Search Results (71)

The rapid pace of modern life has contributed to a significant decline in sleep quality, which has become an urgent global public health issue. Melatonin, an endogenous hormone that regulates circadian rhythms, is vital in maintaining normal sleep cycles. While oral melatonin supplementation is widely used, transdermal delivery systems present advantages that include the avoidance of first-pass metabolism effects and enhanced bioavailability. In this study, a novel melatonin transdermal delivery system was successfully developed using a thermosensitive poly(N-vinylcaprolactam) [p(NVCL)]-based carrier. The p(NVCL) polymer was synthesized through free radical polymerization and characterized for its structural properties and phase transition temperature, in alignment with skin surface conditions. Orthogonal optimization experiments identified 3% azone, 3% menthol, and 4% borneol as the optimal enhancer combination for enhanced transdermal absorption. The formulation demonstrated exceptional melatonin loading characteristics with high encapsulation efficiency and stable physicochemical properties, including an appropriate pH and optimal moisture content. Comprehensive in vivo evaluation using normal mouse models revealed significant sleep quality improvements, specifically a shortened sleep latency and extended non-rapid eye movement sleep duration, with elevated serum melatonin and serotonin levels. Safety assessments including histopathological examination, biochemical analysis, and 28-day continuous administration studies confirmed excellent biocompatibility with no adverse reactions or systemic toxicity. Near-infrared fluorescence imaging provided direct evidence of enhanced transdermal absorption and superior biodistribution compared to oral administration. These findings indicate that the p(NVCL)-based melatonin transdermal gel system offers a safe, effective and convenient non-prescription option for sleep regulation, with promising potential for clinical translation as a consumer sleep aid. Full article

The generation of hot electrons through non-radiative decay processes of surface plasmons (SPs) has been extensively demonstrated, enabling the preparation of high-performance hot-electron photodetectors without limitations imposed by material band gap widths. In this paper, a near-infrared wideband hot-electron metal semiconductor photodetector (WHEMSPD) is proposed based on a metal grating plasmonic structure, and its optical and electrical properties are numerically verified. This structure exhibits excellent broadband characteristics within the long-wave near-infrared range (LW-NIR) of 1200–1800 nm, achieving an absorption of approximately 0.7 between 1200 and 1700 nm, with a peak of 0.98 at 1400 nm. The metal grating structure can effectively enhance the excitation of plasmons on the surface and thus increase the absorption within a larger bandwidth. In terms of electrical performance, the responsivity of the WHEMSPD reaches over 20 mA/W within the wavelength range of 1200–1500 nm, with the peak responsivity reaching 28.3 mA/W around 1320 nm. WHEMSPDs in the LW-NIR can be widely used in military, remote sensing, communication, and other related fields. Full article

Solar steam generation (SSG) has garnered significant attention for its potential in water purification applications. While composites with physically combined structures based on semiconductors or biomass have been developed for SSG, there remains a critical need for low-cost, high-efficiency devices. In this study, TiO₂ composites exhibiting excellent stability, high solar absorption, porous microstructure, and hydrophilic surfaces were identified as effective materials for SSG and water purification for the first time. A novel SSG device was designed by decorating TiO₂ onto three-dimensional carbonized Osmanthus fragrans leaves (TiO₂/carbonized OFL). Compared to directly carbonized OFL (without TiO₂) and Osmanthus fragrans leaves with templated TiO₂ (OFL-templated TiO₂), the TiO₂/carbonized OFL carbon composites demonstrated enhanced solar absorption, achieving over 99% in the visible region and more than 80% in the near-infrared region. Under solar illumination of 1 kW·m⁻², the TiO₂/carbonized OFL device achieved a high water evaporation rate of 2.31 kg·m⁻²·h⁻¹, which is 1.6 times higher than that of carbonized OFL and 3.45 times higher than OFL-templated TiO₂. Additionally, the TiO₂/carbonized OFL system exhibited remarkable efficiency in treating pharmaceutical wastewater, with a chemical oxygen demand (COD) removal efficiency of 98.9% and an ammonia nitrogen removal efficiency of 90.8% under solar radiation. Full article

Photodetectors with broad spectral response and high responsivity demonstrate significant potential in optoelectronic applications. This study proposes a Si/Ge avalanche photodiode featuring nanostructures that enhance light absorption. By optimizing the device epitaxial structure and these nanostructures, a wide spectral responsivity from 0.4 to 1.6 μm is achieved. The results demonstrate that introducing surface photon-trapping nanoholes and SiO₂ reflective grating nanostructures increases the average light absorptivity from 0.64 to 0.84 in the 0.4–1.1 μm range and from 0.31 to 0.56 in the 1.1–1.6 μm range. At an applied bias of 0.95 V_br-apd, the responsivity reaches 17.24 A/W at 1.31 μm and 17.6 A/W at 1.55 μm. This research provides theoretical insights for designing high-responsivity photodetectors in the visible–near-infrared broadband spectrum. Full article

Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has emerged as a promising non-invasive cancer treatment, addressing issues like drug resistance and systemic toxicity common in conventional breast cancer therapies. Recent research has shown that copper sulphide (CuS) nanoparticles and polydopamine (PDA) exhibit exceptional photothermal conversion efficiency under 808 nm near-infrared (NIR) laser irradiation, making them valuable for cancer phototherapy. However, the effectiveness of PDT is limited in hypoxic tumour environments, which are common in many breast cancer types, due to its reliance on local oxygen levels. Moreover, single-modality approaches, including phototherapy, often prove insufficient for complete tumour elimination, despite their therapeutic strength. In this paper, a microfluidic-assisted approach was used to create multifunctional silk-based nanoparticles (SFNPs) encapsulating the chemotherapeutic drug Epirubicin (EPI), the PTT/PDT agent CuS, and the heat-activated, oxygen-independent alkyl radical generator AIPH for combined chemotherapy, PTT, and PDT, with a polydopamine (PDA) coating for enhanced photothermal effects and surface-bound folic acid (FA) for targeted delivery in breast cancer treatment. The synthesised CuS-EPI-AIPH@SF-PDA-FA nanoparticles achieved a controlled size of 378 nm, strong NIR absorption, and high photothermal conversion efficiency. Under 808 nm NIR irradiation, these nanoparticles selectively triggered the release of alkyl radicals and EPI, improving intracellular drug levels and effectively killing various breast cancer cell lines while demonstrating low toxicity to non-cancerous cells. We demonstrate that novel core–shell CuS-EPI-AIPH@SF-PDA-FA NPs have been successfully designed as a multifunctional nanoplatform integrating PTT, PDT, and chemotherapy for targeted, synergistic breast cancer treatment. Full article

Regarding photocatalytic oxidative desulphurization (PODS), titanium oxide (TiO₂) is a promising contender as a catalyst due to its photocatalytic prowess and long-term performance in desulphurization applications. This work demonstrates the effectiveness of double-doping TiO₂ in silver (Ag) and molybdenum (Mo) for use as a novel catalyst in the desulphurization of light-cut hydrocarbons. FESEM, EDS, and AFM were used to characterize the morphology, doping concentration, surface features, grain size, and grain surface area of the Ag/Mo powder. On the other hand, XRD, FTIR spectroscopy, UV-Vis, and PL were used for structure and functional group detection and light absorption analysis based on TiO₂’s illumination properties. The microscopic images revealed nanoparticles with irregular shapes, and a 3D-AFM image was used to determine the catalyst’s physiognomies: 0.612 nm roughness and a surface area of 811.79 m²/g. The average sizes of the grains and particles were calculated to be 32.15 and 344.4 nm, respectively. The XRD analysis revealed an anatase structure for the doped TiO₂, and the FTIR analysis exposed localized functional groups, while the absorption spectra of the catalyst, obtained via UV-Vis, revealed a broad spectrum, including visible and near-infrared regions up to 1053.34 nm. The PL analysis showed luminescence with a lower emission intensity, indicating that the charge carriers were not thoroughly combined. This study’s findings indicate a desulphurization efficiency of 97%. Additionally, the promise of a nano-homogeneous particle distribution bodes well for catalytic reactions. The catalyst retains its efficiency when it is dried and reused, demonstrating its sustainable use while maintaining the desulphurization efficacy. This study highlights the potential of the double doping approach in enhancing the catalytic properties of TiO₂, opening up new possibilities for improving the performance of photo-oxidative processes. Full article

A series of TiN/ITO composite films with various thickness of ITO buffer layer were fabricated in this study. The enhancement of optical properties was realized in the composite thin films. The absorption spectra showed that absorption intensity in the near-infrared region was obviously enhanced with the increase of ITO thickness due to the coupling of surface plasma between TiN and ITO. The epsilon-near-zero wavelength of this composite can be tuned from 935 nm to 1895 nm by varying the thickness of ITO thin films. The nonlinear optical property investigated by Z-scan technique showed that the nonlinear absorption coefficient (β = 3.03 × 10⁻⁴ cm/W) for the composite was about 14.02 times greater than that of single-layer TiN films. The theoretical calculations performed by finite difference time domain were in good agreement with those of the experiments. Full article

This research aims to enhance the near-infrared (NIR) shielding ability of cesium tungsten bronze (CsWO₃) by increasing the spectral absorption in this region through the incorporation of gold nanorods (Au_NR). Two approaches were used to prepare the composite materials: physical mixing and solvothermal process. The effects of gold nanorods content on the crystalline size, particle size, shape, and optical properties of the composite were investigated systematically using DLS, TEM, XRD, and UV–Vis spectroscopy techniques, respectively. The physical mixing process synergizes Au_NR and CsWO₃ into a composite which has better NIR absorption than that of neat Au_NR and CsWO₃ nanorods. A composite with 10 mol% of Au_NR shows the highest NIR absorption ability due to the surface plasmon resonance and energy coupling between Au and CsWO₃. With the solvothermal process, the CsWO₃ nanorods grow up to 4–7 microns when the Au_NR content increases to 0.8 mol% due to the incorporation of the Au atoms. The microsized CsWO₃ rods have superior NIR shielding property compared to other conditions, including the Au_NR+CsWO₃ nanocomposite with 10 mol% of Au_NR from the physical mixing process. Full article

Satellite-based hyper-spectral infrared (IR) sensors such as the Atmospheric Infrared Sounder (AIRS), the Cross-track Infrared Sounder (CrIS), and the Infrared Atmospheric Sounding Interferometer (IASI) cover many methane (CH₄) spectral features, including the ν1 vibrational band near 1300 cm⁻¹ (7.7 μm); therefore, they can be used to monitor CH₄ concentrations in the atmosphere. However, retrieving CH₄ remains a challenge due to the limited spectral information provided by IR sounder measurements. The information required to resolve the weak absorption lines of CH₄ is often obscured by interferences from signals originating from other trace gases, clouds, and surface emissions within the overlapping spectral region. Consequently, currently available CH₄ data product derived from IR sounder measurements still have large errors and uncertainties that limit their application scope for high-accuracy climate and environment monitoring applications. In this paper, we describe the retrieval of atmospheric CH₄ profiles using a novel spectral fingerprinting methodology and our evaluation of performance using measurements from the CrIS sensor aboard the Suomi National Polar-orbiting Partnership (SNPP) satellite. The spectral fingerprinting methodology uses optimized CrIS radiances to enhance the CH₄ signal and a machine learning classifier to constrain the physical inversion scheme. We validated our results using the atmospheric composition reanalysis results and data from airborne in situ measurements. An inter-comparison study revealed that the spectral fingerprinting results can capture the vertical variation characteristics of CH₄ profiles that operational sounder products may not provide. The latitudinal variations in CH₄ concentration in these results appear more realistic than those shown in existing sounder products. The methodology presented herein could enhance the utilization of satellite data to comprehend methane’s role as a greenhouse gas and facilitate the tracking of methane sources and sinks with increased reliability. Full article

With the improvement in people’s living standards, the development and application of smart textiles are receiving increasing attention. In this study, a carbon nanosurface was successfully coated with a SiO₂ layer to form C@SiO₂ nanomaterials, which improved the dispersion of carbon nanomaterials in an aqueous solution and enhanced the absorption of light by the carbon nanoparticles. C@SiO₂ nanoparticles were coupled on the surface of silk fabric with the silane coupling agent KH570 to form C@SiO₂ nanosilk fabric. The silk fabric that was subjected to such surface modification was endowed with a special photothermal function. The results obtained with scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and infrared spectroscopy (FTIR) showed that C@SiO₂ nanoparticles were successfully modified on the surface of the silk fabric. In addition, under the irradiation of near-infrared light with a power of 20 W and a wavelength of 808 nm, the C@SiO₂ nanosilk fabric experienced rapid warming from 23 °C to 60 °C within 30 s. After subjecting the functional fabric to hundreds of photothermal experiments and multiple washes, the photothermal efficiency remained largely unchanged and proved to be durable and stable. In addition, the thermogravimetric (TG) analysis results showed that the C@SiO₂ nanoparticles contributed to the thermal stability of the silk fabric. The UV transmittance results indicated that C@SiO₂ nanofabric is UV-resistant. The silk modification method developed in this study is low-cost, efficient, and environmentally friendly. It has some prospects for future applications in the textile industry. Full article

Polydopamine (PDA) as a melanin-like biomimetic material with excellent biocompatibility, full spectrum light absorption capacity and antioxidation property has been extensively applied in the biomedical field. Based on the high reactivity of dopamine (DA), exploiting new strategies to fabricate novel PDA-based nano-biomaterials with controllable size and improved performance is valuable and desirable. Herein, we reported a facile way to synthesize pyrrole-doped polydopamine-pyrrole nanoparticles (PDA-nPY NPs) with tunable size and enhanced near-infrared (NIR) absorption capacity through self-oxidative polymerization of DA with PY in an alkaline ethanol/H₂O/NH₄OH solution. The PDA-nPY NPs maintain excellent biocompatibility and surface reactivity as PDA. By regulating the volume of added PY, PDA-150PY NPs with a smaller size (<100 nm) and four-fold higher absorption intensity at 808 nm than that of PDA can be successfully fabricated. In vitro and in vivo experiments effectively further demonstrate that PDA-150PY NPs can effectively inhibit tumor growth and completely thermally ablate a tumor. It is believed that these PY doped PDA-nPY NPs can be a potential photothermal (PT) agent in biomedical application. Full article

In this study, a fractal absorber was designed to enhance light absorptivity and improve the efficiency of converting solar energy into electricity for a range of solar energy technologies. The absorber consisted of multiple layers arranged from bottom to top, and the bottom layer was made of Ti metal, followed by a thin layer of MgF₂ atop it. Above the two layers, a structure comprising square pillars formed by three layers of Ti/MgF₂/Ti was formed. This pillar was encompassed by a square hollow with cylindrical structures made of Ti material on the exterior. The software utilized for this study was COMSOL Multiphysics^® (version 6.0). This study contains an absorption spectrum analysis of the various components of the designed absorber system, confirming the notion that achieving ultra-wideband and perfect absorption resulted from the combination of the various components. A comprehensive analysis was also conducted on the width of the central square pillar, and the analysis results demonstrate the presence of several remarkable optical phenomena within the investigated structure, including propagating surface plasmon resonance, localized surface plasmon resonance, Fabry–Perot cavity resonance, and symmetric coupling plasma modes. The optimal model determined through this software demonstrated that broadband absorption in the range of 276 to 2668 nm, which was in the range of UV-B to near-infrared, exceeded 90.0%. The average absorption rate in the range of 276~2668 nm reached 0.965, with the highest achieving a perfect absorptivity of 99.9%. A comparison between absorption with and without outer cylindrical structures revealed that the resonance effects significantly enhanced absorption efficiency, as evidenced by a comparison of electric field distributions. Full article

Nanostructures and nanomaterials, especially plasmonic nanostructures, often show optical properties that conventional materials lack and can manipulate light, as well as various light–matter interactions, in both their near-field and far-field regions with a high efficiency. Thanks to these unique properties, not only can they be used to enhance the sensitivity of chemical sensing and analysis techniques, but they also provide a solution for designing new sensing devices and simplifying the design of analytical instruments. The earliest applications of optical nanostructures are surface-enhanced spectroscopies. With the help of the resonance field enhancement of plasmonic nanostructures, molecular signals, such as Raman, infrared absorption, and fluorescence can be significantly enhanced, and even single-molecule analysis can be realized. Moreover, the resonant field enhancements of plasmonic nanostructures are often associated with other effects, such as optical forces, resonance shifts, and photothermal effects. Using these properties, label-free plasmonic sensors, nano-optical tweezers, and plasmonic matrix-assisted laser desorption/ionization have also been demonstrated in the past two decades. In the last few years, the research on optical nanostructures has gradually expanded to non-periodic 2D array structures, namely metasurfaces. With the help of metasurfaces, light can be arbitrarily manipulated, leading to many new possibilities for developing miniaturized integrated intelligent sensing and analysis systems. In this review, we discuss the applications of optical nanostructures in chemical sensing and analysis from both theoretical and practical aspects, aiming at a concise and unified framework for this field. Full article

This study experimentally demonstrates two types of ultra-broadband metamaterial absorbers with high performance in the visible-to-near-infrared range by using different anti-reflection coatings (i.e., SiO₂ and Si₃N₄) and a multi-subcell Ti-SiO₂-Ti metasurface. Compared to the bare metamaterial nanostructure, the absorption bandwidth of the coated metasurfaces exhibit increases of 594 nm and 1093 nm, respectively. Such improvements benefit from nearly perfect impedance matching to the free space enhanced by the anti-reflection coating, thin film interference, and excitations of different surface plasmon resonances. As a result, the absorber with SiO₂ coating exhibits a measured bandwidth with an absorption of 0.9 ranging from 502 nm to 1892 nm, while the absorber with Si₃N₄ coating further broadens the bandwidth from 561 nm to 2450 nm. The measured average absorptions for both cases remain above 95% and 87%, respectively. Moreover, both nanostructures are robust to large incident angles of up to 60° for both TE and TM modes. Our findings highlight the promising potential of these absorbers for various applications, including solar energy harvesting, thermal emitters, and photodetectors. Full article

Frontiers in theranostics are driving the demand for multifunctional nanoagents. Upconversion nanoparticle (UCNP)-based systems activated by near-infrared (NIR) light deeply penetrating biotissue are a powerful tool for the simultaneous diagnosis and therapy of cancer. The intercalation into large polymer micelles of poly(maleic anhydride-alt-1-octadecene) provided the creation of biocompatible UCNPs. The intrinsic properties of UCNPs (core@shell structure NaYF₄:Yb³⁺/Tm³⁺@NaYF₄) embedded in micelles delivered NIR-to-NIR visualization, photothermal therapy, and high drug capacity. Further surface modification of micelles with a thermosensitive polymer (poly-N-vinylcaprolactam) exhibiting a conformation transition provided gradual drug (doxorubicin) release. In addition, the decoration of UCNP micelles with Ag nanoparticles (Ag NPs) synthesized in situ by silver ion reduction enhanced the cytotoxicity of micelles at cell growth temperature. Cell viability assessment on Sk-Br-3, MDA-MB-231, and WI-26 cell lines confirmed this effect. The efficiency of the prepared UCNP complex was evaluated in vivo by Sk-Br-3 xenograft regression in mice for 25 days after peritumoral injection and photoactivation of the lesions with NIR light. The designed polymer micelles hold promise as a photoactivated theranostic agent with quattro-functionalities (NIR absorption, photothermal effect, Ag NP cytotoxicity, and Dox loading) that provides imaging along with chemo- and photothermal therapy enhanced with Ag NPs. Full article