Biosynthesis of Metallic Nanoparticles and Their Applications - Intracellular Delivery: Fundamentals and Applications - page 398

Fabrication of otherwise difficult-to-synthesize NPs is undoubtedly an asset of
bio methods. Ahmad et al. ( 2007 ) reported such a synthesis - multifunctional
CuAlO 2 NPs (fungus based).
Phase transfer of biosynthesizes Au and AgNPs was published in a paper by
Ankamwar et al. ( 2005a ). NPs were fabricated using Emblica officinalis (amla,
Indian Gooseberry) fruit extract. The experiments contained also their subse-
quent phase transfer to an organic solution (methanol) and the transmetallation
reaction of hydrophobized AgNPs with hydrophobized chloroaurate ions
(resulted in AuNPs).
Different shapes of resulting NPs also play a role in determining their properties.
Tamarind leaf extract served as the reducing agent for the synthesis of gold nano-
triangles ranged 20-40 nm in thickness (Ankamwar et al. 2005b ). The effect of
different organic solvent vapors like methanol, benzene and acetone on the conduc-
tivity of AuNPs triangles was investigated. Current-voltage characteristics were
determined in presence of aforementioned organic solvent vapors and observation
suggests possible application as chemical sensors. Biofabrication of anisotropic
gold nanotriangles was also reported by Verma et al. ( 2010 ). On the other hand, Xie
et al. ( 2007 ) performed experiments resulting in silver nanoplates employing green
algal species Chlorella vulgaris.
Fabrication of alloys without sophisticated equipment or appropriately high
temperature (Haverkamp et al. 2007 ) demonstrated the ability to synthesis the
Au-Ag-Cu class of alloy by means of the Brassica juncea seed. Similarly, studies
dealing with bimetallic Au-Ag alloy biosynthesis processes employing fungi were
also published (Senapati et al. 2005 ; Sawle et al. 2008 ).
Morph-biotemplates, hollowed, former-bacterial cells, coated by chalcogenide
NPs also represent an innovative approach to material science (Zhou et al. 2009 ).
Moreover, these PbS and ZnS structures, prepared by the sonochemical method in
presence of different cocci and bacillus (rod) templates, exhibited light harvesting
and photocatalytic properties. Hollow structures possess superior photocatalytic
activity to their solid counterparts during photocatalytic degradation of acid
fuchsine and can be used as electromagnetic wave absorbers, ultraviolet shielding
materials, photocatalysts or solar cells.

4 Summary, Conclusions, and Outlook

In this review, recent advances in the application of biosynthesized metallic NPs
have been addressed. Applications have been categorized into a wide spectrum of
sections such as catalysis, medicine, disinfection, sensors etc. When possible, com-
parison with the common chemical and physical synthesis approaches was investi-
gated and discussed. In addition, the introduction of the relatively novel
biosynthesized metallic NPs phenomenon into medicine, electrochemistry, optics
and material science can reinforce their unique functions and properties, resulting
in new methods and strategies for applied research and industrial utilization.