Combined Gold Recovery and Nanoparticle Synthesis in Microbial Systems Using Fractional Factorial Design

Abstract

Green synthesis of gold nanoparticles (AuNPs) using microorganisms has been generally studied aiming for high-yield production and morphologies appropriated for various applications, such as bioremediation, (bio)sensors, and (bio)catalysis. Numerous approaches showed the individual effect of factors influencing the synthesis of AuNPs with limited analysis of the governing factors enhancing the production and desired quality of the precipitates. This study proposes a fractional-factorial design to investigate the simultaneous influence of seven environmental factors (cell concentration, temperature, anoxic/oxic conditions, pH, gold concentration, electron donor type, and bacterial species) on the recovery yield and synthesis of targeted AuNPs. Various sizes and morphologies of the AuNPs were obtained by varying the environmental factors studied. The factors with significant effects (i.e., 0.2 mM Au and pH 5) were selected according to statistical analysis for optimal removal of 88.2 ± 3.5% of gold and with the production of valuable 50 nm AuNPs, which are known for their enhanced sensitivity. Implications of the cytochrome-C on the bacterial mechanisms and the provision of electron donors via an electrochemical system are further discussed. This study helps develop gold recovery and nanoparticle synthesis methods, focusing on the determining factor(s) for efficient, low-cost, green synthesis of valuable materials.

Green Synthesis of Silver Nanoparticles Loaded Hydrogel for Wound Healing; Systematic Review

“…Different pH conditions lead to variations in the arrangement and morphology of the nanoparticles. The pH affects reaction rates and intermediate stability during the formation process [38,61].…”

A Uni-Micelle Approach for the Controlled Synthesis of Monodisperse Gold Nanocrystals

“…The gold nanoparticles (AuNPs) have received widespread attention in various fields, including photothermal conversion [ 1 ], medical detection [ 2 , 3 , 4 ], catalysis [ 5 , 6 , 7 , 8 , 9 ], and sensing [ 10 , 11 ], which are attributed to the small-size effect and localized surface plasmon resonance (LSPR) effect [ 12 , 13 ]. There are several methods for synthesizing AuNPs [ 14 , 15 ], including a phase transfer [ 14 ], microemulsion [ 16 ], biosynthesis [ 17 , 18 ], etc.…”

Fractional Factorial Design to Evaluate the Synthesis and Electrochemical Transfer Parameters of h-BN Coatings

“…Factorial design has often been used for the control of the synthesis process of nanomaterials such as nanoparticles [60][61][62], nanocomposites [62], and nanofibers [63], but has not been used before for CVD growth of h-BN. This approach not only allows us to determine which factors are relevant (or not) when synthesizing this material, but these experiments also give us a clearer idea of the degree to which each variable interacts with each other.…”