Top down and bottom-top approach

1. TOP-DOWN APPROACH
BOTTOM –TOP APPROACH
PREPARATION OF NANO PARTICLES

2. TOP-DOWN APPROACH
 nano objects are constructed from larger entities
without atomic level and control.
 These seek to create smaller devices by using
larger ones to direct their assembly .
 many technologies that descended from
conventional solid state metods for fabricating
microprocessors are capable of creating features
smaller than 100nm.

3. BOTTOM –TOP APPROACH
 materials and devices are built from
molecular components which assemble
themselves chemically by principles of
molecular recoginiton .
 These seek to arranges smaller components
into more complex assemblies .
 DNA nanotechnology utilises the specificity
of Watson – Crick base pairing to construct
well defined structures out of DNA and other
nucleic acids.