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I. A. Adelere and A. Lateef
metals and further convert them to non-toxic forms. They are effective in nanoparticles synthesis, as they grow rapidly in eco-friendly atmosphere producing large
amount of biomass in a very short time and can accumulate high quantity of metals
followed by subsequent reduction. Their production costs are also negligible. Quite
a number of microalgal live cells and microalgal extracts has been utilized for the
biosynthesis of nanomaterials as presented in Table 1.
The biosynthesis of nanoparticles using microalgae can be divided into four
methods: the first method involves the exploitation of the biomolecules extracted
from the disrupted cells of microalgae; the second method resides in the use of
supernatants devoid of cells; this is obtained after the centrifugation or filtration of
the culture media; the third method depends on harvested whole cells of microalgae,
removed from their culture media and re-suspended in the corresponding salt solution
to promote the biosynthesis of NPs; the last method relies on the use of living cells
of microalgae maintained under their normal culturing conditions (Dahoumane et al.
2016). The design of photobioreactors for nanoparticles production is allowed by
microalgae because the process often requires photosynthetic enzymatic machinery.
Several microalgal species have been investigated for their potential to produce
metallic nanoparticles. For instance, strains of Leptolyngbya foveolarum, Anabaena
flos-aquae, and Calothrix pulvinata were successfully used for the biosynthesis of
nanoparticles of Au, Ag, Pt, and Pd. After the synthesis within the cells, the NPs
were released into the culture media, where they form stable colloids which ease
their recovery (Brayner et al. 2007). Authors have reported the biogenic production
of metallic nanoparticles using microalgal species belonging to Haptophyta, Ochrophyta, Chlorophyta, Bacillariophyta, Cyanobacteria, Euglenozoa, and Chlorophyta
(Merin et al. 2010; Luangpipat et al. 2011; Mohseniazar et al. 2011; Dahoumane
et al. 2012, 2014, 2016).
4.1 Phycosynthesis of Silver Nanoparticles (AgNPs)
The aqueous extract of Chlorella pyrenoidosa was used to synthesize AgNPs by
Aziz et al. (2015). The synthesis was carried out by adding 10 ml of cell extract of
C. pyrenoidosa to 90 ml of 1 mM AgNO 3 solution, followed by incubation at 28 ±
2 °C for 24 h. The biosynthesis was also performed under different pH to comprehensively study its effect on the process of synthesis. The biosynthesized AgNPs
showed impressive antibacterial activities against some pathogens, possibly due to
the intrinsic protein cap leading to an easier mode of entry into the bacterial cell. They
had remarkable photocatalytic properties in comparison to chemically synthesized
nanoparticles, due to their inherent porosity and therefore larger surface area. Khalifa
et al. (2016) synthesized AgNPs through the aqueous extract of Calothrix marchica,
Anabaena oryzae, and Nostoc muscorum. The biosynthesized AgNPs showed UV
absorption peaks at wavelength varying from 400 to 450 nm. The cytotoxic activity
of biosynthesized AgNPs was evaluated in vitro against EAC cell line. Results of
I. A. Adelere and A. Lateef
metals and further convert them to non-toxic forms. They are effective in nanoparticles synthesis, as they grow rapidly in eco-friendly atmosphere producing large
amount of biomass in a very short time and can accumulate high quantity of metals
followed by subsequent reduction. Their production costs are also negligible. Quite
a number of microalgal live cells and microalgal extracts has been utilized for the
biosynthesis of nanomaterials as presented in Table 1.
The biosynthesis of nanoparticles using microalgae can be divided into four
methods: the first method involves the exploitation of the biomolecules extracted
from the disrupted cells of microalgae; the second method resides in the use of
supernatants devoid of cells; this is obtained after the centrifugation or filtration of
the culture media; the third method depends on harvested whole cells of microalgae,
removed from their culture media and re-suspended in the corresponding salt solution
to promote the biosynthesis of NPs; the last method relies on the use of living cells
of microalgae maintained under their normal culturing conditions (Dahoumane et al.
2016). The design of photobioreactors for nanoparticles production is allowed by
microalgae because the process often requires photosynthetic enzymatic machinery.
Several microalgal species have been investigated for their potential to produce
metallic nanoparticles. For instance, strains of Leptolyngbya foveolarum, Anabaena
flos-aquae, and Calothrix pulvinata were successfully used for the biosynthesis of
nanoparticles of Au, Ag, Pt, and Pd. After the synthesis within the cells, the NPs
were released into the culture media, where they form stable colloids which ease
their recovery (Brayner et al. 2007). Authors have reported the biogenic production
of metallic nanoparticles using microalgal species belonging to Haptophyta, Ochrophyta, Chlorophyta, Bacillariophyta, Cyanobacteria, Euglenozoa, and Chlorophyta
(Merin et al. 2010; Luangpipat et al. 2011; Mohseniazar et al. 2011; Dahoumane
et al. 2012, 2014, 2016).
4.1 Phycosynthesis of Silver Nanoparticles (AgNPs)
The aqueous extract of Chlorella pyrenoidosa was used to synthesize AgNPs by
Aziz et al. (2015). The synthesis was carried out by adding 10 ml of cell extract of
C. pyrenoidosa to 90 ml of 1 mM AgNO 3 solution, followed by incubation at 28 ±
2 °C for 24 h. The biosynthesis was also performed under different pH to comprehensively study its effect on the process of synthesis. The biosynthesized AgNPs
showed impressive antibacterial activities against some pathogens, possibly due to
the intrinsic protein cap leading to an easier mode of entry into the bacterial cell. They
had remarkable photocatalytic properties in comparison to chemically synthesized
nanoparticles, due to their inherent porosity and therefore larger surface area. Khalifa
et al. (2016) synthesized AgNPs through the aqueous extract of Calothrix marchica,
Anabaena oryzae, and Nostoc muscorum. The biosynthesized AgNPs showed UV
absorption peaks at wavelength varying from 400 to 450 nm. The cytotoxic activity
of biosynthesized AgNPs was evaluated in vitro against EAC cell line. Results of