Interaction force measurement between E. coli cells and nanoparticles immobilized surfaces by using AFM.

Area of Science:

• Environmental Science
• Nanotechnology
• Microbiology

Background:

• Understanding nanoparticle (NP) environmental behavior is crucial.
• Interactions between NPs and microorganisms like E. coli influence environmental fate and biological effects.
• Limited data exists on the forces governing these interactions.

Purpose of the Study:

• To quantify interaction forces between E. coli and NPs.
• To investigate the influence of NP size on these forces.
• To develop a model explaining size-dependent adhesion.

Main Methods:

• Atomic force microscopy (AFM) was used to measure forces.
• Hematite (α-Fe(2)O(3)) and corundum (α-Al(2)O(3)) NPs of varying sizes were studied.
• The Johnson-Kendall-Roberts (JKR) model was adapted to analyze contact areas.

Main Results:

• Adhesion force decreased significantly with increasing NP size for both hematite and corundum NPs.
• For hematite NPs, adhesion force dropped from 6.3±0.7nN (26nm) to 0.8±0.4nN (98nm).
• A new model incorporating local effective contact area accurately predicted the experimental size-dependence of adhesion.

Conclusions:

• Nanoparticle size is a critical factor determining adhesion forces with E. coli cells.
• Size effects on adhesion are likely due to variations in local effective contact areas.
• Findings offer fundamental insights into NP environmental and biological interactions.