Green Preparation of Fluorescent Carbon Quantum Dots from Cyanobacteria for Biological Imaging.

Xi Wang,Qian Feng,Jingquan Han,Pei Yang,Changyan Xu,Jing Wei,Taotao Meng

doi:10.3390/polym11040616

Abstract

Biomass-based carbon quantum dots (CQDs) have become a significant carbon materials by their virtues of being cost-effective, easy to fabricate and low in environmental impact. However, there are few reports regarding using cyanobacteria as a carbon source for the synthesis of fluorescent CQDs. In this study, the low-cost biomass of cyanobacteria was used as the sole carbon source to synthesize water-soluble CQDs by a simple hydrothermal method. The synthesized CQDs were mono-dispersed with an average diameter of 2.48 nm and exhibited excitation-dependent emission performance with a quantum yield of 9.24%. Furthermore, the cyanobacteria-derived CQDs had almost no photobleaching under long-time UV irradiation, and exhibited high photostability in the solutions with a wide range of pH and salinity. Since no chemical reagent was involved in the synthesis of CQDs, the as-prepared CQDs were confirmed to have low cytotoxicity for PC12 cells even at a high concentration. Additionally, the CQDs could be efficiently taken up by cells to illuminate the whole cell and create a clear distinction between cytoplasm and nucleus. The combined advantages of green synthesis, cost-effectiveness and low cytotoxicity make synthesized CQDs a significant carbon source and broaden the application of cyanobacteria and provide an economical route to fabricate CQDs on a large scale.

Highlights

Carbon quantum dots (CQDs) have attracted considerable attention for their unique and tunable photoluminescence properties [1,2,3], easy of functionalization [4,5], high photostability [6], excellent biocompatibility [7,8,9] and negligible environmental impact [10]
Over the past several years, extensive research efforts have focused on synthesizing CQDs with diverse emission performances and controlled chemical compositions using a variety of synthetic routes, such as arc discharge treatment [18], electrochemical exfoliation [19], laser ablation [20] and chemical oxidation [21]
Recent progress has promoted the development of CQDs, most of these approaches usually suffer from the high cost of raw materials, complex procedures, harsh synthetic conditions or reliance on energy-consuming devices, which seriously limit the availability of large-scale production of the CQDs for practical applications

Summary

Introduction

Carbon quantum dots (CQDs) have attracted considerable attention for their unique and tunable photoluminescence properties [1,2,3], easy of functionalization [4,5], high photostability [6], excellent biocompatibility [7,8,9] and negligible environmental impact [10] Benefiting from these features and others, CQDs have been widely applied in electrochemical immune-sensing [11], bio-imaging [12,13,14], fluorescent probes [15], photocatalysis [16] and optoelectronics [17]. Among the proposed synthetic strategies for CQD fabrication, the hydrothermal method has been widely adopted as an effective bottom-up synthesis route for the preparation of CQDs from numerous molecules and has several distinct advantages, including simple preparation, low-cost equipment and economical consumption [22,23,24,25].

Methods

Results

Conclusion