Defect-related luminescence in BaF₂ nanoparticles for plant cell imaging

Materials with luminescent defects, serving as energy traps and luminescence centers, exhibit the advantages of tunable emission spectra and cost-effective synthesis processes and can be used for biological imaging applications. In this paper, we present an experimental investigation into the defect-related luminescence of small-sized (< 30 nm) BaF₂ nanoparticles (NPs) and explore their application in plant cell imaging. Uniformly morphological BaF₂ NPs are synthesized via the solvothermal method. Photoluminescence (PL) studies have demonstrated that these NPs exhibit broad and defect-related luminescence across a wide range of excitation wavelength in the UV-Vis region, characterized by high luminescent efficiency, excellent optical stability, and reversible temperature dependence. Utilizing a 4F-configuration two-dimensional (2D) laser-scan optical system, a prototype fluorescence imaging experiment is conducted on onion epidermal cells incubated with BaF₂ NPs under continuous-wave (cw) laser excitation at varying wavelengths. The scanned fluorescence images, which accurately reproduced the cell structures, underscore the unique target specificity and high biocompatibility of the prepared NPs, positioning them as a competitive candidate for fluorescence probes in biological applications.