Low Dose of X-Ray-Excited Long-Lasting Luminescent Concave Nanocubes in Highly Passive Targeting Deep-Seated Hepatic Tumors

Chromium-doped zinc gallate, ZnGa₂O₄:Cr³⁺ (ZGC), is viewed as a long-lasting luminescence (LLL) phosphor that can avoid tissue autofluorescence interference for in vivo imaging detection. ZGC is a cubic spinel structure, a typical agglomerative or clustered morphology lacking a defined cubic shape, but a sphere-like feature is commonly obtained for the nanometric ZGC. The substantial challenge remains achieving a well-defined cubic feature in nanoscale. The process by which dispersed and well-defined concave cubic ZGC is obtained is described, exhibiting much stronger LLL in UV and X-ray excitation for the dispersed cubic ZGC compared with the agglomerative form that cannot be excited using X-rays with a low dose of 0.5 Gy. The cubic ZGC reveals a specific accumulation in liver and 0.5 Gy used at the end of X-ray excitation is sufficient for imaging of deep-seated hepatic tumors. The ZGC nanocubes show highly passive targeting of orthotopic hepatic tumors.