Biosynthesis of Metallic Nanoparticles and Their Applications - Intracellular Delivery: Fundamentals and Applications - page 386

biological methods is the need to purify the sample and extract the NPs. This is due
to potential pathogens or poisons that might contaminate material and is particu-
larly important for medical applications. Despite these problems, we can still find
some useful studies and potential applications.
Biocompatibility is a very important property for all material possibly dealing
with medical usage in living organisms. Moulton et al. ( 2010 ) reported biosynthesis
experiments with tea leaf extract as a reducing and capping agent for AgNP fabrica-
tion. Evaluation of mitochondrial function to assess cell viability and membrane
integrity in human keratinocytes showed that the AgNPs were nontoxic. This may
be attributed to the tea antioxidants on the NP surface. Although this method of
synthesis appears to be promising based on the initial in vitro studies, they need to
be followed by future in vivo tests to accurately evaluate the biocompatibility.
Wound healing activity of AgNPs, synthesized extracellularly using Aspergillus
niger , was evaluated on rat model for case of excision wound and thermal wound
(Sundaramoorthi et al. 2009 ). Researchers illustrated the efficient antimicrobial
property of AgNPs and also confirmed the ability of nanosilver to modulate the
cytokines involved in wound healing.
Shape of NPs can critically influence their properties, especially the optical.
Gold nanotriangles with tunable size were biofabricated by a simple method involv-
ing the reduction of aqueous gold ions with an extract of the lemongrass plant
(Shankar et al. 2005 ). Interestingly, absorption in the near-infrared region of the
electromagnetic spectrum is “expected to be of application” in hyperthermia of
cancer cells and in infra red (IR) - absorbing optical coatings.
As an elegant application of bacterial magnetosomes (BM), Sun et al. ( 2008 )
presented experiments leading to employment of BM from Magnetospirillum gry-
phiswaldense as a chemotherapy drug carrier (doxorubicin was loaded isolated and
cleaned BMs using a bifunctional crosslinker). As drug efficiency and toxicity may
be significantly altered by structural modification, evaluation of the drug effect
(drug coupled with BM) was also performed. The antitumor effects of doxorubicin
loaded BMs were evaluated by HL60 and EMT-6 carcinoma cells. They were cyto-
toxic to the cancer cells, inhibited cancer cell proliferation and suppressed the
mRNA levels of the significant oncogene c-myc . The drug releasing process from
BMs was also monitored. The assets of this approach (compare to artificial mag-
netic particles) may be the ability to carry larger amounts of drug, ease for prepara-
tion and dispersion, high stability and more uniformity. Being surrounded with
membrane that consists of lipids and proteins, purified and sterilized magneto-
somes were not toxic to mouse fibroblasts in vitro (Li et al. 2007 ). This indicates
the advantage of biocompatibility.
Another medical application deals with diabetes, particularly with inhibion of
enzyme protein tyrosine phosphatase (PTP), type PTP1B. Disturbance of the normal
balance of PTP function has been implicated as the source of several human dis-
eases, including diabetes, cancer, and inflammation (Tonks 2003 ). The rapid forma-
tion of AuNPs with guavanoic acid from the leaf extract of Psidium guajava was
reported by Basha et al. ( 2010 ). These were used in an antidiabetic PTP 1B inhibi-
tory assay and showed significant inhibitory effect with an IC 50 of 1.14 mg/mL.