Silver nanomaterials have attracted a great deal of interest due to their broad-spectrum antimicrobial activity. However, it is still challenging to balance the high antibacterial efficiency with low damage to biological cells of silver nanostructures, especially when the diameter decreases to less than 10 nm. Here, we developed a new type of Ag nanohybrid material via a unimolecular micelle template method, which presents amazing antibacterial activities and almost noncytotoxicity. First, watersoluble multiarm star-shaped brushlike copolymer α-CD-g-[(PEO 40 -g-PAA 50 )-b-PEO 5 ] 18 was precisely synthesized and its micelle behavior in different solvents was revealed. Then, nanocrystal clusters assembled by Ag grains (Ag@Template NCs) were prepared through an in situ redox route using the unimolecular micelle of α-CD-g-[(PEO 40 -g-PAA 50 )-b-PEO 5 ] 18 as the soft template, AgNO 3 as a precursor, and tetrabutylammonium borohydride (TBAB) as the reducing agent. The overall size of the achieved Ag@Template NCs is controlled by the template structure at around 40 nm (D h in DMF), and the size of the Ag grain can be easily regulated from ∼1 to ∼5 nm by adjusting the feeding ratio of AgNO 3 /acrylic acid (AA) units in the template from 1:10 to 1:1. Benefitting from the structural design of the template, all Ag@Template NCs prepared here exhibit excellent dispersibility and chemical stability in different aqueous environments (neutral, pH = 5.5, and 0.9% NaCl physiological saline solution), which play a crucial role in the long-term storage and potential application in a complex physiological environment. The antibacterial and cytotoxicity tests indicate that Ag@Template NCs display much better performance than Ag nanoparticles (Ag NPs), which have a comparable overall size of ∼25 nm. The inhibitory capability of Ag@Template NCs to bacteria strongly depends on the grain size. Specifically, the Ag@ Template-1 NC assembled by the smallest grains (1.6 ± 0.3 nm) presents the best antibacterial activity. For E. coli (−), the MIC value is as low as 5 μg/mL (0.36 μg/mL of Ag), while for S. aureus (+), the value is around 10 μg/mL (0.72 μg/mL of Ag). The survival rate of L02 cells and lactate dehydrogenase assay together illustrate the low cytotoxicity possessed by the prepared Ag@ Template NCs. Therefore, the proposed Ag@Template NC structure successfully resolves the high reactivity, instability, and fast oxidation issues of the ultrasmall Ag nanoparticles, and integrates high antibacterial efficiency and nontoxicity to biological cells into one platform, which implies its broad potential application in biomedicine.
Photo-induced electron/energy transfer RAFT (PET-RAFT) polymerization can produce well-defined polymers with spatio-temporal control. Semiconductor graphitic carbon nitride (g-C3N4) as thermally and chemically stable photocatalyst, has achieved PET-RAFT method under UV-irradiation...
Highly pure α-Al2O3 colloidal nanocrystals with tunable surface chemistry and dimensions were fabricated using semi-aromatic polyamide (PA6Py) with pyridine rings as a functional matrix.
Au Nanocrystals were recognized to be unprecedented photocatalyst owing to the strong localized surface plasmon resonance (LSPR). Here we exploited Au nanocrystals as plasmonic photocatalysts for photo-regulated reversible addition–fragmentation chain-transfer...
Highly ordered TiO2 nanotube arrays (TNTAs)
and their
heterostructure nanocomposites by structural engineering design were
utilized as heterogeneous photocatalysts for highly efficient broadband
photoinduced controlled radical polymerization (photoCRP), including
photoATRP and PET-RAFT. Highly efficient broadband UV–visible
light responsive photoCRP was achieved by combining the acceleration
effects of electron transfer derived from the distinctive highly ordered
nanotube structure of TNTAs and the localized surface plasmon resonance
(LSPR) effect combined with the formation of the Schottky barrier
via modification of Au nanoparticles. This polymerization system was
capable to polymerize acrylate and methacrylate monomers with high
conversion, “living” chain-ends, tightly regulated molecular
weights, and outstanding temporal control properties. The heterogeneous
nature of the photocatalysts enabled simple separation and effective
reusability in subsequent polymerizations. These results highlight
the modular design of highly efficient catalysts to optimize the controlled
radical polymerization process.
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