Synthesis of silver nanoparticles using marine macroalgae Padina sp. and its antibacterial activity towards pathogenic bacteria

Abstract

Background: Marine algae used as a food source for ocean life and range in color from red to green to brown grow along rocky shorelines around the world. The synthesis of silver nanoparticles by marine alga Padina sp. and its characterization were fulfilled by using UV-visible spectrophotometer, Fourier transform infrared spectroscopy, scanning electron microscopy and field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Results: UV-visible absorption spectrum revealed that the formation of Ag nanoparticles was increased by the addition of marine algae and the spectral peak observed between a wavelength of~420 nm and 445 nm. In addition, SEM and FESEM images examined the surface morphology and the size of the synthesized NPs was relatively uniform in size~25-60 nm. Energy-dispersive X-ray spectroscopy analysis confirmed the purity of Ag NPs with atomic percentage of 48.34% Ag. The synthesized Ag NPs showed highly potent antibacterial activity. The Staphylococcus aureus and Pseudomonas aeruginosa were found to be more susceptible to silver nanoparticles by forming 15.17 ± 0.58 mm and 13.33 ± 0.76 mm of diameter of the inhibition zone, respectively. Conclusions: The study suggested that marine alga Padina sp. could be an alternative source for the production of Ag nanoparticles and are efficient antimicrobial compounds against both gram-negative and gram-positive bacteria which can be a promising material against infectious bacteria.

A hybrid lipid membrane coating “shape-locks” silver nanoparticles to prevent surface oxidation and silver ion dissolution

“…is indicative of Cl À ion oxidation of Ag 0 to Ag + ions. 55,59 Citrate capping agents offer no protection to Cl À oxidation of the AgNPs. The triangular and spherical Ag-Cit-SOA-PC without thiols underwent slower surface oxidation and Ag + ion dissolution.…”

“…47,48 Although these synthetic methods have produced AgNPs shaped as spheres, 49 cubes, 50 bipyramids, 51 stars, 52 nanoprisms, 53 triangular plates 53 these methods are energy-intensive, the size and shape distributions are not always homogenous, and chemicals used can be toxic. Consequently, this has given rise to alternative green synthetic approaches employing biological entities such as microorganisms 10,12,54,55 and plant extracts 4, [56][57][58][59][60][61][62][63] to replace more complex syntheses of AgNPs free from toxic capping agents and hazardous byproducts.…”

Exploration of bioactive compounds and antibacterial activity of marine blue-green microalgae (Oscillatoria sp.) isolated from coastal region of west Malaysia

“…Most of all indicated that the methanol extraction yielded more compared to hexane and ethyl acetate. [7,25,26]. Ethyl acetate and methanol were determined as the most effective organic solvent for the isolation of antibacterial compounds [27,28].…”

“…Cyanobacteria is an incredible old group of prokaryotic organisms that produces a variety of secondary metabolites such as antibiotic, cytotoxic, immunosuppressive and enzyme inhibiting agents [4][5][6]. Bioactive compounds are defined as the secondary metabolites that can be isolated and purified from the microalgae, plant, microbes and other organisms that has ability in biological activities [7]. The production of bioactive compounds from microalgae can be beneficial in pharmaceutical industry [8,9].…”

Screening of effective solvents for obtaining antioxidant‐rich seaweed extracts using principal component analysis

“…Marine bioactives can be obtained from various sources such as marine plants/seaweeds, microorganisms, sponges, etc. Among the various sources, seaweeds are reported to possess bioactive compounds having high antioxidant, antimicrobial, antiviral, antidiabetic, anti‐inflammatory, antiviral, antitumor properties, etc., which is why they have gained the status of “superfood” recently (Bhuyar, Rahim, Sundararaju, Maniam, & Govindan, 2020; Bhuyar, Rahim, Sundararaju, Ramaraj, et al, 2020; Gormley & Holm, 2010; Gupta & Abu‐Ghannam, 2011). Among all (green, red, and brown), brown seaweeds, which is the second most abundant group, is reported to possess comparatively high structural diversity with polyphenols, polysaccharides, bioactive peptides, polyunsaturated fatty acids, etc.…”