RESUMEN
Autonomous generation of energy, specifically adenosine triphosphate (ATP), is critical for sustaining the engineered functionalities of synthetic cells constructed from the bottom-up. In this mini-review, we categorize studies on ATP-producing synthetic cells into three different approaches: photosynthetic mechanisms, mitochondrial respiration mimicry, and utilization of non-conventional approaches such as exploiting synthetic metabolic pathways. Within this framework, we evaluate the strengths and limitations of each approach and provide directions for future research endeavors. We also introduce a concept of building ATP-generating synthetic organelle that will enable us to mimic cellular respiration in a simpler way than current strategies. This review aims to highlight the importance of energy self-production in synthetic cells, providing suggestions and ideas that may help overcome some longstanding challenges in this field.
RESUMEN
In this study, a composite was manufactured by mixing graphene quantum dots, silicon oxide, and carbon nanoparticles, and the characteristics of the anode materials for secondary batteries were examined. To improve the capacity of the graphene quantum dot (GQD) anode material, the added silicon oxide content was varied among 0, 5, 10, 15, and 30 wt%, and carbon nanoparticles were added as a structural stabilizer to alleviate silicon oxide volume expansion. The physical properties of the prepared GQD/SiOx/C composite were investigated through XRD, SEM, EDS, and powder resistance analysis. Additionally, the electrochemical properties of the manufactured composite were observed through an analysis of the charge-discharge cycle, rate, and impedance of a lithium secondary battery. In the GQD/SiOx/C composite, by adding carbon nanoparticles, an internal cavity was formed that can alleviate the volume expansion of silicon oxide, and the carbon nanoparticles and silicon oxide particles were uniformly distributed. The formed internal cavity had a silicon oxide content of 5 wt%. Low initial efficiency was observed, and above 30 wt%, low cycle stability was observed. The GQD/SiOx/C composite with 15 wt% of silicon oxide added showed an initial discharge capacity of 595 mAh/g, a capacity retention rate of 92%, and a rate characteristic of 81 at 2 C/0.1 C. Silicon oxide was added to improve the capacity of the anode material, and carbon nanoparticles were added as a structural stabilizer to buffer the volume change of the silicon oxide. To use GQD/SiOx/C composite as a highly efficient anode material, the optimal silicon oxide content and carbon nanoparticle mechanism as a structural stabilizer were discussed.
RESUMEN
Cell signaling through direct physical cell-cell contacts plays vital roles in biology during development, angiogenesis, and immune response. Intercellular communication mechanisms between synthetic cells constructed from the bottom up are majorly reliant on diffusible chemical signals, thus limiting the range of responses in receiver cells. Engineering contact-dependent signaling between synthetic cells promises to unlock more complicated signaling schemes with different types of responses. Here, we design and demonstrate a light-activated contact-dependent communication tool for synthetic cells. We utilize a split bioluminescent protein to limit signal generation exclusively to contact interfaces of synthetic cells, driving the recruitment of a photoswitchable protein in receiver cells, akin to juxtacrine signaling in living cells. Our modular design not only demonstrates contact-dependent communication between synthetic cells but also provides a platform for engineering orthogonal contact-dependent signaling mechanisms.
RESUMEN
The ability of cells to sense and respond to their physical environment plays a fundamental role in a broad spectrum of biological processes. As one of the most essential molecular force sensors and transducers found in cell membranes, mechanosensitive (MS) ion channels can convert mechanical inputs into biochemical or electrical signals to mediate a variety of sensations. The bottom-up construction of cell-sized compartments displaying cell-like organization, behaviors, and complexity, also known as synthetic cells, has gained popularity as an experimental platform to characterize biological functions in isolation. By reconstituting MS channels in the synthetic lipid bilayers, we envision using mechanosensitive synthetic cells for several medical applications. Here, we describe three different concepts for using ultrasound, shear stress, and compressive stress as mechanical stimuli to activate drug release from mechanosensitive synthetic cells for disease treatments.
Asunto(s)
Células Artificiales , Mecanotransducción Celular/fisiología , Canales Iónicos/metabolismo , Membrana Celular/metabolismoRESUMEN
Stimuli-responsive hydrogels are intriguing biomimetic materials. Previous efforts to develop mechano-responsive hydrogels have mostly relied on chemical modifications of the hydrogel structures. Here, we present a simple, generalizable strategy that confers mechano-responsive behavior on hydrogels. Our approach involves embedding hybrid vesicles, composed of phospholipids and amphiphilic block copolymers, within the hydrogel matrix to act as signal transducers. Under mechanical stress, these vesicles undergo deformation and rupture, releasing encapsulated compounds that can control the hydrogel network. To demonstrate this concept, we embedded vesicles containing ethylene glycol tetraacetic acid (EGTA), a calcium chelator, into a calcium-crosslinked alginate hydrogel. When compressed, the released EGTA sequesters calcium ions and degrades the hydrogel. This study provides a novel method for engineering mechano-responsive hydrogels that may be useful in various biomedical applications.
RESUMEN
Engineering synthetic interfaces between membranes has potential applications in designing non-native cellular communication pathways and creating synthetic tissues. Here, InterSpy is introduced as a synthetic biology tool consisting of a heterodimeric protein engineered to form and maintain membrane-membrane interfaces between apposing synthetic as well as cell membranes through the SpyTag/SpyCatcher interaction. The inclusion of split fluorescent protein fragments in InterSpy allows tracking of the formation of a membrane-membrane interface and reconstitution of functional fluorescent protein in the space between apposing membranes. First, InterSpy is demonstrated by testing split protein designs using a mammalian cell-free expression (CFE) system. By utilizing co-translational helix insertion, cell-free synthesized InterSpy fragments are incorporated into the membrane of liposomes and supported lipid bilayers with the desired topology. Functional reconstitution of split fluorescent protein between the membranes is strictly dependent on SpyTag/SpyCatcher. Finally, InterSpy is demonstrated in mammalian cells by detecting fluorescence reconstitution of split protein at the membrane-membrane interface between two cells each expressing a component of InterSpy. InterSpy demonstrates the power of CFE systems in the functional reconstitution of synthetic membrane interfaces via proximity-inducing proteins. This technology may also prove useful where cell-cell contacts and communication are recreated in a controlled manner using minimal components.
Asunto(s)
Membrana Dobles de Lípidos , Liposomas , Animales , Membrana Celular , Membranas , Procesamiento Proteico-Postraduccional , Colorantes , MamíferosRESUMEN
In the pursuit of understanding life, model membranes made of phospholipids were envisaged decades ago as a platform for the bottom-up study of biological processes. Micron-sized lipid vesicles have gained great acceptance as their bilayer membrane resembles the natural cell membrane. Important biological events involving membranes, such as membrane protein insertion, membrane fusion, and intercellular communication, will be highlighted in this review with recent research updates. We will first review different lipid bilayer platforms used for incorporation of integral membrane proteins and challenges associated with their functional reconstitution. We next discuss different methods for reconstitution of membrane fusion and compare their fusion efficiency. Lastly, we will highlight the importance and challenges of intercellular communication between synthetic cells and synthetic cells-to-natural cells. We will summarize the review by highlighting the challenges and opportunities associated with studying membrane-membrane interactions and possible future research directions.
RESUMEN
We have investigated highly flexible memristive devices using reduced graphene oxide (RGO) nanosheet nanocomposites with an embedded GQD Layer. Resistive switching behavior of poly (4-vinylphenol):graphene quantum dot (PVP:GQD) composite and HfOx hybrid bilayer was explored for developing flexible resistive random access memory (RRAM) devices. A composite active layer was designed based on graphene quantum dots, which is a low-dimensional structure, and a heterogeneous active layer of graphene quantum dots was applied to the interfacial defect structure to overcome the limitations. Increasing to 0.3-0.6 wt % PVP-GQD, Vf changed from 2.27-2.74 V. When negative deflection is applied to the lower electrode, electrons travel through the HfOx/ITO interface. In addition, as the PVP-GQD concentration increased, the depth of the interfacial defect decreased, and confirmed the repetition of appropriate electrical properties through Al and HfOx/ITO. The low interfacial defects help electrophoresis of Al+ ions to the PVP GQD layer and the HfOx thin film. A local electric field increase occurred, resulting in the breakage of the conductive filament in the defect.
RESUMEN
Microalgae can accumulate various carbon-neutral products, but their real-world applications are hindered by their CO2 susceptibility. Herein, the transcriptomic changes in a model microalga, Chlamydomonas reinhardtii, in a high-CO2 milieu (20%) are evaluated. The primary toxicity mechanism consists of aberrantly low expression of plasma membrane H+-ATPases (PMAs) accompanied by intracellular acidification. Our results demonstrate that the expression of a universally expressible PMA in wild-type strains makes them capable of not only thriving in acidity levels that they usually cannot survive but also exhibiting 3.2-fold increased photoautotrophic production against high CO2 via maintenance of a higher cytoplasmic pH. A proof-of-concept experiment involving cultivation with toxic flue gas (13 vol% CO2, 20 ppm NOX, and 32 ppm SOX) shows that the production of CO2-based bioproducts by the strain is doubled compared with that by the wild-type, implying that this strategy potentially enables the microalgal valorization of CO2 in industrial exhaust.
Asunto(s)
Dióxido de Carbono/metabolismo , Dióxido de Carbono/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Microalgas/genética , Microalgas/metabolismo , Bombas de Protones/genética , Bombas de Protones/metabolismo , Biodegradación Ambiental , Biocombustibles , Carbono/metabolismo , Chlamydomonas reinhardtii/metabolismo , Tolerancia a Medicamentos , Microalgas/crecimiento & desarrollo , Organismos Modificados Genéticamente , Transcriptoma , Emisiones de VehículosRESUMEN
Most previous studies of perovskite core/shell structures have been based on ZnO/TiO2 nanowires (NWs), which are not suitable for high photoelectric conversion efficiency. Here, core/shell ZnO/TiO2 NWs with AgCl-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We designed CdSe with AgCl dopants that were synthesized by a colloidal process. An improvement of the recombination barrier (Rct1), due to shell supplementation with AgCl-doped CdSe quantum dots, improved the open circuit voltage, the fill factor, and the adsorption capacity of CH3NH3PbI3 perovskite with NWs. The enhanced cell steady state was attributable to TiO2 with AgCl-doped CdSe QD supplementation. A maximum power conversion efficiency of 15.12% was attained in an atmospheric environment. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 core/shell arrays was investigated to represent the merit of ZnO/TiO2 core/shell arrays as an electron transport layer in effective devices. These results showed an uncomplicated approach for restraining non-radiative recombination loss in hetero-structure core/shell arrays to significantly improve perovskite solar cell performance and increase the effectiveness of photovoltaics.
Asunto(s)
Nanocables/química , Puntos Cuánticos , Compuestos de Selenio/química , Compuestos de Plata/química , Titanio/química , Óxido de Zinc/química , Suministros de Energía Eléctrica , Transporte de Electrón , Nanocables/ultraestructura , Análisis EspectralRESUMEN
Along with the increase in global awareness of rising CO2 levels, microalgae have attracted considerable interest as a promising CO2 reduction platforms since they exhibit outstanding biomass productivity and are capable of producing numerous valuable products. At this moment, however, two major barriers, relatively low photosynthetic CO2 fixation efficiency and necessity of carbon-intensive microalgal process, obstruct them to be practically utilized. This review suggests effective approaches to improve life-cycle CO2 reduction of microalgal biorefinery. In order to enhance photosynthetic CO2 fixation, strategies to augment carbon content and to increase biomass productivity should be considered. For reducing CO2 emissions associated with the process operations, introduction of efficient process elements, designing of energy-saving process routes, reuse of waste resources and utilization of process integration can be noteworthy options. These comprehensive strategies will provide guidance for microalgal biorefineries to become a practical CO2 reduction technology in near future.
Asunto(s)
Dióxido de Carbono/metabolismo , Microalgas/metabolismo , Biomasa , Carbono/metabolismo , FotosíntesisRESUMEN
An acidic cultivation strategy was developed to prevent contamination of a lethal fungus Paraphysoderma sedebokerensis in Haematococcus pluvialis culture for astaxanthin production. Instead of generally used neutral pH, an acidic condition (pH 4) was applied to the cultivation, resulting in a significant inhibition of the fungal contamination. This could be ascribed to the acidity-associated denaturation of a surface protein of P. sedebokerensis, which plays an important role in recognition of H. pluvialis. Stress relief strategies including stepwise light irradiation and naturally occurring nitrogen deficiency were employed in the induction stage to minimize the reduction of astaxanthin production caused by acidic pH. Accordingly, an astaxanthin titer of 84.8â¯mgâ¯L-1 was obtained, which is 141-fold of that from the completely contaminated culture and double of that without the stress relief methods. This strategy provides a persistent contamination control method that can be used for practical astaxanthin production by H. pluvialis.
Asunto(s)
Chlorophyceae/metabolismo , Hongos no Clasificados/metabolismo , Ácidos , Concentración de Iones de Hidrógeno , Nitrógeno/metabolismo , Xantófilas/biosíntesisRESUMEN
An amphipathic leucine (L) and lysine (K)-rich α-helical peptide is multimerized based on helix-loop-helix structures to maximize the penetrating activities. The multimeric LK-based cell penetrating peptides (LK-CPPs) can penetrate cells as protein-fused forms at 100-1000-fold lower concentrations than Tat peptide. The enhanced penetrating activity is increased through multimerization by degrees up to the tetramer level. The multimeric LK-CPPs show rapid cell penetration through macropinocytosis at low nanomolar concentrations, unlike the monomeric LK, which have slower penetrating kinetics at much higher concentrations. The heparan sulfate proteoglycan (HSPG) receptors are highly involved in the rapid internalization of multimeric LK-CPPs. As a proof of concept of biomedical applications, an adipogenic transcription factor, peroxisome proliferator-activated receptor gamma 2 (PPAR-γâ2), is delivered into preadipocytes, and highly enhanced expression of adipogenic genes at nanomolar concentrations is induced. The multimeric CPPs can be a useful platform for the intracellular delivery of bio-macromolecular reagents that have difficulty with penetration in order to control biological reactions in cells at feasible concentrations for biomedical purposes.
RESUMEN
The aim of this work was to develop a new approach for simple and high-throughput selection of astaxanthin-hyperproducing Haematococcus mutants through a sequential combination method of azide-based colorimetric assessment and oil-based astaxanthin quantification. Randomly mutagenized cells were spotted on solid culture medium containing 50⯵M of sodium azide to accelerate the biosynthesis of astaxanthin. After 3â¯days, highly-induced mutants were preliminarily isolated by visual inspection and their astaxanthin accumulations were rapidly quantified by soybean oil-based extraction method. On the whole, the selected mutants showed reduced vegetative growth rates but eventually exhibited higher astaxanthin productions than the parental strain owing to their improved inductive growths. Among them, M13 showed 174.7⯱â¯5.69â¯mgâ¯L-1 of the highest astaxanthin production, which is 1.59-times higher than that of wild-type. This wide-scope screening method expedites both upstream and downstream astaxanthin quantification, making it a useful tool for isolating microalgae with high astaxanthin production.
Asunto(s)
Chlorophyta/genética , Azidas , Chlorophyta/metabolismo , Colorimetría , Xantófilas/biosíntesisRESUMEN
The use of phytochemicals for preventing chronic diseases associated with oxidative stress such as cataracts is hindered by their low bioavailability. The effects of nano-carriers on the antioxidant activities of extracts of black rice with giant embryo (BRGEx) and soybeans (SBx) have been determined in human lens epithelial B3 cells. Scanning (SEM) and transmission electron microscopy (TEM) demonstrated that rGO (reduced graphene oxide) has a flat surface unlike GO (graphene oxide), which has a distinctive wrinkled structure with defects. UPLC analysis revealed 41.9 µg/100 g of γ-oryzanols in water extract of BRGE, and 111.8 µg /100 g of lutein, 757.7 µg/100 g of γ-tocotrienol, 4071.4 µg/100 g of γ-tocopherol in 40% ethanol extract of soybeans, respectively. Even though a low concentration of BRGEx alone did not show any antioxidant activity in B3 cells, co-treatment of BRGEx with rGO together substantially reduced hydrogen peroxide and methylglyoxal-induced DNA damage, as determined by phosphorylated γH2AX. In addition, SBx with rGO also attenuated DNA damage. Furthermore, intracellular reactive oxygen species were significantly decreased by combining extracts of these colored grains with rGO. These results suggest a potential application of nanocarriers for enhancing the bioavailability of phytochemicals.
Asunto(s)
Antioxidantes/química , Antioxidantes/farmacología , Grano Comestible/química , Epitelio Corneal/efectos de los fármacos , Nanopartículas , Extractos Vegetales/química , Extractos Vegetales/farmacología , Daño del ADN/efectos de los fármacos , Epitelio Corneal/metabolismo , Grafito/química , Histonas/metabolismo , Humanos , Oxidación-Reducción , Estrés Oxidativo/efectos de los fármacos , Especies Reactivas de Oxígeno/química , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Recently, we have demonstrated that excitation of plasmon-polaritons in a mechanically-derived graphene sheet on the top of a ZnO semiconductor considerably enhances its light emission efficiency. If this scheme is also applied to device structures, it is then expected that the energy efficiency of light-emitting diodes (LEDs) increases substantially and the commercial potential will be enormous. Here, we report that the plasmon-induced light coupling amplifies emitted light by â¼1.6 times in doped large-area chemical-vapor-deposition-grown graphene, which is useful for practical applications. This coupling behavior also appears in GaN-based LEDs. With AuCl3-doped graphene on Ga-doped ZnO films that is used as transparent conducting electrodes for the LEDs, the average electroluminescence intensity is 1.2-1.7 times enhanced depending on the injection current. The chemical doping of graphene may produce the inhomogeneity in charge densities (i.e., electron/hole puddles) or roughness, which can play a role as grating couplers, resulting in such strong plasmon-enhanced light amplification. Based on theoretical calculations, the plasmon-coupled behavior is rigorously explained and a method of controlling its resonance condition is proposed.
RESUMEN
Coupling dissimilar oxides in heterostructures allows the engineering of interfacial, optical, charge separation/transport and transfer properties of photoanodes for photoelectrochemical (PEC) water splitting. Here, we demonstrate a double-heterojunction concept based on a BiVO4/WO3/SnO2 triple-layer planar heterojunction (TPH) photoanode, which shows simultaneous improvements in the charge transport (â¼93% at 1.23 V vs RHE) and transmittance at longer wavelengths (>500 nm). The TPH photoanode was prepared by a facile solution method: a porous SnO2 film was first deposited on a fluorine-doped tin oxide (FTO)/glass substrate followed by WO3 deposition, leading to the formation of a double layer of dense WO3 and a WO3/SnO2 mixture at the bottom. Subsequently, a BiVO4 nanoparticle film was deposited by spin coating. Importantly, the WO3/(WO3+SnO2) composite bottom layer forms a disordered heterojunction, enabling intimate contact, lower interfacial resistance, and efficient charge transport/transfer. In addition, the top BiVO4/WO3 heterojunction layer improves light absorption and charge separation. The resultant TPH photoanode shows greatly improved internal quantum efficiency (â¼80%) and PEC water oxidation performance (â¼3.1 mA/cm2 at 1.23 V vs RHE) compared to the previously reported BiVO4/WO3 photoanodes. The PEC performance was further improved by a reactive-ion etching treatment and CoOx electrocatalyst deposition. Finally, we demonstrated a bias-free and stable solar water-splitting by constructing a tandem PEC device with a perovskite solar cell (STH â¼3.5%).
RESUMEN
Förster resonance energy transfer (FRET), referred to as the transfer of the photon energy absorbed in donor to acceptor, has received much attention as an important physical phenomenon for its potential applications in optoelectronic devices as well as for the understanding of some biological systems. If one-atom-thick graphene is used for donor or acceptor, it can minimize the separation between donor and acceptor, thereby maximizing the FRET efficiency (EFRET). Here, we report first fabrication of a FRET system composed of silica nanoparticles (SNPs) and graphene quantum dots (GQDs) as donors and acceptors, respectively. The FRET from SNPs to GQDs with an EFRET of â¼78% is demonstrated from excitation-dependent photoluminescence spectra and decay curves. The photodetector (PD) responsivity (R) of the FRET system at 532 nm is enhanced by 10(0)â¼10(1)/10(2)â¼10(3) times under forward/reverse biases, respectively, compared to the PD containing solely GQDs. This remarkable enhancement is understood by network-like current paths formed by the GQDs on the SNPs and easy transfer of the carriers generated from the SNPs into the GQDs due to their close attachment. The R is 2â¼3 times further enhanced at 325 nm by the FRET effect.
RESUMEN
Reactive carbonyl species generated by the oxidation of polyunsaturated fatty acids and sugars are highly reactive due to their electrophilic nature, and are able to easily react with the nucleophilic sites of proteins as well as DNA causing cellular dysfunction. Levels of reactive carbonyl species and their reaction products have been reported to be elevated in various chronic diseases, including metabolic disorders and neurodegenerative diseases. In an effort to identify sequestering agents for reactive carbonyl species, various analytical techniques such as spectrophotometry, high performance liquid chromatography, western blot, and mass spectrometry have been utilized. In particular, recent advances using a novel high resolution mass spectrometry approach allows screening of complex mixtures such as natural products for their sequestering ability of reactive carbonyl species. To overcome the limited bioavailability and bioefficacy of natural products, new techniques using nanoparticles and nanocarriers may offer a new attractive strategy for increased in vivo utilization and targeted delivery of bioactives.