Nano Particles Nano drug delivery
Published on: Mar 3, 2016
Transcripts - nano particles
NANOPARTICLES AS DRUG
FACILITATED BY : PRESENTED BY:
PROF. S.J SHANKAR N.ANANTHA LAKSHMI
DEPT.OF PHARMACEUTICS IST YEAR M.PHARM
PESCP,BANGALORE DEPT. OF PHARMACEUTICS
• Nano particles are solid colloidal particles ranging in
size from 10 nm to 1000nm (1 micron). They consist of
macromolecular materials in which the active principle
is dissolved, entrapped or encapsulated and/or to which
the active principle is adsorbed or attached to and can
be used for therapeutic disease management, silicon
chip, bio-medical applications etc..
• Life sciences :- drug delivery, Lab-on- a –chip,
• Security :- molecular barcoding, chemical
• Materials :- powder, polymers
• Electronics :- LCD, semi-conductors, memory
• Energy :- Solar cells, fuel cells, membranes
• Nano tools :- STM. AFMs
Some terms in Nano-science
• Nano structure :- 1 to 100 nm
• Nano- crystals :- Crystalline solid with grain
sizes 1to 100 nm
• Nano coatings :- individual layers or multi-
layer surface coating in the range 1 to 100 nm
• Nano powders :- extremely fine powders with
average particles size in range of 1 to 100 nm
• Nano fibres :- fibers with a diameter in the
range of 1 to 100 nm
TEM (a, b, and c) images of prepared mesoporous silica nanoparticles with mean outer diameter:
(a) 20nm, (b) 45nm, and (c) 80nm. SEM (d) image corresponding to (b). The insets are a high
magnification of mesoporous silica particle
TYPES OF NANO PARTICLES
There are two types of nanoparticles depending on the preparation
The term nanoparticles are a collective name for both nanospheres and
NANOSPHERES have a monolithic-type structure (matrix) in which
drugs are dispersed or adsorbed onto their surfaces or encapsulated
within the particles.
NANOCAPSULES are the vesicular system in which the drug is confined
to a cavity consisting of an inner liquid core surrounded by a polymeric
membrane. In this case the active substance is usually dissolved in the
inner core, but may also be adsorbed to the capsule surface
Nano capsules are
systems in which the
drug is confined to a
cavity surrounded by a
Nanospheres are matrix
systems in which the drug
is physically and uniformly
1.PHOSPHOLIPID-chain creates the structure of
4.PHOSPOLIPID chain breaking apart
5.HYDROPHILIC ingredients slowly releasing.
6.LIPOPHILIC ingredients slowly releasing.
• SOLID LIPID NANO PARTICLES:
New type of colloidal drug carrier system for i.v.
Consists of spherical solid lipid particles in the nm
range, dispersed in water or in aqueous surfactant
• POLYMERIC NANO PARTICLES:
Are defined as particulate dispersions or solid
particles with size in the range of 10-1000nm.
Composed of synthetic or semi-synthetic
Polymers. Biodegradable polymeric
nanoparticles Polylactic acid (PLA), polyglycolic
acid (PGA), Polylactic - glycolic acid (PLGA), and
Polymethyl methacrylate (PMMA)
Phospholipids Hydrophobic core
•CERAMIC NANO PARTICLES :
These are the nanoparticles made up of
inorganic (ceramic) compounds silica, (
Inorganic/metal) titania and alumina. Exist in
size less than 50 nm, which helps them in
evading deeper parts of the body.
Polymeric system involving the self-assembly
and self aggregation of natural polymer
amphiphiles cholesteroyl pullulan , cholesteroyl
dextran and agarose cholesterol groups provide
cross linking points.
•Copolymerized Peptide Nanoparticles:
Drug moiety is covalently bound to the carrier
instead of being physically entrapped.
•Nanocrystals And Nanosuspensions:
Pure drug coated with surfactant, Aggregation
of these particles in crystalline form .Drug
powder dispersed in aqueous surfactant
Biological materials like proteins, enzymes,
peptides etc… are being utilized as a carriers for
the drug delivery.
Particle size and
of nanoparticles can
be easily manipulated
to achieve both
passive and active
drug targeting after
They control and sustain
release of the drug during
the transportation and at
the site of localization,
altering organ distribution
of the drug and
subsequent clearance of
the drug so as to achieve
increase in drug
therapeutic efficacy and
reduction in side effects.
be readily modulated
by the choice of
matrix constituents .
Drug loading is
relatively high and
drugs can be
incorporated into the
systems without any
this is an important
factor for preserving
the drug activity.
The system can
be used for
can lead to
s difficult in
size and large
readily result in
NANOPARTICLES DRUG DELIVERY SYSTEMS
IDEAL CHARACTERISTICS :
It should be biochemical inert , non toxic and non-
It should be stable both physically and chemically in
Invivo & invitro conditions.
Restrict drug distribution to non-target cells or
tissues or organs & should have uniform distribution.
Controllable & Predicate rate of drug release.
Drug release should not effect drug action
Specific Therapeutic amount of drug release must be
Carriers used must be biodegradable or readily
eliminated from the body without any problem and
no carrier induced modulation in disease state.
The preparation of the delivery system should be
easy or reasonable
simple, reproducible & cost effective.
POLYMERIC NANO PARTICLES
• Polymers are macromolecules composed of a large number of
repeating units organized in a chain-like molecular architecture
exhibiting a multiplicity of compositions, structures, and properties.
It is because of this variety of compositions, structures, and
properties that polymers are being used in nanoparticle systems to
generate nanoparticles suited for each specific biomedical
application. The main use of polymeric nanoparticles is in drug
delivery, although they are also used in bioimaging and biosensing
• The use of nanoparticles in drug delivery due to the emerging
importance of targeted delivery in medicine, polymeric
nanoparticles that are efficient, tissue specific, and most
importantly, nontoxic. For the preparation of nanoparticles for drug
delivery, there are a variety of methods depending on how the drug
will be loaded onto the nanoparticle. The resulting nanoparticle-drug
compounds may have the structure of capsules, (polymeric
nanoparticles or polymeric nanoconjugates), amphiphilic core/shell
(polymeric micelles), or hyperbranched macromolecules of
nanometer dimensions (dendrimers)
Easy to synthesize and characterize
Biocompatible and Biodegradable
Non-toxic and water soluble
Inert and Non-immunogenic
TYPES OF POLYMERIC
Natural hydrophilic polymers
The polymers used for the preparation of nano particles are
as follows :
NATURAL HYDRO PHILIC POLYMERS
• Proteins such as albumin, gelatin, legumin or vicilin as well as
polysaccharides like alginates or agarose have been
extensively studied and characterized.
• These macromolecules have attracted wide interest as
biomaterials due to intrinsic biodegradability and
• Natural hydrophilic polymers have been classified as proteins
1. Alginate based drug delivery systems are homo-
compatible and convincingly acceptable for parentral
administration of bio actives.
2. In contrast dextran , albumin and gelatin which are
though acceptable materials manifest
immunogenicity due to use of cross-linking agents
which employed during their preparation.
3. Chitosan on the other hand is homo non compatible
material and hence it should be restricted to
extracorporeal uses only.
• Batch-batch variation
• Conditional biodegradability
• Antigenicity. Parentral adminstration of polymeric
nanoparticles get compromised mainly due to
Chitosan is a modified natural carbohydrate polymer
prepared by the partial N-de acetylation of the
crustacean-derived natural biopolymer chitin. There
are at least four methods reported for the preparation
of chitosan nanoparticles. The four methods are
ionotropic gelation, microemulsion, emulsification
solvent diffusion and polyelectrolyte complex
Gelatin is extensively used in food and medical
products and is a nontoxic alternative. Gelatin NPs are
very efficient in delivery and controlled release of the
drugs. They are nontoxic, biodegradable, bioactive and
inexpensive. Gelatin is a poly ampholyte consisting of
both cationic and anionic groups along with a
hydrophilic group. It is known that the mechanical
properties such as swelling behavior and thermal
properties of gelatin NPs depend significantly on the
degree of cross-linking between cationic and anionic
groups. These properties of gelatin can be
manipulated to prepare desired type of NPs from
gelatin. Gelatin nanoparticles can be prepared by the
desolvation/coacervation or emulsion methods.
SYNTHETIC HYDROPHOBIC POLYMERS
Polymers which are used for nanoparticle preparations are mainly
those, which are conceivably employed in the preparation of
The polymers used are either pre-polymerized or synthesized
before (first group) or during the (second group ) process of
Various synthetic polymers used for the preparation of Nanoparticles
Pre-polymerised Polymerized in process
Poly(ε-caprolactone) (PECL) Poly (isobutylcyanoacrylates)(PICA)
Poly (Lactic acid) (PLA) Poly(butylcyanoacrylates)(PBCA)
Polystyrene Polymethyl(methacrylate) (PMMA)
• poly-ε-caprolactone is degraded by hydrolysis of its ester
linkages under the normal physiological conditions in the
human body and has minimal or no toxicity. Therefore, PCL
has grabbed the attention of researchers as a candidate of
choice for use in drug delivery and long-term implantable
devices. PCL's slower rate of degradation compared to
polylactides has made it better candidate for making long-
term implantable devices. PCL nanoparticles have been
prepared mostly by nanoprecipitation, solvent displacement
and solvent evaporation.
POLYLACTIC ACID (PLA)
• PLA is a biocompatible and biodegradable polymer which is broken
down to monomeric units of lactic acid in the body. Lactic acid is a
natural intermediate/by product of anaerobic respiration, which is
converted into glucose by the liver during the Cori cycle. Glucose
then is used as an energy source in the body. The use of PLA
nanoparticles is therefore safe and devoid of any major toxicity. PLA
nanoparticles have been mostly prepared by the solvent
evaporation, solvent displacement, salting out and solvent diffusion
methods. The salting out procedure is based on the separation of a
water- miscible solvent from aqueous solution by adding a salting
out agent like magnesium chloride or calcium chloride. The main
advantage of the salting out procedure is that it minimizes stress to
protein encapsulants .
• Poly-D-L- lactide-co-glycolide (PLGA) is one of the most successfully
used biodegradable polymers. It undergoes hydrolysis in the body
to produce biodegradable metabolite monomers such as lactic acid
and glycolic acid.. Since lactic acid and glycolic acids are normally
found in the body and participate in a number of physiological and
biochemical pathways, there is very minimal systemic toxicity
associated with the use of PLGA for the drug delivery or biomaterial
applications. PLGA NPs have been mostly prepared by the
emulsification-diffusion, the solvent evaporation and the nano
precipitation methods . PLGA nanoparticles have been used to
develop protein and peptide based nano medicines, nano-vaccines,
and genes containing nanoparticles for in-vivo delivery systems
PREPARATION OF NANO PARTICLES
PREPARATION TECHNIQUES OF
The selection of the appropriate method for the preparation of
nanoparticles depends on the physicochemical characteristics
of the polymer and the drug to be loaded.
The preparation techniques largely determine the inner
structure, in vitro release profiles and the biological fate of
these polymeric delivery systems .
Two types of systems with different inner structures are
apparently possible including :
A matrix type system consisting of an entanglement of
oligomer or polymer units (Nanoparticles/Nanospheres).
A reservoir type of system comprised of an oily core
surrounded by an embryonic polymeric shell
The drug can either be entrapped within the reservoir or the matrix
or otherwise be absorbed on the surface of these particulate
The polymers are strictly structured to a nano metric size range
particles using appropriate methodologies.
These methodologies are classified as follows :
1.AMPIPHILIC MACROMOLECULE CROSS-LINKING
a.) Heat cross-linking
B.) Chemical cross-linking
2.POLYMERIZATION BASED METHODS
a.)Polymerization of monomers in situ
b.)Emulsion (micellar) polymerization
d.)Interfacial condensation Polymerization
3.POLYMER PRECIPITATION METHOD
Nano particles preparation by cross-
linking of Amphiphilic Macromolecules :
• Nano particles can be prepared from amphiphilic macromolecules,
proteins and polysaccharides which have affinity for aqueous and
• The technique involves firstly , the aggregation of amphiphiles
followed by further stabilization either by heat denaturation or
• These processes may occur in biphasic O/W or W/O type dispersed
• It may also take place in an aqueous amphphilic solution where
removal , extraction, or diffusion of solvent, amphiphiles are
aggregated as tiny particulates and subsequently rigidized via
• The cross-linking generally executed following dispersed phase
solvent extraction or depletion.
A.) CROSS-LINKING IN W/O EMULSION
• The cross-linking method is exhaustively used for the nano-
encapsulation of drugs,
• This method involves the emulsification of bovine serum albumin
(BSA)/ Human serum albumin (HSA) or protein aqueous solution in oil
using high pressure homogenization or high frequency sonication.
• The W/O emulsion so formed is then poured into preheated oil (
temperature above 100oc).
• The suspension in the preheated oil maintained above 100oc is held
stirred for specified time in order to denature and aggregate the
protein contents of aqueous pool completely and to evaporate the
• Proteinaceous sub-nanoscopic particles are thus formed where the
size of the internal phase globules mainly determines the ultimate
size of particulates.
• The particles are finally washed with an organic solvent to remove
any adherent or absorbed oil traces and subsequently collected by
• Factors which govern the size and shape of nano partilces are mainly
emulsification energy and temperature (used of denaturation and
• High temperatures used restrict the application of method to
temperature- sensitive drugs. As an alternative to heat stabilzation a
chemical cross- linking agent usually glutaraldehyde is incorporated.
B.) EMULSION CHEMICAL DEHYDRATION
• Chemical dehydration has been reported for
producing BSA nano particles with a narrow size
• Hydroxypropyl solution in chloroform was used as a
continuous phase while chemical dehydrating agent
i.e., 2,2 di-methyl propane , was used to translate
internal aqueous phase into a solid particulate
• This method reportedly avoided coalescence of
droplets and could produce nano particles of smaller
size (<300nm) .
C.) PHASE SEPARATION IN AQUEOUS
MEDIUM ( DESOLVATION )
• The protein or polysaccharide from an aqueous phase can be
desolvated by pH change , or change in temperature by adding some
appropriate counter ions
• Cross-linking may be affected simultaneously or subsequent to the
• The method essentially proceeds involving three steps :
• Appropriate levels of desolvation and resolvation of the aggregate
size are maintained and the aggregated nanoparticulates are cross-
linked using glutaraldehyde.
• Solvent competing agent , sodium sulphate is mainly used as a
desolving agent while alcohol, i.e., ethanol and isopropanol
are carefully added as de solvating or de-aggregating agent.
• This additionally can be optimized turbidometrically using a
• Only de solvation may give the final product as nanospheres.
Desolvation aggregates the protein and turns the suspension
colloidal and hence milky in appearance.
• Both lipophilic and hydrophilic drugs could be entrapped in
nano particles using this technique.
A two step deslovation method for manufacturing gelatin nano
particles. After the first desolvation step , the lower molecular
gelatin fractions present in the supernatent were removed by
decanting. The high molecular weight fractions present in the
sediment were dissolved and then desolvated at pH 2.5 in the
second step . Centrifugation and redispersion methods were
used to purify particles so obtained
PH INDUCED AGGREGATION
• The protein phase may also be separated through PH change. The PH
induced aggregation to prepare nanoparticles has been extensively
used and Insulin nanospheres were the successfully prepared first.
• Insulin was precipitated and then redissolved forming nanodroplets ,
which were hardened using glutaraldehyde . The method yielded
nanoparticles of Insulin.
• Similarly in the preparation of Gelatin nanospheres. Gelatin and
Tween 20 were dissolved in aqueous phase and the PH of the solution
was adjusted to optimum value. The clear solutions so obtained were
heated to 40oC followed by its quenching at 4oc for 24 hrs and
subsequently left at ambient temperature for 48h. The sequential
temperature treatment resulted into a colloidal dispersion of
aggregated gelatin the aggregates were finally cross-linked using
glutaraldehyde as cross-linking agent. The nanospheres thus resulted
were of 200nm average size with uniform dispersity
COUNTER-ION INDUCED AGGREGATION
• Separation of protein phase may also occur by the presence of
counter ions in the aqueous medium.
• The aggregation of dispersed phase (polysaccharide) can effectively
be initiated by adding some appropriate counter ions
• The aggregation can be propagated by adding secondary species of
counter ions followed by rigidization step.
• Alginate nanoparticles have recently prepared using counter ion
induced gelation technique, where gelation was induced by ca++ and
continued by addition of poly (1-lysine ) . Thus these nanospheres
are classically based on polyelectrolyte complex.
• Similarly chitosan nanospheres were prepared by adding
triphosphate (highly negatively charged ions) to the medium. The
size was found to be critically dependent on the concentration of
both i.e., chitosan and tri-phosphate ions.
Nanoparticle preparation using
polymerization based methods
Two different approaches are generally adopted for the preparation
of nanospheres using in situ polymerization technique.
• Methods in which the monomer to be polymerized is emulsified
in a non-solvent phase (emulsion polymerization) or
• Methods in which the monomer is dissolved in a solvent that is
non-solvent for the resulting polymer (dispersion
In emulsion polymerization method, the monomer is dissolved in
an internal phase while in the case of dispersion polymerization , it
is taken in the dispersed phase. It is interesting ,that in either of the
cases following polymerization , the polymer tends to be insoluble
in internal phase or dispersed phase thus results into an ordered
suspension of nanospheres.
• The process of emulsion polymerization can be conventional or
inverse , depending upon the nature of the continuous phase in
• In the former case , the continuous phase is aqueous (O/W
emulsion) , whereas in the latter case it is organic (W/O emulsion).
• Two different mechanisms were proposed for the emulsion
polymerization process and they include :
MICELLAR NUCLEATION AND
• The micellar nucleation and polymerization involve the swollen
monomer micelles as the site of nucleation and polymerization.
• The monomer is emulsified in the non-solvent phase with the help of
• This process leads to the formation of monomer-swollen micelles and
stabilized monomer droplets.
• The polymerization reaction proceeds through nucleation and
propagation stage in the presence of a chemical or physical initiator
• The energy provided by the initiator creates free reactive monomers
in the continuous phase , which then collide with the surrounding
unreactive monomers and initiate the polymerization chain reaction.
• Being slightly soluble in the surrounding phase , the monomer
molecules reach the micelles by diffusion from the monomer
droplets through the continuous phase, thus allowing the
polymerization to progress within the micelles.
HOMOGENOUS NUCLEATION AND
• Homogenous nucleation and polymerization applies in
cases where the monomer is sufficiently soluble in the
continuous outer phase.
• The nucleation and polymerization stages occur in this
phase leading to the formation of primary chains called
• Both micelles and droplets play the role of monomer
reservoirs throughout the polymer chain length.
• When the oligomers have reached a certain length ,
they precipitate and form primary particles, which are
stabilized by the surfactant molecules provided by the
micelles and the droplets.
• Poly(alkylcyanoacrylate) (PACA) , a biodegradable polymer are
essentially prepared by emulsion polymerization.
• Water insoluble monomer is emulsified in an external acid
aqueous phase that contains a stabilizer.
• Monomer polymerized rapidly following anion polymerization
• The polymerization rate is dependent on the PH of the
• Anionic polymerization takes place in micelles after diffusion
of monomer molecules through the water phase and is
initiated by negatively charged compound.
• Thus at neutral PH the rate of polymerization being extremely
fast leads to formation of aggregates.
• However , at acidic PH ,i.e., PH 2-4 , the reaction rate remains
well controlled and slow, thus producing uniform sized
nanospheres of relatively high molecular weight.
• During polymerization the medium is stirred in order to
maintain size and dispersibility of phase undergoing
• The polymerization is continued for carried time depending
upon the monomer, where alkyl chain length is the
determinant , i.e., longer the chain length, longer is the time
of polymerization needed.
• For instance, with ethyl cyanoacrylate it is 2 h and for hexyl
cyanoacrylate the polymerization is conducted for 10-12 h.
• The colloidal suspension on completion of polymerization is
finally neutralized and lyophilized in the presence of some
cryo protectants, i.e., glucose.
• Water-soluble drugs may be associated with PACA
nanoparticles either by dissolving the drug in the aqueous
polymerization medium or by incubating the blank
nanospheres with an aqueous solution of drug.
• The drug molecules are entrapped within the polymer matix
and are also adsorbed onto the surface of the nanoparticles.
The drug molecules are physically adsorbed only on the
• Polymer based nano capscule preparation and
incorporation/loading of lipophilic drug.
• The monomer and drug are dissolved in a mixture of polar
(methanol/acetone) solvents, and oil (benzyl benzoate,
coconut oil) using a lipophilic surfactant , i.e., lecithin.
• The oil phase is then added to an aqueous phase containing a
hydrophilic surfactant. Polaxmer 188 is often used.
• After oil phase is dispersed into an aqueous phase, critically
two processes occur at the oil-water interface.
• Diffusion of polar solvents from oil phase to the bulk aqueous
phase and monomer polymerization at the O/W interface.
• The polymerization process is catalyzed by OH- ions.
• Thus on completion of polymerization a nanocapscular system
results where lipophilic drug dissolved in oil is incorporated in
a polymeric sac.
• Conversely, a dispersion system, W/O type, where dispersed
aqueous phase contains the drug and stabilizer , which organic
phase is typically consisted of an organic solvent (
chloroform/n-hexane) and a monomer , can be used to
prepare nano capscules based upon inverse emulsification
• The interfacial OH- ions initiated polymerization occurs at W/O
interface enveloping aqueous phase with its drug contents in
the form of nano capscules.
• The inverse polymerization process was rapidly adopted for
the preparation of poly(alkyl cyanoacrylate) or PACA
• In these studies , the drug was dissolved in a small amount od
water or hydrophilic solvent (methanol) and emulsified in an
organic phase (i.e., isooctane, cyclohexane-chloroform,
hexane) in the presence of large amount of surfactants.
• Alkylcyanoacrylate monomers were then added directly or
dissolved in an organic solvent to the preformed W/O
emulsion under stirring.
• Hydrophilic compounds such as doxorubicin, fluorescein, and
methylene blue as well as lipophilic compounds such as
triamcinolone acetonide were sufficiently incorporated into
PACA nanoparticles prepared using this technique.
• In dispersion polymerization the monomer instead of being
emulsified , is dissolved in a aqueous medium which acts as a
precipitant for subsequently formed polymer.
• Polymerization based methods essentially involve in situ controlled
polymerization of appropriate monomers where drug may be
added to monomeric phase or may be added to monomeric phase
or may be added to the formed polymeric nano particulates
dispersion for adsorpive loading
• The monomer is introduced into the dispersion medium (phase) of
an emulsionor an inversed emulsion into non-solvent based
• The polymerization is initiate by adding a catalyst and proceeds
with nucleation phase followed by a growth phase (propagation).
• On the other hand,in the case of dispersion polymerization,the
nucleation is directly inducedin the aqueous monomer solution
and the presence of stabilizer or surfactants is not absolutely
necessary for the formation of stable nanospheres.
• The method is used to prepare biodegradable polyacrylamide and
poly methyl-methacrylate(PMMA) nanoparticles.
• The acrylamide or methyl methacrylate monomer is dissolved in
aqueous phase and polymerized by γ-irradiation or by chemical
initiation (ammonium or potassium peroxdisulphate) combined
with heating to temperature above 65oc.
• The polymerization is initiated by γ-irradiation from a 60C source
at elevated temperature.
• The redox catalyst may be used as a chemical initiator , i.e.,
• The oligomers formed subsequently aggregate and above a
certain molecular weight precipitate in the form of primary
particles and propagate as nanosphere which may or may not be
stabilized by surfactant molecules.
• The monomer concentration has linear effect on the size of
nanospheres where size increases with increasing monomer
concentration , decreasing initiator concentration and decreasing
• Being very slowly biodegradable and biocompatible , PMMA
nanoparticles have been considered as optimal polymeric
systems for vaccination purpose.
• For this application, initiation by γ-irradiation is useful for the
production of nano particles by polymerization in the presence of
antigenic material ,because it operates at temperatures suitable
for preservation of heat sensitive antigenic materials , as their
structure and nature remain unaffected.
• The antigenic materials entrapped in PMMA nanoparticles using
this technique include influenza virion , influenza sub unit antigen
,bovine serum albumin , HIV-1 and HIV-2 antigens.
• Besides PMMA nano particles , co polymeric methacrylic acid
based nano particles are also prepared by dispersion
polymerization process using blends of methyl methacrylate with
one or several other acrylic acid derivatives ( eg. Hydroxyethyl
methacrylate, methacrylic acid , ethylene glycol dimethyl
• These copolymer nanoparticles were developed within the
intention of modifying the surface properties of the
nanoparticles, namely the hydrophilicity and charge, which are
important parameters governing the in vivo distribution of the
• The preformed polymer phase is finally transformed to an
• A polymer that eventually becomes core of nano particles
and drug molecules to be loaded are dissolved in a volatile
• The solution is then poured into a non-solvent for both
polymer and core phase.
• The polymer phase is separated as a coacervate phase at
• The resultant mixture instantaneously turns milky owing to
the formation of nano capscules .
• Interfacial polymerization for the encapsulation of proteins,
enzymes , antibodies and cells .
• The method is based on the process of microencapsulation .
In the case of nano particle preparation, aqueous poly
electrolyte solution is carefully dissolved in reverse micelles in
an apolar bulk phase with the help of an appropriate surface
active agent. Subsequently competing poly electrolyte is added
to the bulk, which allows a layer of insoluble poly electrolyte
complex to coacervate at the interface.
• SOLVENT EXTRACTION :
In this method , the hydrophobic polymer ( except dextran,
mainly polyester) and /or a hydrophobic drug is dissolved in a
particular organic solvent followed by its dispersion in a
continuous phase , in which polymer is insoluble.
External phase also contains a stabilizer.
Depending upon solubility miscibility technique they are
designated as :
Using an organic solvent that is completely soluble in continuous
aqueous phase (i.e., acetone ) – nano precipitation.
By evaporation of the organic solvent at room temperature or at
accelerated temperatures or using vaccum.
By incorporating additional amount of water into the
ultraemulsion ( to extract or diffuse the solvent).
Increasing the solubility of the organic solvent in the external
medium by adding an alcohol (i.e., isopropanol).
The polymer precipitation occurs as a consequences of the solvent extraction or
evaporation , which can be brought up by :
SOLVENT EXTRACTION METHOD
• This method involves the formation of a conventional O/W
emulsion between a partially water miscible solvent
containing the polymer and the drug and an aqueous phase
containing the stabilizer.
• The subsequent removal of solvent or the additions of water
to the systems so as to affect the fusion of the solvent to the
external phase are two variants of the solvent extraction
• Ex: in a classical procedure plga nanospheres, the polymer
solubilised in a solvent and dispersed in gelatin solution by
sonicationto yield emulsion(o/w), then the solvent is
eliminated by evaporation.
• For the evaporation purpose apart from sonication,high speed
or pressure homogenization methods are widely employed.
• The homogenizer breaks the initial coarse emulsion in
nanodroplets , yielding nanosphere with narrow size
DOUBLE EMULSION SOLVENT
• Emulsion solvent evaporation technique has been further modified
and a double emulsion ( or multiple emulsion ) of water in oil in
water type has been used.
• PLGA nanoparticles were prepared loaded with bovine serum
albumin using double emulsion solvent evaporation method , Owing
to the high solubility of the protein in water , the double emulsion
technique has been chosen as one of the appropriate methods.
• BSA and PLGA are dissolved separately in aqueous and organic
phases respectively (containing the stabilizer) and subjected to ultra
sonication to yield a W/O emulsion . The W/O emulsion further
added to a PVA aqueous solution to yield the water-in-oil-in-water
(W/O/W) double emulsion. The organic solvent is allowed to
evaporate while being stirred first at atmosphere pressure for 16 h
and then gradually at reduced pressure (from 100mm Hg to 30mm
Hg) to yield nanoparticles .
Schematic representation of EC microparticles preparation using
double-emulsification the W/O1/O2 method.
• This method is based on the interfacial deposition of a polymer
following displacement of a semi – polar solvent miscible with
water from a lipophilic solution .
• Solvent displacement method involves the use of an organic
phase ,which is completely soluble in the external aqueous
• The organic solvent diffuses instantaneously to the external
aqueous phase, inducing immediate polymer precipitation
because of the complete miscibility of both the phases.
• Consequently neither separation nor extraction of the solvent is
required for the polymer precipitation .
• After nanoparticle preparation, the solvent is eliminated an the
free flowing nanoparticles can be obtained under reduced
pressure. This method is particularly useful for drugs that are
slightly soluble in water.
• If the drug is highly hydrophilic , it diffuses out into the external
aqueous phase whereas if the drug is highly hydrophobic , it may
precipitate in the aqueous phase as nano crystals , which further
grow during storage.
• In case of hydrophilic polymer , an aqueous solution of polymer is
dispersed or emulsified in oil phase.
• The precipitation of polymer proceeds on addition of acetone.
Using this technique ovalbumin loaded dextran nano spheres of
~1μm size were prepared. The nano spheres were fairly stable and
uniform in size.
• However, the loading efficiency of lipophilic drugs , such as
indomethacin , metipranol , betaxolol in nano particles of PLA,
PLGA and PECL has been increased using a modified solvent
• In this method the drug is dissolved in a small volume of an
appropriate oil and then diluted in the polar organic solvent (
actone/ethanol/methanol). When the organic solution is dispersed
in the aqueous phase , the polymer precipitates around the
nanodroplets forming a reservoir system
• Salting out process is one of the most commonly used methods
used to prepare nano particles.
• This method involves the incorporation of a saturated aqueous
solution of polyvinyl alcohol (PVA) into an acetone solution of the
polymer under magnetic stirring to form O/W emulsion.
• However, the process differs from nano precipitation technique as
in the latter the polymeric solution (in acetone ) is completely
miscible with the external aqueous medium.
• But in the salting out technique the miscibility of both the phases is
prevented by the saturation of the external phase with PVA.
• The precipitation of the polymer occurs when a sufficient amount
of water is added to the external phase to allow complete diffusion
of the acetone from the internal phase into the aqueous phase.
This technique is suitable for drugs and polymers that are soluble in
polar solvents such as acetone or ethanol.
• The need to develop environmentally safer methods for the
production of PNP has motivated research on the utility of
supercritical fluids as more environmental friendly solvents, with the
potential to produce PNPs with high purity and without any trace of
organic solvent. Supercritical fluid and dense gas technology are
expected to offer an interesting and effective technique of particle
production, avoiding most of the drawbacks of the traditional
• Two principles have been developed for the production of
nanoparticles using supercritical fluids:
1. Rapid expansion of supercritical solution (RESS)
2. Rapid expansion of supercritical solution into liquid solvent
Rapid expansion of
• the solute is dissolved in a supercritical fluid to form a
solution, followed by the rapid expansion of the solution
across an orifice or a capillary nozzle into ambient air.
• The high degree of super saturation, accompanied by the
rapid pressure reduction in the expansion, results in
homogenous nucleation and thereby, the formation of well-
• The RESS experimental apparatus consists of three major
units: a high-pressure stainless steel mixing cell, a syringe
pump, and a pre-expansion unit.
• The concentration and degree of saturation of the polymer
have a considerable effect on the particle size and morphology
of the particles
Experimental set-up for preparation of polymer nanoparticles
by rapid expansion of supercritical fluid solution
Rapid expansion of supercritical
solution into liquid solvent
• A simple, but significant modification to RESS involves
expansion of the supercritical solution into a liquid solvent
instead of ambient air,
• Poly (heptadecafluorodecyl acrylate) nanoparticles having an
average size of less than 50 nm. Even though in RESS
technique no organic solvents used for the formation of PNPs,
the prime products obtained using this technique are micro
scaled rather than nanoscaled, which is the main drawback of
• In order to overcome this drawback a new supercritical fluid
technology known as RESOLV has been developed. In RESOLV
the liquid solvent apparently suppresses the particle growth in
the expansion jet, thus making it possible to obtain primarily
nano sized particles.
Experimental set-up for the rapid expansion of supercritical fluid
solution into liquid solvent process
EVALUATION OF NANOPARTICLES
Structure and crystallinity
Specific surface area
Surface charge & electronic mobility
Drug entrapment efficiency
• Particle size and size distribution are the most important
characteristics of nanoparticle systems.
• They determine the in vivo distribution, biological fate, toxicity
and the targetting ability of nano particle systems
• In addition they can also influence the drug loading, drug release
and stability of nano particles
Photon correlation spectroscopy (PCS) : For smaller particle.
Laser diffractrometry : For larger particle.
Electron microscopy (EM) : Required coating of conductive
material such as gold & limited to dry sample.
Transmission electron microscopy (TEM) : Easier method &
Permits differntiation among nanocapsule & nanoparticle.
Atomic force microscope
Laser force microscope Highresolution
Scanning electron microscope microscope
Helium or air using a gas pycnometer
Density gradiant centrifugation
3. Molecular weight :
Gel permeation chromatography using refractive
4. Structure & Crystallinity :
Thermoanalytical method such as,
1) Differential scanning calorimetry
2) Differential thermal analysis
5. Specific surface area :
specific surface area A = 6
Density * diameter of particle
6. Surface charge & electronic mobility :
Surface charge of particle can be determined by measuring particle
velocity in electrical field.
Laser Doppler Anemometry tech. for determination of Nanoparticles
Surface charge is also measured as electrical mobility.
Charged composition critically decides bio-distribution of
Zeta potential can also be obtain by measuring the electronic mobility.
7. Surface Hydrophobicity :
Important influence on intraction of nanoparticles with biological
Several methods have been used,
1. Hydrophobic interaction chromatography.
2. Two phase partition.
3. contact angle measurement.
8. Invitro release :
Recently introduce modified Ultra-filtration tech.
Media used : phosphate buffer
9. Nanoparticle yield :
% yield = Actual weight of product
Drug entrapment % = Mass of drug in Nanoparticles *100
Mass of drug used in formulation
Total weight of excipient & Drug
10. Drug entrapment efficiency :
Supercritical Fluid Technology
HOMOGENISER SONICATOR SPRAY MILLING
SUPER CRITICAL FLUID TECHNOLOGY
NANO CRYSTALS AND
Drug nanocrystals are pure solid drug particles with a
mean diameter below 1000 nm. A nanosuspension
consists of drug nanocrystals, stabilizing agents such as
surfactants and/or polymeric stabilizers, and a liquid
dispersion medium. The dispersion media can be water,
aqueous solutions, or nonaqueous media. The term .drug
nanocrystals. implies a crystalline state of the discrete
particles, but depending on the production method they
can also be partially or completely amorphous. Drug
nanocrystals have to be distinguished from polymeric
nano particles, which consist of a polymeric matrix and
an incorporated drug. Drug nanocrystals do not consist of
any matrix material.
PROPERTIES OF NANO
PRODUCTION OF NANOCRYSTALS
• There are three possible methods involved in the production of nano
crystals and they are :
1. PRECIPITATION METHOD: The drug is dissolved in a solvent and
subsequently added to a nonsolvent, leading to the precipitation of
finely dispersed drug nanocrystals. This method is used to prepare
ointments containing finely dispersed, precipitated drugs.
2. MILLING METHOD: Bead or a pearl mill to achieve particle size
diminution. Milling media, dispersion medium (generally water),
stabilizer and the drug are charged into the milling chamber. Shear
forces of impact, generated by the movement of the milling media,
lead to particle size reduction. There are two basic milling
principles. Either the milling medium is moved by an agitator, or
the complete container is moved in a complex movement leading
consequently to a movement of the milling media.
3. HOMOGENIZATION METHOD
• there are three important technologies namely: Microfluidizer
technology (IDD-P™™ technology), Piston gap homogenization in
water (Dissocubes® technology) and in water mixtures or in
nonaqueous media (Nanopure® technology).
PRODUCTS IN MARKET
• Nanosuspensions are colloidal dispersions of nanosized drug
particles stabilized by surfactants. They can also be defined as
a biphasic system consisting of pure drug particles dispersed in
an aqueous vehicle in which the diameter of the suspended
particle is less than 1μm in diameter.
Enhance the solubility and bioavailabilty of drugs
Suitable for hydrophilic drugs.
Higher drug loading can be achieved
Dose reduction is possible
Enhance the physical and cheical stability of drugs.
Provides a passive drug targeting .
PREPARATION OF NANO
PREPARATIVE TECHNIQUES FOR NANOSUSPENSION WITH MERITS AND
• EVALUATION OF NANO SUSPENSIONS :
IN-VITRO EVALUATION :-
Particle size and size distribution
Partice charge (zeta potential)
Crystalline state and morphology
Saturation solubility and dissolution velocity
EVALUATION FOR SURFACE – MODIFIED
Interaction with body proteins
BIOAVAILABILITY ENHANCEMENT: Bioavailability enhances
drug with poor solubility , poor permeability or poor solubility
in GI tract that leads to poor oral bioavailability.
OCULAR ADMINSTRATION: Delivery of poorly soluble drug in
cul-de-sac suspensions and ointments.
PULMONARY ADMINSTRATION: The nanoparticulate delivery
of the drug allows the rapid diffusion and dissolution of the
drug at the site of action .Nano suspension offers rapid onset
of action and then control release of the active moiety is
TARGETED DRUG DELIVERY: Nano suspensions can be
designed for targeted delivery of antimycrobial, fungal or
leishmanial drugs to macrophages.