Quantum dots in pharmaceutics. NOVEL APPROACH .Advantages, disadvantages ,structure, application,methods of preparation of quantum dots.

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QUANTUM DOTS
Prepared by : Kinal Darji
Guided by: Dr. Hemal Tandel
Pharmaceutical Technology
M.Pharm sem 2
Roll. No. : 17

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TABLE OF CONTENTS
• Introduction to quantum dots
• Structure of QD
• How quantum dots work?
• Properties
• Classification
• Synthesis of quantum dots
• Characterization techniques of QD
• Advantages & Limitations
• Application
• Patented products
• Marketed products
• Case studies
• Review of literature
• References

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INTRODUCTION TO QUANTUM DOTS
• Nanotechnology is one of the most emerging
fields of science.
• Among the nanoparticle systems, the most widely
discussed ones are buckyballs, fullerenes, carbon
tubes, liposomes, nano-shells, dendrimers,etc and
among them, Quantum dots (QDs) have gained
popularity in recent times. [1]
• Apart from being a carrier for drug delivery, QDs
can also act as a model platform as a diagnostic
agent.
• Quantum dot was discovered by the Russian
Physicist, Alexei Ekimov.

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• Quantum dots (QDs), also known as nanoscale
semiconductor crystals (range of 1-10 nm), are
nanoparticles with unique optical and electronic
properties such as bright and intensive fluorescence.
[2]
• Quantum dots (QDs) are luminescent nanocrystals
with rich surface chemistry and unique optical
properties that make them useful as probes or
carriers for traceable targeted delivery and therapy
applications [3]
• They are usually made up of materials such as
silicon, cadmium selenide, indium arsenide or
cadmium sulphide. They are able to glow a
particular colour after being illuminated by a light
source.
• The glow is dependent on the size of the
nanoparticle.

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• semiconductor CORE
• made of CdSe, CdTe, InP, or InAs
• determines optical and
fluorescence characteristics,
• exhibiting blinking,
photobleaching, and toxicity
inorganic
SHELL
Usually
made up
of ZnS
reduces
toxicity
improves water
solubility
enables ligand
binding
Additional
polymer
coatings, such
as PEG,
enhance
biocompatibilit
y and provide
functional
groups for
biomolecule
attachment
STRUCTURE
&
TRAITS
OF QD [4]

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HOW QUANTUM DOTS WORK? [5]
1. Incident Light Absorption
• . 2. Electron Excitation
- Electron absorbs energy and jumps to a higher
energy level
- Leaves behind a positively charged hole
3. Exciton Formation
- Electron and hole pair attracted by Coulomb’s force
- The distance between them is called the Bohr’s radius
4. Excited State
- Electron remains in the higher energy state for nanoseconds

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5. Electron Relaxation & Light Emission
- Electron returns to valence band
- Releases energy in the form of fluorescence
6. Quantum Confinement Effect
- Defines unique optical properties of QDs

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PROPERTIES
• QDs are about thousand times smaller than width of a hair, and made of tiny
bits of metal.
• It’s possible to mould QD’s into different shapes and coat with a variety of bio
molecules.
• They have sharper density. [6]
• Band gap energy is inversely proportional to the size of quantum dot. Band
gap energy 1/Size of Quantum dots. Smaller is the size of the quantum dot
∝
larger is the band gap and vice versa.
• Quantum dots show color glow when it is illuminated by UV radiation. As
quantum dots increase in size, the emission color will have a red spectral shift
and decrease in size shows blue color. Color irradiation depends on the size of
the quantum dot and band gap.
• QDs possess luminescence properties.
• Thermal stability is high (depending on the shell) [7]

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CLASSIFICATION [4]
BASED ON
MATERIAL USED
SEMICONDUCTOR
QD
Eg. Biomedical
imaging, biosensing
CARBON QD
Eg. Drug delivery

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SYNTHESIS OF QUANTUM DOTS
1) PHYSICAL METHODS
1. Arc discharge technique:
[6]
• Carbonaceous materials are
fractionated, oxidized with
3.3 M nitric acid and
extracted with NaOH
solution (pH 8.4).
• The stable black
suspension produced is
then subjected to gel
electrophoresis to separate
quantum dots and carbon
nanotubes.
2. Laser Ablation technique: [4]
• Carbon quantum dots are
prepared through hot
pressing of graphite powder
by argon gas flow.
• In this technique surface
passivation is required by
polyethylene glycol and
diamine containing PEG.

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1) CHEMICAL METHODS [6]
1)Combustion/Thermal
Methods:
Water soluble multicolour
fluorescent C- dots are
produced from combustion
soot of candles through
oxidative acid treatment,
which introduces -OH and -
COOH groups to the dot
surface
2)Electrochemical Oxidation:
C-dots are synthesized by the
electrochemical oxidation of
graphite rod with a platinum mesh
counter electrode and Ag/AgCl
reference electrode assembly in
phosphate buffer solution (pH 7.0).
3)Microwave/ultrasonic synthesis:
PEG-200 and a saccharide (glucose and fructose)
were combined in water to form a transparent solution
followed by heating in a 500 W microwave oven for 2-
10 minutes to synthesize C-dots.

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CHARACTERIZATION TECHNIQUES OF QD[4]

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ADVANTAGES AND LIMITATIONS [6]
• .
1.QDs help track cell processes longer and reveal molecular
interactions better since they resist degradation more than other
imaging probes. Their key feature is real-time imaging.
2.As nanocrystals, QDs enhance contrast in electron microscopy due to
increased scattering.
3.They have size-dependent emission, ranging from UV to IR.
4.QDs offer longer-lasting fluorescence compared to traditional dyes.
5.Their high optical activity makes them useful in biotechnology and
life sciences.
6.Their tiny size allows them to be used in various environments like
liquids, fabrics, and polymers.

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.
1)When placed into live cells QDs exhibit aggregation which can interfere
with cell function.
2)There is also a dilemma in trying to get the QDs inside the cells without
killing the cells in the delivery process.
3)Although quantum dots are in the nano-meter range, bioconjugation
with different biomolecules will increase the size of the dots, making their
delivery difficult.
4)Toxicity of QDs is a major issue. Toxicity includes – cytotoxicity, hepato-
toxicity due to free ions, carcinogenicity potential, lung toxicity.

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APPLICATIONS [6]
1)Pharmaceutical field:
Used in the field of diagnostics, magnetic resonance imaging (MRI), medical imaging as well as
for the detection of the active ingredient with fluorescence.
2) Diagnostics:
Cancer diagnosis as its luminescent and stable conjugates make it possible to
visualize cancer cells in living animals. When combined with florescence
microscopy it enables to follow cells at high resolution in living animals.

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3)Drug delivery
• The structural design involved encapsulating luminescent QDs with a triblock
copolymer and binding this amphiphilic polymer to tumour-targeting ligands
and drug-delivery functionalities.
4) For brain tumour
QD labelled antibodies for rapid visualization of epidermal growth factor receptor
(EGFR)expression in human brain tumour cells. This can also be used to measure
the ability of particles of different sizes to access the tumour and simultaneously
image and differentiate tumour vessels from both the peri vascular cells and the
matrix.

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5) Evaluating multiple biomarkers
• A remarkable feature of QDs is that they are available in a variety of colours,
allowing uniquely coloured QD for each biomarker being assayed.
• The fluorescence emitted by the QD is then analysed by multiplexed imaging
and computer aided analysis that provides quantitative results for each
biomarker.
VARIOUS EXAMPLES OF DRUGS THAT ARE DELIVERED VIA
QD [8]
18

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MARKETED PRODUCTS [1]

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CASE STUDY
1)Fluorescent carbon dots as carriers for intracellular doxorubicin
delivery and track [9]
• This paper reported a simple pH-responsive fluorescent therapeutic drug
delivery system of doxorubicin (DOX)-loaded carbon dots (CDs) for intracellular
drug delivery and track in human gastric cancer cells.
• Drug loading efficiency of this system was 75.3 wt%.
• The CDs-DOX system had about a 2-fold inhibitory effect on MGC-803 cells
growth compared to GES-1 cells according to the MTT assay.
• The cell imaging results showed that the CDs-DOX system could be internalized
into the cells efficiently.
• The intracellular uptake and drug delivery efficiency of this system in GES-1 cells
was about 30% of that in the MGC-803 cells.

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• The fluorescent CDs enabled the optical labeling and tracking of the drug
delivery process at least 48 h.
Because of its specific drug delivery and fluorescence tracking properties, the
multifunctional CDs-DOX system possesses potential applications in bioimaging,
biolabeling and cancer therapy.

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2)Synthesis of fluorescent carbon dots using Daucus carota subsp.
Sativus(carrot) roots for mitomycin drug delivery [10]
• In this work, fluorescent CDs using Daucus carota subsp. sativus (carrot) roots
as a carbon source through hydrothermal method were synthesized.
• The synthesized CDs were loaded with mitomycin drug.
• For mytomycin loading, the CDs and mitomycin were vortexed in PBS pH at 7.4
and mitomycin drug loading and releasing were evaluated by UV–visible and FT-
IR techniques.
• Biocompatible nature of CDs and mitomycin-loaded CDs was confirmed by MTT
assay, suggesting that the CDs and mitomycin-loaded CDs can also be used as
bio-imaging probes in cancer cells and Bacillus subtilis cells.
• Thus, unique optical (fluorescence) and physico-chemical properties
(morphology, size, and zeta potential) of CDs allow them to behave as a trigger at
lower intracellular pH to release mitomycin from the CDs surfaces with high
degree.

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REVIEW OF LITERATURE [11,12,13]
Sr
n
0
Name Of
Authors
Year Journa
l
Title Principle Finding
1. Vaibhavkumar
N. Mehta &
Shiva Shankaran
Chettiar3 & Jigna
R. Bhamore &
Suresh Kumar
Kailasa &
Ramesh M. Patel
2016 Journal
of
flouros
cence
Green
Synthetic
Approach
for
Synthesis of
Fluorescent
Carbon
Dots for
Lisinopril
Drug
Delivery
System and
their
Highly luminescent carbon dots (CDs) were
synthesized by the hydrothermal method .
The lisinopril (Lis)-loaded CDs were
fabricated by self-assembly of lisinopril on
the surfaces of CDs, which were
characterized by UV-visible and FT-IR
spectroscopic techniques. The controlled
release of lisinopril from the Lis-CDs was
realized at pH values of 5.2, 6.2 and 7.4,
respectively. The results of the cytotoxicity
and confocal laser scanning microscopic
images indicate that the Lis-CDs were
successfully uptaken by HeLa cells without

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2
.
Dan Lei, Wen
Yang,
Yunqian
Gong, Jing
Jing, Hailiang
Nie, Bin Yu,
Xiaoling
Zhang
201
6
Sensors
and
Actuators
B
Non-
covalent
Decoration
of Carbon
Dots with
Folic Acid
via a
Polymer-
Assisted
Strategy for
Fast and
Targeted
Cancer Cell
Fluorescenc
e Imaging
An efficient approach for targeting and
detecting folate-receptor (FR)-positive cancer
cells was developed through non-covalent
conjugation of folic acid (FA) on
polyethyleneimine modified CDs (PEI-CDs).
The fluorescent CDs were prepared by a facile
hydrothermal method, and their surfaces
were wrapped with positively charged PEI for
further conjugation with FA through
electrostatic interaction. The FA targeted PEI
modified CDs (FA-PEI-CDs) can be used as a
turn-on fluorescent nanoprobe for folate
receptor (FR)-positive cancer cells in vivo and
in vitro. The uptake of the designed FA-PEI-
CDs by HeLa and HepG2 cancer cells was
verified by confocal laser scanning
microscopy after 10 min incubation and
competition experiments, as well as a

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3
.
Zhenshun Li
a,b, Wei Xua,
Yuntao
Wanga,
Bakht Ramin
Shaha,
Chunlan
Zhanga, Yijie
Chena,c, Yan
Li a,c, Bin Li
a,c,
2015 Carbohydrate
Polymers
Quantum dots
loaded
nanogels for
low
cytotoxicity,
pH-sensitive
fluorescence,
cell imaging
and drug
delivery
In this study, an available, low
toxic and facile approach was
developed to synthesize CdTe
quantum dots loaded nanogels
(QDs-NGs). The QDs-NGs
retained the intrinsic pH
sensitivity of the QDs with
regard to the fluorescence
intensity. The QDs-NGs were
easily internalized by the cells as
fluorescence probes, and acted
as carriers for delivering
methotrexate (MTX). MTT
assay demonstrated that the
QDs-NGs greatly decreased the
cytotoxicity of the QDs. The MTX
loaded QDs-NGs exhibited slow
release property in PBS buffer.

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REFERENCES
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Generation of Smart Nano-Systems. Pharm Nanotechnol. 2019;7(3):234-245.
2) Matea CT, Mocan T, Tabaran F, Pop T, Mosteanu O, Puia C, Iancu C, Mocan L. Quantum dots in
imaging, drug delivery and sensor applications. Int J Nanomedicine. 2017;12:5421-5431
3) Yong KT, Wang Y, Roy I, Rui H, Swihart MT, Law WC, Kwak SK, Ye L, Liu J, Mahajan SD, Reynolds JL.
Preparation of quantum dot/drug nanoparticle formulations for traceable targeted delivery and therapy.
Theranostics. 2012;2(7):681-94.
4) Gidwani, B., Sahu, V., Shukla, S. S., Pandey, R., Joshi, V., Jain, V. K., Vyas, A.Quantum dots: prospectives,
toxicity, advances and applications,J. Drug Deliv. Sci. Technol. 61, 102308, 2021.
5) Sanmartín, Jesús & Bermejo-Barrera, Pilar & Aboal-Somoza, Manuel & Fondo, Matilde & García-Deibe,
Ana & Corredoira-Vázquez, Julio & Alves-Iglesias, Yeneva. (2022). Semiconductor Quantum Dots as Target
Analytes: Properties, Surface Chemistry and Detection. Nanomaterials. 12. 2501.
6) Jha, S., Mathur, P., Ramteke, S., & Jain, N. K. (2017). Pharmaceutical potential of quantum dots. Artificial
Cells, Nanomedicine, and Biotechnology, 46(sup1), 57–65.
7) Sathe K, Garud N, Bangar V, Gadakh N. A REVIEW ON QUANTUM DOTS (QDS). JASR [Internet].
31Jul.2022 [cited 27Feb.2025];13(06):23-7.

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8) Chapter 2 Nanoparticles Types , Classifi cation , Characterization , Fabrication Methods and Drug
Delivery Applications, 2020
9) Qianqian Duan, Yuan Ma, Mingxuan Che, Boye Zhang, Yixia Zhang, Yi Li, Wendong Zhang, Shengbo
Sang, Fluorescent carbon dots as carriers for intracellular doxorubicin delivery and track, Journal of
Drug Delivery Science and Technology, Volume 49,2019,Pages 527-533,ISSN 1773-2247
10)D’souza, S. L., Chettiar, S. S., Koduru, J. R., & Kailasa, S. K. (2018). Synthesis of fluorescent carbon dots
using Daucus carota subsp. sativus roots for mitomycin drug delivery. Optik, 158, 893–900.
11) Mehta VN, Chettiar SS, Bhamore JR, Kailasa SK, Patel RM. Green Synthetic Approach for Synthesis of
Fluorescent Carbon Dots for Lisinopril Drug Delivery System and their Confirmations in the Cells. J
Fluoresc. 2017 Jan;27(1):111-124. doi: 10.1007/s10895-016-1939-4. Epub 2016 Sep 28. PMID: 27679993.
12) Dan Lei, Wen Yang, Yunqian Gong, Jing Jing, Hailiang Nie, Bin Yu, Xiaoling Zhang, Non-covalent
Decoration of Carbon Dots with Folic Acid via a Polymer-Assisted Strategy for Fast and Targeted Cancer
Cell Fluorescence Imaging, Sensors and Actuators B: Chemical
13) Zhenshun Li, Wei Xu, Yuntao Wang, Bakht Ramin Shah, Chunlan Zhang, Yijie Chen, Yan Li, Bin Li,
Quantum dots loaded nanogels for low cytotoxicity, pH-sensitive fluorescence, cell imaging and drug
delivery, CarbohydratePolymers,Volume 121,2015,Pages 477-485

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