Lipopolysaccharide-stabilized ionic colloids induce biomineralization

Biomineralization inducing by bacteria is common in nature. It involves interactions between bacterial surface and metal ions that are usually present in the form of ionic colloids. Lipopolysaccharide (LPS) is the major component of Gram-negative bacterial surfaces. In the present study, interactions between LPS and metal ions (Ag⁺, Fe³⁺, Cd²⁺, Co²⁺, Cu²⁺, Mn²⁺, Ni²⁺), as well as ionic colloids (Ag⁺/Cl^-, Fe³⁺/OH^-) were evaluated by means of isothermal titration calorimetry and Zeta potential measurement. It was found that LPS increases the energy barrier for the collapse of ionic colloids and prevents ionic colloids from aggregation. The roles of LPS-stabilized ionic colloids in inducing biomineralization on the bacterial surface were explored by means of scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray Diffraction. It showed that reducing colloidal stability by increasing the ionic strength significantly inhibited biomineralization of ionic colloids on bacterial surfaces. While the formation of ionic colloids promoted biomineralization on bacterial surfaces. This study provides a novel insight into biomineralization as well as biomineralization-based techniques with biological stabilizers for producing biominerals.