Synthesis of calcium monosilicide nanowires by reactive deposition technique

The CaSi nanowires were synthesized on Si substrate by reactive deposition technique. A great amount of Ca vapor reacted with surface of cleaned Si substrate, and CaSi nanowires was grown on the as-synthesized CaSi film. The diameter of nanowires could achieve with a minimum value about 25 nm. The CaSi nanowire was self-orient along the <001> direction. We can control the length of nanowires by experimental parameter settings, such as quantity of Ca source, duration time and temperature. The formation mechanism of Ca-silicides on Si substrate was discussed in detail. Raman spectroscopy shows that the nanosized character for CaSi phase was confirmed. Meanwhile, the Ca-silicides layer showed a strong absorption in the ultraviolet (UV) region of the solar spectrum, indicating their potential applications.

Investigation on Light Extraction Behavior of Surface Plasmon-Coupled Deep-Ultraviolet LED in Different Emission Directions

The light extraction behavior of an AlGaN-based deep-ultraviolet LED covered with Al nanoparticles (NPs) is investigated by three-dimensional finite-difference time-domain simulation. For the transmission spectra of s- and p-polarizations in different emission directions, the position of maximum transmittance can be changed from (θ = 0°, λ = 273 nm) to (θ = 0°, λ = 286 nm) by increasing the diameter of Al NPs from 40 nm to 80 nm. In the direction that is greater than the critical angle, the transmittance of s-polarization is very small due to the strong absorption of Al NPs, while the transmittance spectrum of p-polarization can be observed obviously for the 80 nm Al NPs structure. For a ~284 nm AlGaN-based LED with surface plasmon (SP) coupling, although the luminous efficiency is significantly improved due to the improvement of the radiation recombination rate as compared with the conventional LED, the light extraction efficiency (LEE) is lower than 2.61% of the conventional LED without considering the lateral surface extraction and bottom reflection. The LEE is not greater than ~0.98% (~2.12%) for an SP coupling LED with 40 nm (80 nm) Al NPs. The lower LEE can be attributed to the strong absorption of Al NPs.

A Green Method to Synthesize Size-Controllable Gold Nanostars for Photothermal Therapy and Photoacoustic Imaging

Photothermal therapy (PTT) is a novel therapy for cancer treatment which is based on the conversion of photon energy into heat (>43 °C), and photoacoustic imaging (PAI) is a new bioimaging method for diagnosing and monitoring cancer. To enhance the impact depth of PTT and the signal of PAI, near-infrared (NIR)-absorbing photothermal agents are usually used. The development of novel NIR-absorbing photothermal agents with excellent properties, such as a high stability under long-term irradiation, strong absorption in the NIR range, and excellent biocompatibility, is needed in modern biomedicine. Previous research has proved that gold nanostars (AuNSs) have promising potential applications in photo-based therapies owing to their strong absorption in the NIR range and strong photothermal effects. However, the reported methods to synthesize AuNSs are complicated and toxic, which can limit its practical application. In this work, we proposed a new environmental strategy to synthesize AuNSs by using chitosan and vitamin C. Chitosan plays multiple roles, acting as stabilizing, shape-directing, and size-controllable agents in this method for the first time. The obtained AuNSs show strong NIR absorption and biocompatibility toward non-cancerous and cancerous cell lines. The in vitro tests proved the high efficiency of the obtained AuNSs in both PTT and PAI.

An innovative high frequency hyperthermia approach against SARS-CoV-2 and related virus: feasibility analysis

Heating is a strong enemy of SARS-CoV and related virus. Starting from both this consideration and from the basic principle of the microwave ovens which are based on the strong absorption, from organic tissues, of the radiation centered around 2.15 GHz, we examine the feasibility of using this frequency range to both lower the strength of the SARS-CoV (and related virus) inside the human body and to easily sterilize objects or closed rooms. We underline that this is only a preliminary theoretical feasibility analysis, which, of course, should be experimentally proven.

Near-infrared Inorganic Nanomaterials-based Nanosystem for Photothermal Therapy

The development of robust materials for treating diseases through non-invasive photothermal therapy (PTT) has attracted increasing attention in recent years. Among many types of nanomaterials, inorganic nanomaterials with strong absorption...

Femtosecond Intersystem Crossing to the Reactive Triplet State of the 2,6-Dithiopurine Skin Cancer Photosensitizer

Site-selected sulfur-substituted nucleobases are a class of all organic, heavy-atom-free photosensitizers for photodynamic therapy applications that exhibit excellent photophysical properties such as strong absorption in the ultraviolet-A region of the...