Photomodulation of bacterial growth and biofilm formation using carbohydrate-based surfactants

Naturally occurring and synthetic carbohydrate amphiphiles have emerged as a promising class of antimicrobial and antiadhesive agents that act through a number of dynamic and often poorly understood mechanisms. In this paper, we provide the first report on the application of azobenzene trans-cis photoisomerization for effecting spatial and temporal control over bacterial growth and biofilm formation using carbohydrate-based surfactants. Photocontrollable surface tension studies and small angle neutron scattering (SANS) revealed the diverse geometries and dimensions of self-assemblies (micelles) made possible through variation of the head group and UV-visible light irradiation. Using these light-addressable amphiphiles, we demonstrate optical control over the antibacterial activity and formation of biofilms against multi-drug resistant (MDR) 'Pseudomonas aeruginosa', methicillin-resistant 'Staphylococcus aureus' (MRSA) and Gram-negative 'Escherichia coli'. To probe the mechanism of bioactivity further, we evaluated the impact of trans-cis photoisomerization in these surfactants on bacterial motility and revealed photomodulated enhancement in swarming motility in 'P. aeruginosa'. These light-responsive amphiphiles should attract significant interest as a new class of antibacterial agents and as investigational tools for probing the complex mechanisms underpinning bacterial adhesion and biofilm formation.