244
I. A. Adelere and A. Lateef
and incubated at room temperature. Optimization of the synthesis was held at pH
values of 5, 6, 7, and 8 and various times of 0, 3, 6, 9, and 12 h. The UV–vis spectroscopy showed that the AgNPs synthesized have SPR around 450 nm. Particles were
very dispersed with size range of 5–50 nm. They have face-centered cubic structure
according to XRD result. The biosynthesized AgNPs have potential biomedical application as they demonstrated potent antibacterial activity against bacterial pathogens.
The intracellular and extracellular biosynthesis of AgNPs by Euglena intermedia
(EI) and Euglena gracilis (EG) strains were established by Li et al. (2014). The
AgNPs produced have characteristic absorption peak of 420 nm. The TEM analyses
of the in vitro and in vivo synthesized AgNPs indicated the sizes ranging from 15 to
60 nm and 6 to 24 nm in diameter, respectively. The AgNPs generally were polydispersed with spherical shape. The FTIR analysis identified amine as the predominant
functional group responsible for the capping and stabilization of the particles.
Khalid et al. (2017) carried out a comparative study on three novel freshwater microalgae strains for AgNPs synthesis. In the study, ethanolic extract
of Dictyosphaerium sp. strain HM1 (DHM1), Dictyosphaerium sp. strain HM2
(DHM2), and Pectinodesmus sp. strain HM3 (PHM3) was used to synthesize AgNPs
using 5 mM solution of AgNO 3 with ethanolic extracts of microalgae in a ratio of 5:1
and incubated at 37 °C. SEM and TEM analyses showed homogeneous and uniformly
distributed AgNPs with narrow size range for each species, but of different sizes and
shapes. XRD results confirmed the crystalline structure, as well as formation of
mono-centered and face-centered cubic structure of these particles. The biosynthesized AgNPs displayed significant activities against 14 pathogenic bacterial strains,
Candida albicans, hepatocellular carcinoma (HepG2), breast cancer (MCF7) cell
lines, and Newcastle disease virus (NDV). Mahdieh et al. (2012) treated AgNO 3
solution with Spirulina platensis for the synthesis of AgNPs. The synthesis was
carried out by dispersing 5 g of a thoroughly washed Spirulina platensis biomass
from an exponential growth phase in 100 ml of 1 m Maqueous AgNO 3 solution (pH
7) for 24 h. The entire process of metal ion reduction to nanoparticles was held at
25 °C. They particles were crystalline with an average size of 11.6 nm.
Biosynthesis of AgNPs was investigated using water soluble fraction of the extracellular polysaccharides (EPS) matrix of Nostoc commune (Morsy et al. 2014). In
the synthesis, 50 ml of water containing EPS (10 mg/ml) of cyanobacterium Nostoc
commune and 30 mM of AgNO 3 which was autoclaved at 15 psi and 121 °C for
5 min. Centrifugation was conducted at 15,000 × g for 30 min at 20 °C to precipitate the synthesized AgNPs. The particles displayed characteristic absorption peak
of 415 nm, and the size was 15–54 nm. The AgNPs possessed strong antibacterial
and surface sterilizing effect on seed crops against phytopathogenic fungi. Chokshi
et al. (2016) reported the synthesis of AgNPs using de-oiled biomass of Acutodesmus
dimorphus. In the synthesis, 10 ml aqueous extract of the de-oiled biomass was mixed
with 90 ml of 1 mM AgNO 3 and stirred at room temperature for 24 h. The AgNPs
were polydispersed, spherical, and 2–15 nm in size. The particles demonstrated
remarkable free radicals scavenging activity. The green synthesis of AgNPs using
the aqueous extract of microalgae, Chlorella vulgaris and the diatom, Chaetoceros
calcitrans was investigated by Karthikeyan et al. (2015). The absorbance spectra of
I. A. Adelere and A. Lateef
and incubated at room temperature. Optimization of the synthesis was held at pH
values of 5, 6, 7, and 8 and various times of 0, 3, 6, 9, and 12 h. The UV–vis spectroscopy showed that the AgNPs synthesized have SPR around 450 nm. Particles were
very dispersed with size range of 5–50 nm. They have face-centered cubic structure
according to XRD result. The biosynthesized AgNPs have potential biomedical application as they demonstrated potent antibacterial activity against bacterial pathogens.
The intracellular and extracellular biosynthesis of AgNPs by Euglena intermedia
(EI) and Euglena gracilis (EG) strains were established by Li et al. (2014). The
AgNPs produced have characteristic absorption peak of 420 nm. The TEM analyses
of the in vitro and in vivo synthesized AgNPs indicated the sizes ranging from 15 to
60 nm and 6 to 24 nm in diameter, respectively. The AgNPs generally were polydispersed with spherical shape. The FTIR analysis identified amine as the predominant
functional group responsible for the capping and stabilization of the particles.
Khalid et al. (2017) carried out a comparative study on three novel freshwater microalgae strains for AgNPs synthesis. In the study, ethanolic extract
of Dictyosphaerium sp. strain HM1 (DHM1), Dictyosphaerium sp. strain HM2
(DHM2), and Pectinodesmus sp. strain HM3 (PHM3) was used to synthesize AgNPs
using 5 mM solution of AgNO 3 with ethanolic extracts of microalgae in a ratio of 5:1
and incubated at 37 °C. SEM and TEM analyses showed homogeneous and uniformly
distributed AgNPs with narrow size range for each species, but of different sizes and
shapes. XRD results confirmed the crystalline structure, as well as formation of
mono-centered and face-centered cubic structure of these particles. The biosynthesized AgNPs displayed significant activities against 14 pathogenic bacterial strains,
Candida albicans, hepatocellular carcinoma (HepG2), breast cancer (MCF7) cell
lines, and Newcastle disease virus (NDV). Mahdieh et al. (2012) treated AgNO 3
solution with Spirulina platensis for the synthesis of AgNPs. The synthesis was
carried out by dispersing 5 g of a thoroughly washed Spirulina platensis biomass
from an exponential growth phase in 100 ml of 1 m Maqueous AgNO 3 solution (pH
7) for 24 h. The entire process of metal ion reduction to nanoparticles was held at
25 °C. They particles were crystalline with an average size of 11.6 nm.
Biosynthesis of AgNPs was investigated using water soluble fraction of the extracellular polysaccharides (EPS) matrix of Nostoc commune (Morsy et al. 2014). In
the synthesis, 50 ml of water containing EPS (10 mg/ml) of cyanobacterium Nostoc
commune and 30 mM of AgNO 3 which was autoclaved at 15 psi and 121 °C for
5 min. Centrifugation was conducted at 15,000 × g for 30 min at 20 °C to precipitate the synthesized AgNPs. The particles displayed characteristic absorption peak
of 415 nm, and the size was 15–54 nm. The AgNPs possessed strong antibacterial
and surface sterilizing effect on seed crops against phytopathogenic fungi. Chokshi
et al. (2016) reported the synthesis of AgNPs using de-oiled biomass of Acutodesmus
dimorphus. In the synthesis, 10 ml aqueous extract of the de-oiled biomass was mixed
with 90 ml of 1 mM AgNO 3 and stirred at room temperature for 24 h. The AgNPs
were polydispersed, spherical, and 2–15 nm in size. The particles demonstrated
remarkable free radicals scavenging activity. The green synthesis of AgNPs using
the aqueous extract of microalgae, Chlorella vulgaris and the diatom, Chaetoceros
calcitrans was investigated by Karthikeyan et al. (2015). The absorbance spectra of