Facile Synthesis of Surface-Modified Carbon Quantum Dots (CQDs) for Biosensing and Bioimaging

Abstract

Recently, fluorescent probes became one of the most efficient tools for biosensing and bioimaging. Special attention is focused on carbon quantum dots (CQDs), which are characterized by the water solubility and lack of cytotoxicity. Moreover, they exhibit higher photostability comparing to traditional organic dyes. Currently, there is a great need for the novel, luminescent nanomaterials with tunable properties enabling fast and effective analysis of the biological samples. In this article, we propose a new, ecofriendly bottom-up synthesis approach for intelligent, surface-modified nanodots preparation using bioproducts as a raw material. Obtained nanomaterials were characterized over their morphology, chemical structure and switchable luminescence. Their possible use as a nanodevice for medicine was investigated. Finally, the products were confirmed to be non-toxic to fibroblasts and capable of cell imaging.

New Insight into the Fluorescence Quenching of Nitrogen-Containing Carbonaceous Quantum Dots—From Surface Chemistry to Biomedical Applications

“…Carbon-based quantum dots (CQDs), by the reason of their biocompatibility and contrary to inorganic quantum dots, are widely suggested as the most beneficial fluorescent carriers of drugs, genes, or other bioactive molecules. The excitation-dependent fluorescence emission of carbon quantum dots allows to follow their distribution within the cells [ 3 , 21 , 22 , 23 , 24 , 25 , 31 ]. Connection of a therapeutic compound to the surface of the tailored nanomaterial should allow to decrease the systemic administration of drug and to minimize its side effects [ 6 , 7 ].…”

“…There are numerous in vitro and in vivo studies focused on the cell or tissue imaging through carbon-based-quantum-dots-mediated labeling or facilitated tracking of CQD-linked drugs [ 21 , 22 , 23 , 24 , 25 ]. However, the bio-imaging of the carbonaceous nanocarrier-based therapeutics, together with their precise quantification in the living cells, is still the key challenge on their way from bench to bedside use.…”

Recent Advances in Carbon Nanodots: A Promising Nanomaterial for Biomedical Applications

“…Sensing metal ions and macromolecules in biological systems needs to be developed to provide efficient, reliable, and affordable detection. The relative ease of preparing fluorescent CNDs and photostability allows for their use as economical alternatives in sensing crucial biomarkers [91][92][93][94][95][96][97][98][99][100]. Green-luminescent CNDs have been used to probe ROS such as ONOO− with high sensitivity in HeLa cells exposed for 4 h [49].…”

Protein Corona Hinders N-CQDs Oxidative Potential and Favors Their Application as Nanobiocatalytic System

“…In our opinion, the context of oxidative properties of CQDs in their application as enzyme carriers seems to be an unexploited and not fully recognized issue in the field of nanomedicine. Nevertheless, the most recent literature data suggest that CQDs are promising nanodevices for theranostics (combining drug delivery and imaging), benefiting from their biocompatibility, ability to penetrate the cell membranes and to accumulate in cytoplasm [ 4 , 5 , 6 , 7 ]. One of the possible solutions to protect cells from oxidative damage is the protein coat formed on the nanomaterial surface.…”

“…They are characterized by negligible cytotoxicity in comparison to inorganic quantum dots or other highly graphitized carbonaceous materials, high biocompatibility, and low cost of their synthesis. CQDs are chemically inert, have many functional groups on their surface, are well dispersed in water, and additionally, can be easily decorated [ 1 , 4 , 23 , 24 , 25 ]. A sustainable and pollution-free preparation of biocompatible nitrogen-containing carbon quantum dots (N-CQDs) from biomass waste has recently drawn particular attention [ 26 , 27 ].…”