ZnGa₂O₄:Cr³⁺ nanophosphors with an average crystallite size of 5 nm were prepared by a combustion method. We observed changes in the luminescence properties compared with the micro-crystalline system, such as a high brightnessemission band at 696 nm and a decrease in the persistent luminescence decay time for the near-infrared emission. The system does not show a change in the band gap. The emission intensity for the broad band with near-infrared emission was very high under excitation with both UV and visible wavelengths.

The system presents good stability in colloidal suspensions in water and phosphate-buffered saline, which were found to conserve the luminescence properties.

The system is non-toxic and shows applications for in vivo optical imaging due to the rather high penetration depth of near-infrared radiation into human tissue. Its small crystallite size enables it to enter cells for bioimaging, exhibit good dispersion in a biological environment and resist photobleaching.

通过燃烧法制备平均晶粒尺寸为5nm的ZnGa ₂ O ₄：Cr ³⁺纳米磷光体 。与微晶系统相比，我们观察到了发光特性的变化，例如在696  nm处的高亮度发射带和近红外发射的持续发光衰减时间的减少。系统未显示带隙变化。在紫外和可见光波长的激发下，具有近红外发射的宽带发射强度非常高。

该系统在水和磷酸盐缓冲盐水中的胶体悬浮液中表现出良好的稳定性，发现它们可以保留发光特性。

该系统无毒，并且由于近红外辐射对人体组织的穿透深度很高，因此显示了在体内光学成像中的应用。它的微晶尺寸小，使其能够进入细胞进行生物成像，在生物环境中表现出良好的分散性，并且能够抵抗光漂白。