Fluorescent nanomaterials for bioapplications

We have developed several new fluorescent nanomaterials, including graphene-based quantum dots, graphene quantum dot (GQD)-based nanozymes, and polymer dots (Pdots). In this presentation, the methods used to synthesize these nanomaterials will be introduced. A series of characterization techniques, including TEM, SEM, EDS, UV-vis absorption spectroscopy, XRD, FT-IR, and fluorescence spectroscopy, will be discussed to demonstrate the structural, morphological, and optical properties of these materials. Finally, applications of these nanomaterials in biomedical research will be presented, including fluorescence imaging, biodetection, cell culture, and photothermal therapy. For example, we will introduce a novel GQD-based nanozyme, an enzyme-free platform that combines strong intrinsic fluorescence with highly sensitive and selective NADPH detection. The nanozyme demonstrated a concentration-dependent and specific fluorescence-quenching response toward NADPH. Biocompatibility studies using mouse brain-derived microvascular endothelial cells (BMVECs) confirmed that the nanozyme is suitable for use under both normal and metabolically distressed conditions, demonstrating its potential for applications in metabolic disease research. We will also introduce a multifunctional Pdot system using poly(styrene-co-maleic anhydride) (PSMA) as both a crosslinker and a polymer backbone. The polystyrene component enables the formation of Pdots with compact cores, resulting in small nanoparticles with high fluorescence yields. Mn ions were subsequently incorporated into the Pdots to catalyze the conversion of H₂O₂ and promote O₂ production. Through this rational design, we developed Pdots with enhanced H₂O₂-to-¹O₂ conversion capability, which can help reverse a hypoxic cellular microenvironment and improve the therapeutic efficiency of photodynamic therapy (PDT). When tested in MCF-7 human breast adenocarcinoma cells, the Pdots achieved a photothermal conversion efficiency of up to 53%. These results demonstrate the potential of these Pdots for synergistic PDT/PTT treatment and enhanced cytotoxicity toward cancer cells.

Dr. Julia Xiaojun Zhao is a Chester Fritz Distinguished Professor in the Department of Chemistry at the University of North Dakota, USA. She has worked in the field of nanoscience and nanotechnology for 26 years. She has authored more than 90 peer-reviewed publications and holds seven issued U.S. patents. She has served as the Principal Investigator on research grants funded by the U.S. National Science Foundation. Dr. Zhao’s research group focuses on the development of fluorescent nanomaterials and their applications in biological studies.