Adsorption of Microorganisms to Minerals

Understanding Nanoscale Interactions between Minerals and Microbes: Opportunities for Green Remediation of Contaminated Sites

“…93,94 The attachment of nanoparticles to microbes can be facilitated by increasing surface area of the mineral nanoparticles, and by surface modulation (e.g., crystalline phases and exposed facets) and functionalization of the nanoparticles to promote polar interactions and complexation. 95,96 The accumulation of macromolecules at the microbe−mineral interface, which is critical for indirect charge transfer, 97 is another important design consideration. Interestingly, adsorption of macromolecules to crystalline minerals also depends on the surface topography and atomic arrangements of the nanocrystals.…”

“…120,122 The passivated layer can be removed through dissolution facilitated by organic acids or ligands excreted by microorganisms. 96,123 Alternatively, certain microbes (e.g., dissimilatory iron-reducing bacteria 124 and sulfate-reducing bacteria 125 ) may be used to reductively transform the passivated nanoparticles by providing electrons, thereby reinvigorating the nanoparticles. Ideally, these electrons may be obtained from the microbial degradation of pollutants.…”

“…All the above-mentioned strategies involve the fabrication of microbe–mineral composites. In situ formation of mineral nanoparticles on microbial cell surfaces can be realized through the precipitation of reactants or biomineralization. − An alternative approach is binding mineral nanoparticles to microbes via electrostatic interactions, hydrophobic interactions, or covalent binding. , The attachment of nanoparticles to microbes can be facilitated by increasing surface area of the mineral nanoparticles, and by surface modulation (e.g., crystalline phases and exposed facets) and functionalization of the nanoparticles to promote polar interactions and complexation. , The accumulation of macromolecules at the microbe–mineral interface, which is critical for indirect charge transfer, is another important design consideration. Interestingly, adsorption of macromolecules to crystalline minerals also depends on the surface topography and atomic arrangements of the nanocrystals .…”

“…Surface passivation of nanomaterials undermines the longevity of nanoreagents for site remediation. , One solution to this problem is using microbes to reactivate passivated mineral nanoparticles (Figure ). For instance, mineral nanoparticles (particularly, iron-based nanoparticles such as zerovalent iron and iron oxides) acting as electron donors are oxidized during reduction of heavy metals and organic contaminants (e.g., Cr(VI) and chlorinated solvents), forming a surface with higher-valence metal species and becoming passivated. , The passivated layer can be removed through dissolution facilitated by organic acids or ligands excreted by microorganisms. , Alternatively, certain microbes (e.g., dissimilatory iron-reducing bacteria and sulfate-reducing bacteria) may be used to reductively transform the passivated nanoparticles by providing electrons, thereby reinvigorating the nanoparticles. Ideally, these electrons may be obtained from the microbial degradation of pollutants.…”