An Improved Synthesis of Water-Soluble Dual Fluorescence Emission Carbon Dots from Holly Leaves for Accurate Detection of Mercury Ions in Living Cells

Abstract

Background Carbon dots (CDs) emitting near-infrared fluorescence were recently synthesized from green leaves. However, the Hg 2+ detection of CDs was limited because of the insufficient water solubility, low fluorescence and poor stability. Methods Dual fluorescence emission water-soluble CD (Dual-CD) was prepared through a solvothermal method from holly leaves and low toxic PEI 1.8k . PEG was further grafted onto the surface to improve the water solubility and stability. Results The Dual-CD solution can emit 487 nm and 676 nm fluorescence under single excitation and exhibit high quantum yield of 16.8%. The fluorescence at 678 nm decreased remarkably while the emission at 470 nm was slightly affected by the addition of Hg 2+ . The ratiometric Hg 2+ detection had a wide linear range of 0–100 μM and low detection limit of 14.0 nM. In A549 cells, there was a good linear relation between F 487 /F 676 and the concentration of Hg 2+ in the range of 0–60 μM; the detection limit was 477 nM. Furthermore, Dual-CD showed visual fluorescence change under Hg 2+ . Conclusion Dual-CD has ratiometric responsiveness to Hg 2+ and can be applied for quantitative Hg 2+ detection in living cells.

A Fluorescent Vector of Carbon Dot to Deliver Rab13 and Rab14 Plasmids for Promoting Neurite Outgrowth

“…This observation confirmed that the prepared CD-PEI contained carbon (71.43%), nitrogen (9.07%), and oxygen (19.50%). The C 1s band could be deconvoluted into three peaks, namely, those at 284.8, 286.5, and 283.5 eV, which are attributed to C–C/C–H, C–OH/C–O–C, and π-bonded carbon atoms, respectively. , Two deconvoluted peaks of O 1s band at 529.7 and 531.3 eV were associated with the contributions of OC–OH and CO/O–CO/–OH, respectively. , The N 1s band could be deconvoluted into three peaks, namely, those at 398.2, 399.5, and 401.2 eV, which are ascribed to C–N–C, (C) 3 –N, and N–H, respectively. , …”

“…XPS spectroscopy was adopted to qualitatively investigate the element compositions and surface functional groups of the prepared CDs and CD-PEI in Figure 1d− 62,63 The N 1s band could be deconvoluted into three peaks, namely, those at 398.2, 399.5, and 401.2 eV, which are ascribed to C−N−C, (C) 3 −N, and N−H, respectively. 57,64 The FTIR spectroscopic analyses of CD and CD-PEI were also performed to confirm the PEI functionalization on the CD surface. In the FTIR spectrum of CD (Figure S1), strong absorption was observed at 1697 cm −1 , which is attributed to the C�O stretching vibration of carboxylic groups.…”

Encapsulation of Carbon Dots in a Core–Shell Mesh through Coaxial Direct Ink Writing for Improved Crop Growth

“…Such difference in the fluorescence signal can be due to the enhanced stability and better dispersion of C-dots facilitated by the presence of PEG200. PEG is a hydrophilic polymer with excellent solubility in water and other polar solvents and is recognized for its ability to improve the solubility and dispersibility of C-dots in aqueous solutions. , When PEG is added to a C-dot dispersion, it would act as a stabilizing agent and prevents the aggregation or agglomeration of C-dots. PEG molecules form a protective layer around the C-dots, contributing to particle stability due to a steric hindrance.…”

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

“…The importance of developing methods to detect mercury (II) ion (Hg 2+ ) is evident from its environmental abundance and effects on the CNS and endocrine system. Early design of CNDs allowed Hg 2+ did not allow for sensing in anything but water, which excluded any buffers or electrolytes [43,[103][104][105][106][107][108][109][110]. Hg 2+ nanosensing was further developed by Gao et al with a nanohybrid of red-emission QDs and blue-emission CNDs.…”