Red fluorescent AuNDs with conjugation of cholera toxin subunit B (CTB) for extended-distance retro-nerve transporting and long-time neural tracing

Yueqi Zhao; Suraj Maharjan; Yuanqing Sun; Zhe Yang; Enfeng Yang; Nan Zhou; Laijin Lu; Andrew K Whittaker; Bai Yang; Quan Lin

doi:10.1016/j.actbio.2019.11.045

Red fluorescent AuNDs with conjugation of cholera toxin subunit B (CTB) for extended-distance retro-nerve transporting and long-time neural tracing

Acta Biomater. 2020 Jan 15:102:394-402. doi: 10.1016/j.actbio.2019.11.045. Epub 2019 Dec 4.

Authors

Yueqi Zhao¹, Suraj Maharjan², Yuanqing Sun³, Zhe Yang¹, Enfeng Yang¹, Nan Zhou⁴, Laijin Lu², Andrew K Whittaker⁵, Bai Yang¹, Quan Lin⁶

Affiliations

¹ State Key Laboratory of Supramolecular Structure and Material, College of Chemistry, Jilin University, Changchun 130012, China.
² Department of Hand Surgery, Jilin Provincial Key Laboratory of Tissue Repair, Reconstruction and Regeneration, First Hospital of Jilin University, Changchun 130021, China.
³ State Key Laboratory of Heavy Oil Processing, College of Science, China University of Petroleum, Beijing 102249, China.
⁴ Department of Orthopedics, the First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe Rd., Zhengzhou, 450000, China.
⁵ Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland 4072, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of Queensland, Brisbane, Queensland 4072, Australia.
⁶ State Key Laboratory of Supramolecular Structure and Material, College of Chemistry, Jilin University, Changchun 130012, China. Electronic address: linquan@jlu.edu.cn.

PMID: 31809883
DOI: 10.1016/j.actbio.2019.11.045

Abstract

A retrograde transportation nerve probe, Au nanodots-cholera toxin B subunit (AuNDs-CTB), are prepared and fully characterized, which emit bright red fluorescence and show high quantum yield (7.2%) and good stability. The fluorescence emitted by the AuNDs is constant across a wide pH range (4-10) and after prolonged UV irradiation (>4 h). Previously, CTB has shown targeting characteristic for nerve cells with high sensitivity and effectiveness. After linking CTB to AuNDs through amidation reactions, AuNDs-CTB are obtained with excellent fluorescence property, nerve target characteristic, and, particularly, neural retrograde transportation feature. The red emission of the AuNDs-CTB is well distinguished from the blue autofluorescence of normal tissues, which provides potential for detection by naked eyes. Further, the fluorescence emission intensity maintains for 10 days in vivo, suggesting great utility for long-time monitoring and sensing of the nerve tissue. Furthermore, the AuNDs-CTB with bright red fluorescence can travel through the peripheral nerve to the spinal cord rapidly by retrograde transportation. The transportation occurs for a long distance (>5 cm) within only 2 days after injection of the AuNDs-CTB into the sciatic nerve. The present study exhibits a novel method for nerve visualization and drug delivery. STATEMENT OF SIGNIFICANCE: Au nanodots (AuNDs) conjugated with cholera toxin subunit B (CTB) have been developed for nerve labeling and neural retro-transporting. The red fluorescence from AuNDs-CTB is stable in vitro (pH 4-10 and 4 h UV irradiation) and in vivo (for a long time, more than 10 days). When injecting AuNDs-CTB into the sciatic nerve located at the midpiece of the thigh, the targeted nerve emits bright red fluorescence under UV light. Furthermore, the nerve can retrograde transport the AuNDs-CTB to the spinal cord for a distance of more than 5 cm just in 2 days. This work exhibits a novel method for nerve visualization by naked eyes and demonstrates the potential for intraoperative navigation.

Keywords: Extended-distance transportation; Long-time neural trace; Nerve visualization; Neural rapid retro-transporting; Red fluorescent AuNDs-CTB.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Cholera Toxin / chemistry*
Cholera Toxin / metabolism
Fluorescent Dyes / chemistry*
Fluorescent Dyes / metabolism
Fluorescent Dyes / radiation effects
Gold / chemistry
Gold / metabolism
Gold / radiation effects
Male
PC12 Cells
Quantum Dots / chemistry*
Quantum Dots / metabolism
Quantum Dots / radiation effects
Rats
Rats, Wistar
Sciatic Nerve / diagnostic imaging*
Sciatic Nerve / metabolism
Spinal Cord / diagnostic imaging*
Spinal Cord / metabolism
Ultraviolet Rays

Substances

Fluorescent Dyes
Gold
Cholera Toxin