Presentation: 2025 ND EPSCoR Annual conference 

October 21, 2025, NDSU Memorial Union, Fargo, North Dakota

Synthesis of Spinel-type Near-Infrared Co-Doped Persistent Luminescence Nanoparticles for Autofluorescence-Free Bioimaging

Persistent luminescence nanoparticles (PLNPs), also known as long-afterglow luminescence nanoparticles, have emerged as promising nanoscale materials capable of emitting luminescence for minutes to several days after initial excitation. This unique optical property makes them compelling candidates for a variety of bioimaging and biosensing applications. In this study, zinc (II) nitrate and gallium (III) nitrate were employed to synthesize a spinel-type host structure (ZGO), with chromium (III) nitrate and europium (III) nitrate introduced as co-dopants for emitting persistent luminescence through an ultrasonic-assisted hydrothermal synthesis method. The resulting nanoparticles exhibited an average size of 76.1  2.7 nm. The X-ray diffraction (XRD) analysis demonstrated that the ZGO: Cr, Eu nanoparticles possessed the typical spinel phase of ZnGa2O4, confirming the successful synthesis of the well-organized ZGO nanocrystals. Fourier transform infrared spectroscopy (FT-IR) showed the bonds between elements as designed. UV-Vis absorption and fluorescence spectra revealed continuous absorbance, and a distinct near-infrared fluorescence emission peak at 695 nm. Fluorescence time course results showed the PLNPs remained a long photostability over 300 min. The in-vitro cell culture experiments demonstrated that the PLNPs possessed low cytotoxicity. Further PLNPs were successfully internalized by M. D. Anderson Metastasis Breast cancer-231 (MDA-MB-231) cells, enabling strong fluorescence cellular imaging. These findings highlight a promising potential of ZGO: Cr, Eu PLNPs as a candidate for future bio-imaging applications.