Nanogel drug delivery system
Description About Nanogel Brief View
Published on: Mar 3, 2016
Transcripts - Nanogel drug delivery system
Prepared by :
Mayur N. Pandya
1st Sem M.Pharm
Guided by :
Dr. Tejal A. Mehta
Dept. Of Pharmaceutics
DEPARTMENT OF PHARMACEUTICS
Classification of nanogels
Properties of nanogels
Routes of administration
Mechanism of drug release from nanogels
Synthesis of nanogels
Advantages of nanogels
Disadvantages of nanogels
Application of nanogels
Advances In Technology
The term ‘nanogels’ defined as the nanosized particles formed by
physically or chemically crosslinked polymer networks that is swell in a
The term “nanogel” was first introduced to define cross-linked bifunctional
networks a polyion and a nonionic polymer for delivery of polynucleotides
and poly ethylene glycol(PEG).
With the emerging field of polymer sciences it has now become inevitable
to prepare smart nano-systems which can prove effective for treatment as
well as clinical trials progress.
Nanogels are cross-linked nanoscale particles made of flexible hydrophilic
They are soluble in water and allow spontaneous loading of drugs in
The nanogel collapses to form dense nanoparticles after adding the drug
Nanogels possess large surface area tunable sizes and a network to allow
incorporation of molecule.
They have been used to incorporate drugs, DNA/RNA and inorganic
molecules such as quantum dots.
Nanogels are very promising in drug delivery applications due to their high
Fig. 1: NANOGEL
Biocompatibility and degradability
Swelling property in aqueous media
Higher drug loading capacity
1. The particle size and surface properties can be manipulated to avoid rapid
clearance by Phagocytic cells, allowing both passive and active drug targeting.
2. Controlled and sustained drug release at the target site, improving the
therapeutic efficacy and reducing side effects. Drug loading is relatively high
and may be achieved without chemical reactions; this is an important factor for
preserving the drug activity.
3. Ability to reach the smallest capillary vessels, due to their tiny volume, and
to penetrate the tissues either through the paracellular or the transcellular
4. Highly biocompatible and biodegradable. A model of drug release from
nanogel is given in figure 4.
Fig. 4: Drug release model from nanogel.
The first classification is based on their responsive behavior, which can be
either stimuli-responsive or nonresponsive.
1. In the case of non-responsive nanogels, they simply swell as a result of
2. Stimuli-responsive nanogels swell or deswell upon exposure to
environmental changes such as temperature, pH, magnetic field, and ionic
strength. Multi-responsive microgels are responsive to more than one
The second classification is based on the type of linkages present in the
network chains of gel structure, polymeric gels divided in 4 types.
1.Physical cross-linked gels:
Physical gels or pseudo gels are formed by weaker linkages through either
(a) van derWaals forces,
(b) hydrophobic, electrostatic interactions, or
(c) hydrogen bonding.
These systems are sensitive and this sensitivity depends on polymer
composition, temperature, ionic strength of the medium,
concentrations of the polymer and of the cross-linking agent.
2.Liposome Modified Nanogels:
Liposomes bearing succinylated polyglycidol these liposomes undergo
chain fusion below pH 5.5 that has been shown to efficiently deliver
calcein to the cytoplasm.
Liposomes anchored by or modified with poly(N isopropylacrylamide)-
based copolymeric groups are suitable for thermo- and pH-responsive
nanogels, which are being investigated for transdermal drug delivery
Polymer micellar nanogels can be obtained by the supramolecular self-assembly of
amphiphilic block or graft copolymers in aqueous solutions. They possess unique
core-shell morphological structures, where a hydrophobic block segment in the
form of a core is surrounded by hydrophilic polymer blocks as a shell (corona) that
stabilizes the entire micelle.
The core of micelles provides enough space for accommodating various drug or
biomacromolecules by physical entrapment. Furthermore, the hydrophilic blocks
may form hydrogen bonds with the aqueous media that lead to a perfect shell
formation around the core of micelle. Therefore, the drug molecules in the
hydrophobic core are protected from hydrolysis and enzymatic degradation.
In the delivery of prednisone acetate above its lower critical solution temperature
(LCST) was demonstrated.
Fig. 2: Y-shaped copolymer self-assembly to give micelle structures.
Hybrid nanogels are defined as a composite of nanogel particles dispersed
in organic or inorganic matrices.
These nanogels have the ability to form complexes with various proteins,
drugs, and DNA and it is even possible to coat surfaces of liposomes,
particles, and solid surfaces including cells.
These hybrid nanogels are also capable of delivering insulin and anticancer
drugs more effectively. CHP(cholesterol-bearing pullulan) is composed of
pullulan backbone and cholesterol branches. The CHP molecules self
aggregate to form mono-dispersed stable nanogels through the association
of hydrophobic groups that provide physical crosslinking points as shown
in Figure 3
Fig. 3: Schematic representation of CHP nanogel preparation by physical
Example: The diffusional release of doxorubicin from stable hydrogel
nanoparticles based on pluronic block copolymer This release mechanism
is simple and has been successfully employed in various nanomedicines.
3.Displacement by ions present in the environment
Photochemical internalization and photoisomerisation
Excitation of photosensitizers loaded nanogels leads to production of
singlet oxygen and reactive oxygen species which cause oxidation of
cellular compartment walls such as endosomal barrier walls which effects
release of therapeutics into cytoplasm.
Fabrication of biopolymers
Water-in-oil (W/O) heterogeneous emulsion methods
Inverse (mini) emulsion method
Reverse micellar method
Chemical cross linking
Heterogeneous free radical polymerization
Inverse (mini) emulsion polymerization
Inverse microemulsion polymerization
Heterogeneous controlled/living radical polymerization
Photolithography has been explored to fabricate 3D hydrogel particles and
microgel or nanogel rings for drug delivery. photolithography consists of five steps.
1.The UV cross-linkable polymer, which possesses low surface energy, as a substrate
is released on the pre-baked photo resist-coated water.
2.It involves molding the polymer into patterns on the silicon wafer by pressing the
quartz template onto the polymer and exposed it to the intense UV light.
3.The particles with a thin residual interconnecting film layer are uncovered by
removing the quartz template.
4. This residual thin layer is removed by a plasma containing oxygen that oxidizes it.
5.The fabricated particles are directly collected by dissolution of the substrate in water
Fig. 5: Schematic diagram of five steps involved in photolithography
In the membrane emulsification technique, the dispersed phase is passed
through the membrane (glass or ceramic).
Under certain conditions the emulsion droplets or microgels with specific
morphology are formed on the surface of the membrane and afterwards,
with a continuous phase that is flowing across the membrane, these
fabricated emulsion droplets or microgels are recovered.
These fabricated emulsion droplets can be in different emulsion formation
such as water-in oil (W/O), oil-in-water (O/W), oil-in-water-in-oil
(O/W/O), and water-in-oil-in-water (W/O/W).
Fig. 6: Schematic diagram of the membrane emulsification technique.
3.Chemical cross linking
Biodegradable Dex-based microgels and nanogels were prepared by
various methods based on chemical cross linking including Carbodiimide
coupling, Michael addition reaction, Free radical polymerization.
4.Inverse (mini) emulsion polymerization:
Inverse (mini) emulsion polymerization is a W/O polymerization process
that contains aqueous droplets (including water-soluble monomers) stably
dispersed with the aid of oil soluble surfactants in a continuous organic
Stable dispersions are formed by mechanical stirring for inverse emulsion
process and by sonification for inverse miniemulsion polymerization.
1. Highly biocompatible.
3. Non immunological responses.
4. Invasion by reticuloendothelial system is prevented.
5. Release of therapeutics can be regulated by cross-linking densities.
6. Good permeation capabilities due to extreme small size.
7. Applied to both hydrophilic and hydrophobic drugs and charged solutes.
8. Good transport characteristics.
1. Expensive technique to completely remove the solvents and surfactants
at the end of preparation process.
2. Surfactant or monomer traces may remain and can impart adverse
Cancer treatment involves targeted delivery of drugs with expected low
toxicities to surrounding tissues and high therapeutic efficacy.
An Injectable Nano-Network that Responds to Glucose and Releases Insulin
has been developed.
It contains a mixture of oppositely charged nanoparticles that attract each
Glucose molecules can easily enter and diffuse through the gel. Thus when
levels are high, lots of glucose passes through the gel and triggers release of
the enzyme that converts it to gluconic acid. This increases acidity, which
triggers the release of the insulin.
Nanogel is a promising system for delivery of ODN(godeoxynucleotides) to
Nanogels bound or encapsulated with spontaneously negatively charged ODN
results in formation of stable aqueous dispersion of polyelectrolyte complex
with particle sizes less than 100 nm which can effectively transported across
6.In stopping bleeding
A nanogel composed of protein molecules in solution has been used to stop
bleeding. The proteins self-assemble on the nanoscale into a biodegradable gel
Hydroxypropyl methyl cellulose (HPMC) and Carbopol with the desired
viscosity were utilized to prepare the nanogels.
Two anti-inflammatory drugs, spantide II and ketoprofen drugs which are
effective against allergic contact dermatitis and psoriatic plaque were applied
topically along with nanogel.
Nanogels are promising and innovative drug delivery system that can
play a vital role by addressing the problems associated with old and
modern therapeutics such as nonspecific effects and poor stability.
Nanogels appear to be excellent candidates for brain delivery.
One future goal of research in this area should be the improved design of
microgels/nanogels with specific targeting residues to enable highly
selective uptake into particular cells.
This will be especially important for the targeting of cancer cells, thereby
reducing non-specific uptake into healthy cells.
More and more in vivo and in vitro study should be needed to confirm the
use of this delivery system on human being.
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