Nano-particles and targeting strategies in drug delivery
Published on: Mar 3, 2016
Transcripts - Nano-particles and targeting strategies in drug delivery
K . G A U T H A M R E D D Y
2 0 1 1 A 8 P S 3 6 4 G
Various nanoforms have been attempted as drug
Biological substances - albumin, gelatin and
phospholipids for liposomes.
Chemical substances - Superparamagnetic NPs
and solid metal-containing NPs
Liposomes are self-assembled artificial vesicles
developed from amphiphilic phospholipids.
The ability to entrap both hydrophilic and
Advantage: Liposome properties, such as size,
surface charge and functionality, can be easily
tuned through the addition of agents to the lipid
Polymeric NPs are colloidal particles with a size range of
Fabricated using biodegradable synthetic polymers,
such as polycaprolactones or natural polymers, such as
Methods : solvent evaporation, spontaneous
emulsification, solvent diffusion etc have been used to
prepare the NPs.
Smart polymer NP
Stimuli-sensitive polymer which can change its
physicochemical properties in response to
Physical (temperature, ultrasound, light, electricity
and mechanical stress), chemical (pH and ionic
strength) and biological signals (enzymes and
copolymers answering multiple stimuli
Advantage: High sensitivity in response to a given
stimulus within a narrow range, leading to more
accurate in drug delivery.
Super paramagnetic nanoparticles
The superparamagnetic NP are used to guide
microcapsules in place for delivery by external
Another advantage of using magnetic NPs is the
ability to heat the particles after
internalization, which is known as the hyperthermia
Super paramagnetic nanoparticles in controlled drug delivery
Affect the permeability of microcapsules by applying external
oscillating magnetic fields and releasing encapsulated
Controlled release of substances by applying an external
Integrated nanocomposite particles
Each type of nanoparticle has unique advantages
By combining the specific function of each
material, new hybrid nanocomposite materials can
Liposomes are routinely coated with a hydrophilic
polymer, such as PEG or poly ethylene oxide, to
improve the circulation time in vivo
The combination of liposomes and dendrimers has
resulted in higher drug loading , as compared with
Tumor vessels are highly disorganized and dilated
with a high number of pores, resulting in enlarged
gap junctions between endothelial cells .
Migration of macromolecules up to 400 nm in
diameter into the surrounding tumor region.
One of the earliest nanoscale technologies for
passive targeting of drugs was based on the use of
Liposomes are coated with a synthetic polymer
that protects the agents from immune destruction
The microenvironment surrounding tumor tissue, is
different from that of healthy cells which supports
• Based on the high metabolic rate of fast-growing tumor
cells, they require more oxygen and nutrients.
Consequently, glycolysis is stimulated to obtain extra
energy, resulting in an acidic environment.
• Taking advantage of this, pH-sensitive liposomes have
been designed to be stable at physiological pH 7.4, but
degraded to release drug molecules at the acidic pH.
• Disadvantage:The passive strategy is further limited
because certain tumors do not exhibit an EPR
effect, and the permeability of vessels may not be the
same throughout a single tumor.
One way to overcome the limitations of passive
targeting is to attach affinity ligands that only bind
to specific receptors on the cell surface to the
surface of the nanocarriers by a variety of
Nanocarriers will recognize and bind to target cells
through ligand–receptor interactions
Advances in this area have allowed some
nanomedicines in the market to achieve desirable
pharmacokinetic properties, reduce toxicity etc