One of the most significant challenges in the diagnosis of brain cancer is efficient in vivo imaging using nontoxic nanoprobes. Core-shell gold nanorod@MIL-88(Fe) nanostars are successfully constructed as triple-modality imaging (computed tomography/magnetic-resonance imaging/photoacoustic imaging) nanoprobes that show low cytotoxicity, high contrast, high penetration depth, and high spatial resolution for accurate and noninvasive imaging and diagnosis of gliomas.

We report on near-GeV electron beam generation from an all-optical cascaded laser wakefield accelerator (LWFA). Electron injection and acceleration are successfully separated and controlled in different LWFA stages by employing two gas cells filled with a He/O2 mixture and pure He gas, respectively. Electrons with a Maxwellian spectrum, generated from the first LWFA assisted by ionization-induced injection, were seeded into the second LWFA with a 3-mm-thick gas cell and accelerated to be a 0.8-GeV quasimonoenergetic electron beam, corresponding to an acceleration gradient of 187  GV/m. The demonstrated scheme paves the way towards the multi-GeV laser accelerators.

Effective nanoprobes and contrast agents are urgently sought for earlystage cancer diagnosis. Upconversion nanoparticles (UCNPs) are considerable alternatives for bioimaging, cancer diagnosis, and therapy. Yb 3+ / Tm 3+ co-doping brings both emission and excitation wavelengths into the near-infrared (NIR) region, which is known as "optical transmission window" and ideally suitable for bioimaging. Here, NIR emission intensity is remarkably enhanced by 113 times with the increase of Yb 3+ concentration from 20% to 98% in polyethylene glycol (PEG) modifi ed NaYF 4 :Yb 3+ / Tm 3+ UCNPs. PEG-UCNPs-5 (98% Yb 3+ ) can act as excellent nanoprobes and contrast agents for trimodal upconversion (UC) optical/CT/T 2 -weighted magnetic resonance imaging (MRI). In addition, the enhanced detection of lung in vivo long-lasting tracking, as well as possible clearance mechanism and excretion routes of PEG-UCNPs-5 have been demonstrated. More signifi cantly, a small tumor down to 4 mm is detected in vivo via intravenous injection of these nanoprobes under both UC optical and T 2 -weighted MRI modalities. PEG-UCNPs-5 can emerge as bioprobes for multi-modal bioimaging, disease diagnosis, and therapy, especially the early-stage tumor diagnosis.