Donghao Gu

In this study, hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) were used for the synthesis of novel targeted nanocarrier carbon dots (CD_C-H) with photo-luminescence using a one-step hydrothermal method. Doxorubicin (DOX), a common chemotherapeutic agent, was loaded with the CD_C-H through electrostatic interactions to form DOX–CD_C-H complexes as a targeted antitumor drug delivery system. The synthesized CD_C-H show a particle size of approximately 6 nm and a high fluorescence quantum yield of 11.64%. The physical and chemical character properties of CD_C-H and DOX–CD_C-H complexes were investigated using various techniques. The results show that CD_C-H have stable luminescent properties and exhibit excellent water solubility. The in vitro release study showed that DOX–CD_C-H exhibited pH-dependent release for 24 h. Confocal laser scanning microscopy was applied to investigate the potential of CD_C-H for cell imaging and the cellular uptake of DOX–CD_C-H in different cells (NIH-3T3 and 4T1 cells), and the results confirmed the target cell imaging and cellular uptake of DOX–CD_C-H by specifically binding the CD₄₄ receptors on the surface of tumor cells. The r MTT results suggest that the DOX–CD_C-H complex may induce apoptosis in 4T1 cells, reducing the cytotoxicity of free DOX-induced apoptosis. In vivo antitumor experiments of DOX–CD_C-H exhibited enhanced tumor cancer therapy. CD_C-H have potential applications in bioimaging and antitumor drug delivery.

We developed a potential composite ocular drug delivery system for the topical administration of diclofenac sodium (DS). The novel carbon dot CD_C-HP was synthesized by the pyrolysis of hyaluronic acid and carboxymethyl chitosan through a one-step hydrothermal method and then embedded in a thermosensitive in situ gel of poloxamer 407 and poloxamer 188 through swelling loading. The physicochemical characteristics of these carbon dots were investigated. The results of the in vitro release test showed that this composite ocular drug delivery system (DS-CD_C-HP-Gel) exhibited sustained release for 12 h. The study of the ex vivo fluorescence distribution in ocular tissues showed that it could be used for bioimaging and tracing in ocular tissues and prolong precorneal retention. Elimination profiles in tears corresponded to the study of ex vivo fluorescence imaging. The area under the curve of DS in the aqueous humor in the DS-CD_C-HP-Gel group was 3.45-fold that in the DS eye drops group, indicating a longer precorneal retention time. DS-CD_C-HP with a positive charge and combined with a thermosensitive in situ gel might strengthen adherence to the corneal surface and prolong the ocular surface retention time to improve the bioavailability. This composite ocular delivery system possesses potential applications in ocular imaging and drug delivery.