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Development of titania-integrated silica cell walls of the titanium-resistant diatom, <i>Fistulifera solaris</i>
摘要： We report the biological synthesis of titania that is integrated into the silica-based cell walls of a titanium-resistant diatom, Fistulifera solaris. Titania is deposited across the diatom cell walls by simply incubating F. solaris in a culture medium containing a high concentration (2 mM) of a water-soluble organo-titanium compound, titanium(IV) bis(ammonium lactato) dihydroxide (TiBALDH) that would otherwise inhibit the growth of other diatom species. Furthermore, we genetically engineered the interfaces of the diatom cell walls with a titanium-associated peptide, which subsequently increased the Ti/Si atomic ratio by more than 50% (i.e., from 6.2 ± 0.2 % to 9.7 ± 0.5 %, as identified by inductively coupled plasma-atomic emission spectrometry). The titanium content on the F. solaris silica cell walls is one of the highest reported to date, and comparable to that of chemically synthesized TiO2-silica composites. Subsequent thermal annealing at 500°C in air converted the wall-bound titania to nanocrystalline anatase TiO2, a highly photocatalytically active phase. We propose that incubation of the titanium-resistant F. solaris with TiBALDH as demonstrated in this study could be a promising bioprocess towards the scalable synthesis of TiO2. In addition, the genetic engineering we used to modulate the surface properties of diatom silica cell walls could be extended to synthesize controlled nanomaterials for multiple applications including bioremediation, water purification, and energy conversion/storage.
关键词： Genetic engineering,silica cell wall,TiO2,Fistulifera solaris,diatom
更新于2025-09-23 15:21:21
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A genetically encoded photosensitizer protein facilitates the rational design of a miniature photocatalytic CO2-reducing enzyme
摘要： Photosensitizers, which harness light energy to upgrade weak reductants to strong reductants, are pivotal components of the natural and artificial photosynthesis machineries. However, it has proved difficult to enhance and expand their functions through genetic engineering. Here we report a genetically encoded, 27 kDa photosensitizer protein (PSP), which facilitates the rational design of miniature photocatalytic CO2-reducing enzymes. Visible light drives PSP efficiently into a long-lived triplet excited state (PSP*), which reacts rapidly with reduced nicotinamide adenine dinucleotide to generate a super-reducing radical (PSP?), which is strong enough to reduce many CO2-reducing catalysts. We determined the three-dimensional structure of PSP? at 1.8 ? resolution by X-ray crystallography. Genetic engineering enabled the site-specific attachment of a nickel–terpyridine complex and the modular optimization of the photochemical properties of PSP, the chromophore/catalytic centre distance and the catalytic centre microenvironment, which culminated in a miniature photocatalytic CO2-reducing enzyme that has a CO2/CO conversion quantum efficiency of 2.6%.
关键词： quantum efficiency,photosensitizer protein,visible light,photocatalytic CO2-reducing enzymes,X-ray crystallography,nickel–terpyridine complex,genetic engineering
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 13th International Conference on Power Electronics and Drive Systems (PEDS) - Toulouse, France (2019.7.9-2019.7.12)] 2019 IEEE 13th International Conference on Power Electronics and Drive Systems (PEDS) - A Novel Fast-Switching SOI LIGBT with Anode Junction Paralleled by a Diode
摘要： Bacterial plasmids employ copy number control systems to ensure that they do not overburden their hosts. Plasmid incompatibility is caused by shared components of copy number control systems, resulting in mutual inhibition of replication. Incompatible plasmids cannot be stably maintained within a host cell. Unilateral incompatibility, in which the plasmid replicons are compatible but one plasmid encodes for the replication inhibitor of the other, leads to rapid displacement of the inhibited plasmid. Thus, we propose that the unilateral incompatibility can be used to eradicate an undesirable plasmid from a population. To investigate this process, we developed deterministic and stochastic models of plasmid dynamics. An analysis of these models provides predictions about the efficacy of plasmid displacement.
关键词： Biological system modeling,genetic engineering,synthetic biology
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Increased Power Output of Thin Film GaAs Solar Cells on Flexible Metal Substrates Using PDMS Microconcentrators
摘要： Bacterial plasmids employ copy number control systems to ensure that they do not overburden their hosts. Plasmid incompatibility is caused by shared components of copy number control systems, resulting in mutual inhibition of replication. Incompatible plasmids cannot be stably maintained within a host cell. Unilateral incompatibility, in which the plasmid replicons are compatible but one plasmid encodes for the replication inhibitor of the other, leads to rapid displacement of the inhibited plasmid. Thus, we propose that the unilateral incompatibility can be used to eradicate an undesirable plasmid from a population. To investigate this process, we developed deterministic and stochastic models of plasmid dynamics. An analysis of these models provides predictions about the efficacy of plasmid displacement.
关键词： Biological system modeling,genetic engineering,synthetic biology
更新于2025-09-19 17:13:59