The combination of gold and copper is a good way to pull down the cost of gold and ameliorate the instability of copper. Through shape control, the synergy of these two metals can be better exploited. Here, we report an aqueous phase route to the synthesis of pentacle gold–copper alloy nanocrystals with fivefold twinning, the size of which can be tuned in the range from 45 to 200 nm. The growth is found to start from a decahedral core, followed by protrusion of branches along twinning planes. Pentacle products display strong localized surface plasmon resonance peaks in the near-infrared region. Under irradiation by an 808-nm laser, 70-nm pentacle nanocrystals exhibit a notable photothermal effect to kill 4T1 murine breast tumours established on BALB/c mice. In addition, 70-nm pentacle nanocrystals show better catalytic activity than conventional citrate-coated 5-nm Au nanoparticles towards the reduction of p-nitrophenol to p-aminophenol by sodium borohydride.

Silver nanoparticles (Ag NPs) are cytotoxic to cancer cells and possess excellent potential as an antitumor agent. A variety of nanoparticles have been shown to induce autophagy, a critical cellular degradation process, and the elevated autophagy in most of these situations promotes cell death. Whether Ag NPs can induce autophagy and how it might affect the anticancer activity of Ag NPs has not been reported. Here we show that Ag NPs induced autophagy in cancer cells by activating the PtdIns3K signaling pathway. The autophagy induced by Ag NPs was characterized by enhanced autophagosome formation, normal cargo degradation, and no disruption of lysosomal function. Consistent with these properties, the autophagy induced by Ag NPs promoted cell survival, as inhibition of autophagy by either chemical inhibitors or ATG5 siRNA enhanced Ag NPs-elicited cancer cell killing. We further demonstrated that wortmannin, a widely used inhibitor of autophagy, significantly enhanced the antitumor effect of Ag NPs in the B...

T ₁–T₂ dual modal magnetic resonance imaging (MRI) has attracted considerable interest because it offers complementary diagnostic information, leading to more precise diagnosis. To date, a number of nanostructures have been reported as T₁–T₂ dual modal MR contrast agents (CAs). However, hybrids of nanocubes with both iron and gadolinium (Gd) elements as T₁–T₂ dual modal CAs have not been reported. Herein, we report the synthesis of novel core/shell Fe₃O₄/Gd₂O₃ nanocubes as T₁–T₂ dual-modal CAs and their application for enhanced T₁–T₂ MR imaging of rat livers. A relaxivity study at 1.5 T indicated that our Fe₃O₄/Gd₂O₃ nanocubes have an r₁ value of 45.24 mM⁻¹ s⁻¹ and an r₂ value of 186.51 mM⁻¹ s⁻¹, which were about two folds of those of Gd₂O₃ nanoparticles and Fe₃O₄ nanocubes, respectively. In vivo MR imaging of rats showed both T₁-positive and T₂-negative contrast enhancements in the livers. We envision that our Fe₃O₄/Gd₂O₃ nanocubes could be applied as T₁–T₂ dual modal MR CAs for a wide range of theranostic applications in the near future.

Autophagy is a cellular stress response that results in the activation of a lysosomal degradation pathway. In this report, we showed that cationic lipids, a common-used class of transfection reagents, induced genuine autophagy in mammalian cells. Extensive LC3 dot formation was observed by treatment with cationic lipids (with or without DNA), but not neutral lipids, in a HeLa cell line stably expressing GFP-LC3 (HeLa-LC3). Further proofs for autophagy were obtained by the co-localization of the LC3 dots with lysosome-specific staining patterns, observation of LC3-I to LC3-II form conversion and appearance of autophagic vacuoles under TEM. The autophagic flux assay with bafilomycin A1 and degradation of p62/SQSTM1 suggested that the autophagy induced by cationic lipids was primarily due to increased formation of autophagosomes and not decreased turnover. Moreover, cationic lipids induced autophagy in an mTOR-independent manner.