Fluorescence Intensity Enhancement of Green Carbon Dots: Synthesis, Characterization and Cell Imaging

Abstract

The hydrothermal treatment of green carbon dots (CDs) is an appropriate fluorescent probe synthesis method. CDs are exploited as biological staining agents, especially for cellular detection and imaging. The nitrogen‐doped green carbon dots (N‐CDs) formation can improve the fluorescence intensity property in a one‐step process. Here, we report two N‐CDs from lemon and tomato extraction in the presence of hydroxylamine. Lemon and tomato N‐CDs showed the blue fluorescence under ultraviolet radiation of about 360 nm. The characterization of CDs and N‐CDs showed the presence of N‐H and C–N bonds which enhanced the fluorescence efficiency. The mean size of lemon and tomato N‐CDs were about 2 and 3 nm with an increased quantum yield (QY) of 5% and 3.38%, respectively. The CDs and N‐CDs cytotoxicity assay exhibited high cell viability approximately 85% and 73%, respectively. N‐CDs show superior fluorescent intensity in different solvents and significant stability under long‐time UV irradiation, different PH and high ionic strength. Our results indicated that the use of N‐CDs in cell imaging can lead to fluorescence intensity enhancement as well as proper biocompatibility. Therefore, the safe and high fluorescence intensity of green N‐CDs can be utilized for fluorescent probes in biolabeling and bioimaging applications.

A Review on Carbon Dots: Synthesis, Characterization and Its Application in Optical Sensor for Environmental Monitoring

“…Lemon peels, prunus avium extract, cornstalk, corn bract, dried lemon peels, pulp-free lemon juice, citrus lemon peels, citrus sinensis peels, etc. are another precursor that have been used in the development of CDs, as shown in Table 1 [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. Among these precursors, acidic fruits, such as lemon peels, lemon juice, and citrus sinensis, were frequently chosen.…”

“…Water and ethanol Carbonization ---2018 [25] Acerola fruit Water Hydrothermal -λ em -504 nm λ ex -360 nm -2019 [26] Bitter orange juice -Hydrothermal AFM-2-4 nm DLS-1-2 nm λ em -390 nm λ ex -325 nm 19.9% 2019 [27] Citrus lemon juice Ethylenediamine Hydrothermal HRTEM-3 nm λ em -452 nm λ ex -360 nm 31% 2019 [28] Lemon and onion juices Ammonium hydroxide solution Microwave assisted carbonization TEM-6.15 nm λ em -425 nm λ ex -340 nm 23.6% 2019 [29] Lemon juice -Hydrothermal HRTEM-3-15 nm λ em -524 nm λ ex -420 nm 21.37% 2019 [30] Durian shell Tris base and deionized water Hydrothermal carbonization TEM-6.5 nm λ em -414 nm λ ex -340 nm 12.93% 2019 [31] Lemon Hydroxylamine Hydrothermal HRTEM-2 nm λ em -430-470 nm λ ex -360 nm 5% 2020 [32] Pomegranate Sodium hydroxide and polyethylene glycol Microwave HRTEM-1 to 5 nm λ em -532 nm -2020 [33] Watermelon peels λ em -515 nm Rosa roxburghii fruits Water Hydrothermal TEM-2.5 nm λ em -450 nm λ ex -360 nm 24.8% 2020 [34] Citrus fruit peels Deionized water Sand bath TEM-4.6 nm λ em -510 nm λ ex -420 nm -2021 [35] Banana peel Deionized water Hydrothermal TEM-5 nm λ ex -355 nm 20% 2021 [36] Elaeagnus angustifolia Ultrapure water Hydrothermal TEM-<10 nm λ em -410 nm λ ex -330 nm 16.8% 2021 [37] have heated an ethanol solution of pulp-free lemon juice to produce very high red-luminescent CDs, which hold the promise for in vitro and in vivo bio-imaging [17]. At present, Bael patra fruit-derived CDs turned out to be an excellent carbon source without the need of chemical additives [39].…”

Synthesis and Properties of Nitrogen-Doped Carbon Quantum Dots Using Lactic Acid as Carbon Source

“…The FTIR spectrum of N-CQDs in Figure 1c demonstrates a peak at 1447 cm −1 corresponding to the stretching vibration band of the amine C-N bond [37], and the peak at 3292 cm −1 owing to the stretching vibration bands of O-H and N-H [38], indicating the existence of amino functional groups. Meanwhile, the stretching vibration of C=C is associated with the peak at 1540 cm −1 [39,40]. Stretching C-H of alkyl groups results in the two peaks at 2942 and 2985 cm −1 [35,41].…”

The Application of Carbon Nanomaterials in Sensing, Imaging, Drug Delivery and Therapy for Gynecologic Cancers: An Overview

“…Besides sensing biological signals, the fluorescence of CDs-based nanomaterials can also realize the fluorescence labeling and quantitative determination of HE4-positive ovarian cancer cells [ 34 ], selective imaging of the OVCAR-3 line cells [ 53 ], and cellular multicolor imaging of Hela cells [ 62 ]. Recently, Zarghami et al reported two nitrogen-doped green carbon dots (N-CDs) from lemon and tomato extraction in the presence of hydroxylamine with enhanced fluorescence efficiency, which enhanced fluorescence intensity and biocompatibility for bio labeling and bioimaging of Hela cells [ 63 ]. To overcome the easily diffuse and quench of CDs, connecting their functional groups with other nanoparticles such as hydroxyapatite (HAp) will obtain long-time fluorescence, as reported by Ma et al [ 64 ].…”

“…Up to now, the results about the toxicity of carbon-based nanomaterials are often contradictory. Some studies have even directly explored the carbon-based nanomaterials as anticancer drugs by virtue of their cellular damage [ 116 ], while others have claimed that they have no toxic effects with good biocompatibility [ 43 , 63 ]. In fact, carbon-based nanomedicines always have very complex compositions and different structures, which may result in different cytotoxicity in vitro and in vivo [ 117 , 118 , 119 ].…”