Tumor Microenvironment Cascade‑Responsive Nanodrug with Self‑Targeting Activation and ROS Regeneration for Synergistic Oxidation‑Chemotherapy

Carrier-free nanodrug with exceptionally high drug payload has attracted increasing attentions.Herein,we construct a pH/ROS cascade-responsive nanodrug which could achieve tumor acidity-triggered targeting activation followed by circularly amplified ROS-triggered drug release via positive-feedback loop.The di-selenide-bridged prodrug synthesized from vitamin E succinate and methotrexate(MTX)self-assembles into nanoparticles(VSeM);decorating acidity-cleavable PEG onto VSeM surface temporarily shields the targeting ability of MTX to evade immune clearance and consequently elongate circulation time.Upon reaching tumor sites,acidity-triggered detachment of PEG results in targeting recovery to enhance tumor cell uptake.Afterward,the VSeM could be dissociated in response to intracellular ROS to trigger VES/MTX release;then the released VES could produce extra ROS to accelerate the collapse of VSeM.Finally,the excessive ROS produced from VES could synergize with the released MTX to efficiently suppress tumor growth via orchestrated oxidation-chemotherapy.Our study provides a novel strategy to engineer cascade-responsive nanodrug for synergistic cancer treatment.

Neoproterozoic Diamictite of the Luoquan Formation from the North China Block and Their Implications

Glacial diamictite may provide important information on paleoenvironment and average composition of the upper continental crust(UCC).In this study,we report sedimentary facies,petrological and geochemical characteristics of Neoproterozoic diamictite from a profile of the Luoquan Formation on the southern margin of the North China Block(NCB).Upwards the sampling profile,lithostratigraphic strata vary from massive diamictite with poorly sorted carbonate gravels to laminated diamictite with small gravels of terrestrial detrital materials.Along the profile,CaO-MgO-LOI-Sr values decrease with the increase of SiO_(2)-Al2O_(3)-K2O contents.All these petrological and geochemical variations indicate a change from lodgement till deposition in the proximal of ice sheet to ice-rafting deposition in glacial-marine environment with less dolomite to supply their source.Together with previous studies on diamictite from other outcrops on the NCB,the deposition of Luoquan diamictite reflects that the glaciation on the NCB vanished and the ice-rafting effect weakened with glacial transgression process.In addition,significant co-variations of various elements with La and Al2O_(3)confirm the significant conservation of most analyzed elements during the sedimentary processes to produce diamictite.

2D graphene oxide-L-arginine-soybean lecithin nanogenerator for synergistic photothermal and NO gas therapy

Nitric oxide(NO) gas therapy has been regarded as a promising strategy for cancer treatment. However,its therapeutic efficiency is still unsatisfying due to the limitations of monotherapy. Previous preclinical and clinical studies have shown that combination therapy could significantly enhance therapeutic efficiency. Herein, a graphene oxide(GO)-L-arginine(L-Arg, a natural NO donor) hybrid nanogenerator is developed followed by surface functionalization of soybean lecithin(SL) for synergistic enhancement of cancer treatment through photothermal and gas therapy. The resultant GO-Arg-SL nanogenerator not only exhibited good biocompatibility and excellent endocytosis ability, but also exhibited excellent photothermal conversion capability and high sensitivity to release NO within tumor microenvironment via inducible NO synthase(i NOS) catalyzation. Moreover, the produced hyperthermia and intracellular NO could synergistically kill cancer cells both in vitro and in vivo. More importantly, this nanogenerator can efficiently eliminate tumor while inhibiting the tumor recurrence because of the immunogenic cell death(ICD) elicited by NIR laser-triggered hyperthermia and the immune response activation by massive NO generation. We envision that the GO-Arg-SL nanogenerator could provide a potential strategy for synergistic photothermal and gas therapy.