| 1. |
- Weierstall, Uwe, et al.
(författare)
-
Lipidic cubic phase injector facilitates membrane protein serial femtosecond crystallography
- 2014
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5, s. 3309-
-
Tidskriftsartikel (refereegranskat)abstract
- Lipidic cubic phase (LCP) crystallization has proven successful for high-resolution structure determination of challenging membrane proteins. Here we present a technique for extruding gel-like LCP with embedded membrane protein microcrystals, providing a continuously renewed source of material for serial femtosecond crystallography. Data collected from sub-10-mu m-sized crystals produced with less than 0.5 mg of purified protein yield structural insights regarding cyclopamine binding to the Smoothened receptor.
|
|
| 2. |
- Zhao, Haiguang, et al.
(författare)
-
Gram-scale synthesis of carbon quantum dots with a large Stokes shift for the fabrication of eco-friendly and high-efficiency luminescent solar concentrators
- 2021
-
Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 14:1, s. 396-406
-
Tidskriftsartikel (refereegranskat)abstract
- Luminescent solar concentrators (LSCs) are large-area sunlight collectors coupled to small area solar cells, for efficient solar-to-electricity conversion. The three key points for the successful market penetration of LSCs are: (i) removal of light losses due to reabsorption during light collection; (ii) high light-to-electrical power conversion efficiency of the final device; (iii) long-term stability of the LSC structure related to the stability of both the matrix and the luminophores. Among various types of fluorophores, carbon quantum dots (C-dots) offer a wide absorption spectrum, high quantum yield, non-toxicity, environmental friendliness, low-cost, and eco-friendly synthetic methods. However, they are characterized by a relatively small Stokes shift, compared to inorganic quantum dots, which limits the highest external optical efficiency that can be obtained for a large-area single-layer LSC (>100 cm2) based on C-dots below 2%. Herein, we report highly efficient large-area LSCs (100–225 cm2) based on colloidal C-dots synthesized via a space-confined vacuum-heating approach. This one batch reaction could produce Gram-scale C-dots with a high quantum yield (QY) (∼65%) using eco-friendly citric acid and urea as precursors. Thanks to their very narrow size distribution, the C-dots produced via the space-confined vacuum-heating approach had a large Stokes shift of 0.53 eV, 50% larger than C-dots synthesized via a standard solvothermal reaction using the same precursors with a similar absorption range. The large-area LSC (15 × 15 × 0.5 cm3) prepared by using polyvinyl pyrrolidone (PVP) polymer as a matrix exhibited an external optical efficiency of 2.2% (under natural sun irradiation, 60 mW cm−2, uncharacterized spectrum). After coupling to silicon solar cells, the LSC exhibited a power conversion efficiency (PCE) of 1.13% under natural sunlight illumination (20 mW cm−2, uncharacterized spectrum). These unprecedented results were obtained by completely suppressing the reabsorption losses during light collection, as proved by optical spectroscopy. These findings demonstrate the possibility of obtaining eco-friendly, high-efficiency, large-area LSCs through scalable production techniques, paving the way to the lab-to-fab transition of this kind of devices.
|
|
| 3. |
- Han, Yi, et al.
(författare)
-
Highly efficient ratiometric nanothermometers based on colloidal carbon quantum dots
- 2021
-
Ingår i: Journal of materials chemistry. B. - : Royal Society of Chemistry. - 2050-750X .- 2050-7518. ; 9:20, s. 4111-4119
-
Tidskriftsartikel (refereegranskat)abstract
- Optical nanothermometers have attracted much attention due to their non-contact and precise measurement with high spatial resolution at the micro- and nanoscales. They can be applied in various fields such as micro-opto-electronics, photonics, and biomedical thermal and pH sensing, while most thermal sensors reported so far contain heavy metals or have low sensitivity. Herein, we demonstrate a highly sensitive ratiometric thermal sensor based on colloidal C-dots. C-dots exhibit dual emission originating from the band gap emission and surface-dominant emission, which show a different temperature-dependent photoluminescence (PL) response. Among different surface-functionalized C-dots, C-dots@OH exhibit an absolute thermal sensitivity of -0.082 degrees C-1, which is the highest among various types of ratiometric thermosensors, making it a very promising candidate for high-sensitivity, self-calibrated nanoscale thermometry. As a proof-of-concept, C-dots@OH were employed to monitor the intracellular temperature (32-42 degrees C), showing a clear trend for temperature variation in a single cell, indicating that C-dots could offer a powerful tool for a potential precise measurement of the intracellular temperature. They could also be used as thermal sensors for nano-electronic and optoelectronic devices.
|
|
| 4. |
- Kupitz, Christopher, et al.
(författare)
-
Serial time-resolved crystallography of photosystem II using a femtosecond X-ray laser
- 2014
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 513:7517, s. 261-265
-
Tidskriftsartikel (refereegranskat)abstract
- Photosynthesis, a process catalysed by plants, algae and cyanobacteria converts sunlight to energy thus sustaining all higher life on Earth. Two large membrane protein complexes, photosystem I and II (PSI and PSII), act in series to catalyse the light-driven reactions in photosynthesis. PSII catalyses the light-driven water splitting process, which maintains the Earth's oxygenic atmosphere. In this process, the oxygen-evolving complex (OEC) of PSII cycles through five states, S0 to S4, in which four electrons are sequentially extracted from the OEC in four light-driven charge-separation events. Here we describe time resolved experiments on PSII nano/microcrystals from Thermosynechococcus elongatus performed with the recently developed technique of serial femtosecond crystallography. Structures have been determined from PSII in the dark S1 state and after double laser excitation (putative S3 state) at 5 and 5.5 Å resolution, respectively. The results provide evidence that PSII undergoes significant conformational changes at the electron acceptor side and at the Mn4CaO5 core of the OEC. These include an elongation of the metal cluster, accompanied by changes in the protein environment, which could allow for binding of the second substrate water molecule between the more distant protruding Mn (referred to as the 'dangler' Mn) and the Mn3CaOx cubane in the S2 to S3 transition, as predicted by spectroscopic and computational studies. This work shows the great potential for time-resolved serial femtosecond crystallography for investigation of catalytic processes in biomolecules.
|
|
| 5. |
- Lee, Ho-Hsien, et al.
(författare)
-
Expression, purification and crystallization of CTB-MPR, a candidate mucosal vaccine component against HIV-1
- 2014
-
Ingår i: IUCrJ. - 2052-2525. ; 1:5, s. 305-317
-
Tidskriftsartikel (refereegranskat)abstract
- CTB-MPR is a fusion protein between the B subunit of cholera toxin (CTB) andthe membrane-proximal region of gp41 (MPR), the transmembrane envelopeprotein ofHuman immunodeficiency virus 1(HIV-1), and has previously beenshown to induce the production of anti-HIV-1 antibodies with antiviralfunctions. To further improve the design of this candidate vaccine, X-raycrystallography experiments were performed to obtain structural informationabout this fusion protein. Several variants of CTB-MPR were designed,constructed and recombinantly expressed inEscherichia coli. The first variantcontained a flexible GPGP linker between CTB and MPR, and yielded crystalsthat diffracted to a resolution of 2.3 A ̊, but only the CTB region was detectedin the electron-density map. A second variant, in which the CTB was directlyattached to MPR, was shown to destabilize pentamer formation. A thirdconstruct containing a polyalanine linker between CTB and MPR proved tostabilize the pentameric form of the protein during purification. The purificationprocedure was shown to produce a homogeneously pure and monodispersesample for crystallization. Initial crystallization experiments led to pseudo-crystals which were ordered in only two dimensions and were disordered inthe third dimension. Nanocrystals obtained using the same precipitant showedpromising X-ray diffraction to 5 A ̊resolution in femtosecond nanocrystallo-graphy experiments at the Linac Coherent Light Source at the SLAC NationalAccelerator Laboratory. The results demonstrate the utility of femtosecondX-ray crystallography to enable structural analysis based on nano/microcrystalsof a protein for which no macroscopic crystals ordered in three dimensions havebeen observed before.
|
|
| 6. |
- Liu, Guiju, et al.
(författare)
-
High efficiency sandwich structure luminescent solar concentrators based on colloidal quantum dots
- 2019
-
Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 60, s. 119-126
-
Tidskriftsartikel (refereegranskat)abstract
- Luminescent solar concentrators (LSCs) have received significant attention because of their low cost, large-area and high efficiency sunlight energy harvesting. Colloidal core/shell quantum dots (QDs) are promising candidates as absorbers/emitters in LSCs. However, due to the limitation of QDs properties and device architectures, LSCs fabricated using QDs still face the challenges of low optical efficiency and limited long-term stability for the large-area LSCs. In this work, we synthesized CdSe/CdS QDs, and found that higher CdS shell growth temperature results in improved uniformity in structure and morphology and more suitable optical properties. Based on the CdSe/CdS QDs, a large-area (∼100 cm 2 ) sandwich structure luminescent solar concentrator (LSC) was fabricated. By laminating the QDs layer between two sheets of optical clear glass, the reabsorption losses of the device can be reduced due to the decrease of photon escape. The as-fabricated sandwich structure device exhibits an external optical efficiency of ∼ 2.95% under natural sunlight illumination, which represents a 78% enhancement in efficiency over the single layer film LSCs based on CdSe/CdS QDs. More importantly, the sandwich structure can protect the QDs interlayer from the impact of the ambient environment (e.g. oxygen, moisture and alkalinity) and enhance the long-term stability of LSCs. Our work shows that the use of suitably tuned core-shell QDs and the sandwich structure in LSC architecture can dramatically enhance the external optical efficiency of LSC devices based on CdSe/CdS QDs.
|
|
| 7. |
- Liu, Guiju, et al.
(författare)
-
Red-emissive carbon quantum dots enable high efficiency luminescent solar concentrators
- 2023
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:16, s. 8950-8960
-
Tidskriftsartikel (refereegranskat)abstract
- Luminescent solar concentrators (LSCs) are large-area sunlight collectors for efficient solar-to-electricity conversion. The key point for highly efficient LSCs is the choice of fluorophores, which need to have broad absorption, high quantum yield and large Stokes shift. Among various fluorophores, carbon quantum dots (C-dots) hold great promise as eco-friendly alternatives to heavy-metal-containing quantum dots (QDs) due to their adjustable absorption and emission spectra, non-toxicity, low cost and eco-friendly synthetic methods. However, due to the limited absorption band and relatively low quantum yield in the red region, it is a challenge to obtain efficient LSCs based on C-dots. Here, we demonstrated highly efficient LSCs based on red-emissive C-dots. The as-synthesized C-dots have a cubic structure, broad absorption covering 300-600 nm, and red emission (peak located at 595 nm), with a high quantum yield of ∼65% and a large Stokes shift of 0.45 eV. Transient absorption experiments of the C-dots revealed the ultrafast formation of the broad emissive state (1 ps). Based on the excellent optical properties of the C-dots, the as-prepared large-area LSC (10 × 10 × 0.52 cm3) exhibited an optimized external optical efficiency of 4.81% and a power conversion efficiency of 2.41% under natural sun irradiation (70 mW cm−2). Furthermore, a tandem LSC using green-emissive C-dots (top layer) and red-emissive C-dots (bottom layer) as fluorophores exhibited an external optical efficiency as high as 6.78%. These findings demonstrate the possibility of using eco-friendly carbon-based nanomaterials for highly efficient large-area LSCs.
|
|
| 8. |
- Liu, Guiju, et al.
(författare)
-
Role of refractive index in highly efficient laminated luminescent solar concentrators
- 2020
-
Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 70
-
Tidskriftsartikel (refereegranskat)abstract
- As a large-area solar radiation collector, luminescent solar concentrators (LSCs) can be used as power generation units in semitransparent solar windows, modernized agricultural greenhouses and building facades. However, the external optical efficiency and long-term stability of the LSCs limit their practical applications due to the sensitivity of the emitters to the light and environmental conditions. Here, we used the concept of “laminated glass” to prepare LSCs, which consist of two waveguide layers and the quantum dots (QDs)/polymer interlayer, and we tune the refractive index of the different parts of the system to improve the external optical efficiency and stability of the LSCs, simultaneously. The waveguide layer can be glass, quartz, polymethyl methacrylate (PMMA) and other transparent materials. The CdSe/CdS core/shell QDs were used as fluorophores to prepare the interlayer of the LSCs. The external optical efficiency of the laminated LSCs is associated with the refractive index of the three layers: the closer the refractive index, the higher the ηopt. The highest external optical efficiency of 3.4% has been achieved for the laminated PMMA/QDs-polymer/PMMA LSCs, which improved ~92% compared to the single-layered CdSe/CdS based LSCs. To the best of our knowledge, this is the highest efficiency for the LSCs based on CdSe/CdS QDs. These results pave the way to realize high efficiency laminated windows as power generation units by suitably tuning the structure of the LSC, and provide the theoretical guidance for the LSCs utilized in building integrated photovoltaics.
|
|
| 9. |
- Munke, Anna, et al.
(författare)
-
Data Descriptor : Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source
- 2016
-
Ingår i: Scientific Data. - : Nature Publishing Group. - 2052-4463. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a wellcharacterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 mu m diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 angstrom ngstrom were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here.
|
|
| 10. |
- Wang, Rui, et al.
(författare)
-
Environmentally friendly Mn-alloyed core/shell quantum dots for high-efficiency photoelectrochemical cells
- 2020
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 8:21, s. 10736-10741
-
Tidskriftsartikel (refereegranskat)abstract
- Colloidal quantum dot (QD)-based photoelectrochemical (PEC) cells are cost-effective devices showing remarkable solar-to-fuel conversion efficiency. However, the extensive use of highly toxic elements (e.g. Pb and Cd) in QDs' synthesis and device fabrication is still a major challenge towards their practical development. Herein, we fabricate a solar-driven PEC cell based on environmentally friendly Mn-alloyed CuInS2 (MnCIS)/ZnS core/shell QDs, showing more favorable band alignment, efficient charge transfer, reduced charge recombination and lower charge transfer resistance with respect to the control device fabricated using unalloyed CuInS2 (CIS)/ZnS core/shell QDs. An unprecedented photocurrent density of ∼5.7 mA cm−2 with excellent stability was obtained for the as-fabricated MnCIS/ZnS core/shell QD-based PEC device when operated under standard one sun irradiation (AM 1.5G, 100 mW cm−2). These results indicate that the transition metal-alloyed environmentally friendly core/shell QDs are promising for next-generation solar technologies.
|
|
