Probing the magnetization switching with in-plane magnetic anisotropy through field-modified magnetoresistance measurement

Effective probing current-induced magnetization switching is highly required in the study of emerging spin-orbit torque(SOT)effect.However,the measurement of in-plane magnetization switching typically relies on the giant/tunneling magnetoresistance measurement in a spin valve structure calling for complicated fabrication process,or the non-electric approach of Kerr imaging technique.Here,we present a reliable and convenient method to electrically probe the SOT-induced in-plane magnetization switching in a simple Hall bar device through analyzing the MR signal modified by a magnetic field.In this case,the symmetry of MR is broken,resulting in a resistance difference for opposite magnetization orientations.Moreover,the feasibility of our method is widely evidenced in heavy metal/ferromagnet(Pt/Ni_(20)Fe_(80) and W/Co_(20)Fe_(60)B_(20))and the topological insulator/ferromagnet(Bi_(2)Se_(3)/Ni_(20)Fe_(80)).Our work simplifies the characterization process of the in-plane magnetization switching,which can promote the development of SOT-based devices.

Polymeric dual-modal imaging nanoprobe with two-photon aggregation-induced emission for fluorescence imaging and gadolinium-chelation for magnetic resonance imaging

Nanoprobes that offer both fluorescence imaging(FI)and magnetic resonance imaging(MRI)can provide supplementary information and hold synergistic advantages.However,synthesis of such dual-modality imaging probes that simultaneously exhibit tunability of functional groups,high stability,great biocompatibility and desired dual-modality imaging results remains challenging.In this study,we used an amphiphilic block polymer from(ethylene glycol)methyl ether methacrylate(OEGMA)and N-(2-hydroxypropyl)methacrylamide(HPMA)derivatives as a carrier to conjugate a MR contrast agent,Gd-DOTA,and a two-photon fluorophore with an aggregation-induced emission(AIE)effect,TPBP,to construct a MR/two-photon fluorescence dual-modality contrast agent,Gd-DOTA-TPBP.Incorporation of gadolinium in the hydrophilic chain segment of the OEGMA-based carrier resulted in a high r_(1)value for Gd-DOTA-TPBP,revealing a great MR imaging resolution.The contrast agent specifically accumulated in the tumor region,allowing a long enhancement duration for vascular and tumor contrast-enhanced MR imaging.Meanwhile,coupling TPBP with AIE properties to the hydrophobic chain segment of the carrier not only improved its water solubility and reduced its cytotoxicity,but also significantly enhanced its imaging performance in an aqueous phase.Gd-DOTA-TPBP was also demonstrated to act as an excellent fluorescence probe for two-photon-excited bioimaging with higher resolution and greater sensitivity than MRI.Since high-resolution,complementary MRI/FI dual-modal images were acquired at both cellular and tissue levels in tumor-bearing mice after application of Gd-DOTA-TPBP,it has great potential in the early phase of disease diagnosis.

Enzyme-triggered deep tumor penetration of a dual-drug nanomedicine enables an enhanced cancer combination therapy

Cancer cells could be eradicated by promoting generation of excessive intracellular reactive oxygen species(ROS)via emerging nanomedicines.However,tumor heterogeneity and poor penetration of nanomedicines often lead to diverse levels of ROS production in the tumor site,and ROS at a low level promote tumor cell growth,thus diminishing the therapeutic effect of these nanomedicines.Herein,we construct an amphiphilic and block polymer-dendron conjugate-derived nanomedicine(Lap@pOEGMA-b-p(GFLG-Dendron-Ppa),GFLG-DP/Lap NPs)that incorporates a photosensitizer,Pyropheophorbide a(Ppa),for ROS therapy and Lapatinib(Lap)for molecular targeted therapy.Lap,an epidermal growth factor receptor(EGFR)inhibitor that plays a role in inhibiting cell growth and proliferation,is hypothesized to synergize with ROS therapy for effectively killing cancer cells.Our results suggest that the enzyme-sensitive polymeric conjugate,pOEGMA-b-p(GFLG-Dendron-Ppa)(GFLG-DP),releases in response to cathepsin B(CTSB)after entering the tumor tissue.Dendritic-Ppa has a strong adsorption capacity to tumor cell membranes,which promotes efficient penetration and long-term retention.Lap can also be efficiently delivered to internal tumor cells to play its role due to the increased vesicle activity.Laser irradiation of Ppa-containing tumor cells results in production of intracellular ROS that is sufficient for inducing cell apoptosis.Meanwhile,Lap efficiently inhibits proliferation of remaining viable cells even in deep tumor regions,thus generating a significant synergistic anti-tumor therapeutic effect.This novel strategy can be extended to the development of efficient membrane lipid-based therapies to effectively combat tumors.