246
I. A. Adelere and A. Lateef
flaccidum. In this study, green algae was grown 2 weeks in the incubator (20 °C, 16 h
light/8 h dark) before the addition of HAuCl 4 aqueous solution. Strong color modification of the biomass and the culture medium from yellow to purple was observed
within a few days suggesting gold metallic nanoparticles formation. The organism
demonstrated strong adaptation to high concentration of metal ion as it showed no
sign of serious physiological damage after nanoparticles recovery. The biosynthesized AuNPs were spherical with an average size of 8.6 ± 4.2 nm according to TEM
analysis.
MubarakAli et al. (2013) conducted a comparative study on the synthesis and
application of AuNPs by prokaryotic (Phormidium sp) and eukaryotic (Coelastrella
sp) photosynthetic microorganisms. It was discovered that the bioreduction of gold
ion to form AuNPs occurred intracellularly by protein molecules in the algal cells. The
biosynthesized AuNPs by these prokaryote and eucakaryote were 25 nm sized nanotriangles and 30 nm sized spherical shape, respectively. They demonstrated potent
potential biomedical applications. Also, Luangpipat et al. (2011) biosynthesized
AuNPs by incubating the live cells of green microalgae Chlorella vulgaris with gold
chloride solution. The reduction of gold ion by the biomolecules occurred predominantly in the cell cytoplasm. The biosynthesized AuNPs were mostly spheroidal
or polyhedral in shape with diameter range of 40–60 nm. In a study conducted by
Shakibaie et al. (2010), biogenic synthesis of AuNPs was reported using extract
of disrupted cells of Tetraselmis suecica. The biosynthesized AuNPs displayed
maximum SPR peak of 530 nm. They were crystalline in nature, polydispersed, with
an average particle size of 79 nm. Moreover, the synthesis of bioactive AuNPs by
locally isolated Nitzschia diatoms was reported by Borase et al. (2017). The particles
displayed characteristic ruby red color with sharp absorbance peak at 529 nm. The
biosynthesized AuNPs have irregular shape, average size of 43 nm with zeta potential of −16.8 mV. FTIR analysis revealed that fungal proteins and polysaccharides
were actively involved in the gold ions reduction to AuNPs. The particles produced
synergistic antibacterial effect when combined with conventional antibiotics against
some clinical bacterial isolates.
The biosynthesis of AuNPs was also established by Spirulina platensis under
ambient conditions (Kalabegishvili et al. 2012). Characterization of the AuNPs was
done by UV–vis, TEM, SEM, EDAX, and XRD. Results of the complex analytical
studies of the particles revealed that they were synthesized extracellularly through
bioreduction of gold ions by proteins and enzymes produced by Spirulina platensis
with UV maximum absorbance at 530 nm. The particles had crystalline property,
spherical shape, and 30 nm average size. A large quantity of gold materials was
synthesized through a simple, one-pot method (Xie et al. 2007). The synthesis was
carried out by reacting chloroauric acid solution with the aqueous extract of Chlorella
vulgaris at room temperature. It was observed that the protein molecules in the algal
extract was predominantly involved in the reduction of gold ion to nanogold crystals.
Precisely, a protein (gold shape-directing protein, GSP) with a molecular weight of
approximately 28 kDa was identified to possess both reduction and shape-directing
functionalities. The biosynthesized nanogold crystals were triangular and hexagonal
in shape. The kinetics of the reduction reaction was manipulated by changing the
I. A. Adelere and A. Lateef
flaccidum. In this study, green algae was grown 2 weeks in the incubator (20 °C, 16 h
light/8 h dark) before the addition of HAuCl 4 aqueous solution. Strong color modification of the biomass and the culture medium from yellow to purple was observed
within a few days suggesting gold metallic nanoparticles formation. The organism
demonstrated strong adaptation to high concentration of metal ion as it showed no
sign of serious physiological damage after nanoparticles recovery. The biosynthesized AuNPs were spherical with an average size of 8.6 ± 4.2 nm according to TEM
analysis.
MubarakAli et al. (2013) conducted a comparative study on the synthesis and
application of AuNPs by prokaryotic (Phormidium sp) and eukaryotic (Coelastrella
sp) photosynthetic microorganisms. It was discovered that the bioreduction of gold
ion to form AuNPs occurred intracellularly by protein molecules in the algal cells. The
biosynthesized AuNPs by these prokaryote and eucakaryote were 25 nm sized nanotriangles and 30 nm sized spherical shape, respectively. They demonstrated potent
potential biomedical applications. Also, Luangpipat et al. (2011) biosynthesized
AuNPs by incubating the live cells of green microalgae Chlorella vulgaris with gold
chloride solution. The reduction of gold ion by the biomolecules occurred predominantly in the cell cytoplasm. The biosynthesized AuNPs were mostly spheroidal
or polyhedral in shape with diameter range of 40–60 nm. In a study conducted by
Shakibaie et al. (2010), biogenic synthesis of AuNPs was reported using extract
of disrupted cells of Tetraselmis suecica. The biosynthesized AuNPs displayed
maximum SPR peak of 530 nm. They were crystalline in nature, polydispersed, with
an average particle size of 79 nm. Moreover, the synthesis of bioactive AuNPs by
locally isolated Nitzschia diatoms was reported by Borase et al. (2017). The particles
displayed characteristic ruby red color with sharp absorbance peak at 529 nm. The
biosynthesized AuNPs have irregular shape, average size of 43 nm with zeta potential of −16.8 mV. FTIR analysis revealed that fungal proteins and polysaccharides
were actively involved in the gold ions reduction to AuNPs. The particles produced
synergistic antibacterial effect when combined with conventional antibiotics against
some clinical bacterial isolates.
The biosynthesis of AuNPs was also established by Spirulina platensis under
ambient conditions (Kalabegishvili et al. 2012). Characterization of the AuNPs was
done by UV–vis, TEM, SEM, EDAX, and XRD. Results of the complex analytical
studies of the particles revealed that they were synthesized extracellularly through
bioreduction of gold ions by proteins and enzymes produced by Spirulina platensis
with UV maximum absorbance at 530 nm. The particles had crystalline property,
spherical shape, and 30 nm average size. A large quantity of gold materials was
synthesized through a simple, one-pot method (Xie et al. 2007). The synthesis was
carried out by reacting chloroauric acid solution with the aqueous extract of Chlorella
vulgaris at room temperature. It was observed that the protein molecules in the algal
extract was predominantly involved in the reduction of gold ion to nanogold crystals.
Precisely, a protein (gold shape-directing protein, GSP) with a molecular weight of
approximately 28 kDa was identified to possess both reduction and shape-directing
functionalities. The biosynthesized nanogold crystals were triangular and hexagonal
in shape. The kinetics of the reduction reaction was manipulated by changing the