Insight into the differences in carbon dots prepared from fish scales using conventional hydrothermal and microwave methods

Abstract

The preparation of carbon dots (CDs) from waste sh scales is an attractive and high-value transformation. In this study, sh scales were used as a precursor to prepare CDs, and the effects of hydrothermal and microwave methods on their uorescence properties and structures were evaluated.The microwave method was more conducive to the self-doping of nitrogen due to rapid and uniform heating. However, the low temperature associated with the microwave method resulted in the insu cient dissolution of the organic matter in sh scales; thus, the organic matter was di cult to completely dehydrate and condense, but formed nanosheet-like CDs, whose emission behavior had no signi cant correlation with excitation. Although the CDs prepared using the conventional hydrothermal had a lower doping amount of N element, the relative pyrrolic N content was higher, which was bene cial in improving their quantum yield. Additionally, the controllable high temperature and sealed environment used for the conventional hydrothermal could promote the dehydration and condensation of the organic matter in sh scales to form CDs with a higher degree of carbonization, uniform size, and higher C = O/COOH content. CDs prepared using the conventional hydrothermal exhibited higher quantum yield and excitation wavelength-dependent emission behavior. Declarations

An overview on animal/human biomass-derived carbon dots for optical sensing and bioimaging applications

“…Collagen protein-, fat-, and vitamin-rich fish scale can be employed as another waste bio-precursor for the synthesis of doped CDs. Fish scales of grass carp, 222–224 crucian carp, 225 Lethrinus lentjan , 226 Ctenopharyngodon idella , 227 Dicentrarchus labrax , 228,229 Labeo rohita , 230 and silver carp 231 have been employed in the synthesis of heteroatom-containing CDs using the HT or MW synthetic protocol (Table 1). Besides fish scale, other fish byproducts such as shark cartilage, 232 carp roe, 233 and fish scale collagen peptides 234 have also been employed to produce doped CDs.…”

“…172 This unique phenomenon was explained by the generation of ˙OH radicals, which effectively destroyed the surface emissive centers in N-CDs (responsible for their emission) rather than the nuclear states (mainly cause absorption). The recently reported doped CDs from crayfish shell, 186,187 milk powder, 200 fish scales, 231 and fish scale collagen peptides 234 also showed excellent photo-stability. The photo-stability of animal/human biomass-derived CDs was also demonstrated for different period of times in air 134,150,172,174,183,247 and even after storage for many days/months/year under ambient conditions.…”

“…11a) or blue-green luminescence under the irradiation of UV light (l ex = 365 nm) (Table S1 †). The EWD emission is a distinct observation (Table S1 †); however, EWID emissions 135,145,185,200,212,215,227,231 or the combination of both EWD and EWID 223,225 were also noticed in animal biomass-derived CDs (Table S1 †). For example, recently synthesized N,S-CDs (from a mixture of milk powder and methionine) exhibited EWID emission (l em = ∼ 470 nm) in the l ex range of 360-410 nm and maximum emission intensity at l ex = 383 nm (Fig.…”

Green synthesis of carbon dots from fish scales for selective turn off–on detection of glutathione

“…31 The rational use of fish scales, skin, and other aquatic wastes can promote the sustainable development of aquatic processing and reduce environmental pollution. 32 We have used fish scales as the precursor for the preparation of nitrogen-doped CDs via simple hydrothermal treatment for the accurate fluorescence detection of lidocaine hydrochloride in 2018. 14 Crucian carp scale CDs were efficiently and selectively used for the quantitative detection of Fe 3+ by us in 2019.…”

Microwave synthesized novel biomass carbon dots applied in the fluorescent detection of crystal violet

“…The synthesis methods of CDs can be divided into top-down and bottom-up methods [21]. Among these methods, the microwave method has become the preferred one to swiftly manufacture CDs due to its advantages of easy operation, time-saving conformation, and low energy consumption [22][23][24][25]. In recent years, natural substances have gradually become ideal carbon sources for CDs owing to their advantages of abundant derivation, easy collection, environmental protection, and low depletion [26].…”