and the quantum yield of disappearance at 350 nm, e. The concentration of the saturated solution in K-MOPS (pH 7.2) (&#956;g mL&#8722;1).

Watch this Scientific Journal Video about Design, Synthesis, and Photochemical Properties of Clickable Caged Compounds at JoVE.com

Design, Synthesis, and Photochemical Properties of Clickable Caged Compounds

A protocol for the synthesis and measurement of the photochemical properties of modular caged compounds with clickable moieties is presented.

Caged compounds enable the photo-mediated manipulation of the cell physiology with high spatiotemporal resolution. However, the limited structural ...

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Chemistry

12.1K Views.  Toho University. A protocol for the synthesis and measurement of the photochemical properties of modular caged compounds with clickable moieties is presented.

Video: Design, Synthesis, and Photochemical Properties of Clickable Caged Compounds

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

The direct functionalization of C-H bonds is an important and long standing goal in organic chemistry. Such transformations can be very powerful in order to streamline synthesis by saving steps, time and material compared to conventional methods that require the introduction and removal of activating or directing groups. Therefore, the functionalization of C-H bonds is also attractive for green chemistry. Under oxidative conditions, two C-H bonds or one C-H and one heteroatom-H bond can be transformed to C-C and C-heteroatom bonds, respectively. Often these oxidative coupling reactions require synthetic oxidants, expensive catalysts or high temperatures. Here, we describe a two-step procedure to functionalize indole derivatives, more specifically tetrahydrocarbazoles, by C-H amination using only elemental oxygen as oxidant. The reaction uses the principle of C-H functionalization via Intermediate PeroxideS (CHIPS). In the first step, a hydroperoxide is generated oxidatively using visible light, a photosensitizer and elemental oxygen. In the second step, the N-nucleophile, an aniline, is introduced by Br&#248;nsted-acid catalyzed activation of the hydroperoxide leaving group. The products of the first and second step often precipitate and can be conveniently filtered off. The synthesis of a biologically active compound is shown.

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS

A two-step procedure for the synthesis of pharmaceutically active indole-derivatives by C-H functionalization with anilines is described, using photo- and Br&#248;nsted acid catalysis.

The direct functionalization of C-H bonds is an important and long standing goal in organic chemistry. Such transformations can be very powerful in order ...

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma sintering techniques. Polycrystalline ceramics possessing a unique morphology can be achieved by optimizing the process parameters, particularly spark plasma sintering heating rate. The phase and morphology of the synthesized ceramics were investigated in detail using X-ray diffraction, scanning electron microcopy and energy-dispersive X-ray spectroscopy. It was observed that the grains of these bulk Pr-doped SrTiO3 ceramics were enhanced with Pr-rich grain boundaries. Electronic and thermal transport properties were also investigated as a function of temperature and doping concentration. Such a microstructure was found to give rise to improved thermoelectric properties. Specifically, it resulted in a significant improvement in carrier mobility and the thermoelectric power factor. Simultaneously, it also led to a marked reduction in the thermal conductivity. As a result, a significant improvement (> 30%) in the thermoelectric figure of merit was achieved for the whole temperature range over all previously reported maximum values for SrTiO3-based ceramics. This synthesis demonstrates the steps for the preparation of bulk polycrystalline ceramics of non-uniformly Pr-doped SrTiO3.

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma ...

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

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 properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

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

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

Synthesis and Characterization of Fe-doped Aluminosilicate Nanotubes with Enhanced Electron Conductive Properties

The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe aims at lowering the band gap of imogolite, an insulator with the chemical formula (OH)3Al2O3SiOH, and at modifying its adsorption properties towards azo-dyes, an important class of organic pollutants of both wastewater and groundwater.
Fe-doped nanotubes are obtained in two ways: by direct synthesis, where FeCl3 is added to an aqueous mixture of the Si and Al precursors, and by post-synthesis loading, where preformed nanotubes are put in contact with a FeCl3&#8226;6H2O aqueous solution. In both synthesis methods, isomorphic substitution of Al3+ by Fe3+ occurs, preserving the nanotube structure. Isomorphic substitution is indeed limited to a mass fraction of ~1.0% Fe, since at a higher Fe content (i.e., a mass fraction of 1.4% Fe), Fe2O3 clusters form, especially when the loading procedure is adopted. The physicochemical properties of the materials are studied by means of X-ray powder diffraction (XRD), N2 sorption isotherms at -196 &#176;C, high resolution transmission electron microscopy (HRTEM), diffuse reflectance (DR) UV-Vis spectroscopy, and &#950;-potential measurements. The most relevant result is the possibility to replace Al3+ ions (located on the outer surface of the nanotubes) by post-synthesis loading on preformed imogolite without perturbing the delicate hydrolysis equilibria occurring during nanotube formation. During the loading procedure, an anionic exchange occurs, where Al3+ ions on the outer surface of the nanotubes are replaced by Fe3+ ions. In Fe-doped aluminosilicate nanotubes, isomorphic substitution of Al3+ by Fe3+ is found to affect the band gap of doped imogolite. Nonetheless, Fe3+ sites on the outer surface of nanotubes are able to coordinate organic moieties, like the azo-dye Acid Orange 7, through a ligand-displacement mechanism occurring in an aqueous solution.

Here, we present a protocol to synthesize and characterize Fe-doped aluminosilicate nanotubes. The materials are obtained by either sol-gel synthesis upon addition of FeCl3&#8226;6H2O to the mixture containing the Si and Al precursors or by post-synthesis ionic exchange of preformed aluminosilicate nanotubes.

The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) with a 4.6 nm pore size, and ordered silica porous matrix, SBA-15, with a 5.3 nm pore size. This work describes the surface properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the differently ordered porous materials with similar pore sizes. For this purpose, OMC and SBA-15 with highly ordered nanoporous structures are synthesized via impregnation of the silica matrix by applying a carbon precursor and by the sol-gel method, respectively. The porous structure of investigated systems is characterized by an N2 adsorption-desorption analysis at 77 K. To determine the electrochemical character of the surface of synthesized materials, potentiometric titration measurements are conducted; the obtained results for OMC shows a significant pHpzc shift toward the higher values of pH, relative to SBA-15. This suggests that investigated OMC has surface properties related to oxygen-based functional groups. To describe the surface properties of the materials, the contact angles of liquids penetrating the studied porous beds are also determined. The capillary rise method has confirmed the increased wettability of the silica walls relative to the carbon walls and an influence of the pore roughness on the fluid/wall interactions, which is much more pronounced for silica than for carbon mesopores. We have also studied the melting behavior of D2O confined in OMC and SBA-15 by applying the dielectric method. The results show that the depression of the melting temperature of D2O in the pores of OMC is about 15 K higher relative to the depression of the melting temperature in SBA-15 pores with a comparable 5 nm size. This is caused by the influence of adsorbate/adsorbent interactions of the studied matrices.

Here we report the synthesis and characterization of ordered nanoporous carbon (with a 4.6 nm pore size) and SBA-15 (with a 5.3 nm pore size). The work describes the surface and textural properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the materials.

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) ...

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 ...

Hierarchical and Programmable One-Pot Oligosaccharide Synthesis

This article presents a general experimental protocol for programmable one-pot oligosaccharide synthesis and demonstrates how to use Auto-CHO software for generating potential synthetic solutions. The programmable one-pot oligosaccharide synthesis approach is designed to empower fast oligosaccharide synthesis of large amounts using thioglycoside building blocks (BBLs) with the appropriate sequential order of relative reactivity values (RRVs). Auto-CHO is a cross-platform software with a graphical user interface that provides possible synthetic solutions for programmable one-pot oligosaccharide synthesis by searching a BBL library (containing about 150 validated and &#62;50,000 virtual BBLs) with accurately predicted RRVs by support vector regression. The algorithm for hierarchical one-pot synthesis has been implemented in Auto-CHO and uses fragments generated by one-pot reactions as new BBLs. In addition, Auto-CHO allows users to give feedback for virtual BBLs to keep valuable ones for further use. One-pot synthesis of stage-specific embryonic antigen 4 (SSEA-4), which is a pluripotent human embryonic stem cell marker, is demonstrated in this work.

This protocol demonstrates how to use the Auto-CHO software for hierarchical and programmable one-pot synthesis of oligosaccharides. It also describes the general procedure for RRV determination&#160;experiments and one-pot glycosylation of SSEA-4.

This article presents a general experimental protocol for programmable one-pot oligosaccharide synthesis and demonstrates how to use Auto-CHO software for ...