Fluorescent Nanodiamond - Hyaluronate Conjugates for Molecular Imaging

Abstract

Recently, molecular imaging systems have been widely investigated for the diagnosis of liver diseases such as hepatitis virus infections, liver fibrosis, and liver cancers. Among various molecular imaging agents, fluorescent nanodiamonds (FNDs) are carbon based photostable and biocompatible materials as a promising molecular imaging contrast agent. Because FNDs have negatively charged nitrogen vacancy (NV-) centers, they emit red bright light. In this work, FNDs were conjugated to hyaluronate (HA), which is a biocompatible and biodegradable polymer, and interacts with HA receptors in the liver, enabling liver targeted molecular imaging. The biocompatibility of HA-FND conjugates was verified by the cell viability test. The liver-targeted delivery was confirmed by the cellular uptake test, in vivo imaging system (IVIS) analysis, and ex vivo biodistribution test in organs. After intravenous injection of HA–FND conjugates, IVIS images revealed that fluorescent intensity in the liver was 1.4 times higher than that of FNDs. HA-FND conjugates appeared to be safe in vivo through histological analysis. All these results confirmed the feasibility of HA-FND conjugates as a contrast agent for liver diseases.