Photothermal effects in plasmonic nanostructures have great potentials in applications for photothermal cancer therapy, optical storage, thermo-photovoltaics, etc. However, the transient temperature ...behavior of a nanoscale material system during an ultrafast photothermal process has rarely been accurately investigated. Here a heat transfer model is constructed to investigate the temporal and spatial variation of temperature in plasmonic gold nanostructures. First, as a benchmark scenario, we study the light-induced heating of a gold nanosphere in water and calculate the relaxation time of the nanosphere excited by a modulated light. Second, we investigate heating and reshaping of gold nanoparticles in a more complex metamaterial absorber structure induced by a nanosecond pulsed light. The model shows that the temperature of the gold nanoparticles can be raised from room temperature to >795 K in just a few nanoseconds with a low light luminance, owing to enhanced light absorption through strong plasmonic resonance. Such quantitative predication of temperature change, which is otherwise formidable to measure experimentally, can serve as an excellent guideline for designing devices for ultrafast photothermal applications.
Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system ...of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.
We theoretically and numerically study the absorption effect and the heat generation in plasmonic metamaterials under light radiation at their plasmonic resonance. Three different types of ...structures, all possessing high-performance absorption for visible lights, are investigated. The main aim of this work is to present an intuitive and original understanding of the high-performance absorption effects. From the macroscopic electromagnetic point of view, the effective-medium approach is used to describe the absorption effects of the plasmonic metamaterials. On the other hand, the field distributions and heat generation effects in such plasmonic nanostructures are investigated, which also provides a satisfactory qualitative description of such absorption behavior based upon the microscopic perspective.
Safe and efficacious systemic delivery of messenger RNA (mRNA) to specific organs and cells in vivo remains the major challenge in the development of mRNA-based therapeutics. Targeting of ...systemically administered lipid nanoparticles (LNPs) coformulated with mRNA has largely been confined to the liver and spleen. Using a library screening approach, we identified that N-series LNPs (containing an amide bond in the tail) are capable of selectively delivering mRNA to the mouse lung, in contrast to our previous discovery that O-series LNPs (containing an ester bond in the tail) that tend to deliver mRNA to the liver. We analyzed the protein corona on the liver- and lung-targeted LNPs using liquid chromatography-mass spectrometry and identified a group of unique plasma proteins specifically absorbed onto the surface that may contribute to the targetability of these LNPs. Different pulmonary cell types can also be targeted by simply tuning the headgroup structure of N-series LNPs. Importantly, we demonstrate here the success of LNP-based RNA therapy in a preclinical model of lymphangioleiomyomatosis (LAM), a destructive lung disease caused by loss-of-function mutations in the
gene. Our lung-targeting LNP exhibited highly efficient delivery of the mouse tuberous sclerosis complex 2 (
) mRNA for the restoration of TSC2 tumor suppressor in tumor and achieved remarkable therapeutic effect in reducing tumor burden. This research establishes mRNA LNPs as a promising therapeutic intervention for the treatment of LAM.
By using the rigid full-vectorial three-dimensional finite-difference time-domain method, we show that the enhanced transmission through a metallic film with a periodic array of subwavelength holes ...results from two different resonances: (i) localized waveguide resonances where each air hole can be considered as a section of metallic waveguide with both ends open to free space, forming a low-quality-factor resonator, and (ii) well-recognized surface plasmon resonances due to the periodicity. These two different resonances can be characterized from electromagnetic band structures in the structured metal film. In addition, we show that the shape effect in the enhanced transmission through the Au film with subwavelength holes is attributed to the localized waveguide resonance.
Dynamic thermal emission control has attracted growing interest in a broad range of fields, including radiative cooling, thermophotovoltaics and adaptive camouflage. Previous demonstrations of ...dynamic thermal emission control present disadvantages of either large thickness or requiring sustained electrical or thermal excitations. In this paper, an ultrathin (∼0.023λ, λ is the emission peak wavelength) metal‐insulator‐metal plasmonic metamaterial‐based zero‐static‐power mid‐infrared thermal emitter incorporating phase‐changing material GST is experimentally demonstrated to dynamically control the thermal emission. The electromagnetic modes can be continuously tuned through the intermediate phases determined by controlling the temperature. A typical resonance mode, which involves the coupling between the high‐order magnetic resonance and anti‐reflection resonance, shifts from 6.51 to 9.33 μm while GST is tuned from amorphous to crystalline phase. This demonstration will pave the way towards the dynamical thermal emission control in both the fundamental science field and a number of energy‐harvesting applications.
An ultrathin plasmonic thermal emitter is experimentally demonstrated to dynamically control thermal emission based on MIM plasmonic metamateirals. The dynamic low‐power‐consumption control is implemented by incorporating zero‐static‐power phase‐changing material Ge2Sb2Te5 (GST). The whole structure shows a total thickness of 550 nm (∼0.023λ), which is well below the subwavelength scale. This ultrathin plasmonic nanostructure combined with zero‐static‐power phase‐changing material paves a new way to dynamically control thermal emission.
We analyze transmission characteristics of two coupled identical cavities, of either standing-wave (SW) or traveling-wave (TW) type, based on temporal coupled mode theory.Mode splitting is observed ...for both directly (cavity-cavity) and indirectly (cavity-waveguide-cavity) coupled cavity systems. The effects of direct and indirect couplings, if coexisting in one system, can offset each other such that no mode splitting occurs and the original single-cavity resonant frequency is retained. By tuning the configuration of the coupled cavity system, one can obtain different characteristics in transmission spectra, including splitting in transmission, zero transmission, Fano-type transmission, electromagnetically-induced-transparency (EIT)-like transmission, and electromagnetically-induced-absorption (EIA)-like transmission. It is also interesting to notice that a side-coupled SW cavity system performs similarly to an under-coupled TW cavity. The results are useful for the design of cavity-based devices for integration in nanophotonics.
It is a formidable challenge to simultaneously achieve wide-gamut, high-resolution, high-speed while low-cost manufacturability, long-term stability, and viewing-angle independence in structural ...colors for practical applications. The conventional nanofabrication techniques fail to match the requirement in low-cost, large-scale and flexible manufacturing. Processing by pulsed lasers can achieve high throughput while suffering from a narrow gamut of ~15% sRGB or angle-dependent colors. Here, we demonstrate an all-in-one solution for ultrafast laser-produced structural colors on ultrathin hybrid films that comprise an absorbent dielectric TiAlN layer coating on a metallic TiN layer. Under laser irradiation, the absorption behaviours of the TiAlN-TiN hybrid films are tailored by photothermal-induced oxidation on the topmost TiAlN. The oxidized films exhibit double-resonance absorption, which is due to the non-trivial phase shifts both at the oxide-TiAlN interface, and at the TiAlN-TiN interface. By varying the accumulated laser fluence to modulate the oxidation depth, angle-robust structural colors with unprecedented large-gamut of ~90% sRGB are obtained. The highest printing speed reaches 10 cm
/s and the highest resolution exceeds 10000 dpi. The durability of the laser-printed colors is confirmed by fastness examination, including salt spray, double-85, light bleaching, and adhesion tests. These features render our technique to be competitive for industrial applications.
Interminable surveillance and reconnaissance through various sophisticated multispectral detectors present threats to military equipment and manpower. However, a combination of detectors operating in ...different wavelength bands (from hundreds of nanometers to centimeters) and based on different principles raises challenges to the conventional single-band camouflage devices. In this paper, multispectral camouflage is demonstrated for the visible, mid-infrared (MIR, 3-5 and 8-14 μm), lasers (1.55 and 10.6 μm) and microwave (8-12 GHz) bands with simultaneous efficient radiative cooling in the non-atmospheric window (5-8 μm). The device for multispectral camouflage consists of a ZnS/Ge multilayer for wavelength selective emission and a Cu-ITO-Cu metasurface for microwave absorption. In comparison with conventional broadband low emittance material (Cr), the IR camouflage performance of this device manifests 8.4/5.9 °C reduction of inner/surface temperature, and 53.4/13.0% IR signal decrease in mid/long wavelength IR bands, at 2500 W ∙ m
input power density. Furthermore, we reveal that the natural convection in the atmosphere can be enhanced by radiation in the non-atmospheric window, which increases the total cooling power from 136 W ∙ m
to 252 W ∙ m
at 150 °C surface temperature. This work may introduce the opportunities for multispectral manipulation, infrared signal processing, thermal management, and energy-efficient applications.
The nanoparticles interact with the biomaterials in biological fluids, resulting in protein corona formation that may influence their properties and in vivo fate. The design strategies of drug ...delivery systems have been expanded due to the better understanding of protein corona composition and the interaction between nanoparticles and proteins.
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With the emerging advances in utilizing nanocarriers for biomedical applications, a molecular-level understanding of the in vivo fate of nanocarriers is necessary. After administration into human fluids, nanocarriers can attract proteins onto their surfaces, forming an assembled adsorption layer called protein corona (PC). The formed PC can influence the physicochemical properties and subsequently determine nanocarriers' biological behaviors. Therefore, an in-depth understanding of the features and effects of the PC on the nanocarriers’ surface is the first and most important step towards controlling their in vivo fate. This review introduces fundamental knowledge such as the definition, formation, composition, conformation, and characterization of the PC, emphasizing the in vivo environmental factors that control the PC formation. The effect of PC on the physicochemical properties and thus biological behaviors of nanocarriers was then presented and thoroughly discussed. Finally, we proposed the design strategies available for engineering PC onto nanocarriers to manipulate them with the desired surface properties and achieve the best biomedical outcomes.
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