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<a href="#Synthesis and Characterization">Synthesis and Characterization</a>

<a href="#Synthesis and Characterization">Synthesis and Characterization</a>

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Quantum dots (QDs) and nanorods (NRs), as semiconductor nanocrystals, are of fundamental and technical importance. Owing to their extraordinary optical properties and high quantum-yield efficiency, these nanoobjects are often geared towards many energy-relevant applications. <B>In our IGEM project, we conceive to harness those nanoscale objects as solar energy harvester.</B> When firmly anchored onto E. coli biofilms through coordination chemistry, they can be easily recycled together with scalable biofilm coatings when necessary, and meanwhile, still possess <B>the capability to efficiently convert photons into electrons upon light exposure. The aquired electrons would then tap into the electron chains of engineered strain harboring hydrogenase gene cluster, thereby assisting the enzymes to fulfill hydrogen production.</B>  

Quantum dots (QDs) and nanorods (NRs), as semiconductor nanocrystals, are of fundamental and technical importance. Owing to their extraordinary optical properties and high quantum-yield efficiency, these nanoobjects are often geared towards many energy-relevant applications. <B>In our IGEM project, we conceive to harness those nanoscale objects as solar energy harvester.</B> When firmly anchored onto E. coli biofilms through coordination chemistry, they can be easily recycled together with scalable biofilm coatings when necessary, and meanwhile, still possess <B>the capability to efficiently convert photons into electrons upon light exposure. The aquired electrons would then tap into the electron chains of engineered strain harboring hydrogenase gene cluster, thereby assisting the enzymes to fulfill hydrogen production.</B>  

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Ligand is also an important feature of nanocrystals. The presence of some types of ligands would increase the difficulty of growth on some lattice plane while decrease it on the others, leading to NRs using QDs as nuclei. A ligand not only can serve as a stabilizer in solution but also a functional decoration for nanocrystals. In our experiements, the product QDs and NRs are originally synthesized with lipophilic ligands and dissolve in nonpolar organic solvents such as octadecene and trioctylphophine.  Ligand exchanging would allow the products to enter into water phase and thereby enable ligand-decorated QDs that would be able to bind to biofilms. The ligand we used has a NTA functional group, which was developed by the Zhong group at ShanghaiTech (Patent application submitted). NTA-capped QDs or NRs can firmly bind with His-tagged CsgA, major protein components of E. coli biofilms. In addition, we further utilize this specific binding system and unique optical properties of QDs to scrutinize the expression and formation of biofilms (as revealed in our biofilms session).

Ligand is also an important feature of nanocrystals. The presence of some types of ligands would increase the difficulty of growth on some lattice plane while decrease it on the others, leading to NRs using QDs as nuclei. A ligand not only can serve as a stabilizer in solution but also a functional decoration for nanocrystals. In our experiements, the product QDs and NRs are originally synthesized with lipophilic ligands and dissolve in nonpolar organic solvents such as octadecene and trioctylphophine.  Ligand exchanging would allow the products to enter into water phase and thereby enable ligand-decorated QDs that would be able to bind to biofilms. The ligand we used has a NTA functional group, which was developed by the Zhong group at ShanghaiTech (Patent application submitted). NTA-capped QDs or NRs can firmly bind with His-tagged CsgA, major protein components of E. coli biofilms. In addition, we further utilize this specific binding system and unique optical properties of QDs to scrutinize the expression and formation of biofilms (as revealed in our biofilms session).

    

    

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<p>Briefly, we achieved following goals:  

<p>Briefly, we achieved following goals:  

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<h3 class="bg"><b>Methods</b></h3>

<h3 class="bg"><b>Methods</b></h3>

To increase the solubility and enable selective binding ability of the nanomaterials, the lipophilic ligands of our synthesized nanomaterials should be replaced by special ligands through ligand exchange. We used a well-developed procedure (developed in Zhong Lab@ShanghaiTech) to synthesize this ligand. We performed the ligand exchange experiment to replace the origin ligand of the nanomaterials. The result of ligand exchange experiment was shown by the following image. After this experiment, the nanomaterials were ready to be harnessed as the binding material of the biofilm and the solar energy harvester of the Solar Hunter.</p><p></p>

To increase the solubility and enable selective binding ability of the nanomaterials, the lipophilic ligands of our synthesized nanomaterials should be replaced by special ligands through ligand exchange. We used a well-developed procedure (developed in Zhong Lab@ShanghaiTech) to synthesize this ligand. We performed the ligand exchange experiment to replace the origin ligand of the nanomaterials. The result of ligand exchange experiment was shown by the following image. After this experiment, the nanomaterials were ready to be harnessed as the binding material of the biofilm and the solar energy harvester of the Solar Hunter.</p><p></p>

The Photoluminescence(PL) spectroscopy is a widely used tool for characterization of electronic and optical properties of analytes, especially quantum dots and nanorods. Briefly, the PL spectroscopy detects photon emitted in a certain spectral region when the samples are excited by light at a certain wavelength. The PL spectroscopy can be used to determine the excitation peak and emission peak. The position of the emission peak can indicate whether the synthesis of QDs and NRs is successfully performed. The best excitation wavelength and the best emission wavelength, which are of great importance for utilizing the use of QDs and NRs as characterization tools, can also be known from the position of the peaks. The PL spectrometer we use is HORIBA FL-3.</p><p></p>

The Photoluminescence(PL) spectroscopy is a widely used tool for characterization of electronic and optical properties of analytes, especially quantum dots and nanorods. Briefly, the PL spectroscopy detects photon emitted in a certain spectral region when the samples are excited by light at a certain wavelength. The PL spectroscopy can be used to determine the excitation peak and emission peak. The position of the emission peak can indicate whether the synthesis of QDs and NRs is successfully performed. The best excitation wavelength and the best emission wavelength, which are of great importance for utilizing the use of QDs and NRs as characterization tools, can also be known from the position of the peaks. The PL spectrometer we use is HORIBA FL-3.</p><p></p>

<h3 class="bg"><b>Results</b></h3>

<h3 class="bg"><b>Results</b></h3>

<p class="bg"><b>Synthesis and Characterization of CdS Nanorods</b></p><p>

<p class="bg"><b>Synthesis and Characterization of CdS Nanorods</b></p><p>

We synthesized CdS nanorods following a procedure adapted from a previously published protocol[1]. The synthesis procedure mainly contains two steps: synthesis of CdS seeds, followed by growth of CdS nanorods using CdS nanoparticles as nuclei. </p><p></p>

We synthesized CdS nanorods following a procedure adapted from a previously published protocol[1]. The synthesis procedure mainly contains two steps: synthesis of CdS seeds, followed by growth of CdS nanorods using CdS nanoparticles as nuclei. </p><p></p>

<center><div><p></p><img src="https://static.igem.org/mediawiki/2016/c/cf/T--ShanghaitechChina--CdS1.png" style="width:35%;"><figcaption >

<center><div><p></p><img src="https://static.igem.org/mediawiki/2016/c/cf/T--ShanghaitechChina--CdS1.png" style="width:35%;"><figcaption >

<p class="cap"><b>Figure 3.</b>  Solutions of CdS nanoparticle seeds in TOP (left), CdS NRs in toluene (right)</p>

<p class="cap"><b>Figure 3.</b>  Solutions of CdS nanoparticle seeds in TOP (left), CdS NRs in toluene (right)</p>

<p class="bg"><b>Synthesis and Characterization of CdSe QDs</b></p><p>

<p class="bg"><b>Synthesis and Characterization of CdSe QDs</b></p><p>

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         <p>1. K. A. Brown et al., Light-driven dinitrogen reduction catalyzed by a CdS: nitrogenase MoFe protein biohybrid. Science 352, 448-450 (2016).</p><p>

         <p>1. K. A. Brown et al., Light-driven dinitrogen reduction catalyzed by a CdS: nitrogenase MoFe protein biohybrid. Science 352, 448-450 (2016).</p><p>

2. C. Pu et al., Highly reactive, flexible yet green Se precursor for metal selenide nanocrystals: Se-octadecene suspension (Se-SUS). Nano research 6, 652-670 (2013).

2. C. Pu et al., Highly reactive, flexible yet green Se precursor for metal selenide nanocrystals: Se-octadecene suspension (Se-SUS). Nano research 6, 652-670 (2013).