MnO Nanocrystals: A Platform for Integration of MRI and Genuine Autophagy Induction for Chemotherapy

Abstract

Herein, a kind of novel monocomponent hydrophilic and paramagnetic manganese(II) oxide nanocrystal is prepared in polar solution by a one‐pot microwave‐assisted synthesis. This kind of nanocrystal can be taken up efficiently to serve as an excellent T1 magnetic resonance imaging (MRI) contrast agent with an enhanced r1 value of 0.81 mM−1 s−1. The key to the success of this method is that no additional capping agents are required for coating onto the surface via ligand exchange, facilitating research of their intrinsic biological activities. Furthermore, multiple lines of convincing evidence are presented to prove that MnO nanocrystals (NCs) elicit p53‐activation‐independent and authentic functional autophagy via inducing autophagosome formation. Notably, there are very few reports so far of the autophagy phenomenon induced by magnetic nanocrystals. Moreover, these results offer an indication for cancer therapy that MnO NCs combined with doxorubicin at a nontoxic concentration can have a definite synergistic effect, which is mediated through the genuine autophagy induction, on killing cancer cells in vitro and in vivo.

Is the autophagy a friend or foe in the silver nanoparticles associated radiotherapy for glioma？

“…Autophagy could be induced by many physical, chemical and biological factors such as starvation, radiation, and chemotherapeutic treatment. However, in fact, a variety of nano materials such as quantum dots [22], fullerene C60 [7], gold and iron core-gold shell nanoparticles [23], grapheme [24], iron oxide [25], MnO nanocrystals [26], rare earth nanocrystals [27], have also been proved to be inducers of autophagy. For cells treated by the agents above, there are three possible effects of elevated autophagy: pro-survival, pro-death, or neutral [28].…”

Harnessing Calcium‐Oxalate‐ (CaOx‐) Nanocrystal‐Induced Prodeath Autophagy for Attenuating Human Renal Proximal Tubular Epithelial Cell Injury

“…Autophagic activity can be triggered under hypoxia, starvation, endoplasmic reticulum stress, mitochondrial damage, or exposure to nanomaterials . Elevated autophagic activity induced by nanomaterials reflects cellular response and oftentimes has a profound impact on cell fate, promoting either death or survival . Growing evidence suggests that autophagy is involved in pathogenesis of many kidney diseases, such as renal cell cancer and acute kidney injury (AKI) .…”

Inhibition of autophagy enhances the anticancer activity of silver nanoparticles

“…With unique physicochemical properties, nanomaterials are emerging as a new class of autophagy inducers in recent years. 4 A variety of engineered nanomaterials, such as quantum dots, 5 fullerene C60 and its derivatives, 6,7 gold and iron core-gold shell nanoparticle, 8,9 graphene, 10 iron oxide, 11 MnO nanocrystals, 12 rare earth nanocrystals, [13][14][15][16] VO 2 nanocrystals, 17 Ni-Co alloy nanocrystal, 18 europium hydroxide nanorods 19 etc., elicit an autophagic response in the various cancer cell culture systems examined. An elevated level of autophagy during tumor development and in cancer therapy has paradoxically been reported to have roles in promoting both cell survival and cell death.…”

“…In most of the circumstances, elevated autophagy after nanomaterial treatment leads to increased cell death. 6,7,9,12,15,18 But in rare situations, nanomaterial-induced autophagy may also promote cell survival. 17 Silver nanoparticles (Ag NPs) exhibit a variety of biological effects, such as antibacterial, 24,25 antifungal, 26,27 antiviral, [28][29][30] and antiinflammatory, 31,32 and thus are attracting interest for a wide range of biomedical applications.…”