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Biodegradable nanoparticles for drug
and gene delivery to cells and tissues
Presented by
Naila Sajjad
10-arid-1766
PhD Biochemistry
Content
 Significance of nanotechnology for drug therapy
 Nanoparticles
 Significance of particle size
 Biodegradable polymers PLGA &PLA
 Intracellular trafficking
 Therapeutic applications of PLGA nanoparticles
Conti……
 Sustained gene delivery
 Protein delivery
 Vaccine adjuvant
 Intracellular targeting
 Tissue targeting
 conclusion
 Future prospects
 References
Nanotechnology
 Nanoscience
 Research at the scale of 100nm or less
 Nanomedicice
 Drug delivery system
Significance of nanotechnology for
drug therapy
 Suitable means of delivering small mol wt drugs &
macromolecules such as protein peptides or genes (Moghimi
et al.,2001)
 Targeted (cellular/tisue) delivery of drug (Vinagradov et al.,
2002)
Significance of particle size
 High intracellular uptake (Desai et al., 1997)
 Efficiently penetrate throughout submucosal layers
 Cross the blood-brain barrier
Biodegradable polymers PLGA &PLA
 Synthetic polymer
 Polylactide (PLA) and poly (D,L-Lactide-co-
glycolide)(PLGA)
 Hydrolysis
 Polymer biodegradation
Conti…..
Plasmid DNA loaded nanoparticle
Formation of PLGA nanoparticles
 Emulsion solvent evaporation technique (Jain,2000)
 Polyvinyl alcohol (PVA) (Sahoo., 2002)
Commonly used emulsifier
ii. Uniform and smaller in size
iii. hydrophilic
i.
Solvent evaporation technique
Intracellular trafficking
 Delivery of therapeutic agents to specific compartments or
organelles within the cell
 Targeted delivery is the higher bioavailability of therapeutic
agent at its site of action
Release of drug entrapped in PLGA
matrix
 Diffusion
 Block coplymer composition and mol wt.
 Release of encapsulated therapeutic agent (Lin et al., 2000)
Uptake of nanoparticles in S.M.C and
V.E.C
 Phagocytosis
 Fluid phase pinocytosis
 Receptor-mediated endocytosis
Intracellular uptake pathway
Conti…
Primary
endosomes
Sorting
endosomes
Recycling
endosomes
Secondary
endosomes
Intracellular trafficking of
nanoparticles
Transmission electron microscopic picture of PLGA
nanoparticles in the cytoplasm of vascular smooth
muscle
Conti…
 Uptake of nanoparticles is time dependent
 Surface charge reversal
Mechanism responsible for the
endolysosomal escape of nanoparticle
 Nanoparticles interact with vesicular membrane inside the
cell (Panyam et al., 2002)
 Destabilization of membrane
 Escape of nanoparticles into cytoplasmic compartment
Exocytosis of nanoparticles
 Protein (albumin)in serum
 Antiproliferative effect of dexamethasone-loaded
nanoparticles in smooth muscle cell (Davda et al., 2002)
Therapeutic applications of PLGA
nanoparticles
 Sustained gene delivery
 Protein delivery
 Intracellular targeting
 Tissue targeting
Sustained gene delivery
 Nanoparticles containing encapsulated plasmid DNA
 Lysosomal enzymes
 Hedley at al demonstrated protection of DNA from nuclease
when encapsulated into PLGA microsphere
 Rat bone osteotomy model (Labhasetwar et al., 1999)
Marker gene (Fire fly luciferase &heat sensitive
human placental alakaline phosphatase)
 Gene expression in cell culture in the presence of serum
 Use of PLGA emulsion containing alkaline phosphatase as
marker gene for coating gut suture
 Rat skeletal muscles (Cohen et al., 2000)
Protein delivery
 Encapsulation of therapeutic proteins & peptide into
nanoparticles using emulsion solvent technique (Davda et al.,
2000)
 Loss of therapeutic efficiency due to
denaturation/degradation of protein
Reasons of protein inactivation
 Exposure to organic solvents leading to protein adsorption at
oil-water interface (Lu et al., 2000)
 Acidic environment generated during degradation of PLGA
matrix due to formation of acidic monomers and oligomers
(Zhu et al., 2000)
Protection of protein
 Addition of Bovine serum albumin to aqueous phase before
emulsification (Weert et al., 2000)
 By including buffering base such as magnesium hydroxide to
PLGA microsphere formation (Zhu et al., 2000)
Vaccine adjuvant
 Nano and microparticles containing antigen (Raghuvanshi et
al., 2001)
 Alternative to currently used alum
 Provide sustained release of antigen
Systemic and mucosal immunity
Adjuvant properties of PLGA nanoparticles containing
encapsulated staphylococcal enterotoxin B toxoid
Immune response through nanoparticles
injection following injection of alum
 Maximum at 7 weeks then gradually decreased with time
 Secondary immune response at 19th week
 Synergistic immune response after co-injection of TT alum
along with TT-loaded nanoparticles (Raghuvanshi et al.,
2001)
Intracellular targeting
 Surface charge of nanoparticles (Panyam et al., 2002)
 Surface modification of nanoparticles with cationic agents
like didodecyldimethylammonium bromide (DMAB)
 Variation in physical properties
 Attachment of nuclear localization signal to nanoparticle
surface
Tissue targeting
 Monoclonal antibodies
 Epoxy-activation method
 Active and passive targeting
Future prospects
 Sustained dilivery
 Issues in drug delivery are becoming more important
and specific drugs become available with the knowledge
about diseases available from the human genome project
 All therapeutic agents would optimally require drug
delivery and targeting mechanisms to deliver them to
target tissues without reducing their therapeutic efficacy.
Conti…
 As the pathophysiology of disease conditions and their
cellular mechanisms are understood, drug delivery
systems customized to achieve optimal therapeutic
efficacy will be more effective
 Nanoparticles, because of their versatility for
formulation, sustained release properties, sub-cellular
size and biocompatibility with tissue and cells appear to
be a promising system to achieve these important
objectives
Conclusion
 Use of biodegradable nanoparticles formed from poly (D,L-
Lactide-co-glycolide)(PLGA) for target delivery of plasmid
DNA, proteins and low molecular wt compound
 Rapid escape of PLGA nanoparticles from the endo-
lysosomal compartment into cytosol
References
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Vinagradov, S.V., T.K. Bronich and A.V.Kabanov. 2002. Nanosized cationic
hydrogels for drug delivery preparation, properties and interaction with cells.
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Labhasetwar, V., J.Bonadio, S.A.Goldstein and R.J.Levy.1999.Gene transfection
using biodegradable nanosphere: results in tissue culture and rat osteotomy
model. Colloids surfaces. B. Biointerfaces. 281-290.
Desai,M.P., V.Labhasetwar, E.Walter, R.J.Levy and G.L. Amidon.1997. The
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alcohol associated with poly(D,L-Lactide-co-glycolide)nanoparticles affects
their physical properties and cellular uptake. J.Control.Release. 105-114.
Conti…
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effect of a water/organic solvent interface on the structural stability of
lysozyme. J. Control. 351–359
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growth factor beta1 from biodegradable polymer microparticles. J. Biomed.
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biodegradable nanoparticles containing tetanus toxoid. J. Microencapsul. 723–
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 Cohen,H., R.J. Levy, J. Gao, I. Fishbein, V. Kousaev, S. Sosnoski, S.
Slomkowski. 2000. Sustained delivery and expression of DNA encapsulated in
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Conti…..
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