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Dept. of Pharmaceutics M.PHARM (IInd SEM).




Targeted Drug




• Nanoparticles are subnanosized colloidal drug
delivery systems

• Particle size ranges from 10-1000 nm in diameter.
• They are composed of synthetic or semi synthetic

polymers carrying drugs or proteinaceous
substances, i.e. antigen(s).

• Drugs are entrapped in the polymer matrix
particulates or solid solutions or may be bound to
particle surface by physical adsorption or in
chemical form.



The term nanoparticle is a combined name for both
nanosphares and nanocapsules.


Nanospheres and


Advantages of nanoparticles
• Nanoparticles can be administer by various routes

including oral, nasal, parenteral, intra-ocular etc.
• Due to small particle size nanoparticles overcome

resistance by physiological barriers in the body and easily
penetrates to cell walls, blood vessels, stomach epithelium
and blood–brain barrier.

• As a targeted drug carrier nanoparticles reduce drug
toxicity and enhance efficient drug distribution

• Polymeric nanoparticle an ideal drug delivery system for
cancer therapy, vaccines, contraceptives and antibiotics.

• Useful to diagnose various diseases
• Enhanced stability of ingredients
• Prolonged shelf life
• Used in dental surgery also as filling the tiny holes in teeth.


Disadvantages Of Nanoparticles

• Small size & large surface area can lead to
particle aggregation.

• Physical handling of nano particles is
difficult in liquid and dry forms.

• Limited drug loading.
• Toxic metabolites may form.
• Difficult to maintain stability of dosage

E.g.: Resealed erythrocytes stored at 40C.


Preparation Techniques

• The appropriate method selection depends on
the physicochemical characteristics of the
polymer and the drug to be loaded.

• The preparation technique largely determine
 Inner structure
 In vitro release profile
Biological fate of the systems.



Emulsion polymerization (EP)
• Initiator which generates either radicals or ions

depending upon the type of initiator & these radicals
or ions nucleate the monomeric unit & starts
polymerization process.


Dispersion polymerization (DP)

• Used for preparation of biodegradable polyacrylamide &
polymethyl methacrylate (PMMA).


Solvent Evaporation
• Polymer dissolved in organic solvent (dichloromethane,

chloroform or ethyl acetate).
• Drug is dispersed in this solution.
• Mixture emulsified in an aqueous phase containing surfactant
• Ex. Polysorbates, poloxamers sodium dodecyl sulfates

polyvinyl alcohol, gelatin
• Water emulsion by using mechanical stirring, sonication, or

micro fluidization (high-pressure homogenization through
narrow channels).

• Formation of emulsion the organic solvent evaporate by
increased the temperature and reduced pressure with
continuous stirring.


Fig: Preparation of nanoparticles by solvent evaporation method


Emulsifications/ Solvent
Diffusion Method

• It consists in the formation of a conventional o/w
emulsion between a partially water-miscible solvent
containing the polymer and the drug, and an aqueous
solution, containing a surfactant.

• In contrast with methods based on solvent evaporation,
in this technique the droplet size decreases suddenly in a
millisecond time scale during solvent diffusion.

• Nanospheres are produced by this method but
nanocapsules can be obtained just by adding a small
amount of oil, for example miglyol, in the organic phase.

• Finally, depending on its boiling point, the solvent can be
eliminated by evaporation or filtration.


Fig: Representation of the emulsification-solvent diffusion method for the preparation of


Double emulsification method

Fig: Preparation of nanoparticles by double emulsification method


Emulsification–reverse salting-out

• The main difference comes from the composition of the
emulsion which is formulated from a water-miscible
polymer solvent like acetone and an aqueous gel
containing the salting-out agent

• Fig: representation of the emulsification-reverse salting-out technique.


Nanoprecipitation method
• This is another method which is widely used for nanoparticle

preparation which is also called solvent displacement method.
• Useful for slightly water soluble drug.



• Firstly polymer (such as Poly(benzyl-l-glutamate)-b-

poly(ethylene oxide), Poly (lactide)-b-poly(ethylene oxide))
• Drug dissolved in a organic solvent.
• This solution added to a dialysis tube and dialysis performed

against a non-solvent miscible with the former miscible.
• The displacement of the solvent inside the membrane is

followed by the progressive aggregation of polymer due to a
loss of solubility and the formation of homogeneous
suspensions of nanoparticles.

• Dialysis mechanism for formation of nanoparticle is not fully
understood at present.

• It may be based based on a mechanism similar to that of


Fig: representation of the dialysis method for the preparation of


Supercritical fluid technology
• Formation of dry nanoparticles.
• Rapid precipitation process.
• Contain very low traces of organic solvent.
• Involves use of environment friendly solvent like super

critical carbon dioxide or nitrogen.





Evaluation parameter of

1. Particle size
2. Density
3. Molecular weight
4. Structure and crystallinity
5. Specific surface area
6. Surface charge & electronic mobility
7. Surface hydrophobicity
8. Invitro release
9. Nanoparticle yield
10.Drug entrapment efficiency


1.Particle size :
• Photon correlation spectroscopy (PCS) : For smaller

• 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 &

• Atomic force microscope
Laser force microscope
Scanning electron microscope


2.Density :
• Helium or air using a gas pycnometer
• Density gradiant centrifugation

3. Molecular weight :
• Gel permeation chromatography using refractive index


4. Structure & Crystallinity :
• X-ray diffraction
• Thermoanalytical method such as,
1) Differential scanning calorimetry
2) Differential thermal analysis
3) Thermogravimetry


5. Specific surface area :
• Sorptometer

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 velocities.
• Surface charge is also measured as electrical

• Charged composition critically decides bio-

distribution of nanoparticle .
• Zeta potential can also be obtain by measuring the

electronic mobility.


7. Surface Hydrophobicity :
• Important influence on intraction of

nanoparticles with biological environment.
• Several methods have been used,
1 Hydrophobic interaction chromatography.
2 Two phase partition.
3 Contact angle measurement.

8. Invitro release :
• Diffusion cell

Recently introduce modified Ultra-filtration tech.
• Media used : phosphate buffer


9. Nanoparticle yield :

10.Drugentrapment efficiency: