Environmental Engineering Reference
In-Depth Information
example, if penetration through a pore structure of a cellular membrane
is required. h e size and size distribution become extremely critical
when quantum-sized ef ects are used to control material properties. A
tight control of the average particle size and a narrow distribution of
sizes allow creating very ei cient l uorescent probes that emit narrow
light in a very wide range of wavelengths. h is helps with creating bio-
markers with many well-distinguished colors. h e core itself might have
several layers and may be multifunctional. For example, by combining
magnetic and luminescent layers one can both detect and manipulate
the particles.
h e core particle is ot en protected by several monolayers of inert mate-
rial, for example, silica. Organic molecules that are adsorbed or chemi-
sorbed on the surface of the particle are also used for this purpose. h e
same layer might act as a biocompatible material. However, more ot en
an additional layer of linker molecules is required to proceed with further
functionalisation. h is linear linker molecule has reactive groups at both
ends. One group is aimed at attaching the linker to the nanoparticle surface
and the other is used to bind various moieties like biocompatibles (dex-
tran), antibodies, l uorophores, etc., depending on the function required
by the application.
12.9
Detecting the Antipathogenicity of
Nanoparticles on Microorganisms
in Vitro
For clarifying and proving the antipathogenic ef ect of nanoparticles
against various microbes, the most suited technique employed in the labo-
ratory is zone inhibition technique, which is performed in petridishes con-
taining dif erent culture medium for the growth of microorganism, such as
potato-dextrose medium, zepeck medium, and many others according to
the specii city of the particular microbe [74].
h is method is also known as zone of inhibition technique. In this
method, in a petridish autoclave culture medium (e.g., agar media) is uni-
formly poured. One selects any microbe, fungi, bacteria, etc., to be tested
for the antimicrobial activity (e.g.
penicillium
). h e desired microorganism
is inoculated in the petridish. Next, any of the nanoparticle or nanocom-
posite material of appropriate concentration is poured in the media and
incubated for 24 hours. h en the ei cacy of nanoparticle treatment can be
evaluated at intervals of 2, 4, 6, 8 days by measuring the diameter of zone
of inhibition. It was shown that dif erent concentrations of ZnO NPs treat-
ment inhibit the growth of
penicilium
dif erently.
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