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Effect of Laser Irradiation on Reversibility and Drug Release of Light-Activatable Drug-Encapsulated Liposomes
摘要： Although several studies have demonstrated repetitive drug release using light-activatable liposomes, inconsistent drug release at each activation limits widespread usage. Here, we report reversible plasmonic material-coated encapsulated liposomes for proportional controlled delivery of methotrexate (MTX), which is a common drug for cancer and autoimmune diseases, using repetitive laser irradiation. Our results suggest a proportional increase in total drug release after repetitive laser irradiation. We hypothesize that the drug is released via “melted” lipid bilayers when the plasmonic materials on the liposome surface are heated by laser irradiation followed by reversible formation of the liposome. To evaluate our hypothesis, the number density of liposomes after laser irradiation was measured using single-particle (liposome) collision experiments at an ultramicroelectrode. Collisional frequency data suggest that the number density of liposomes remains unaltered even after 60 s of laser irradiation at 1.1 and 1.8 W, indicating that the liposome structure is reversible. The results were further compared with gold nanorod-coated nanodroplets where drug is released via irreversible phase transition. In contrast to what was observed with the liposome particles, the number density of the nanodroplets decreased with increasing laser irradiation duration. The structure reversibility of our liposome particles may be responsible for repetitive drug release with laser heating. We also studied the temperature rise in the lipid bilayer by incorporating polymerized 10,12-pentacosadiynoic acid (PCDA) in the lipid composition. The red shift in the UV?vis spectrum due to the structural change in PCDA lipids after laser irradiation indicates a rise in temperature above 75 °C, which is also above the chain-melting temperature of the main lipid used in the liposomes. All these results indicate that drug is released from the light-activatable liposomes due to reversible nanostructural alteration in the lipid bilayer by plasmonic resonance heating. The liposomes have potential to be a drug carrier for dose-controlled repetitive drug delivery.
关键词： drug release,reversible nanostructural alteration,light-activatable liposomes,plasmonic materials,laser irradiation,methotrexate
更新于2025-09-23 15:19:57
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Zirconium Nitride for Plasmonic Cloaking of Visible Nanowire Photodetectors
摘要： Light scattered by a photodetector disturbs the probing field, resulting in noise. Cloaking is an effective method to reduce this noise. Here we investigate theoretically an emerging plasmonic material, zirconium nitride (ZrN), as a plasmonic cloak for silicon (Si) nanowire-based photodetectors and compare it with a traditional plasmonic material, gold (Au). Using Mie formalism, we have obtained the scattering cancelation across the visible spectrum. We found that ZrN cloaks produce a significant decrease in the scattering from bare Si nanowires, which is 40% greater than that obtained with Au cloaks in the wavelength region of 400–500 nm. The scattering cancelations become comparable at 550 nm, with Au providing a better scattering cancelation compared to ZrN over the wavelength region of 600–700 nm. To include the absorption and provide a measure of overall performance on noise reduction, a figure of merit (FOM), defined as the ratio of the absorption efficiency and the scattering efficiency of the cloaked nanowire to that of the bare Si nanowire, was calculated. We show that the optimized ZrN cloak provides up to 3 times enhancement of the FOM over a bare Si NW and a 60% improvement over an optimized Au-cloaked NW, in the wavelength region of 400–500 nm. An optimized Au-cloaked NW shows up to 17.69 times improvement in the wavelength region of 600–700 nm over a bare Si NW and up to a 2.7 times improvement over an optimized ZrN-cloaked NW. We also predicted the optimal dimensions for the cloaked NWs with respect to the largest FOM at various wavelengths between 400 and 650 nm.
关键词： Plasmonic cloaking,Core-shell,Nanowires,Emerging plasmonic materials,Zirconium nitride,Scattering cancelation
更新于2025-09-19 17:13:59
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Optoelectronic Impacts of Particle Size in Water-Dispersible Plasmonic Copper Selenide Nanoparticles
摘要： There is significant interest in earth-abundant plasmonic materials, but whether or not their performance can match or even surpass their noble metal counterparts remains to be established. An important step in determining the extent of their versatility is to understand basic aspects of their plasmonic features. In this work, we measure near-infrared plasmonic molar extinction coefficients of water-dispersible copper selenide nanoparticles of different diameters. Obtaining molar extinction coefficients of these materials has traditionally been challenging because particles could not be synthesized at size ranges that avoid convoluting factors such as carrier density anomalies, surface depletion, and quantum confinement effects. Here, we report a straightforward synthesis that can control particle diameter within a size range that mitigates these convolutions, and then use these materials to establish their molar extinction coefficients. Importantly, we determine that size-dependent increases in molar extinction coefficients are likely a result of increases only in scattering cross-section, much like their noble metal analogues. Further, we show that the size-dependent trends in molar extinction coefficient follow the trends predicted by Mie theory well. These results suggest a promising outlook for the future implementation of earth-abundant and alternative plasmonic technologies from this material class.
关键词： plasmonic materials,copper selenide nanoparticles,molar extinction coefficients,earth-abundant materials,Mie theory
更新于2025-09-19 17:13:59
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Simulative Parametric Study on Heterojunction Thin Film Solar Cells Incorporating Interfacial Nanoclusters Layer
摘要： Organic solar cells deal with small organic molecules for absorption of light at low cost and high efficiency. In this paper, we have analyzed the photovoltaic (PV) characteristics of double heterojunction solar cell that consists of copper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic bis-benzimidazole (PTCBI) thin films. Here, CuPc and PTCBI layers are combined by an interfacial layer consisting of nanoscale dots. Different plasmonic materials (i. e. Ag, Au, and graphene) are selected as alternative nanoscale dot layer to examine their effect on solar cell performance. Further, the solar cell performance is also examined via variation in active layer thickness. The choice of interfacial layer material and variation in active layer thickness offer grounds for future efficient PV cells.
关键词： energy conversion efficiency,plasmonic materials,CuPc/PTCBI solar cells,excitons
更新于2025-09-16 10:30:52
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Editorial: Plasmonic Technologies for Bioanalytical Applications
摘要： Bioanalytical technologies that provide quantitative information about bioanalytes of interest in biological systems are becoming widespread in biomedical applications, environment monitoring, and food quality and safety. Among recent developments, plasmonic-based technologies made significant strides toward real life applications. They are based on surface plasmons, which are collective oscillations of conductive electrons on noble metal film or nanoparticle surfaces induced by electromagnetic radiation at the metal-dielectric interface. Plasmonic nanostructures have the ability to control and manipulate visible light at the nanometer scale and have been used to create plasmonic filters, wave-guides, nanoscopic light sources, and other devices with unique or improved properties. In addition, plasmonics has helped further our understanding of the interaction of molecules with nanostructures and has been used in biosensing applications. Their low ohmic and optical losses, chemical activity, tunable optical properties, specific response to incident light, and the ability to enhance signals such as fluorescence and Raman scattering, have been exploited in biomedical applications. Specific plasmonic-based technologies include nanoscale optical absorption spectroscopy, surface plasmon resonance (SPR), localized surface plasmon resonance (LSPR), surface-enhanced Raman scattering spectroscopy (SERS), tip-enhanced Raman spectroscopy (TERS), surface-enhanced infrared absorption spectroscopy (SEIRAS), single molecule plasmonics (SMP), and chiral plasmonics (CP). This special issue is needed for chemists, biologists, and materials scientists who work in the area of plasmonics applications in bioanalytical sensing.
关键词： plasmonic materials,plasmonics,bioanalytical,medical diagnosis,extracellular vesicles
更新于2025-09-16 10:30:52
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2D Plasmonic Tungsten Oxide Enabled Ultrasensitive Fiber Optics Gas Sensor
摘要： Functional materials coated on optical fibers have demonstrated great potential for optical gas sensing applications. However, their sensitivity is typically limited to the sub-parts per million (sub-ppm) range. Here, for the first time a 2D near-infrared plasmonic tungsten oxide (WOx) enabled ultrasensitive fiber optics gas sensor on a side-polished D-shape single mode optical fiber is presented. The plasmon resonance wavelength range of 2D WOx is matched with a conventional telecommunications wavelength of 1550 nm for driving the optical fiber, therefore inducing a strong light–matter interaction. Upon the surface adsorption of gas molecules, free electrons in the 2D WOx body are redistributed changing the plasmon resonance properties and hence the transmission through the optical fiber. The sensor is selectively responsive to NO2 at concentrations down to 44 parts per billion (ppb) with a limit of detection of 8 ppb at a relatively low elevated temperature. Such an excellent sensing performance is significantly improved over the previously reported fiber optics NO2 sensors, which suggests the integration of 2D plasmonic degenerated semiconductors as a viable approach to develop high-performance fiber optics gas sensors.
关键词： fiber optics,2D materials,NO2 gas sensors,plasmonic materials
更新于2025-09-11 14:15:04
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Generation of hot electrons in nanostructures incorporating conventional and unconventional plasmonic materials
摘要： The generation of energetic electrons is an effect occurring in any plasmonic nanostructure. However, the number of electrons with high energies generated optically in a plasmonic nanostructure can be relatively small. This is an intrinsic property of the collective plasmon excitations in a Fermi gas of electrons. But the choices of material and geometry have a great impact on the generation rate, which are therefore crucial to design nanostructure with a large rate of generation of energetic (hot) electrons. Here we test different plasmonic materials from the point of view of the generation of hot electrons (HEs). Our choice of materials includes both strongly-plasmonic materials (Au, Ag, Cu and Al) and crystals with strongly broadened plasmonic resonances (Pt, TiN, ZrN). Regarding the choice of geometry, we consider two types of nanostructures, single nanocrystals deposited over a dielectric substrate and metastructure absorber, observing interesting opto-electronic properties. For single nanocrystals, the rate of HE generation is strongly material-dependent since the HE generation rate strongly depends on several physical parameters such as plasmonic enhancement, plasmonic resonance wavelength, Fermi energy, etc. Interestingly, the plasmonic meta-absorbers exhibit a different behaviour. The strongly-plasmonic metals, such as Au, Ag, Cu or Al, show very similar performances, while the materials with damped plasmon resonances demonstrate diverse and reduced rates of HE generation. The physical reason for these differentiated behaviours lies in the dielectric functions of these materials. In the metastructures, plasmonic resonances are in the infrared and the strongly-plasmonic materials behave as an almost ideal metal, whereas the second group of the materials exhibits strong dissipation. This makes the responses from the metastructures made of crystals with damped plasmons strongly dependent on the choice of material. The physical principles described in our study can be useful for designing metastructures and nanodevices based on HEs, which can be used in photo-chemistry and opto-electronics.
关键词： metastructures,hot electrons,nanostructures,opto-electronics,plasmonic materials
更新于2025-09-11 14:15:04