One-Pot Hydrothermal Synthesis of Carbon Dots
with Efficient Up-and Down-Converted Photoluminescence
for the Sensitive Detection of Morin in a Dual-Readout Assay
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 187 (2017) 149–155
Presented by Thuan Hoa Nguyen
Department of Chemistry, Faculty of Science and Technology, Thammasat University
Jia-Yu Li, Yang Liu, Qun-Wei Shu, Mark T. Swihart, and Ke-Jun Tan
1
I ntroduction
Carbon quantum dots (properties and applications)
One-Pot Hydrothermal
Up & Down converted photoluminescence (dual readout)
Source of Morin
Method for determination of Morin
2
Strong fluorescence
Easy surface modification
Excellent solubility
High stability
Good conductivity
Low toxicity
Environmental friendliness
Size dependent emission wavelength
Narrow emission peak
Broad excitation range
Small particles of a semiconductor.
Typical dimensions range from 1 nm to 10 nm.
Just as in an atom, the energy levels are quantized due to the confinement of electrons.
Introduction
Carbon quantum dots
3
Introduction
CD solution
Hydrothermal Synthesis
Hydrothermal synthesis includes the various techniques of crystallizing substances from high-temperature aqueous solutions at high vapor pressures.
Stainless-steel shell
Teflon cup
Water (or other solvent)
Agents
Carbon source
Pressure
Melting
Diffusing
Conventional hydrothermal method
One –step hydrothermal method
4
Reagents
Carbon source
Introduction
CD solution
Hydrothermal Synthesis
Conventional hydrothermal method
Materials
Chemical solvent
Hydrothermal
transferred
Functionalization chemical
CQDs
Hydrothermal
CQDs
CQDs
CQDs-Functionalization
CQDs-Passivation
Functionalization
Introduction
CD solution
Hydrothermal Synthesis
One –step hydrothermal method
Materials
transferred
Hydrothermal
CQDs
CQDs
CQDs-Functionalization
CQDs-Passivation
Advantage
Multi synthesis and functionalization
Eco-friendly with reducing chemicals
Save synthesis time
Protective equipment
6
Chemical solvent
Functionalization chemical
Introduction
Up and down conversion
CD solution
Down conversion
Intensity
530 nm
665 nm
Up conversion
Near UV Excitation
IR Excitation
Visible Emission
Visible Emission
Reference
Benefit of dual read out??
7
High Energy
Low Energy
High Energy
Low Energy
CD solution
http://www.jeffpippen.com
Introduction
Source of Morin
8
reducing negative side effects of several drugs, without interfering with their functions
Introduction
CD solution
Determination of Morin
9
CD solution
Objective
Hydrothermal
110 oC 2h
To synthesize carbon dots using one-pot hydrothermal
with efficient up and down-converted photoluminescence
for the sensitive detection of morin in a dual-readout assay.
poly(ethylenimine) (PEI)
Citric acid
10
Experiment and
Results and Discussion
11
Experiment
CD solution
Synthesis of CQD
Citric acid (0.25 g)
PEI (0.05 g)
ultrapure water (4 mL)
Hydrothermal
110 °C 2 h
15,000 rpm
10 min
4 mL of methanol
2 mL of ultrapure
water
Cool down
to room temperature
Freezing
(−80°C)
Drying
under vacuum
12
Experimental
Quantum Yield Calculation
CD solution
Quinine sulfate (Φ = 0.54)
Dissolve in 0.1 M H2SO4 (η = 1.33)
The CDs were dispersed in DI water (η =1.33)
Excitation at 360 nm
This work
Where
Φ : the QY
m : the slope
η : the refractive index of the solvent
QS: the quinine X: the CDs
The quantum yield (Φ) is defined as the ratio of the number of photons emitted to the number of photons absorbed.
Quantum Yield Calculation
13
CD solution
CD solution
CD solution
Synthesis and Characterization of the As-Prepared CDs
optimization conditions
Results and Discussion
14
CD solution
Synthesis and Characterization of the As-Prepared CDs
TEM image
Particle size distribution of the as prepared CDs
Results and Discussion
15
CD solution
Synthesis and Characterization of the As-Prepared CDs
XPS survey spectrum
C 1s XPS pattern
Results and Discussion
N-H
N-H
C-H
C-H
C-NH-C
C=O
FTIR spectrum
13C NMR spectrum of the CDs
16
CD solution
Results and Discussion
Down-converted
Up-converted
459
445
Synthesis and Characterization of the As-Prepared CDs
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The CDs show good optical and colloidal stability
CD solution
Effect of time under illumination on the PL intensity of CDs
PL intensity change of CDs under physiological condition (pH 7.4, 10 mmol/L tris-HCl, 0.15 mmol/L NaCl)
Photographs of CD dispersions in different solvents, under ambient (left) and 365nm UV illumination (right) (c-CD: 5.2 mg/mL)
Results and Discussion
18
RESULTS AND DISCUSSION
CD solution
Colloidal and PL Stability of the CDs
Effect of pH value on the PL intensity of CDs
Emission spectra for CDs at 360 nm excitation for different pH values
Effect of ionic strength on the PL intensity of CDs
Down- and up-converted PL intensities of CDs in serum samples
19
Experimental
CD solution
Detection of Morin
CD solution
2.0 mg/mL
HAc-NaAc buffer
(pH 4.0)
50μL
100μL
Morin solution
ultrapure water
1 mL
Spectrofluorometer
After 30 min
λexcitation : 360 nm for up-converted emission
λexcitation : 710 nm for down-converted emission
20
Colloidal and PL Stability of the CDs
RESULTS and
DISCUSSION
Analytical Application of the As-Obtained CDs
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RESULTS AND DISCUSSION
CD solution
Analytical Application of the As-Obtained CDs
The effects of ionic strength
on the detection of morin
The effect of pH
on the quenching efficiency of CDs by morin
The linear relationship between the morin concentration
and the logarithm of the PL intensity (log F)
22
CD solution
Spiked recovery of morin in human urinary samples
RESULTS AND DISCUSSION
23
CD solution
Analysis parameters of down- and up-conversion fluorescence assay
RESULTS AND DISCUSSION
Down-converted PL
Up-converted PL
Down-converted PL
Up-converted PL
The linear relationship between the morin concentration
and the logarithm of the PL intensity (log F)
24
RESULTS AND DISCUSSION
CD solution
Analytical Application of the As-Obtained CDs
Conclusions
25
CD solution
CONCLUSIONS
Detection of morin
in human urine
Dual-readout
Simple
Sensitive
Timesaving
V
V
One-pot
hydrothermal
Emission: 459 nm
QY: 50%
Up-converted PL
Good dispersibility in water
Photobleaching resistance
Dispersibility in complex media
Salt tolerance
26
RESULTS AND DISCUSSION
CD solution
Analytical Application of the As-Obtained CDs
Acknowledgements
Dr. Siriwit Buajarern
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RESULTS AND DISCUSSION
CD solution
Analytical Application of the As-Obtained CDs
Thank You
for Your Attention
28
nguon VI OLET
