Characterization of Silver Nanoparticle Systems from Microalgae Acclimated to Different CO₂ Atmospheres

Area of Science:

• Biotechnology
• Nanotechnology
• Environmental Science

Background:

• Microalgae are increasingly utilized in biological carbon dioxide (CO2) mitigation systems, producing significant biomass.
• The green synthesis of metallic nanoparticles (NPs) using microalgae, particularly those exposed to elevated CO2, remains underexplored.
• This study investigates the potential of microalgae acclimated to different CO2 atmospheres for silver nanoparticle (AgNP) synthesis.

Purpose of the Study:

• To characterize the efficacy of Desmodesmus abundans strains acclimated to low (LCA) and high (HCA) CO2 atmospheres for AgNP synthesis.
• To compare the AgNP synthesis performance of HCA and LCA strains with Spirulina platensis.
• To analyze the physicochemical properties and antimicrobial activity of the synthesized AgNPs.

Main Methods:

• Utilized cell pellets and supernatants from microalgae strains (D. abundans LCA/HCA, S. platensis) for AgNP synthesis at pH 11.
• Characterized AgNPs using size distribution analysis (dynamic light scattering).
• Employed Fourier-transform infrared and Raman spectroscopies to identify functional groups involved in reduction.
• Assessed antimicrobial properties via agar diffusion tests against Escherichia coli and Lactobacillus plantarum.

Main Results:

• The D. abundans HCA strain demonstrated superior performance, yielding homogeneous AgNPs (14.9 ± 6.4 nm) from cell pellets at pH 11 across various conditions.
• S. platensis produced AgNPs of 18.3 ± 7.5 nm, while the LCA strain resulted in a broader size distribution (>100 nm).
• Spectroscopic analysis indicated proteins, carbohydrates, and fatty acids in cell pellets, and amino acids/sugars in supernatants, contribute to the reducing power.
• Synthesized AgNPs showed antimicrobial activity against E. coli but not L. plantarum.

Conclusions:

• High CO2 acclimation potentiates components within the D. abundans HCA strain for efficient green synthesis of silver nanoparticles.
• Microalgal biomass from CO2 mitigation systems can serve as a sustainable platform for nanotechnology applications.
• The study highlights the potential of specific microalgal strains and their components for producing nanoparticles with tailored properties.