Detection of algae and bacterial biofilms formed on titanium surfaces using micro-Raman analysis

Biofouling is one of the major impediments in the use of titanium in sea-water cooled condensers of power plants, which is otherwise an excellent material with respect to corrosion resistance. Raman microscopic experiments were carried out on biofilms grown on titanium surfaces to find out the chemical composition of complex extracellular polymeric substances (EPS) in the biofilm. Though the spectral resolution of normal Raman experiments on these systems was very poor, it was improved when micro-SERS experiments were carried out using mono and bimetallic Ag and Cu colloids. It was observed that spatial distribution of polysaccharides was higher than that of proteins in algae biofilms formed on titanium matrix. Similar experiments were performed on laboratory cultured bacterial films of Pseudomonas aeruginosa. It was evidenced that algal and bacterial biofilms on titanium can be clearly distinguished with the help of Raman mapping coupled with SERS technique using bimetallic Ag/Cu colloids.