The control of nanogaps lies at the heart of plasmonics for nanoassemblies. The plasmon coupling sensitively depends on the size and the shape of the nanogaps between nanoparticles, permitting fine-tuning of the resonance wavelength and near-field enhancement at the gap. Previously reported methods of molecular or lithographic control of the gap distance are limited to producing discrete values and encounter difficulty in achieving subnanometer gap distances. For these reasons, the study of the plasmon coupling for varying degrees of interaction remains a challenge. Here, we report that by using light, the interparticle distance for gold nanoparticle (AuNP) dimers can be continuously tuned from a few nanometers to negative values (i.e., merged particles). Accordingly, the plasmon coupling between the AuNPs transitions from the classical electromagnetic regime to the contact regime via the nonlocal and quantum regimes in the subnanometer gap region. We find that photooxidative desorption of alkanedithiol linkers induced by UV irradiation causes the two AuNPs in a dimer to approach each other and eventually merge. Light-driven control of the interparticle distance offers a novel means of exploring the fundamental nature of plasmon coupling as well as the possibility of fabricating nanoassemblies with any desired gap distance in a spatially controlled manner.
Multivalent aptamer-siRNA conjugates containing multiple mucin-1 aptamers and BCL2-specific siRNA are synthesized, and doxorubicin, an anthracycline anticancer drug, is loaded into these conjugates through intercalation with nucleic acids. These doxorubicin-incorporated multivalent aptamer-siRNA conjugates are transfected to mucin-1 overexpressing MCF-7 breast cancer cells and their multidrug-resistant cell lines. Doxorubicin-incorporated multivalent aptamer-siRNA conjugates exert promising anticancer effects, such as activation of caspase-3/7 and decrease of cell viability, on multidrug-resistant cancer cells because of their high intracellular uptake efficiency. Thus, this delivery system is an efficient tool for combination oncotherapy with chemotherapeutics and nucleic acid drugs to overcome multidrug resistance.
In this study, natural platelet-derived nanovesicles with a vacant core were prepared by hypotonic sonication. The nanovesicles efficiently formed platelet-like aggregates without a notable release of pro-inflammatory cytokines. These natural and biocompatible platelet-derived nanovesicles have great potential as biomaterials for inflammation-free injectable hemostasis.
Exosomes (EXO) are considered to be versatile carriers for biomolecules; however, the delivery of therapeutic peptides using EXOs poses several challenges. In this study, the efficiency of serum‐derived EXOs in delivering tyrosinase‐related protein‐2 (TRP2) peptides to lymph nodes is determined. TRP2 peptides are successfully incorporated into EXOs, which show a uniform and narrow size distribution of around 45 nm. The TRP2‐incorporated exosomes (EXO‐TRP2) are efficiently internalized into macrophages and dendritic cells, and are seen to display a punctate distribution. EXOs loaded with TRP2 together with MPLA, (EXO‐MPLA‐TRP2) result in a strong release of proinflammatory cytokines (TNF‐α and IL‐6) from both RAW264.7 and DC2.4 cells. Finally, subcutaneous injection of fluorescently labeled EXO‐TRP2 followed by ex vivo imaging using in vivo imaging system (IVIS) show a strong fluorescent signal in the lymph nodes after only 1 h, which is maintained until at least 4 h after injection. Taken together, the findings suggest that serum‐derived EXOs can serve as promising carriers to deliver therapeutic peptides to lymph nodes for immunotherapy.
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