Financial support was provided by IIT Gandhinagar and Government of India. We would also like to thank the extramural funding provided by Science and Engineering Research Board (SERB) (File no. EMR/2015/002462).

1. Synthesis of the photosensitizer-catalyst hybrid
<ol>
	<li>Synthesis of catalyst precursor Co(dmg)2Cl2 complex 
	NOTE: This complex was synthesized following the modified version of the reported procedure29.
	<ol>
		<li>Dissolve 232 mg (1 mmol) of dimethylglyoxime (dmg) ligand (two equivalents in this reaction) in 27 mL of acetone.</li>
		<li>Dissolve 118 mg (0.5 mmol) of CoCl2&#8729;6H2O (one equivalent in this reaction) in 3 mL of deionized water separately that produces a pink color solution.</li>
		<li>Add the aqueous CoCl2 solution drop wise to the acetone solution containing dmg with continuous stirring at room temperature.</li>
		<li>Closely monitor the change in the solution color, which will sequentially turn to bluish green color following the metal addition.</li>
		<li>Continue the reaction for 2 h.</li>
		<li>Filter the reaction mixture through a Grade 40 filter paper and keep the filtrate at 4 &#176;C overnight.</li>
		<li>The next day, obtain the green colored precipitate of Co(dmg)2Cl2 complex (cobaloxime) from the solution and filter it through grade 40 filter paper.</li>
		<li>Dry the sample under air.</li>
	</ol>
	</li>
	<li>Synthesis of the photosensitizer (PS)-cobaloxime hybrid 
	NOTE: The stilbene based photosensitizer (PS) was synthesized as per the reported method28. The following steps were followed for the PS-catalyst hybrid complex synthesis.
	<ol>
		<li>Add 100 mg (0.277 mmol) of cobaloxime (one equivalent) (synthesized in Step 1) in 5 mL of methanol. It will form a green suspension.</li>
		<li>Add 38 &#181;L (0.277 mmol) of triethylamine (TEA) base (one equivalent) to the green suspension with continuous stirring. The solution will turn transparent brown after within 1 min.</li>
		<li>Add 65 mg (0.277 mmol) of solid stilbene dye (one equivalent) to the previously mentioned TEA added cobalt solution in methanol.</li>
		<li>Continue the stirring for 3 h. Closely monitor the change in the solution, which will sequentially produce the reddish-brown precipitate of the PS-cobaloxime hybrid.</li>
		<li>Filter the reddish-brown precipitate with Grade 40 filter paper and wash it with copious amount of cold methanol (20 mL).</li>
		<li>Dissolve the precipitate in chloroform (10 mL) and collect the reddish-brown filtrate.</li>
		<li>Evaporate the filtrate under reduced pressure using a rotavapor at room temperature.</li>
		<li>Collect the solid reddish-brown product [Observed yield: 76 mg (65%)].</li>
		<li>Recrystallize the product from chloroform solution at room temperature, where the chloroform evaporates slowly to produce reddish-brown crystals of the complex.</li>
	</ol>
	</li>
</ol>
2. Characterization of the photosensitizer-cobaloxime hybrid
<ol>
	<li>NMR characterization
	<ol>
		<li>Dissolve 5.0 mg of the purified PS-Cobaloxime hybrid complex in 650 &#956;L of d6-DMSO.</li>
		<li>Record the 1H NMR in NMR spectrometer at room temperature. 
		NOTE: 1H NMR signals, in &#948; (ppm) units with the corresponding number of protons, their identity, and the splitting pattern in parentheses (s = singlet, d = doublet, m = multiplet), are as following: 1H NMR: 2.34 (12H, -dmg-CH3, s), 2.97 (6H, -dye-N-(CH3)2, s), 6.74 (2H, dye-aromatic, d), 6.84 (1H, allylic-H, d), 7.48 (5H, four dye-aromatic, one allylic-H, m), 7.82(2H, dye-aromatic, d), 18.47(2H,dmg-NOH, s).</li>
	</ol>
	</li>
	<li>UV-Vis spectroscopy
	<ol>
		<li>Prepare a 1.0 mM solution of the PS-cobaloxime complex in N,N&#8242;-dimethylformamide (DMF) by adding the appropriately weighed amount of the complex in the solvent.</li>
		<li>Dilute the solution 10 times with blank DMF to generate 0.1 mM solution of the hybrid complex in DMF.</li>
		<li>Further dilute it 5 times with blank DMF to generate 20 &#956;M solution of the hybrid complex in DMF.</li>
		<li>Record the optical spectra of the 20 &#956;M PS-cobaloxime complex solution using a spectrophotometer. 
		NOTE: UV-Vis peaks (&#955;/nm), with the corresponding molar extinction coefficient (&#949; /M-1cm-1) in parentheses, are as follows: 266 (13400) and 425 (14600).</li>
	</ol>
	</li>
	<li>Single crystal structure determination
	<ol>
		<li>Prepare a concentrated 0.2 M sample of the PS-catalyst hybrid complex in 5 mL of chloroform. Grow reddish-brown (cubic) crystals of the complex from that chloroform solution over 3 days.</li>
		<li>Select a suitable crystal of the complex and mount on a cryo-loop using cryoprotectant (e.g., Paratone oil).</li>
		<li>Collect the single crystal diffraction data for the hybrid complex at 298 K on the diffractometer.</li>
		<li>Apply the empirical absorption correction to the data by employing the multi-scan method in SADABS programming30.</li>
		<li>Resolve the structure by direct methods with SHELXS-97 and refine by the full matrix least square methods on F2 using the SHELXL-201431.</li>
	</ol>
	</li>
	<li>Electrochemical studies
	<ol>
		<li>Sample preparation
		<ol>
			<li>Prepare a 1 mM solution of the PS-catalyst hybrid complex in HPLC grade DMF containing 0.1 M tetra-N-butyl ammonium fluoride (n-Bu4N+F&#8722;/TBAF).</li>
			<li>Place 2 mL of the sample solution prepared in step 1 in the electrochemical cell (volume 5 mL).</li>
			<li>Purge N2 gas through the solution for 30 min to remove oxygen.</li>
		</ol>
		</li>
		<li>Electrode preparation
		<ol>
			<li>Polish the 1 mm diameter glassy carbon-disc working electrode with 0.25 &#956;m alumina paste prepared in water on a polishing pad.</li>
			<li>Rinse the polished electrode thoroughly with a copious amount of deionized water.</li>
			<li>Place the clean working electrode in the electrochemical cell.</li>
			<li>Place the Ag/AgCl (in 1.0 M AgNO3) reference electrode and the platinum (Pt)-wire counter electrode in the electrochemical cell.</li>
			<li>Connect all the electrodes accordingly to the potentiostat.</li>
		</ol>
		</li>
		<li>Collecting data
		<ol>
			<li>Stop the N2 gas purging before the electrochemical experiment.</li>
			<li>Keep a continuous flow of N2 above the sample solution in the electrochemical cell.</li>
			<li>Record cyclic voltammograms (CV) of the sample starting from the anodic direction to cathodic direction with appropriate scan rate (0.1 V/s scan rate was used in this experiment).</li>
			<li>Repeat the above experiment by adding appropriate amounts of water (30% water in DMF) and trifluoroacetic acid (TFA) (8 &#956;L of 10x diluted neat TFA), respectively.</li>
			<li>Add ferrocene to the sample solution and record the corresponding CV. Adjust the potential scale with the ferrocene couple (FeCp2+/0 = 0V vs. Ferrocene) for all the collected data. Thus, all the potential values mentioned in this work was internally referenced against Ferrocene couple.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
3. Catalytic H2 production by the photosensitizer-catalyst hybrid in sunlight
<ol>
	<li>Photocatalytic H2 production by the PS-catalyst hybrid complex
	<ol>
		<li>Prepare 0.2 mM PS-catalyst hybrid complex in 10 mL of 70:30 DMF water (pH 7, 0.1 MES buffer) in a two-neck test tube.</li>
		<li>Add 1 mL of triethanolamine (TEOA) as the sacrificial electron donor to the sample solution.</li>
		<li>Close the two openings of the test tube with the air-tight septum.</li>
		<li>Connect this setup with the H2 detector with appropriate tubing connections. 
		NOTE: The H2 detector has two tube connections. One of them acts as the input that goes through an in-built detector to measure the amount of H2 (in ppm units) present in the sample. The measured gas sample then connects back to the reaction vessel by the output tubing.</li>
		<li>Place the set up under sunlight for 30 min and monitor the H2 production rate via the detector.</li>
	</ol>
	</li>
	<li>Monitoring the solar-driven H2 production via gas chromatography (GC)
	<ol>
		<li>Collect 1 mL of headspace gas via gas-tight syringe.</li>
		<li>Inject the collected gas in the gas chromatography (GC) instrument.</li>
		<li>Monitor the resulted gas chromatograph.</li>
		<li>Inject 1 mL of headspace gas collected from a control sample placed under dark.</li>
		<li>Inject 1 mL of gas from a calibrated standard gas mixture containing 1% H2.</li>
	</ol>
	</li>
</ol>

The authors have nothing to disclose.

The organic photosensitizer stilbene moiety was successfully incorporated into the cobaloxime core via the axial pyridine linkage (Figure 1). This strategy allowed us to devise a photosensitizer-cobaloxime hybrid complex C1. The presence of both the oxime and organic dye in the same molecular framework was evident from the single crystal structure of the C1 (Figure 4). The phenyl and pyridine functionalities of the stilbene moti...

In the modern world, fossil fuels such as coal, oil, and natural gas supply a majority share of the energy. However, they produce copious amount of CO2 during the energy harvesting to negatively impact the global climate1. In coming years, a steep rise in energy demand is predicted worldwide following the continuous growth of population and constant improvement in human lifestyle. Thus, there is an active search for a suitable alternative energy resource to match the global energy requirement. Renewable energy resources like solar, wind, and tidal power have emerged as one of the best solutions due to their environment-friendly zero carbon energy transduction process2. However, the intermittent nature of these energy resources has so far limited their extensive application. A possible solution of this problem can be found in biology; solar energy is efficiently transformed into chemical energy during photosynthesis3. Following this clue, researchers have developed artificial photosynthetic strategies for storing solar energy into chemical bonds following a number of small molecule activation reactions4,5. The H2 molecule has been considered one of the most appealing chemical vectors due to their high energy density and simplicity of their chemical transformation6,7.
The presence of a photosensitizer and a H2 production catalyst are essential for an active solar-driven H2 production setup. Here in this work, we will focus on the cobalt-based molecular complex cobaloxime for the catalytic segment. Typically, a hexa-coordinated cobalt center is bound in a square planar N4 geometry, derived from the dimethylglyoxime (dmg) ligands, in cobaloximes. The complementary Cl- ions, solvent molecules (such as water or acetonitrile) or pyridine derivatives ligate in the residual axial positions8. Cobaloximes are long known for active H2 production electrocatalysis and their reactivity can be tuned by appending variable functionalities on the axial pyridine9,10,11,12. The relatively uncomplicated syntheses, oxygen tolerance under catalytic conditions, and moderate catalytic response of cobaloximes have prompted researchers to explore their photocatalytic H2 production reactivity. The Hawecker group was the pioneer in demonstrating the light-driven H2 production activity of cobaloximes by utilizing Ru(polypyridyl)-based photosensitizers13. Eisenberg and his coworkers utilized platinum (Pt)-based inorganic photosensitizers to induce photocatalytic H2 production in tandem with cobaloxime catalysts14,15. Later, the Che group utilized organo-gold photosensitizer to replicate similar activity16. Fontecave and Artero expanded the range of photosensitizers by applying iridium (Ir)-based molecules17. The practical applications of these photocatalytic systems were heading towards a roadblock due to the use of expensive metal-based photosensitizers. The Eisenberg and Sun research groups have countered that by independently devising organic dye-based photo-driven H2 production systems18,19. Despite the successful photo-driven H2 production by all these systems, it was observed that the overall catalytic turnovers were relatively slow20. In all these cases, the photosensitizer and cobaloxime molecules were added as separate moieties in the solution, and the lack of direct communication between them might have hindered the overall efficiency of the system. A number of photosensitizer-cobaloxime dyads were developed to rectify this issue, where a variety of photosensitizers were directly linked with the cobaloxime core via the axial pyridine ligand21,22,23,24,25,26. Sun and co-workers were even successful in developing a noble-metal free device by introducing a Zn-porphyrin motif as a photosensitizer24. Recently, Ott and coworkers have successfully incorporated the cobaloxime catalyst within an metal organic framework (MOF) that displayed photocatalytic H2 production in the presence of organic dye27. However, the inclusion of the high molecular weight photosensitizers into the cobaloxime framework reduced the water solubility while affecting the long-term stability of the dyads under catalytic conditions. The stability of the active dyads under aqueous conditions during the catalysis is crucial as the omnipresent water is an attractive source of protons during the catalysis. Thus, there is a serious need for developing an aqueous soluble, air-stable photosensitizer-cobaloxime dyad system to establish an efficient and economical photo-driven H2 production setup.
Here in this work, we have anchored a stilbene-based organic dye28 as photosensitizer to the cobaloxime core via the axial pyridine linker (Figure 1). The light molecular weight of the dye ensured improved water solubility of the dyad. This stilbene-cobaloxime hybrid molecule was characterized in detail via optical and 1H NMR spectroscopy along with its single crystal structure elucidation. The electrochemical data revealed the active electrocatalytic H2 production by the cobaloxime motif even with the appended organic dye. This hybrid complex exhibited significant photo-driven H2 production when exposed to direct sunlight in the presence of an appropriate sacrificial electron donor in a 30:70 water/DMF (N,N&#8242;-dimethylformamide) solution without any degradation of the hybrid structure as complemented by optical spectroscopy studies. A simple photocatalytic device, consisting of a H2 detector, was employed during the photocatalysis of the hybrid complex that demonstrated continuous production of H2 gas under aqueous aerobic condition without any preliminary lag period. Thus, this hybrid complex has the potential to become the base for developing the next generation of solar-driven H2 production catalysts for efficient renewable energy utilization.

<table>
	<tbody>
		<tr>
			<td>1 mm diameter glassy carbon disc electrode</td>
			<td>ALS Co., Limited, Japan</td>
			<td>2412</td>
			<td>1</td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>SD fine chemicals</td>
			<td>25214L10</td>
			<td>27 mL</td>
		</tr>
		<tr>
			<td>Ag/AgCl reference electrode</td>
			<td>ALS Co., Limited, Japan</td>
			<td>12171</td>
			<td>1</td>
		</tr>
		<tr>
			<td>Co(dmg)2Cl2</td>
			<td>Lab synthesised</td>
			<td>NA</td>
			<td>100 mg</td>
		</tr>
		<tr>
			<td>CoCl2.6H2O</td>
			<td>Sigma Aldrich</td>
			<td>C2644</td>
			<td>118 mg</td>
		</tr>
		<tr>
			<td>d6 dmso</td>
			<td>Leonid Chemicals</td>
			<td>D034EAS</td>
			<td>650 &#181;L</td>
		</tr>
		<tr>
			<td>Deionized water from water purification system</td>
			<td>NA</td>
			<td>NA</td>
			<td>500 mL</td>
		</tr>
		<tr>
			<td>Dimethyl formamide</td>
			<td>SRL Chemicals</td>
			<td>93186</td>
			<td>5 mL</td>
		</tr>
		<tr>
			<td>Dimethyl glyoxime</td>
			<td>Sigma Aldrich</td>
			<td>40390</td>
			<td>232 mg</td>
		</tr>
		<tr>
			<td>Gas-tight syringe</td>
			<td>SGE syringe Leur lock</td>
			<td>21964</td>
			<td>1</td>
		</tr>
		<tr>
			<td>MES Buffer</td>
			<td>Sigma</td>
			<td>M8250</td>
			<td>195 mg</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Finar</td>
			<td>67-56-1</td>
			<td>15 mL</td>
		</tr>
		<tr>
			<td>Platinum counter electrode</td>
			<td>ALS Co., Limited, Japan</td>
			<td>2222</td>
			<td>1</td>
		</tr>
		<tr>
			<td>Stilbene Dye</td>
			<td>Lab synthesised</td>
			<td>NA</td>
			<td>65 mg</td>
		</tr>
		<tr>
			<td>TBAF(Tetra-n-butylammonium fluoride)</td>
			<td>TCI Chemicals</td>
			<td>T1338</td>
			<td>20 mg</td>
		</tr>
		<tr>
			<td>Triethanolamine</td>
			<td>Finar</td>
			<td>102-71-6</td>
			<td>1 mL</td>
		</tr>
		<tr>
			<td>Triethylamine</td>
			<td>Sigma Aldrich</td>
			<td>T0886</td>
			<td>38 &#181;L</td>
		</tr>
		<tr>
			<td>Trifluoroacetic acid</td>
			<td>Finar</td>
			<td>76-05-1</td>
			<td>10 &#181;L</td>
		</tr>
		<tr>
			<td>Whatman filter paper</td>
			<td>GE Healthcare</td>
			<td>1001125</td>
			<td>2</td>
		</tr>
	</tbody>
</table>

developing photosensitizer-cobaloxime hybrids for solar-driven h2 production in aqueous aerobic conditions

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number of photoactive assemblies have emerged where a photosensitizer and cobaloxime-based H2 production catalysts work in tandem to convert light energy into the H-H chemical bonds. However, the long-term instability of these assemblies and the need for hazardous proton sources have limited their usage. Here, in this work, we have integrated a stilbene-based organic dye into the periphery of a cobaloxime core via a distinct axial pyridine linkage. This strategy allowed us to develop a photosensitizer-catalyst hybrid structure with the same molecular framework. In this article, we have explained the detailed procedure of the synthesis of this hybrid molecule in addition to its comprehensive chemical characterization. The structural and optical studies have exhibited an intense electronic interaction between the cobaloxime core and the organic photosensitizer. The cobaloxime was active for H2 production even in the presence of water as the proton source. Here, we have developed a simple airtight system connected with an online H2 detector for the investigation of the photocatalytic activity by this hybrid complex. This photosensitizer-catalyst dyad present in the experimental setup continuously produced H2 once it was exposed in the natural sunlight. This photocatalytic H2 production by the hybrid complex was observed in aqueous/organic mixture media in the presence of a sacrificial electron donor under complete aerobic conditions. Thus, this photocatalysis measurement system along with the photosensitizer-catalyst dyad provide valuable insight for the development of next generation photocatalytic H2 production devices.

In this work, a stilbene photosensitizer-cobaloxime hybrid complex (C1) was synthesized successfully by anchoring the organic dye (L1) derived pyridine motif as the axial ligand to the cobalt core. The 1H NMR data of the hybrid complex clearly demonstrated the presence of both the cobaloxime and organic dye protons in the same complex. As shown in Figure 2, the up-fielded aliphatic region highlighted the presence of both oxime-bound methyl and sti...

Watch this Scientific Journal Video about Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions at JoVE.com

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

We have directly incorporated a stilbene-based organic dye into a cobaloxime core to generate a photosensitizer-catalyst dyad for photocatalytic H2 production. We have also developed a simple experimental setup for evaluating the light-driven H2 production by photocatalytic assemblies.

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number ...

developing-photosensitizer-cobaloxime-hybrids-for-solar-driven-h2

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8.2K Views.  Indian Institute of Technology Gandhinagar. We have directly incorporated a stilbene-based organic dye into a cobaloxime core to generate a photosensitizer-catalyst dyad for photocatalytic H2 production. We have also developed a simple experimental setup for evaluating the light-driven H2 production by photocatalytic assemblies.

Video: Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies

Physical interactions among the lipid-embedded alpha-helical domains of membrane proteins play a crucial role in folding and assembly of membrane protein complexes and in dynamic processes such as transmembrane (TM) signaling and regulation of cell-surface protein levels. Understanding the structural features driving the association of particular sequences requires sophisticated biophysical and biochemical analyses of TM peptide complexes. However, the extreme hydrophobicity of TM domains makes them very difficult to manipulate using standard peptide chemistry techniques, and production of suitable study material often proves prohibitively challenging. Identifying conditions under which peptides can adopt stable helical conformations and form complexes spontaneously adds a further level of difficulty. Here we present a procedure for the production of homo- or hetero-dimeric TM peptide complexes from materials that are expressed in E. coli, thus allowing incorporation of stable isotope labels for nuclear magnetic resonance (NMR) or non-natural amino acids for other applications relatively inexpensively. The key innovation in this method is that TM complexes are produced and purified as covalently associated (disulfide-crosslinked) assemblies that can form stable, stoichiometric and homogeneous structures when reconstituted into detergent, lipid or other membrane-mimetic materials. We also present carefully optimized procedures for expression and purification that are equally applicable whether producing single TM domains or crosslinked complexes and provide advice for adapting these methods to new TM sequences.

Biophysical and biochemical studies of interactions among membrane-embedded protein domains face many technical challenges, the first of which is obtaining appropriate study material. This article describes a protocol for producing and purifying disulfide-stabilized transmembrane peptide complexes that are suitable for structural analysis by solution nuclear magnetic resonance (NMR) and other analytical applications.

Physical  interactions among the lipid-embedded alpha-helical domains of membrane  proteins play a crucial role in folding and assembly of membrane ...

A Guided Materials Screening Approach for Developing Quantitative Sol-gel Derived Protein Microarrays

Microarrays have found use in the development of high-throughput assays for new materials and discovery of small-molecule drug leads. Herein we describe a guided material screening approach to identify sol-gel based materials that are suitable for producing three-dimensional protein microarrays. The approach first identifies materials that can be printed as microarrays, narrows down the number of materials by identifying those that are compatible with a given enzyme assay, and then hones in on optimal materials based on retention of maximum enzyme activity. This approach is applied to develop microarrays suitable for two different enzyme assays, one using acetylcholinesterase and the other using a set of four key kinases involved in cancer. In each case, it was possible to produce microarrays that could be used for quantitative small-molecule screening assays and production of dose-dependent inhibitor response curves. Importantly, the ability to screen many materials produced information on the types of materials that best suited both microarray production and retention of enzyme activity. The materials data provide insight into basic material requirements necessary for tailoring optimal, high-density sol-gel derived microarrays.

A guided material screening approach to develop sol-gel derived protein doped microarrays using an emerging pin-printing method of fabrication is described. This methodology is demonstrated through the development of acetylcholinesterase and multikinase microarrays, which are used for cost-effective small-molecule screening.

Microarrays have found use in the development of high-throughput assays for new materials and discovery of small-molecule drug leads. Herein we describe a ...

Thin-layer Chromatographic (TLC) Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth.&#160;The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions.&#160;This paper describes standard protocols for TLC and contact bioautography&#160;with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light.&#160;Zones are cut out and incubated face down onto agar inoculated with the test microorganism.&#160;Inhibitory bands are visualized by staining the agar plates with tetrazolium red.&#160;The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen.&#160;The TLC methods apply to many types of plant extracts&#160;and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species.

Thin-layer Chromatographic TLC Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

Methods are described for thin-layer chromatographic (TLC) separation of plant extracts and contact bioautography to identify antibacterial metabolites. The methods are applied to the screening of red clover phenolic compounds inhibiting hyper&#160;ammonia-producing bacteria (HAB) native to the bovine rumen.

A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the ...

A Protocol for the Production of Gliadin-cyanoacrylate Nanoparticles for Hydrophilic Coating

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray coating. These nanoparticles are produced by the polymerization reaction of alkyl cyanoacrylate on the surface of cereal protein (gliadin) molecules. Alkyl cyanoacrylate is a monomer that instantly polymerizes at RT when it is applied to the surface of materials. Its polymerization reaction is initiated by the trace amounts of weakly basic or nucleophilic species on the surface, including moisture. Once polymerized, the polymerized alkyl cyanoacrylates show a strong affinity with the object materials because nitrile groups are in the backbone of poly (alkyl cyanoacrylate). Proteins also work as initiator for this polymerization because they contain amine groups that can initiate the polymerization of cyanoacrylate. If aggregated protein is used as an initiator, protein aggregate is surrounded by the hydrophobic poly(alkyl cyanoacrylate) chains after the polymerization reaction of alkyl cyanoacrylate. By controlling the experimental condition, particles in the nanometer range are produced. The produced nanoparticles readily adsorb to the surface of most materials including glass, metals, plastics, wood, leather, and fabrics. When the surface of a material is sprayed with the produced nanoparticle suspension and rinsed with water, the micellar structure of nanoparticle changes its conformation, and the hydrophilic proteins are exposed to the air. As a result, the nanoparticle-coated surface changes to hydrophilic.

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic. The produced nanoparticle is an assembly of gliadin-cyanoacrylate diblock copolymers. Spray coating with the produced nanoparticle changes the surface of target material to a hydrophilic surface.

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray ...

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Major and severe accidents have occurred three times in nuclear power plants (NPPs), at Three Mile Island (USA, 1979), Chernobyl (former USSR, 1986) and Fukushima (Japan, 2011). Research on the causes, dynamics, and consequences of these mishaps has been performed in a few laboratories worldwide in the last three decades. Common goals of such research activities are: the prevention of these kinds of accidents, both in existing and potential new nuclear power plants; the minimization of their eventual consequences; and ultimately, a full understanding of the real risks connected with NPPs. At the European Commission Joint Research Centre&#39;s Institute for Transuranium Elements, a laser-heating and fast radiance spectro-pyrometry facility is used for the laboratory simulation, on a small scale, of NPP core meltdown, the most common type of severe accident (SA) that can occur in a nuclear reactor as a consequence of a failure of the cooling system. This simulation tool permits fast and effective high-temperature measurements on real nuclear materials, such as plutonium and minor actinide-containing fission fuel samples. In this respect, and in its capability to produce large amount of data concerning materials under extreme conditions, the current experimental approach is certainly unique. For current and future concepts of NPP, example results are presented on the melting behavior of some different types of nuclear fuels: uranium-plutonium oxides, carbides, and nitrides. Results on the high-temperature interaction of oxide fuels with containment materials are also briefly shown.

We present experiments in which real nuclear fuel, cladding, and containment materials are laser heated to temperatures beyond 3,000 K while their behavior is studied by radiance spectroscopy and thermal analysis. These experiments simulate, on a laboratory scale, the formation of a lava-phase following a nuclear reactor core meltdown.

Major and severe accidents have occurred three times in nuclear power plants (NPPs), at Three Mile Island (USA, 1979), Chernobyl (former USSR, 1986) and ...

Detection and Quantification of Plasmodium falciparum in Aqueous Red Blood Cells by Attenuated Total Reflection Infrared Spectroscopy and Multivariate Data Analysis

We demonstrate a method of quantification and detection of parasites in aqueous red blood cells (RBCs) by using a simple benchtop Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectrometer in conjunction with Multivariate Data Analysis (MVDA). 3D7 P. falciparum were cultured to 10% parasitemia ring stage parasites and used to spike fresh donor isolated RBCs to create a dilution series between 0&#8211;1%. 10 &#181;L of each sample were placed onto the center of the ATR diamond window to acquire the spectrum. The sample data was treated to improve the signal to noise ratio and to remove the contribution of water, and then the second derivative was applied to resolve spectral features. The data were then analyzed using two types of MVDA: first Principal Component Analysis (PCA) to determine any outliers and then Partial Least Squares Regression (PLS-R) to build the quantification model.

Detection and Quantification of Plasmodium falciparum in Aqueous Red Blood Cells by Attenuated Total Reflection Infrared Spectroscopy and Multivariate Data Analysis

Here, we present a protocol for the detection and quantification of Plasmodium falciparum in infected aqueous red blood cells using an attenuated total reflection infrared spectrometer and multivariate data analysis.

We demonstrate a method of quantification and detection of parasites in aqueous red blood cells (RBCs) by using a simple benchtop Attenuated Total ...

Automation of a Positron-emission Tomography (PET) Radiotracer Synthesis Protocol for Clinical Production

The development of new positron-emission tomography (PET) tracers is enabling researchers and clinicians to image an increasingly wide array of biological targets and processes. However, the increasing number of different tracers creates challenges for their production at radiopharmacies. While historically it has been practical to dedicate a custom-configured radiosynthesizer and hot cell for the repeated production of each individual tracer, it is becoming necessary to change this workflow. Recent commercial radiosynthesizers based on disposable cassettes/kits for each tracer simplify the production of multiple tracers with one set of equipment by eliminating the need for custom tracer-specific modifications. Furthermore, some of these radiosynthesizers enable the operator to develop and optimize their own synthesis protocols in addition to purchasing commercially-available kits. In this protocol, we describe the general procedure for how the manual synthesis of a new PET tracer can be automated on one of these radiosynthesizers and validated for the production of clinical-grade tracers. As an example, we use the ELIXYS radiosynthesizer, a flexible cassette-based radiochemistry tool that can support both PET tracer development efforts, as well as routine clinical probe manufacturing on the same system, to produce [18F]Clofarabine ([18F]CFA), a PET tracer to measure in vivo deoxycytidine kinase (dCK) enzyme activity. Translating a manual synthesis involves breaking down the synthetic protocol into basic radiochemistry processes that are then translated into intuitive chemistry &#34;unit operations&#34; supported by the synthesizer software. These operations can then rapidly be converted into an automated synthesis program by assembling them using the drag-and-drop interface. After basic testing, the synthesis and purification procedure may require optimization to achieve the desired yield and purity. Once the desired performance is achieved, a validation of the synthesis is carried out to determine its suitability for the production of the radiotracer for clinical use.

Automation of a Positron-emission Tomography PET Radiotracer Synthesis Protocol for Clinical Production

Positron-emission tomography (PET) imaging sites that are involved in multiple early clinical research trials need robust and versatile radiotracer manufacturing capabilities. Using the radiotracer [18F]Clofarabine as an example, we illustrate how to automate the synthesis of a radiotracer using a flexible, cassette-based radiosynthesizer and validate the synthesis for clinical use.

The development of new positron-emission tomography (PET) tracers is enabling researchers and clinicians to image an increasingly wide array of biological ...

Experimental Methods for Efficient Solar Hydrogen Production in Microgravity Environment

Long-term space flights and cis-lunar research platforms require a sustainable and light life-support hardware which can be reliably employed outside the Earth's atmosphere. So-called 'solar fuel' devices, currently developed for terrestrial applications in the quest for realizing a sustainable energy economy on Earth, provide promising alternative systems to existing air-revitalization units employed on the International Space Station (ISS) through photoelectrochemical water-splitting and hydrogen production. One obstacle for water (photo-) electrolysis in reduced gravity environments is the absence of buoyancy and the consequential, hindered gas bubble release from the electrode surface. This causes the formation of gas bubble froth layers in proximity to the electrode surface, leading to an increase in ohmic resistance and cell-efficiency loss due to reduced mass transfer of substrates and products to and from the electrode. Recently, we have demonstrated efficient solar hydrogen production in microgravity environment, using an integrated semiconductor-electrocatalyst system with p-type indium phosphide as the light-absorber and a rhodium electrocatalyst. By nanostructuring the electrocatalyst using shadow nanosphere lithography and thereby creating catalytic 'hot spots' on the photoelectrode surface, we could overcome gas bubble coalescence and mass transfer limitations and demonstrated efficient hydrogen production at high current densities in reduced gravitation. Here, the experimental details are described for the preparations of these nanostructured devices and further on, the procedure for their testing in microgravity environment, realized at the Bremen Drop Tower during 9.3 s of free fall.

Efficient solar-hydrogen production has recently been realized on functionalized semiconductor-electrocatalyst systems in a photoelectrochemical half-cell in microgravity environment at the Bremen Drop Tower. Here, we report the experimental procedures for manufacturing the semiconductor-electrocatalyst device, details of the experimental set-up in the drop capsule and the experimental sequence during free fall.

Long-term space flights and cis-lunar research platforms require a sustainable and light life-support hardware which can be reliably employed outside the ...

Nanoparticle Tracking Analysis of Gold Nanoparticles in Aqueous Media through an Inter-Laboratory Comparison

In the field of nanotechnology, analytical characterization plays a vital role in understanding the behavior and toxicity of nanomaterials (NMs). Characterization needs to be thorough and the technique chosen should be well-suited to the property to be determined, the material being analyzed and the medium in which it is present. Furthermore, the instrument operation and methodology need to be well-developed and clearly understood by the user to avoid data collection errors. Any discrepancies in the applied method or procedure can lead to differences and poor reproducibility of obtained data. This paper aims to clarify the method to measure the hydrodynamic diameter of gold nanoparticles by means of Nanoparticle Tracking Analysis (NTA). This study was carried out as an inter-laboratory comparison (ILC) amongst seven different laboratories to validate the standard operating procedure&#8217;s performance and reproducibility. The results obtained from this ILC study reveal the importance and benefits of detailed standard operating procedures (SOPs), best practice updates, user knowledge, and measurement automation.

The protocol described here aims to measure the hydrodynamic diameter of spherical nanoparticles, more specifically gold nanoparticles, in aqueous media by means of Nanoparticle Tracking Analysis (NTA). The latter involves tracking the movement of particles due to Brownian motion and implementing the Stokes-Einstein equation to obtain the hydrodynamic diameter.

In the field of nanotechnology, analytical characterization plays a vital role in understanding the behavior and toxicity of nanomaterials (NMs). ...

Preparation of Expanded Chitin Foams and their Use in the Removal of Aqueous Copper

Chitin is an underexploited, naturally abundant, mechanically robust, and chemically resistant biopolymer. These qualities are desirable in an adsorbent, but chitin lacks the necessary specific surface area, and its modification involves specialized techniques and equipment. Herein is described a novel chemical procedure for expanding chitin flakes, derived from shrimp shell waste, into foams with higher surface area. The process relies on the evolution of H2 gas from the reaction of water with NaH trapped in a chitin gel. The preparation method requires no specialized equipment. Powder X-ray diffraction and N2-physisorption indicate that the crystallite size decreases from 6.6 nm to 4.4 nm and the specific surface area increases from 12.6 &#177; 2.1 m2/g to 73.9 &#177; 0.2 m2/g. However, infrared spectroscopy and thermogravimetric analysis indicate that the process does not change the chemical identity of the chitin. The specific Cu adsorption capacity of the expanded chitin increases in proportion to specific surface area from 13.8 &#177; 2.9 mg/g to 73.1 &#177; 2.0 mg/g. However, the Cu adsorption capacity as a surface density remains relatively constant at an average of 10.1 &#177; 0.8 atom/nm2, which again suggests no change in the chemical identity of the chitin. This method offers the means to transform chitin into a higher surface area material without sacrificing its desirable properties. Although the chitin foam is described here as an adsorbent, it can be envisioned as a catalyst support, thermal insulator, and structural material.

This study describes a method to expand chitin into a foam by chemical techniques that require no specialized equipment.

Chitin is an underexploited, naturally abundant, mechanically robust, and chemically resistant biopolymer. These qualities are desirable in an adsorbent, ...

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H₂ Production in Aqueous Aerobic Conditions

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Detection and Quantification of Plasmodium falciparum in Aqueous Red Blood Cells by Attenuated Total Reflection Infrared Spectroscopy and Multivariate Data Analysis

Automation of a Positron-emission Tomography (PET) Radiotracer Synthesis Protocol for Clinical Production

Experimental Methods for Efficient Solar Hydrogen Production in Microgravity Environment

Nanoparticle Tracking Analysis of Gold Nanoparticles in Aqueous Media through an Inter-Laboratory Comparison

Preparation of Expanded Chitin Foams and their Use in the Removal of Aqueous Copper