Novel biosynthesis, characterization and bio-catalytic potential of green algae (Spirogyra hyalina) mediated silver nanomaterials

Abstract

In recent years green nanotechnology gained significant importance to synthesize nanoparticles due to their cost effectiveness and biosafety. In the current study, silver nanoparticles were synthesized by using extract of Spirogyra hyalina as a capping and reducing agent. The synthesized nanoparticles were characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy, Scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractive analysis. Silver nanoparticles give a characteristic Surface Plasmon Resonance peak of 451 nm at 2.21 a.u (arbitrary unit). SEM micrograph revealed the spherical morphology and average grain size of 52.7 nm. Furthermore, antibacterial, antifungal, insecticidal, antioxidant and membrane damage activities were determined. The maximum antibacterial and antifungal activity was observed for Pseudomonas aeruginosa (18 ± 1.2 mm) and Fusarium solani (14.3 ± 0.6 mm), respectively. In membrane damage assay, Pseudomonas aeruginosa absorbed A₂₆₀ wavelength and gave maximum peak values of 0.286, 0.434 and 0.629 at 25, 35 and 45 µg/mL of silver nanoparticles. The membrane damage assay confirmed that nanoparticles are involved in bacterial cell membrane damage. At 500 ppm silver nanoparticles showed 30% mortality against Tribolium castaneum (a common grain pest). The silver nanoparticles also showed potent antioxidant activity and successfully scavenged the DPPH free radicals upto 53.43 ± 0.17, 43.26 ± 0.97, 31.39 ± 0.33, 24.62 ± 0.85, and 14.13 ± 0.12% at a concentration of 400, 200, 100, 50, and 25 µg/mL of nanoparticles, respectively. It is concluded that silver nanoparticles can easily be synthesized by using green algae Spirogyra hyalina as a capping and reducing agent. Silver nanoparticles showed potent biomedical activities and thus can be used for therapeutic applications invitro and invivo.

Keywords: Bio catalytic efficacy; Biosynthesis; Nanoparticles; Silver; Spirogyra.

Fig. 1

This schematic diagram describes the whole process of silver nanoparticles synthesis. A) Collection of Spirogyra hyalina from a local pond. B) Shade Dried Spirogyra hyalina. C) Powder form of Spirogyra hyalina. D) Extract of Spirogyra hyalina. E) Silver nitrate. F) 1 mM solution of Silver nitrate. G) Mixing of Silver nitrate and Spirogyra hyalina extract. H) Reaction of Algae extract and Silver nitrate, kept on magnetic stirrer. H) Centrifugation after reaction. J) Pure Silver nanoparticles. K) Reaction mechanism of silver nitrate and algae extract for silver nanoparticles synthesis.

Fig. 2

UV–visible spectra of silver nanoparticles.

Fig. 3

Energy dispersive X-ray analysis of silver nanoparticles.

Fig. 4

X-ray diffractive peaks of silver nanoparticles.

Fig. 5

Fourier transform infrared spectroscopy of silver nanoparticles.

Fig. 6

Scanning electron micrograph of silver nanoparticles. A) SEM micrograph at 10,000x. B) SEM micrograph at 30,000x. C) Nano measurer analysis. D) ImageJ analysis of Ag-NPs.

Fig. 7

A & B) Antibacterial assay of silver nanoparticles.

Fig. 8

Membrane damage assay of silver nanoparticles.

Fig. 9

Antifungal activity of silver nanoparticles.

Fig. 10

Insecticidal activity of silver nanoparticles.