Abstract
The lanthanide (Ln) doped CDs have been identified as a useful candidate for dual mode imaging including fluorescence and magnetic resonance imaging (MRI). Their fluorescence and surface properties depend on the selection of the precursor and synthetic method. At present, most of the Ln-doped CDs are prepared by hydrothermal method and only few are made from microwave heating and other methods. In addition, most CDs possess a negative surface charge. Considering the diverse mode of preparation and properties, the development of Ln-CDs as a dual mode imaging agent is still in the early stage. In this work, we focus on (1) developing gadolinium doped CDs with a positive surface charge and compare the properties of CDs prepared from two synthetic methods: hydrothermal and microwave, (2) comparative study of Gd-CNDs produced from gadopentetic acid and gadolinium chloride as a Gd-source, and (3) study of Dysprosium doped CDs. The optical properties of CDs, cytotoxicity, and their applications in bioimaging were discussed. During the study, the Gd-CDs obtained from microwave (MW) method were found less toxic compared to those obtained from hydrothermal (HT) method. In addition, these CDs are less toxic to the non-cancer cells compared to the cancer ones. Furthermore, the magnetic resonance (MR) images produced from the CDs indicate that the Gd-MW CDs appeared much brighter than the images produced from Gd-HT CDs. The overall results and observations indicate that the microwave route of synthesis is preferable over hydrothermal, and the Gd-MW CDs could be a promising candidate for a multimodal theranostics agent due to their capability to image and target the tumor cells simultaneously. In other studies, the properties of Gd-CNDs prepared from two different gadolinium sources (gadopentetic acid and gadolinium chloride) were studied. In addition, Dysprosium doped CDs were presented as a future candidate for contrast agent in the high magnetic field MR imaging.