Removal Efficiency of Bottom Ash and Sand Mixtures as Filter Layers for Fine Particulate Matter.

Permeable pavement is a technology that allows rainwater to infiltrate into the pavement. Permeable pavements not only help reduce surface runoff by allowing rainwater to infiltrate into the pavement, but also improve water quality with the filter layer that removes particulate matter pollutants. This study evaluated the particulate matter removal efficiency of bottom ash-sand mixtures as filter layers for removing fine (≤10 µm) or ultrafine (≤2.5 µm) particulate matter in the laboratory. Five filter media were tested: silica sand, bottom ash, and bottom ash-sand mixtures with 30:70, 50:50, and 70:30 ratios. The mixed filters exhibited more consistent and stable particulate matter removal efficiency over time than either the uniform sand or bottom ash filter. The 50:50 bottom ash-sand mixture demonstrated removal rates of 58.05% for 1.8 µm particles, 93.92% for 10 µm particles, and 92.45% for 60 µm particles. These findings highlight the potential of bottom ash-sand mixtures as effective filter media for removing PM10 road dust, although field validation with actual pavement systems is necessary.

Fabrication of Yolk-Shell Structure with Multifarious Nanoparticles via Double-Layered Encapsulation Strategy.

The post-encapsulation method (such as single-layered encapsulation) is a promising strategy to synthesize yolk-shell structures that protect functional nanoparticles by the molecular sieving effect. However, this method exhibited limited loading capacity and nonuniform encapsulation during the co-encapsulation of various nanoparticles owing to the insufficient surface area for nanoparticle attachment. To address these limitations, we proposed a double-layered encapsulation method comprising an increased number of silica template layers and separate attachment of multifarious nanoparticles to different layers. Compared with conventional methods, this strategy can precisely adjust the ratio of encapsulated nanoparticles and increase the loading amount, which improves the functionality of yolk-shell structures, such as the photothermal properties of gold nanoparticle-encapsulated yolk-shell structures (∼69%). We describe, for the first time, the precise control of the ratio of encapsulated nanoparticles and the loading of numerous nanoparticles. Consequently, this strategy has significant potential for various applications of yolk-shell structures.

Silica-Capped and Gold-Decorated Silica Nanoparticles for Enhancing Effect of Gold Nanoparticle-Based Photothermal Therapy.

BACKGROUND: Various methods based on gold nanoparticles (AuNPs) have been applied to enhance the photothermal effect. Among these methods, combining gold nanoparticles and stem cells has been suggested as a new technique for elevating the efficiency of photothermal therapy (PT) in terms of enhancing tumor targeting effect. However, to elicit the efficiency of PT using gold nanoparticles and stem cells, delivering large amounts of AuNPs into stem cells without loss should be considered. METHODS: AuNPs, AuNPs-decorated silica nanoparticles, and silica-capped and AuNPs-decorated silica nanoparticles (SGSs) were synthesized and used to treat human mesenchymal stem cells (hMSCs). After evaluating physical properties of each nanoparticle, the concentration of each nanoparticle was estimated based on its cytotoxicity to hMSCs. The amount of AuNPs loss from each nanoparticle by exogenous physical stress was evaluated after exposing particles to a gentle shaking. After these experiments, in vitro and in vivo photothermal effects were then evaluated. RESULTS: SGS showed no cytotoxicity when it was used to treat hMSCs at concentration up to 20 µg/mL. After intravenous injection to tumor-bearing mice, SGS-laden hMSCs group showed significantly higher heat generation than other groups following laser irradiation. Furthermore, in vivo photothermal effect in the hMSC-SGS group was significantly enhanced than those in other groups in terms of tumor volume decrement and histological outcome. CONCLUSION: Our results suggest that additional silica layer in SGSs could protect AuNPs from physical stress induced AuNPs loss. The strategy applied in SGS may offer a prospective method to improve PT.

Yolk-Shell-Type Gold Nanoaggregates for Chemo- and Photothermal Combination Therapy for Drug-Resistant Cancers.

Epithelial ovarian cancer is a gynecological cancer with the highest mortality rate, and it exhibits resistance to conventional drugs. Gold nanospheres have gained increasing attention over the years as photothermal therapeutic nanoparticles, owing to their excellent biocompatibility, chemical stability, and ease of synthesis; however, their practical application has been hampered by their low colloidal stability and photothermal effects. In the present study, we developed a yolk-shell-structured silica nanocapsule encapsulating aggregated gold nanospheres (aAuYSs) and examined the photothermal effects of aAuYSs on cell death in drug-resistant ovarian cancers both in vitro and in vivo. The aAuYSs were synthesized using stepwise silica seed synthesis, surface amino functionalization, gold nanosphere decoration, mesoporous organosilica coating, and selective etching of the silica template. Gold nanospheres were agglomerated in the confined silica interior of aAuYSs, resulting in the red-shifting of absorbance and enhancement of the photothermal effect under 808 nm laser irradiation. The efficiency of photothermal therapy was first evaluated by inducing aAuYS-mediated cell death in A2780 ovarian cancer cells, which were cultured in a two-dimensional culture and a three-dimensional spheroid culture. We observed that photothermal therapy using aAuYSs together with doxorubicin treatment synergistically induced the cell death of doxorubicin-resistant A2780 cancer cells in vitro. Furthermore, this type of combinatorial treatment with photothermal therapy and doxorubicin synergistically inhibited the in vivo tumor growth of doxorubicin-resistant A2780 cancer cells in a xenograft transplantation model. These results suggest that photothermal therapy using aAuYSs is highly effective in the treatment of drug-resistant cancers.

Versatile Yolk-Shell Encapsulation: Catalytic, Photothermal, and Sensing Demonstration.

Here, a novel, versatile synthetic strategy to fabricate a yolk-shell structured material that can encapsulate virtually any functional noble metal or metal oxide nanocatalysts of any morphology in a free suspension fashion is reported. This strategy also enables encapsulation of more than one type of nanoparticle inside a single shell, including paramagnetic iron oxide used for magnetic separation. The mesoporous organosilica shell provides efficient mass transfer of small target molecules, while serving as a size exclusion barrier for larger interfering molecules. Major structural and functional advantages of this material design are demonstrated by performing three proof-of-concept applications. First, effective encapsulation of plasmonic gold nanospheres for localized photothermal heating and heat-driven reaction inside the shell is shown. Second, hydrogenation catalysis is demonstrated under spatial confinement driven by palladium nanocubes. Finally, the surface-enhanced Raman spectroscopic detection of model pollutant by gold nanorods is presented for highly sensitive environmental sensing with size exclusion.

Upconverting Oil-Laden Hollow Mesoporous Silica Microcapsules for Anti-Stokes-Based Biophotonic Applications.

A recyclable, aqueous phase functioning and biocompatible photon upconverting system is developed. Hollow mesoporous silica microcapsules (HMSMs) with ordered radial mesochannels were employed, for the first time, as vehicles for the post-encapsulation of oil phase triplet-triplet annihilation upconversion (TTA-UC), with the capability of homogeneous suspension in water. In-depth characterization of such upconverting oil-laden HMSMs (UC-HMSMs) showed that the mesoporous silica shells reversibly stabilized the encapsulated UC oil in water to allow efficient upconverted emission, even under aerated conditions. In addition, the UC-HMSMs were found to actively bind to the surface of human mesenchymal stem cells without significant cytotoxicity and displayed upconverted bright blue emission under 640 nm excitation, indicating a potential of our new TTA-UC system in biophotonic applications. These findings reveal the great promise of UC-HMSMs to serve as ideal vehicles not only for ultralow-power in vivo imaging but also for stem cell labeling, to facilitate the tracking of tumor cells in animal models.

Flexible and Micropatternable Triplet-Triplet Annihilation Upconversion Thin Films for Photonic Device Integration and Anticounterfeiting Applications.

Triplet-triplet annihilation upconversion (TTA-UC) has recently drawn widespread interest for its capacity to harvest low-energy photons and to broaden the absorption spectra of photonic devices, such as solar cells. Although conceptually promising, effective integration of TTA-UC materials into practical devices has been difficult due to the diffusive and anoxic conditions required in TTA-UC host media. Of the solid-state host materials investigated, rubbery polymers facilitate the highest TTA-UC efficiency. To date, however, their need for long-term oxygen protection has limited rubbery polymers to rigid film architectures that forfeit their intrinsic flexibility. This study introduces a new multilayer thin-film architecture, in which scalable solution processing techniques are employed to fabricate flexible, photostable, and efficient TTA-UC thin films containing layers of oxygen barrier and host polymers. This breakthrough material design marks a crucial advance toward TTA-UC integration within rigid and flexible devices alike. Moreover, it introduces new opportunities in unexplored applications such as anticounterfeiting. Soft lithography is incorporated into the film fabrication process to pattern TTA-UC host layers with a broad range of high-resolution microscale designs, and superimposing host layers with customized absorption, emission, and patterning ultimately produces proof-of-concept anticounterfeiting labels with advanced excitation-dependent photoluminescent security features.