Title : Fluorescent and Biocompatible Nitrogen and Sulfur Co-Doped Carbon Nanodots as an Ocular Fundus Angiography Imaging Agent
Purpose: Fundus angiography (FA) imaging is limited by the drawbacks of standard fluorescein dye, including a narrow excitation spectrum, a non-uniform spectral emission pattern, photobleaching, and kidney toxicity. Carbon dots (CDs) nanoparticle may be a feasible alternative to sodium fluorescein dye due to its adjustable fluorescent light wavelength, photostability, low toxicity, and low cost. We examined the FA images of two rats using the conventional fluorescein dye and the newly synthesized nitrogen and sulfur (N&S) co-doped CDs material.
Methods: After chemically characterizing N&S CDs nanoparticle, we evaluated its cytotoxicity on two distinct cell lines, HUVEC (Human umbilic vein endothelial cells) and L929 (Mouse fibroblast cells). In our in vivo experiment comparing the FA image output of N&S CDs and standard fluorescein dye, two 6-8 week old healthy 200-250 g Sprague-Dawley type rats were provided. After intraperitoneal anesthesia with 10% chloral hydrate (0.3mL/100g), and pupillary dilation with %1 tropicamide, one animal received 100 μL of 10% sodium fluorescein intraperitoneally. The other animal received an intraperitoneal injection of 100 μL of 0.3 mg/ml N&S-CDs agent dissolved in 0.9% saline. FA images were started to be taken at intervals 10 minutes after the imaging agents were injected.
Results: N&S CDs nanoparticle was found to be not cytotoxic in HUVEC and L929 cells after 24 hours of incubation (Figure 1). In contrast, N&S CDs nanoparticle was found to inhibit the cell viability of HUVEC cells at the highest concentration of 1 mg/ml. Moreover, N&S CDs nanoparticle was found to significantly inhibit the cell viability of L929 cells at the concentrations of 1 mg/ml and 0.5 mg/ml. The images in Figure 2 were taken 12 minutes following intraperitoneal administration of both imaging agents. The quality of the FA image acquired with the N&S CDs agent is comparable to that obtained with the conventional fluorescein dye in our investigation.
Conclusion: In our study, as a result of its great biocompatibility and inexpensive cost, it was determined that N&S CDs may be a viable alternative to fluorescein.