Concentration-dependent color tunability of nitrogen-doped carbon dots and their application for iron(III) detection and multicolor bioimaging

Highly fluorescent carbon dots as an efficient nanoprobe for detection of clomifene citrate

“…The characteristic vibration bands around 3510-3390, 3267, 3100 and 2925 cm À1 indicate the coexistence of -OH, -NH 2 , and ]C-H/-CH functionalities in the CDs, 32,43 the absorption peaks at 1667, 1552, 1315 and 1299 cm À1 could be assigned to the C]O/CONH 2 , C] C, C-N stretching and tertiary C]N stretching vibrations. 32,44,45 Additionally, the wide absorption band at 1028 cm À1 is attributable to the stretching vibration of C-O-C/C-O groups around CDs. 46 All of these vibrations indicate the presence of multiple N, O functionalities onto the carbonaceous framework, which endow the CDs with high hydrophilicity and enable stable aqueous dispersion, thus facilitates the construction of stable uorescent nanoprobe for guest analytes.…”

Citric Acid Derived Carbon Dots, the Challenge of Understanding the Synthesis-Structure Relationship

“…Wang et al [35], Dhenadhayalan et al [36], and Qu et al [30] prepared CA-based via thermal decomposition, microwave treatment (aqueous solution), and hydrothermal method, respectively, and compared the optical properties of the products. CDs show similar absorption bands, maximum emission, and QY, suggesting that CDs synthesized from the same raw materials possess similar optical features, even though different preparation ways [37][38][39][40][41][42][43] are carried out if the reaction temperature is kept constant (Figure 3). (a-e) hydrothermal method, (f,g) thermal decomposition, and (h) microwave treatment.…”

“…Furthermore, X-ray photoelectron spectroscopy (XPS) characterization has shown that the content of graphitic structure C-C/C=C in the CDs increases with the rise of temperature (see Figure 4a2-d2). [37]) and (a2, Ref. [38]) are synthesized from CA and ammonia by microwave method and hydrothermal treatment, respectively.…”

“…Reproduced from Ref. [37][38][39][40][41][42][43] It is worth considering the reason for the relationship between temperature and fluorescence intensity. A change of the morphology and the structure at a defined temperature range appears as a reasonable hypothesis.…”

Fluorescent Sensors for the Detection of Heavy Metal Ions in Aqueous Media

“…A common approach to tune their fluorescent properties is by doping them of other elements [122]: nitrogen (N) is the most commonly employed one [123,124,125], but boron (B), sulfur (S), and phosphorous (P) are also utilized [126,127,128]. Liu et al [129] improved the performance of carbon dots by N-doping: although the first ones exhibited a larger linear detection range (from 6 × 10 −7 to 1.4 × 10 −5 M, while that of N-doped CQDs was from 0.2−8 µM), their LOD was much lower, 8.7 × 10 −8 M, opposite to that of 2.5 × 10 −7 M of the CQDs, as shown in Figure 9.…”