RESUMEN
In this work, we encapsulated Fe3O4@SiO2@Ag (MS-Ag), a bifunctional magnetic silver core-shell structure, with an outer mesoporous silica (mS) shell to form an Fe3O4@SiO2@Ag@mSiO2 (MS-Ag-mS) nanocomposite using a cationic CTAB (cetyltrimethylammonium bromide) micelle templating strategy. The mS shell acts as protection to slow down the oxidation and detachment of the AgNPs and incorporates channels to control the release of antimicrobial Ag+ ions. Results of TEM, STEM, HRSEM, EDS, BET, and FTIR showed the successful formation of the mS shells on MS-Ag aggregates 50-400 nm in size with highly uniform pores â¼4 nm in diameter that were separated by silica walls â¼2 nm thick. Additionally, the mS shell thickness was tuned to demonstrate controlled Ag+ release; an increase in shell thickness resulted in an increased path length required for Ag+ ions to travel out of the shell, reducing MS-Ag-mS' ability to inhibit E. coli growth as illustrated by the inhibition zone results. Through a shaking test, the MS-Ag-mS nanocomposite was shown to eradicate 99.99+% of a suspension of E. coli at 1 × 106 CFU/mL with a silver release of less than 0.1 ppb, well under the EPA recommendation of 0.1 ppm. This high biocidal efficiency with minimal silver leach is ascribed to the nanocomposite's mS shell surface characteristics, including having hydroxyl groups and possessing a high degree of structural periodicity at the nanoscale or "smoothness" that encourages association with bacteria and retains high Ag+ concentration on its surface and in its close proximity. Furthermore, the nanocomposite demonstrated consistent antimicrobial performance and silver release levels over multiple repeated uses (after being recovered magnetically because of the oxidation-resistant silica-coated magnetic Fe3O4 core). It also proved effective at killing all microbes from Long Island Sound surface water. The described MS-Ag-mS nanocomposite is highly synergistic, easy to prepare, and readily recoverable and reusable and offers structural tunability affecting the bioavailability of Ag+, making it excellent for water disinfection that will find wide applications.
RESUMEN
Anisotropic magnetic nanoparticles with a mesoporous silica shell have the combined merits of a magnetic core and a robust shell. Preparation of magnetically guidable core-shell nanostructures with a robust silica shell that contains well-defined, large, radially aligned silica pores is challenging, and hence this has rarely been described in detail. Herein, a dynamic soft-templating strategy is developed to controllably synthesize hierarchical, dual-mesoporous silica shells on diverse core nanoparticles, in terms of nanoparticle shape (i.e., spherical, chainlike, and disclike), magnetic properties (i.e., hard magnetic and superparamagnetic), and dimensions (i.e., from 3 nm to submicrometers). The developed interfacial coassembly method allows easy design of applicable silica shells containing tunable pore geometries with pore sizes ranging from below 5 nm to above 40 nm, with a specific surface area of 577 m2 g-1 and pore volume of 1.817 cm3 g-1. These are the highest values reported for magnetically guidable anisotropic nanoparticles. The versatility of the method is shown by transfer of the coating procedure to core particles as diverse as spherical superparamagnetic nanoparticles and their clusters as well as by ferromagnetic 3 nm thick hexaferrite nanoplatelets. This method can serve as a general approach for the fabrication of well-designed mesoporous silica coatings on a wide variety of core nanoparticles.
RESUMEN
Zeolitic imidazole frameworks (ZIFs) with tunable pore sizes and high surface areas have recently used as an effective support for immobilizing enzymes. However, the instability in the aqueous acidic environment has limited their practical applications in some cases. In this work, we develop a novel catalase/ZIFs composite with mesoporous silica shell (mSiO2@CAT/ZIFs) via co-precipitation, and controlled self-assembly of silanes. During preparation, the cetyltrimethylammonium bromide induced the formation of the mesostructured silica layer on the outer surface of CAT/ZIFs. The resultant mSiO2@CAT/ZIFs exhibited high activity recovery (92%). Compared with the conventional CAT/ZIFs and free CAT, mSiO2@CAT/ZIFs exhibited excellent acid resistance. For example, after 30â¯min in acetate buffer solution (pH 3.0), the CAT/ZIFs and free CAT almost lost activity whereas the mSiO2@CAT/ZIFs still retained 35% of original activity. Meanwhile, the thermostability of the mSiO2@CAT/ZIFs was enhanced significantly compared with conventional CAT/ZIFs. In addition, the mSiO2@CAT/ZIFs displayed excellent storage stability, and retained 60% of its initial activity after 15 days storage period. Furthermore, the mSiO2@CAT/ZIFs could maintain 70% of its initial activity after 8 continuous uses, demonstrating superior reusability than the free CAT and CAT/ZIFs. These results demonstrated that the mSiO2@CAT/ZIFs are potential for practical applications even in the acidic environment.
Asunto(s)
Ácidos/química , Enzimas Inmovilizadas/química , Nanocompuestos/química , Dióxido de Silicio/química , Catalasa/química , Catalasa/metabolismo , Estabilidad de Enzimas , Enzimas Inmovilizadas/metabolismo , Imidazoles/química , Estructuras Metalorgánicas/química , Estructuras Metalorgánicas/metabolismo , Porosidad , Silanos/químicaRESUMEN
Mesoporous multi-layered silica-coated luminescent Y2O3:Eu nanoparticles (NPs) were prepared by a urea-based decomposition process, and their surfaces were gradually modified with nanoporous and mesoporous silica layers using modified sol-gel methods. The synthesized luminescent core-shell NPs were characterized thoroughly to investigate their structural, morphological, thermal, optical, photo luminescent properties and their surface chemistry. The morphology of the core NPs were nearly spherical in shape and were nano-sized grains. The observed luminescent efficiency of the mesoporous multi-layered silica-coated luminescent core NPs was gradually reduced because of bond formation between the Y2O3:Eu core and the amorphous silica shell via YOSiOH bridges on the surface of the NPs; the bonds suppressed the non-radiative transition pathways. Biocompatibility tests on Human breast cancer cells using the 3(4,5Dimethylthiazol2yl)2,5diphenyltetrazolium bromide and lactate dehydrogenase assays indicated that the core-shell NPs were non-toxic even at high concentrations. The mesoporous SiO2 layer played a key role in perfecting the solubility, biocompatibility, and non-toxicity of the NPs. The zeta potential, surface chemistry (Fourier transform infrared spectroscopy), and optical absorption spectral analyses revealed the high hydrophilicity of the as-prepared core-shell NPs because of the active surface-functionalized silanol (SiOH) groups, which could potentially offer many exciting opportunities in photonic-based biomedical applications.
Asunto(s)
Materiales Biocompatibles Revestidos , Europio , Mediciones Luminiscentes , Ensayo de Materiales , Nanopartículas/química , Dióxido de Silicio , Itrio , Materiales Biocompatibles Revestidos/química , Materiales Biocompatibles Revestidos/farmacología , Europio/química , Europio/farmacología , Humanos , Células MCF-7 , Porosidad , Dióxido de Silicio/química , Dióxido de Silicio/farmacología , Itrio/química , Itrio/farmacologíaRESUMEN
Herein, a novel drug photorelease system based on gold nanostars (AuNSts), coated with a mesoporous silica shell and capped with paraffin as thermosensitive molecular gate, is reported. Direct measurements of the surface temperature of a single gold nanostar irradiated using a tightly focused laser beam are performed via a heat-sensitive biological matrix. The surface temperature of a AuNSt increases by hundreds of degrees (°C) even at low laser powers. AuNSts coated with a mesoporous silica shell using a surfactant-templated synthesis are used as chemotherapeutic nanocarriers. Synthetic parameters are optimized to avoid AuNSt reshaping, and thus to obtain nanoparticles with suitable and stable plasmonic properties for near-infrared (NIR) laser-triggered cargo delivery. The mesoporous silica-coated nanostars are loaded with doxorubicin (Dox) and coated with octadecyltrimethoxysilane and the paraffin heneicosane. The paraffin molecules formed a hydrophobic layer that blocks the pores, impeding the release of the cargo. This hybrid nanosystem exhibits a well-defined photodelivery profile using NIR radiation, even at low power density, whereas the nonirradiated sample shows a negligible payload release. Dox-loaded nanoparticles displayed no cytotoxicity toward HeLa cells, until they are irradiated with 808 nm laser, provoking paraffin melting and drug release. Hence, these novel, functional, and biocompatible nanoparticles display adequate plasmonic properties for NIR-triggered drug photorelease applications.
Asunto(s)
Oro/química , Supervivencia Celular , Doxorrubicina , Sistemas de Liberación de Medicamentos , Liberación de Fármacos , Células HeLa , Humanos , Nanoestructuras , Porosidad , Dióxido de SilicioRESUMEN
Bioresponsive drug delivery systems that can modulate drug release profiles according to different tumor microenvironment are highly desired for improving cancer therapy. In this work, a pH-responsive nanocarrier, layered double hydroxide (LDH) nanoplates coated with ultrathin mesoporous silica layer (LDH@MS), was fabricated with total thickness of around 9 nm. The coating of ultrathin porous silica significantly improved the stability of nanoplates. Moreover, the LDH@MS exhibited pH responsive functionality due to the degradation of silica shell and LDH under moderately acidic pH condition. Notably, the curcumin loaded LDH@MS displayed nearly five-fold greater antitumor efficacy against human breast cancer cells in vitro and marked tumor inhibition in vivo compared to free curcumin under the same drug dosage, most likely due to high dispersibility of the nanocarrier, as well as responsive and steady release of drug molecules. This study opens new avenues to design safer and more effective drug delivery systems with improved therapeutic outcomes.
RESUMEN
Integrating multiple imaging and therapy functionalities into one single nanoscale platform has been proposed to be a promising strategy in cancer theranostics. In this work, WS2 nanosheets with their surface pre-adsorbed with iron oxide (IO) nanoparticles via self-assembly are coated with a mesoporous silica shell, on to which polyethylene glycol (PEG) is attached. The obtained WS2-IO@MS-PEG composite nanoparticles exhibit many interesting inherent physical properties, including high near-infrared (NIR) light and X-ray absorbance, as well as strong superparamagnetism. In the mean time, the mesoporous silica shell in WS2-IO@MS-PEG could be loaded with a chemotherapy drug, doxorubicin (DOX), whose intracellular release afterwards may be triggered by NIR-induced photothermal heating for enhanced cancer cell killing. Upon systemic administration of such drug-loaded nano-theranostics, efficient tumor homing of WS2-IO@MS-PEG/DOX is observed in tumor-bearing mice as revealed by three-modal fluorescence, magnetic resonance (MR), and X-ray computed tomography (CT) imaging. In vivo combined photothermal & chemotherapy is then carried out with WS2-IO@MS-PEG/DOX, achieving a remarkably synergistic therapeutic effect superior to the respective mono-therapies. Our study highlights the promise of developing multifunctional nanoscale theranostics based on two-dimensional transition metal dichalcogenides (TMDCs) such as WS2 for multimodal imaging-guided combination therapy of cancer.