Thermal crowning mechanism in gold-silica nanocomposites: plasmonic-photonic pairing in archetypal two-dimensional structures

Hyaluronic Acid Modified Au@SiO2@Au Nanoparticles for Photothermal Therapy of Genitourinary Tumors

Bladder cancer and prostate cancer are the most common malignant tumors of the genitourinary system. Conventional strategies still face great challenges of high recurrence rate and severe trauma. Therefore, minimally invasive photothermal therapy (PTT) has been extensively explored to address these challenges. Herein, fluorescent Au nanoparticles (NPs) were first prepared using glutathione as template, which were then capped with SiO₂ shell to improve the biocompatibility. Next, Au nanoclusters were deposited on the NPs surface to obtain Au@SiO₂@Au NPs for photothermal conversion. The gaps between Au nanoparticles on their surface could enhance their photothermal conversion efficiency. Finally, hyaluronic acid (HA), which targets cancer cells overexpressing CD44 receptors, was attached on the NPs surface via 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) chemistry to improve the accumulation of NPs in tumor tissues. Photothermal experiments showed that NPs with an average size of 37.5 nm have a high photothermal conversion efficiency (47.6%) and excellent photostability, thus exhibiting potential application as a PTT agent. The temperature of the NPs (100 μg·mL⁻¹) could rapidly increase to 38.5 °C within 200 s and reach the peak of 57.6 °C with the laser power density of 1.5 W·cm⁻² and irradiation time of 600 s. In vivo and in vitro PTT experiments showed that the NPs have high biocompatibility and excellent targeted photothermal ablation capability of cancer cells. Both bladder and prostate tumors disappeared at 15 and 18 d post-treatment with HA-Au@SiO₂@Au NPs, respectively, and did not recur. In summary, HA-Au@SiO₂@Au NPs can be used a powerful PTT agent for minimally invasive treatment of genitourinary tumors.

Programmable hierarchical plasmonic-photonic arrays via laser-induced film dewetting

Hierarchical and periodic nanostructures of dielectrics or metals are highly demanded for wide applications in optical, electrical, biological, and quantum devices. In this work, programmable plasmonic-photonic hierarchical nanostructures are fabricated using a facile and effective method with high controllability and stable reproducibility. The fabrication involves colloidal self-assembly, metal film deposition, and pulsed laser-induced dewetting in sequence for controllably pairing metal nanostructures on dielectric nanospheres in either large area or a local precision. Au nanostructures including Au nanocrown (AuNC), large Au nanosphere (AuNS), and multiple small Au nanoparticles (AuNPs) have been paired one-on-one on assembled SiO2 nanosphere (SiO2NS) arrays, with size and shape controlled by correlating the laser fluence and irradiation time, and the Au film thickness. The fabricated hierarchical nanostructures demonstrate synergistic effect of the photonic effects from the monolayer SiO2NS arrays and the surface plasma resonance effect from the Au nanostructures. The dewetting induced metal film reshaping has been modeled theoretically corresponding to observed experimental results. We can directly "write" the plasmonic Au nanostructures on the photonic crystal array using a focused laser beam to form encode patterns, showing angle-dependent structural colors for anti-counterfeiting information storage and display in rigid/flexible and opaque/transparent devices. It provides a promising path to actively construct on-demand pixelated plasmonic-photonic arrays for optical multiplexing technology in sensing, information encryption, and display.

Silica- Iron Oxide Nanocomposite Enhanced with Porogen Agent Used for Arsenic Removal

This study aims to remove arsenic from an aqueous medium by adsorption on a nanocomposite material obtained by the sol–gel method starting from matrices of silica, iron oxide and NaF (SiO₂/Fe(acac)₃/NaF). Initially, the study focused on the synthesis and characterization of the material by physico–chemical methods such as: X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, atomic force microscopy, and magnetization. Textural properties were obtained using nitrogen adsorption/desorption measurements. The zero load point, pHpZc, was also determined by the method of bringing the studied system into equilibrium. In addition, this study also provides a comprehensive discussion of the mechanism of arsenic adsorption by conducting kinetic, thermodynamic and equilibrium studies. Studies have been performed to determine the effects of adsorbent dose, pH and initial concentration of arsenic solution, material/arsenic contact time and temperature on adsorption capacity and material efficiency. Three theoretical adsorption isotherms were used, namely Langmuir, Freundlich and Sips, to describe the experimental results. The Sips isotherm was found to best describe the experimental data obtained, the maximum adsorption capacity being ~575 µg As(III)/g. The adsorption process was best described by pseudo-second order kinetics. Studies have been performed at different pH values to establish not only the optimal pH at which the adsorption capacity is maximum, but also which is the predominantly adsorbed species. The effect of pH and desorption studies have shown that ion exchange and the physiosorption mechanism are implicated in the adsorption process. From a thermodynamic point of view, parameters such as ΔG°, ΔH° and ΔS° were evaluated to establish the mechanism of the adsorption process. Desorption studies have been performed to determine the efficiency of the material and it has been shown that the material can be used successfully to treat a real-world example of deep water with a high arsenic content.

Functionalization of Se-Te Nanorods with Au Nanoparticles for Enhanced Anti-Bacterial and Anti-Cancer Activities

The use of medical devices for therapeutic and diagnostic purpose is globally increasing; however, bacterial colonization on therapeutic devices can occur, causing severe infections in the human body. It has become an issue for public health. It is necessary to develop a nanomaterial based on photothermal treatment to kill toxic bacterial strains. Appropriately, high photothermal conversion and low-cost powerful photothermal agents have been investigated. Recently, gold nanocomposites have attracted great interest in biological applications. Here, we prepared rod-shaped Se-Te@Au nanocomposites of about 200 nm with uniform shape and surface-coated with gold nanoparticles for the first time showing high anti-bacterial and anti-cancer activities. Se-Te@Au showed proper structural consistency and natural resistance to bacterial and cancer cells. The strong absorption and high photothermal conversion efficacy made it a good photothermal agent material for the photothermal treatment of bacterial and cancer cells. The Se-Te@Au rod showed excellent anti-bacterial efficacy against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, with highest recorded inhibition zones of 25 ± 2 mm and 22 ± 2 mm, respectively. More than 99% of both types of strains were killed after 5 min with a near-infrared (NIR) laser at the very low concentration of 48 µg/mL. The Se-Te@Au rod’s explosion in HeLa cells was extensively repressed and demonstrated high toxicity at 100 µg/mL for 5 min when subjected to an NIR laser. As a result of its high photothermal characteristics, the exceptional anti-bacterial and anti-cancer effects of the Se-Te@Au rod are considerably better than those of other methods previously published in articles. This study could open a new framework for sterilization applications on the industrial level.