Semiconductor quantum dots (QDs) were a modern form of nanostructure that demonstrated excellent qualities for diagnosis and therapy. Controlling QDs size and distribution made it simple to adjust their electrical and optical characteristics. Yet, since certain semiconductor QDs include hazardous substances such as, cadmium, arsenic, selenium, and mercury, they have several disadvantages. One such disadvantage is cytotoxicity. As a result, these QDs are neither environmentally friendly nor biodegradable. On the other hand, since their inception in 2004, carbon nanodots (CNDs) have been recognized as a strong contender to replace the extremely dangerous metallic semiconductor class of quantum dots. This is partly because the characteristics of carbon quantum dots are widely acknowledged to include their nanoscale size, roughly flat or spherical morphologies, great water solubility, broad absorption in the UV-visible light spectrum, and vibrant fluorescence. CNDs have an amorphous or nanocrystalline center, mainly sp2 carbon, graphite grid spacing, and outside oxygenic functional groups, allowing for water solubility and subsequent complexation.
S. No. |
Source | Method of Synthesis | Size | Percentage Yield | Detection Limit | Inference | References |
---|---|---|---|---|---|---|---|
1 | Banana peel | Microwave treatment | 5 to 15 nm | 16.0% | 1.82 × 10–17/mol | CNDs are fabricated by the microwave treatment of banana peels in a single pot for the determination of colitoxin DNA in human serum. | [11] |
2 | Sargassum fluitans | Hydrothermal | 2–8 nm | 18.2% | - | A hydrothermal method is used to produce CNDs from waste seaweed sargassum fluitans (S. fluitans) to detect DNA. | [12] |
3 | Tomato juice | Hydrothermal | 1.3–3.7 nm | 13.9% |
S. No. | Carbon Nanomaterial | Source and Synthesis | Conjugation Chemistry | Biomolecule (Analyte) |
Analytical Method | Detection Limit | Inference | References | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Carbon nanodots (CNDs) | O-phenylene diamine, 2-amino terephthalic acid by solvothermal method | EDC-NHS | miRNA-21 | Fluorescent biosensor | 0.03 fM | CNDs are synthesized and conjugated via EDC-NHS chemistry to detect miRNA-21. | [44] | ||||||||
2 | PEI-Carbon dots | Polyethyleneimine (PEI) by hydrothermal method | - | miRNA-21 | Fluorescence biosensor | - | The synthesized CNDs is employed to detect miRNA-21 by fluorescence biosensor. | [45]0.3 ng/mL | CNDs are synthesized by hydrothermal treatment of tomato juice for the sensing of carcinoembryonic antigen. | [13] | ||||||
3 | CNDs/AO | Citric acid in formamide | π-π conjugation | miRNA-92a-3p | Fluorometric assay (FRET) | 0.14 nM | To detect miRNA-92a-3p, CNDs are fabricated and conjugated using π–π conjugation. | [46] | 4 | Limes | Pyrolyzing | 5-10 nm | - | - | The pyrolyzing process is used to synthesize CNDs for the detection of hepatitis B virus DNA. | |
4 | CNDs–DNA walker | Citric acid and urea by microwave-assisted method | EDC-NHS | miRNA-21 miRNA-155 | [ | Electrochemiluminescence biosensor | 14] | |||||||||
33 fM for miRNA-21. | 33 aM for miRNA-155 | CNDs are created and conjugated via EDC-NHS chemistry to discover miRNA-21 and miRNA-155. | [ | 47 | ] | 5 | Lemon juice | Carbonization | 6–9 nm | - | 0.23 mM | Carbonization of lemon juice is performed to form CNDs for the detection of l-tyrosine. | [15] | |||
5 | CNDs | Oxidized maple leaf by a pyrolytic method | EDC-NHS | miRNA-21 | Electrochemiluminescence biosensor | 21 aM | CNDs are synthesized and conjugated via EDC-NHS chemistry to detect miRNA-21 associated with breast cancer. | [43]6 | Lemon | Pyrolyzing | 10 nm | - | 0.0049 µM | Synthesis of CNDs from a lemon by the process of pyrolysis for the detection of doxorubicin hydrochloride in human plasma. | [16] | |
6 | CNDs | Tiger nut milk by carbonization | - | miRNA-21 | Chemiluminescence biosensor | 0.721 fM | Synthesized CNDs are used to detect miRNA-21 associated with cardiovascular disease. | [ | 7 | Syringa oblata lindl | Hydrothermal | 1.0–5.0 nm | 12.4%, | 0.11 μM | A hydrothermal method is used to fabricate CNDs from syringa oblata lindl for sensors and cell imaging. | [17] |
48 | ] | |||||||||||||||
7 | CNDs | Glutaraldehyde, nitro benzaldehyde by solvothermal method | - | miRNA-21 | Fluorescence sensor | 0.03 fM | An miRNA-21 associated with breast cancer is identified using a fluorescence sensor that is based on carbon dots. | [49] | 8 | Grapefruit | Hydrothermal | >30 nm | 20% | - | Grapefruit is used to create CNDs using a hydrothermal process for the detection of E. coli bacteria. | |
8 | CNDs | Malic acid centrifugation | EDC-NHS | [ | 18 | ] | ||||||||||
miRNAs | Fluorescence | 0.03 pM | The synthesized CNDs is conjugated via EDC NHS chemistry and used to detect miRNA. | [ | 50 | ] | 9 | Alfalfa and garlic | Hydrothermal | |||||||
9 | CNDs | 1.3–6.9 nm | 10% | Citric acid by microwave method | π-π stacking | miRNAs86 nM | A hydrothermal method is used to form CNDs from alfalfa and garlic as a fluorescent probe for cysteine, glutathione, and homocysteine. | [19] | ||||||||
Fluorescence biosensor | 2.78 fM | CNDs were synthesized and employed to detect miRNAs by fluorescence biosensor. | [ | 51 | ] | 10 | Catharanthus roseus (white flowering plant) | |||||||||
10 | CNDs | Hydrothermal carbonization | - | - | - | Catharanthus roseus (white flowering plant) is hydrothermally carbonized to create CNDs to detect the Al3+ and Fe3+ ions. | Tree leaves by hydrothermal method | EDC-NHS | miRNA-155[10] | |||||||
Fluorescence biosensor FRET | 0.3 aM | CNDs were synthesized and conjugated via EDC-NHS chemistry and were used to detect miRNA-155 by fluorescence biosensor. | [ | 52 | ] | 11 | Lemon juice | Hydrothermal | - | - | ||||||
11 | - | CNDs/BHQ 2 | Ethane diamine, p-benzoquinone | Maleimide-thiol | miRNA-141 | The one-pot facile hydrothermal approach was used to create highly luminous carbon dots (C-dots) from lemon juice. | FRET[20] | |||||||||
16.5 pM | miRNA-14 is conjugated with synthesized CNDs via maleimide–thiol conjugation chemistry and detected by a fluorimetry test. | [ | 53 | ] | 12 | Daucus carota | Hydrothermal | - | ||||||||
12 | 7.60% | Carbon nanotubes (CNTs) | Hydrogen tetrachloroaurate trihydrate |
EDC-NHS | - | A hydrothermal method is used to produce CNDs from Daucus carota to detect mitomycin. | miRNA-21 | Fluorescence biosensor | 36 pM[21] | |||||||
A synthesized CNT is conjugated via EDC-NHS chemistry to detect intracellularly | miRNAs-21. | [ | 54 | ] | 13 | Natural polymer starch | Hydrothermal | 2.25–3.50 nm | - | - | Hydrothermal treatment of natural polymer starch is performed to produce CNDs. | [22] | ||||
13 | CNDs | Pyrolysis synthesis | Amine-amine conjugation | miRNA-21 | Ratiometric fluorescence | 1 pM | Synthesized CNDs were used to detect miRNA-21 associated with gastrointestinal cancer. | [55] | 14 | P. acidus | Hydrothermal | 5 nm | ||||
14 | CNDs | 12.5% | - | Citric acid ethylene diamine/carbonization | Amine -glutaraldehyde | miRNA-155CNDs are produced by a hydrothermal process from P. Acidus for live cell imaging. | [23] | |||||||||
FRET | 0.1 aM | Fabricated CNDs are used to identify miRNA-155 present in cancer cells. | [ | 56 | ] | 15 | Citrus peel powder | |||||||||
15 | CNTs (MWCNT/AuNCs) | Sand bath heat-assisted method | 4.6 ± 0.28nm | - | - | The sand bath heat-assisted method is utilized to form CNDs from citrus peel powder for free radical scavenging and cell imaging. | Carboxylic acid-ultrasonic cell disruption[24] |
|||||||||
Thiol conjugation | miRNA-155 | FRET | 33.4 fM | CNTs are synthesized and used to detect miRNA-155. | [ | 57 | ] | 16 | ||||||||
16 | Lentil | Hydrothermal | 7 ± 4 µm | 10% | CNDs3.0 µg | Citric acid– hydrothermal |
π-π stacking | micro-RNAA hydrothermal method is used to form CNDs from lentils for the colorimetric determination of thioridazine hydrochloride. | Fluorescence[25] | |||||||
A CNDs is used to detect miRNA by fluorescence method. | [ | 58 | ] | 17 | Rose flowers | Hydrothermal | 1.0–5.0 nm | - | 0.02–10 µM | CNDs are produced by a hydrothermal process from rose flowers for the determination of diazinon. | [26] | |||||
18 | ||||||||||||||||
17 | CNTs | - | miRNA-21 | Electrochemical biosensor | 1.95 fM | miRNA-21 is detected by a carbon nanotube-based electrochemical biosensor. | [59] | Saffron | Hydrothermal | >20 nm | 23.6% | 1.8 n/mol | A hydrothermal method is used to produce CNDs from saffron for the sensing of prilocaine. | |||
18s | Carbon nanofibers/SPE | - | [ | Amine-carboxylic acid conjugation | miRNA-34a | 27 | Electrochemical biosensor] | |||||||||
54 pM | The electrochemical biosensor is utilized to detect miRNA-34a using carbon nanofibers. | [ | 60 | 19 | Valerian root | Hydrothermal | >10 nm | 14% | 0.6 ng/mL | Valerian root has been used to make CNDs using a hydrothermal process for the determination of imipramine. | [28] | |||||
] | ||||||||||||||||
19 | DNA-CNDs/CNTs | - | π-π stacking | miRNA-7f | Photoelectrochemical biosensor | 34 fM | A CNTs is used to detect miRNA-7f by a photoelectrochemical method. | [61] | 20 | Rosemary leaves | Hydrothermal | Approx. 5 nm. | ||||
20 | Carbon nanoparticles/ssDNA probe | Graphite electrode by an electro-oxidation method | 18% | 8 ng/mL | Rosemary leaves have been used to make CNDs using a hydrothermal process for the determination of thiabendazole in juices. | [ | π-π stacking29] | |||||||||
miRNA let-7a | Fluorescence | 0.35 pM | Synthesized carbon nano-particles conjugated via π–π stacking are used to detect miRNA let-7a. | [ | 62 | ] | 21 | Beetroot | Microwave | 5 & 8 nm | 6% & 5% | - | CNDs made from aqueous beetroot extract by the process of a microwave for in vivo live animal imaging applications. | [30] | ||
22 | Eutrophic algal blooms | Chemical oxidation | Approx. 8 nm | 13% | - | Eutrophic algal blooms have been used to make CNDs using chemical oxidation for in vitro imaging. | [31] | |||||||||
23 | Green tea leaf | Pyrolyzation | 2 nm | 14.8% | - | Synthesis of CNDs from green tea leaf by the process of pyrolysis for the sensing of gefitinib. | [32] | |||||||||
24 | Waste tea residue | Chemical oxidation | 3.2 nm | 2.47% | Be 0.04 μg /mL | Waste tea residue has been used to make CNDs using chemical oxidation for the quantification of tetracycline. | [33] | |||||||||
25 | Palm shell powder | Chemical oxidation | 4–10 nm | 6.8% | 0.079 µM | CNDs are synthesized by the chemical oxidation method from palm shell powder for the sensing of nitrophenol. | [34] | |||||||||
26 | Soybeans | Ultrasonic-assisted method | 2.4 nm | 16.7% | 0.9μM | An ultrasonic-assisted method is used to produce CNDs from soybeans to detect Fe3+ ions. | [35] |