Transcript Graphene and Graphene oxide as a new nanocarriers for drug

Presented by
NOSHEEN RASHID
08-arid-1770
Ph.D 1st
Zoology Department
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Nanotechnology & nanoparticle
 Nanotechnology creates and uses structures that have novel
properties because of their small size
 Nanoparticles are nanosized colloidal structures composed of
synthetic or organo-synthetic polymers
 size range: 1-1000nm
 The drug is dissolved, entrapped, encapsulated and or
attached to the nanoparticle matrix
 The use of nanoparticles allows one to change the
pharmacokinetic properties of the drug without changing the
active compound
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Types of nanoparticles
 Dendrimer
 Liposomes
 Quantum dots
 Metal NPs
 Magnetic NPs
 Polymeric NPs
 Biological NPs
 Gold NPs
 Carbon nanotubes
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Drug delivery
 is the process of administering pharmaceutical compound
to achieve a therapeutic effect in humans and animals
Targeted drug delivery: delivering a drug to a specific site
in the body where it has the greatest effect, instead allowing
it to diffuse to various sites where it may cause damage or
trigger side effects
Controlled drug delivery: is one which deliver drug at
predetermined rate, for a specific period of time
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Advantages of nanoparticles in drug
delivery
 Large surface to volume ratio resulting enhanced interaction
sites
 Release drugs in controlled manner
 More efficient uptake by cells
 Nanoparticle can be administered by oral, occular and nasal
routes
 By attaching specific ligands on to their surfaces, nanoparticles
can be used for directing the drugs to specific target cells
 Improves stability and therapeutic index and reduce toxic
effects
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Graphene
 Single layer of sp2-hybridized carbon atoms arranged in a
honeycomb two-dimentional crystal lattice, viewed as a planar
aromatic macromolecule
 Properties
 High Young’s modulus
 High fracture strength
 Excellent thermal and electrical conductivity
 Fast mobility of charge carriers
 Large surface area
 Biocompatibility
 Immobilize large no. of substances e.g metals, drugs,
biomolecules, fluorescent probes & cells
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Graphene oxide
 GO is synthesized by either the Brodie,
Staudenmaier or
Hummers method.
 Brodie and Staudenmaier used a combination of potassium
chlorate (KClO3 ) with nitric acid (HNO3 ) to oxidize graphite.
 Hummers method involves treatment of graphite with
potassium permanganate (KMnO4 ) and sulfuric acid (H2So4).
 Graphite salts made by intercalating graphite with strong acids
such as H2SO4, HNO3 or HClO4 have also been used as
precursors for the subsequent oxidation to GO.
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2-D Graphene
Graphene
Graphene oxide
0Dbuckballs
1D-nanotubes
3Dgraphite
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Graphene applications
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Quantum physics
Nanoelectronics
Energy research
Catalysis
Engineering of nanocomposites and biomaterials
New generation of biosensors
Nanocarriers for drug delivery
Probes for cell and biological imaging
Drug delivery platform for anticancer/gene delivery
Bioimaging
Antibacterial applications
Cell culture
Tissue engineering
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Bacteria
Proteins
Aptamers
Small drug
molecules
Nucleic acids
Antibodies
Cells
Peptides
Scheme of applications of graphene and graphene oxide for drug delivery of various
therapeutic agents and biomolecules
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Why graphene is better than other
nanocarriers?
 Low cost
 Absence of toxic metal particles
 Superior biocompatibility
 Surface area
Example:
 Polyethylene glycol (PEG) graphene oxide can be used as a
novel drug nanocarrier to load anti-cancer drugs via noncovalent interaction and has in vitro cellular uptake capacity
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Synthesis of G and GO
 By using bottom-up synthetic approaches e.g chemical vapor
deposition, arc discharge and epitaxial growth in SiC.
 For large scale production top-down methods including
mechanical, physical and chemical exfoliation of graphite
using strong acids and oxidants.
 These method requires extensive oxidation of aromatic
structure in order to weaken Vander Waals forces b/w graphene
sheets followed by their exfoliation and dispersion in solution.
 Resulting GO have high density OH and COOH groups.
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Surface modification of G and GO
 The surface modification of nanomaterials is key to building
drug carriers with good biocompatibility and controlled
behavior in biological systems.
 Two methods for surface modification:
PEG
 Covalent modifications
 Non-covalent modifications
PAA
PLL
PVA
FA
Dextran
Chitosan
Fe3O4
PEI
π-π stacking interaction
Vander Waals force
Electrostatic binding
Hydrogen bonding
Coordination bonding
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Covalent modifications
 Can be achieved by
 Nucleophilic substitution
Reactive sites ;
Epoxy groups of GO
Example:
PEGhydrophilic
biocompatible
polymer
PEI-modified GOs used to improve
water solubility of functionalized G and
then FA was attached to specifically target
CBRH7919 cancer cells.
Allow the bonding of groups
with amino functionality
having lone pair of electrons
Method for large
scale modification
of graphene
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Conti…..
 Electrophilic addition
Involves displacement of a
hydrogen atom by electrophile
using diazonium salts
 Condensation reaction
Using a series isocyanate
compounds
showing
easy
dispersion
of
isocyanate
modified graphene
Diazonium salts of paranitroaniline are grafted into
graphene surface to prepare
organo-soluble graphene
organic di-isocyanate
also used for GO
modification and cross
linking
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Conti…..
 Addition
Using thionyl chloride
through the formation of
amide linkage with amino
functional groups
Zhang et al. 2010 functionalized GO sheets with
sulfonic acid groups followed by covalent grafting
of FA molecules. The FA-GO is well dispersed
remain stable
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Non- covalent modifications
 Yang et al. 2009 deposit Fe3O4 nanoparticles onto GO. This
hybrid exhibited super para magnetic properties and can be
loaded with anti-cancer drug DOX with high loading capacity
and enable targeted drug delivery.
 Yang et al. 2012 constructed a nanomolecular assembly by FA
modified β cyclodextrin and GO non-covalently linked by an
adamantane-grafted porphyrin via π-π stacking interaction
 Feng et al. 2011 functionalized GO by PEI polymers by non
covalent electrostatic interaction , yielding GO-PEI complexes
with strong positive charges, high stability in physiological
solutions and reduced cytotoxicity to cells. Disadvantages
Adsorption of polymers is
not strong, vulnerable to
variation in external
environment, less drug
loading capacity
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Schematic illustration of non-covalent modifications of graphene by p–p stacking interaction used for
drug delivery applications. (a) The synthesis of GO–PEI–DNA complexes via a layer-by-layer (LBL)
assembly process, which includes the step of non-covalent functionalization by PEI polymers forming
positively charged GO–PEI complexes followed by electrostatic assembly charged DNA molecules on
the GO–PEI complexes. (b) Synthesis of 1/2/DOX/GO from GO, DOX, adamantane-modified
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porphyrin and folic acid modified cyclodextrin
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Drug delivery applications of G and GO
 Novel drug nanocarrier-loading a variety of therapeutics
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including
Anti-cancer drugs
Poorly soluble drug
Antibiotics
Antibodies
Peptides
DNA
RNA
genes
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1.Targeting drug delivery
 Drawbacks of previous nanocarriers:
 Lack of ability to achieve high targeting concentration and
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efficiency at tumor sites
Limited drug loading capacity
Low degree of functionalization capability
Insufficient cell uptake
leads to non specific
accumulation in normal cells & decreases therapeutic efficacy
of anti-tumor drug
Strategy to achieve efficient tumor targeting is to conjugate
drug carriers with specific ligands e.g folic acids, peptides,
polysaccharides & monoclonal antibodies that can recognize
molecular signatures on the cancer cell surface
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Conti…..
 Targeting drug delivery systems using graphene oxide was first
demonstrated by Zhang et al. 2010.
Sulfonic acid
GO
Covalent
bonding
FA
DOX Camptothecin
Target MCF-7 cells,
human breast cancer
cells with FA receptors
FA-GO
Loaded FA-GO show specific
targeting to MCF-7 cells and
higher cytotoxicity compared to
GO loaded with either DOX or CPT
FA-GO
Ce6
FA-GO-Ce6
Increase the accumulation of Ce6
in tumor cells and lead to
photodynamic efficacy on
MGC803 cells upon irradiation
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2. Delivery of anti-cancer drugs
 Direct
immobilization of anticancer drug molecules (DOX) on
G and GO surfaces.
 DOX, an anthracycline antibiotic
used as anti cancer drug in cancer
chemotherapy
intravenous
administration.
 Yang et al. 2008 showed that DOX
molecules could make a strong
bond with the GO surface through
π-π interactions with quainine, the
hydrophobic part of DOX and with
the hydrogen bond reaction
between carboxyl groups or GO
and amino acids of DOX.
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Conti…..
 Release of DOX is more extensive in acidic and basic medium.
 Depan et al. 2011 confirmed the pH dependence of the loading
and release of DOX from GO, showing the importance of
hydrogen bonding between the DOX molecule and GO. As pH
around cancer cells is slightly acidic so will promote extensive
drug release of DOX.
 Wang et al. 2011 combine GO with gold nanoparticles (AuNP).
It was found that DOX loaded on AuNP-GO inhibits
HepG2cell growth more strongly than DOX or AuNP-GO
alone. This suggests more efficient transport into the cell by
AuNP-GO compared with free DOX.
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3. Photothermal anti-cancer therapy
 PTT and PDT has the ability to destroy cancer cells upon specific
irradiation. They have the ability to kill cancer cells specifically on
tumor sites without side effects.
 Yang et al. (2010) found that PEGylated graphene nanosheets exhibit
ultrahigh in vivo tumor uptake and efficient PTT properties.
 PEG coated GO showed an enhanced NIR absorbance and highly
efficient tumor passive targeting, leading to excellent behaviors in in
vivo treatment efficacy with 100% of tumor elimination.
 Zhang et al. (2011) used PEGylated GO loaded with DOX, both in
vivo and in vitro. The results showed that GO-PEG-DOX
photothermal treatment resulted in complete destruction of tumors
without weight loss or recurrence of tumors, while DOX
chemotherapy alone or GO-PEG photothermal treatment without
DOX did not.
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Conti…..
 PDT relies on reactive oxygen species (ROS) under suitable
irradiation to kill cancer cells.
 Dong et al. (2010) studied graphene based PDT.
 GO-PEG
zinc phthalocyanine(ZnPC)
exhibit significant cytotoxicity
towards cancer cells under Xe
light irradiation
 GO-TiO2
Its PD activity decrease
mitochondrial
membrane potential
Cell apoptosis and death
GO-PEG-ZnPC
Activate superoxide
dimutase, catalase &
glutathione
peroxidase,increase
malondialdehyde
production
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4. Gene delivery
 Based on gene vectors that protect DNA from nuclease
degradation & facilitates cellular uptake of DNA .
 PEI, a cationic polymer shows strong binding to nucleic acids ,
efficient uptake by cells, triggers the endosomal release of DNA
or RNA. Due to high cytotoxicity & poor biocompatibility of PEI
restricts its use. While GO-PEI exhibit low cytotoxicity and good
biocompatibility.
ssDNA
 G
immobilize on G & GO
RNA
protect oligonucleotide
from enzymatic cleavage
 PEI-GO
Lower cytotoxicity&
enhanced anti-cancer
efficacy, improve DNA
binding & condensation
gene carriers
Deliver ssDNA into the cells
ability to condense DNA
Delivery of siRNA and
chemical drugs
Effectively deliver
plasmid
DNA
into the cells
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5. Controlled drug release
 Drug release depend on diffusion process , implies that their
release behavior and amount of released drug cannot be altered.
Add water
Add time
 Chemical control drug release
 External field stimulated drug release
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Chemical control drug release
 DOX-GO
used to avoid undesired drug release during
drug transportation in blood circulation and
improve effective release of anti-tumor drugs
in tumor cells or tissue
 Hydrolysis of ester bond and biodegradable disulfide bonds causes
controlled release of drugs
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Schematic diagram showing synthesis of PAA–GO from GO, conjugation of BCNU to PAA–
GO by covalent binding, delivery of PAA–GO–BCNU to cancer cells and the cytotoxic effect
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of BCNU.
Conclusion
G and GO have high drug loading capacity of many different
drugs and therapeutic molecules. Both covalent and noncovalent modifications can be used to impart specific
biological activity to G and GO, as well as to improve the
biocompatibility and colloidal stability. They have flexibility
and capability to design complex multifunctional drug systems
for combined therapies.
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Future perspective
 There is a need of toxicity studies using in vivo animals to
improve biocompatibility.
 Need of understanding of graphene’s interaction with living
cells (tissues and organs), especially the cellular uptake
mechanism.
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