Gd(III) and Fe(III) ion crosslinked hyaluronic acid microgels composites embedding hetero atom doped carbon quantum...

In this study, we report the development of multifunctional CQ-dot@HA-Gd/Fe(III) microgels that can be readily simultaneously used in fluorescence/MR dual-mode imaging and photodynamic therapy as theragnostic agents. Nitrogen (N-) and sulfur (S-) heteroatom-doped carbon quantum dots (CQ-dot) were prepared in one step microwave treatment within 3 min as a fluorescence and photoinduced antipathogenic nanomaterial. The N/S-doped CQ-dots were spherical shaped and < 50 nm via TEM images and showed high fluorescence intensity with 420 nm emission wavelength at maximum λ_ex:350 nm. The N/S-doped CQ-dots were embedded into ionically crosslinked hyaluronic acid (HA) microgels, employing trivalent metal ions Gd(III) or Fe(III) ions. The prepared CQ-dot@HA-Gd/Fe(III) microgels <5 mm size range are injectable for possible intravenous administration and possess high fluorescent properties. The isoelectric point (IEP) of CQ-dot@HA-Gd and CQ-dot@HA-Fe(III) microgels was determined as pH 1.45. The CQ-dot@HA-Gd/Fe(III) microgels exhibit excellent hemocompatibility without causing noticeable hemolysis and blood clotting at concentrations up to 500 mg/mL. Furthermore, the toxicity of CQ-dot@HA-Gd/Fe(III) microgels on L929 fibroblast cells was found as 100 mg/mL concentration and provide brilliant cell imaging under DAPI filter without any fluorescence dye. Also, the CQ-dot@HA-Gd/Fe(III) microgel suspension afforded great MRI contrast enhancement ability. Photoinduced anticancer activity was observed for CQ-dot@HA-Gd/Fe(III) microgels even at 50 mg/mL against SK-MEL 30 melanoma cells under UV-A light treatment for 30 min. In addition, high reactive oxygen species (ROS) generation was obtained for the pathogenic bacteria cells by light-sensitive CQ-dot@HA-Gd/Fe(III) microgels upon 30 min UV-A light treatment that triggered the destruction of the Staphylococcus aureus (ATCC 6538).