Related Experiment Video
Updated: Jul 3, 2026
08:06
The Use of a β-lactamase-based Conductimetric Biosensor Assay to Detect Biomolecular Interactions
Published on: February 1, 2018
9.5K
BPEI-Based N-Doped Carbon Dots with Sensitive and Selective Cu2+ Ion-Sensing Ability
Sahin Demirci1, Jorge H Torres2, Nurettin Sahiner2,3
1Department of Food Engineering, Faculty of Engineering, Istanbul Aydin University, Florya Halit Aydin Campus, Istanbul 34153, Turkey.
Micromachines
|November 27, 2025
Summary
Branched polyethyleneimine (BPEI)-derived carbon dots (CDs) show promise as fluorescent sensors for detecting metal ions, particularly Cu2+. These BPEI CDs demonstrate high sensitivity and selectivity for Cu2+ in real water samples.
Area of Science:
- Materials Science
- Analytical Chemistry
- Nanotechnology
Background:
- Carbon dots (CDs) are emerging nanomaterials with unique optical properties.
- Polyethyleneimine (PEI) is a versatile polymer for synthesizing nitrogen-doped CDs.
- Developing selective and sensitive fluorescent sensors for metal ion detection remains a significant challenge.
Purpose of the Study:
- To synthesize and characterize branched polyethyleneimine (BPEI)-derived carbon dots (CDs).
- To evaluate the potential of BPEI CDs as fluorescent sensors for various metal ions.
- To investigate the selectivity and sensitivity of BPEI CDs towards specific metal ions, particularly Cu2+.
Main Methods:
- Synthesis of BPEI-derived CDs using BPEI and citric acid at varying ratios (0.5:1, 1:1, 2:1 w/w).
- Characterization of CDs' fluorescence properties (intensity, excitation/emission wavelengths).
- Investigation of fluorescence quenching response of CDs to different metal ions (Cd2+, Co2+, Cu2+, Ni2+, Pb2+) and determination of limit of detection (LOD).
Main Results:
- BPEI CDs synthesized with a higher BPEI:CA ratio (BPEI2 CD) exhibited enhanced fluorescence intensity.
- BPEI CDs demonstrated high sensitivity and selectivity for Cu2+ ions, with a LOD of 0.30 ppm for BPEI2 CDs.
- The sensors showed effective performance in real water samples (tap water, seawater), with over 65% quenching in the presence of 50 ppm Cu2+.
Conclusions:
- BPEI-derived CDs are effective fluorescent sensors for metal ion detection.
- The sensitivity and selectivity towards Cu2+ can be tuned by adjusting the BPEI:CA ratio during synthesis.
- BPEI CDs show potential for practical applications in environmental monitoring and water quality assessment.
Related Concept Videos
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
01:27π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...