Microalgal Nanobiotechnology and Its Applications—A …
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trypan blue exclusion test revealed that EAC cells viability decreases as AgNPs
concentration increases in all tested algae.
Aziz et al. (2014) synthesized AgNPs from cell-free extract of Scenedesmus abundans. The synthesis was carried out by mixing 10 ml of cell-free extract with 90 ml
of 1 mM AgNO 3 and incubated at room temperature for 48 h. The particles exhibited
maximum absorbance of 420 nm. They are well dispersed with the size ranging from
59 to 66 nm. These nanoparticles showed a broad spectrum of antimicrobial activity
against both gram positive and gram negative bacteria. In a related study, Sharma
et al. (2015) synthesized AgNPs using extract obtained from Spirulina platensis cell
mass. The synthesis was done by adding 2 ml of pure microalgal extract dropwise into
the 100 ml of 1 mM of AgNO 3 solution in 250 ml conical flask. The reaction mixture
was held at 60 °C for 10 min under constant mechanical stirring. It was observed
that reduction of Ag ions into AgNPs completed within 10 min. The color change
was monitored visually, and the peak at 437 nm indicated the formation of AgNPs.
The particles were majorly spherical in shape, monodispersed in nature with the size
of 30–50 nm. They displayed potent antibacterial activities against some pathogenic
bacterial isolates.
According to the study of Ebrahiminezhad et al. (2016), synthesis of AgNPs was
done through the addition of 15 ml culture supernatant of Chlorella vulgaris to 30 ml
AgNO 3 solution; the final AgNO 3 concentration was adjusted to 5 mM. The reaction was allowed to take place at 50 °C in a water bath for 24 h without stirring or
shaking. UV–vis characterization of the AgNPs displayed SPR at 434 nm. Data from
the FTIR analysis indicated that carbohydrates present in the supernatant functioned
as the reducing and stabilizing agent for the produced AgNPs. The particles were
fairly uniform and spherical shape with average mean size of 7 nm. They were stable
over six months at room temperature with no observable flocculation or sedimentation traces. The biosynthesized AgNPs have promising biomedical application as
they demonstrated very desirable anticancer and antimicrobial activities. Production of AgNPs by whole cell of microalga (in vivo) and fresh extract (in vitro) of
Chlorococcum humicola was investigated by Jena et al. (2013). The in vitro phycoproduction of AgNPs was carried out by incubating 1 ml of 100 mM AgNO 3 with
19 ml of cell-free algal extract for 48 h at room temperature. The in vivo production
was done by suspending the algal biomass in 47.5 ml of distilled water. Further, 2.5 ml
of 100 mM AgNO 3 was added to get a 5 mM AgNO 3 concentration. The cultures
were incubated at 28 °C for 48 h. After completion of the reaction, biomass was
separated by centrifugation and stored at −20 °C till further characterization. The
UV–visible absorption spectrum recorded for the particles peaked at 430 nm, while
the FTIR analysis revealed the involvement of protein molecules in their formation.
TEM analysis confirms that AgNPs synthesized were 16 nm in size. Also the particles
showed a strong antibacterial effect against the pathogenic bacterial isolates.
The biosynthesis of AgNPs using Spirulina platensis aqueous extract was reported
by Muthusamy et al. (2017). In the synthesis, 5 g of dried, finely powdered Spirulina
platensis was taken in a 100-ml Erlenmeyer flask along with 50 ml of sterilized
double-distilled water and then boiling the mixture for 10–15 min at 50 °C. The
aqueous extract was treated with 1 mM AgNO 3 solution in an Erlenmeyer flask
243
trypan blue exclusion test revealed that EAC cells viability decreases as AgNPs
concentration increases in all tested algae.
Aziz et al. (2014) synthesized AgNPs from cell-free extract of Scenedesmus abundans. The synthesis was carried out by mixing 10 ml of cell-free extract with 90 ml
of 1 mM AgNO 3 and incubated at room temperature for 48 h. The particles exhibited
maximum absorbance of 420 nm. They are well dispersed with the size ranging from
59 to 66 nm. These nanoparticles showed a broad spectrum of antimicrobial activity
against both gram positive and gram negative bacteria. In a related study, Sharma
et al. (2015) synthesized AgNPs using extract obtained from Spirulina platensis cell
mass. The synthesis was done by adding 2 ml of pure microalgal extract dropwise into
the 100 ml of 1 mM of AgNO 3 solution in 250 ml conical flask. The reaction mixture
was held at 60 °C for 10 min under constant mechanical stirring. It was observed
that reduction of Ag ions into AgNPs completed within 10 min. The color change
was monitored visually, and the peak at 437 nm indicated the formation of AgNPs.
The particles were majorly spherical in shape, monodispersed in nature with the size
of 30–50 nm. They displayed potent antibacterial activities against some pathogenic
bacterial isolates.
According to the study of Ebrahiminezhad et al. (2016), synthesis of AgNPs was
done through the addition of 15 ml culture supernatant of Chlorella vulgaris to 30 ml
AgNO 3 solution; the final AgNO 3 concentration was adjusted to 5 mM. The reaction was allowed to take place at 50 °C in a water bath for 24 h without stirring or
shaking. UV–vis characterization of the AgNPs displayed SPR at 434 nm. Data from
the FTIR analysis indicated that carbohydrates present in the supernatant functioned
as the reducing and stabilizing agent for the produced AgNPs. The particles were
fairly uniform and spherical shape with average mean size of 7 nm. They were stable
over six months at room temperature with no observable flocculation or sedimentation traces. The biosynthesized AgNPs have promising biomedical application as
they demonstrated very desirable anticancer and antimicrobial activities. Production of AgNPs by whole cell of microalga (in vivo) and fresh extract (in vitro) of
Chlorococcum humicola was investigated by Jena et al. (2013). The in vitro phycoproduction of AgNPs was carried out by incubating 1 ml of 100 mM AgNO 3 with
19 ml of cell-free algal extract for 48 h at room temperature. The in vivo production
was done by suspending the algal biomass in 47.5 ml of distilled water. Further, 2.5 ml
of 100 mM AgNO 3 was added to get a 5 mM AgNO 3 concentration. The cultures
were incubated at 28 °C for 48 h. After completion of the reaction, biomass was
separated by centrifugation and stored at −20 °C till further characterization. The
UV–visible absorption spectrum recorded for the particles peaked at 430 nm, while
the FTIR analysis revealed the involvement of protein molecules in their formation.
TEM analysis confirms that AgNPs synthesized were 16 nm in size. Also the particles
showed a strong antibacterial effect against the pathogenic bacterial isolates.
The biosynthesis of AgNPs using Spirulina platensis aqueous extract was reported
by Muthusamy et al. (2017). In the synthesis, 5 g of dried, finely powdered Spirulina
platensis was taken in a 100-ml Erlenmeyer flask along with 50 ml of sterilized
double-distilled water and then boiling the mixture for 10–15 min at 50 °C. The
aqueous extract was treated with 1 mM AgNO 3 solution in an Erlenmeyer flask