Potential Application of Nanoparticles as Antipathogens - Advanced Materials for Agriculture, Food and Environmental Safety - page 351

PbS with Ag by separate evaporation/condensation of two
materials followed by coagulation of oppositely charged
PbS and Ag particles.
IV. Liquid Phase Synthesis
Liquid-phase fabrication entails a wet-chemical route and
involves the following processes:
• Solvothermal method
• Sol-gel method
• Synthesis in structured media (microemulsion)

i. Solvothermal Synthesis
In this method, precursors are dissolved in hot solvent (e.g.,
n-butyl alcohol). Solvents other than water can provide
milder and friendlier reaction condition.
ii. Sol-Gel Process
h e sol-gel process is a wet-chemical technique widely used
in the i eld of material science and ceramic engineering; it
involves the following steps:
• Formation of stable sol solution

• Gelation via polycondensation or polyesterii cation

• Gel aging into solid mass

• Drying of gel to remove liquid phases

• Dehydration at 8000 ° C to remove M-OH group for stabi-

lizing gel
• Densii cation and decomposition of gel at high tempera-
ture (T> 8000 C)

h e precursor sol can be either deposited on a substrate to
form a i lm, cast into a suitable container with the desired
shape or used to synthesize powders (e.g., nanospheres).
iii. Synthesis in Structured Medium
h is is the mixing of two microemulsion carrying metal salt
and reducing agent.

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12.12 Biological Synthesis of Nanoparticles

Nanoparticles have been produced physically and chemically for a long
time, but only recently has the critical role of microorganisms and other