Pseudomonas aeruginosa Biofilm formation mechanisms on highly ordered micro and nano-sized colloidal-based patterns

Pseudomonas aeruginosa is an opportunistic pathogen with life threatening complications for hospitalised patients needing catheters or other medical devices when it forms biofilms on the surface of that device. Each year almost 16,000 catheters related blood stream infection cases are found in USA only, with estimated mortality rates ranging from 12% to 25% even with use of uncompromising antibiotics. Some research has shown that extra-cellular DNA is involved in Pseudomonas aeruginosa biofilm formation but the actual part it plays in initiating attachment and how it helps bacteria to form multicellular biofilms is unknown. New surfaces are therefore seriously needed to understand the exact mechanisms and prevent biofilm formation. We use a novel approach for making chemical micro and nano patterns on material surfaces with the help of self-assembled colloidal particles used as masks for creating advanced material surfaces. Recently we have prepared binary colloidal assembly of different crystal structure over a wide range of size ratios (Ƴ=small/large) from 0.01 to 0.2 by tuning Ƴ during assembly and characterised the surface using Scanning Electron Microscope (SEM). We found that zeta potential and size ratio are critical for self-assembly crystal formation. When zeta potential over -30 mV resulted in crystal structure formation. Beyond this range, disordered structure or particle-particle adsorption was found. The crystals are used as masks against gold and plasma polymer deposition to create chemical patterns on the surface that are used for immobilising of eDNA to study how Pseudomonas aeruginosa attaches to surfaces and form biofilms