Microalgal Nanobiotechnology and Its Applications—A …
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the biosynthesized AgNPs showed peaks at 436 and 420 nm by C. vulgaris and C.
calcitrans, respectively. They are mainly spherical in shape with size ranging from 30
to 70 nm. FTIR analysis revealed that the biomolecules responsible for the reduction
of Ag
+ to AgNPs are functional groups like amines, phenols and alcohols ethers, and
aromatic rings.
Sudha et al. (2013) synthesized AgNPs by reacting the cellular metabolites of
Microcoleus sp with AgNO 3 at room temperature for 24 h. The AgNPs are spherical in shape, well distributed with an average size of 40–80 nm. They showed
remarkable antibacterial activity against some antibiotic resistance human bacterial pathogens. Most recently Adenigba et al. (2020) reported rapid biosynthesis of
AgNPs through the mixture of 1 mM AgNO 3 with each of the cell-free aqueous
extracts of Nannochloropsis sp and Chlorella vulgaris. The biosynthesized AgNPs
displayed SPR at a wavelength of 426 nm for C. vulgaris (CV–AgNPs) and 430 nm
for Nannochloropsis sp (NN–AgNPs). The particles were polydispersed and spherical in shape with size ranging from 27 to 90 nm and 41 to 88 nm for CV–AgNPs
and NN–AgNPs, respectively. They demonstrated strong affinity for zinc and lead
bioremediation from pharmaceutical effluent. The particles exhibited very potent
antimicrobial activity against gram positive and gram negative bacteria. Similarly,
Omomowo et al. (2020) synthesized AgNPs upon reacting the 10 ml aqueous extract
of Neodesmus pupukensis (MG257914) with 90 ml of 1 mM AgNO 3 under ambient
conditions. The biosynthesized AgNPs were spherical in shape and particle size
ranged 52–179 nm. They exhibited strong antimicrobial and antioxidant activities
which indicate their potential biotechnological application.
4.2 Phycosynthesis of Gold Nanoparticles (AuNPs)
Feurtet-Mazel et al. (2016) reported a successful intracellular biosynthesis of AuNPs
by freshwater diatom Eolimna minima under a light intensity of 40 µmol photon m
−2
s
−1 , temperature of 20 °C, and a photoperiod of 12L/12D. The absorption spectrum of
the biosynthesized AuNPs showed peak between 520 and 585 nm, while the particle
sizes ranged from 5 to 100 nm. Dahoumane et al. (2014) gave an overview of biological pathways for the biosynthesis of gold colloids. The authors elucidated that when
the living microalgal cultures were suspended in Au (III) solutions, the gold cations
were taken up by the cells, migrated to the photosynthetic organelle, i.e., thylakoid,
where they were reduced to AuNPs. They became stable gold colloids after being
been released into the culture medium due to their interaction with the exopolysaccharides produced by the organisms. In a related study, Brayner et al. (2007) reported the
intracellular synthesis of AuNPs by cyanobacterial strains of Anabaena, Calothrix,
and Leptolyngbya. The intracellular nitrogenase enzyme produced by the strains
played a very active role in the bioreduction of gold ion to AuNPs. The biosynthesized particles when released to the culture medium became stabilized by the algal
polysaccharides. Furthermore, Dahoumane et al. (2012) investigated the cell-based
bioreaction for the production of colloidal gold using microalgae, Klebsormidium
245
the biosynthesized AgNPs showed peaks at 436 and 420 nm by C. vulgaris and C.
calcitrans, respectively. They are mainly spherical in shape with size ranging from 30
to 70 nm. FTIR analysis revealed that the biomolecules responsible for the reduction
of Ag
+ to AgNPs are functional groups like amines, phenols and alcohols ethers, and
aromatic rings.
Sudha et al. (2013) synthesized AgNPs by reacting the cellular metabolites of
Microcoleus sp with AgNO 3 at room temperature for 24 h. The AgNPs are spherical in shape, well distributed with an average size of 40–80 nm. They showed
remarkable antibacterial activity against some antibiotic resistance human bacterial pathogens. Most recently Adenigba et al. (2020) reported rapid biosynthesis of
AgNPs through the mixture of 1 mM AgNO 3 with each of the cell-free aqueous
extracts of Nannochloropsis sp and Chlorella vulgaris. The biosynthesized AgNPs
displayed SPR at a wavelength of 426 nm for C. vulgaris (CV–AgNPs) and 430 nm
for Nannochloropsis sp (NN–AgNPs). The particles were polydispersed and spherical in shape with size ranging from 27 to 90 nm and 41 to 88 nm for CV–AgNPs
and NN–AgNPs, respectively. They demonstrated strong affinity for zinc and lead
bioremediation from pharmaceutical effluent. The particles exhibited very potent
antimicrobial activity against gram positive and gram negative bacteria. Similarly,
Omomowo et al. (2020) synthesized AgNPs upon reacting the 10 ml aqueous extract
of Neodesmus pupukensis (MG257914) with 90 ml of 1 mM AgNO 3 under ambient
conditions. The biosynthesized AgNPs were spherical in shape and particle size
ranged 52–179 nm. They exhibited strong antimicrobial and antioxidant activities
which indicate their potential biotechnological application.
4.2 Phycosynthesis of Gold Nanoparticles (AuNPs)
Feurtet-Mazel et al. (2016) reported a successful intracellular biosynthesis of AuNPs
by freshwater diatom Eolimna minima under a light intensity of 40 µmol photon m
−2
s
−1 , temperature of 20 °C, and a photoperiod of 12L/12D. The absorption spectrum of
the biosynthesized AuNPs showed peak between 520 and 585 nm, while the particle
sizes ranged from 5 to 100 nm. Dahoumane et al. (2014) gave an overview of biological pathways for the biosynthesis of gold colloids. The authors elucidated that when
the living microalgal cultures were suspended in Au (III) solutions, the gold cations
were taken up by the cells, migrated to the photosynthetic organelle, i.e., thylakoid,
where they were reduced to AuNPs. They became stable gold colloids after being
been released into the culture medium due to their interaction with the exopolysaccharides produced by the organisms. In a related study, Brayner et al. (2007) reported the
intracellular synthesis of AuNPs by cyanobacterial strains of Anabaena, Calothrix,
and Leptolyngbya. The intracellular nitrogenase enzyme produced by the strains
played a very active role in the bioreduction of gold ion to AuNPs. The biosynthesized particles when released to the culture medium became stabilized by the algal
polysaccharides. Furthermore, Dahoumane et al. (2012) investigated the cell-based
bioreaction for the production of colloidal gold using microalgae, Klebsormidium