The purpose of this study was using sol-gel method to prepare zinc oxide (ZnO) with specific nanostructures, including the ZnO/PEGMEMA composites with core-shell structure. Pure ZnO nanoparticles (ZnO NPs), ZnO-PEG NPs, and ZnO/SiO2-PEG NPs were prepared. Their chemical composition, particle size distribution, and optical properties were investigated. Under UV light excitation, the prepared ZnO NPs, ZnO-PEG NPs, and ZnO/SiO2-PEG NPs showed light emission in the wavelength of 563 nm, 540 nm, and 510 nm, respectively. The potential biomedical applications of these nanoparticles were further investigated in vitro. Through the cytotoxicity test (MTT assay) by using L929 cell line, better biocompatibility was observed under the concentration below 150 mu g/mL for the PEGylated nanoparticles; and 40 mu g/mL for ZnO comparatively. The fluorescence images taken by a confocal microscope showed that a large amount of materials were uptaken by the cells treated with 10 mu g/mL for 8 hours. The results suggested that these ZnO-related nanoparticles with different light emitting wavelengths are of great potential for in vitro cell imageing.