Bone-targeting carbon dots: effect of nitrogen-doping on binding affinity. Issue 5 (21st January 2019)

• Record Type: Journal Article
• Authors: Lee, Kyung Kwan; Lee, Jae-Geun; Park, Chul Soon; Lee, Sun Hyeok; Raja, Naren; Yun, Hui-suk; Lee, Jeong-Soo; Lee, Chang-Soo
• Is Part Of: RSC advances. Volume 9:Issue 5(2019)
• Page Start: 2708
• Page End: 2717
• Publication Date: 2019-01-21
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c8ra09729a
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Fluorescent carbon dots selectively bind to skull tissues with high affinity, including a strong binding activity for calcium deficient hydroxyapatite, and rat femur, for bone targeted imaging. Abstract : Novel fluorescent carbon dots (CDs) for bone imaging were fabricated via a facile hydrothermal method using alendronate in the absence of a nitrogen-doping precursor to enhance bone affinity. One-step synthesized alendronate-based CDs (Alen-CDs) had strong binding activity for calcium-deficient hydroxyapatite (CDHA, the mineral component of bones) scaffold, rat femur, and bone structures of live zebrafish. This was attributed to the bisphosphonate group present on the CD surface, even after carbonization. For comparison, the surface effects of nitrogen-doped CDs obtained using ethylenediamine (EDA), i.e., Alen-EDA-CDs, were also investigated, focusing on the targeting ability of distinct surface functional groups when compared with Alen-CDs. An in vivo study to assess the impact on bone affinity revealed that Alen-CDs effectively accumulated in the bone structures of live zebrafish larvae after microinjections, as well as in the bone tissues of femur extracted from rats. Moreover, Alen-CD-treated zebrafish larvae had superior toleration, retaining skeletal fluorescence for 7 days post-injection (dpi). The sustainable capability, surpassing that of Alizarin Red S, suggests that Alen-CDs have the potential for targeted drug delivery to damaged bone tissues and provides motivation for additional in vivo investigations. To our knowledge, this is the first in vitro, ex vivo, and in vivo demonstration of direct bone-targeted deliveries, supporting the use of fluorescent CDs in the treatment of various bone diseases such as osteoporosis, Paget's disease, and metastatic bone cancer.