Combatting Antibiotic-Resistant Pathogens: Disrupting Pseudomonas Aeruginosa Biofilm Viscoelasticity Using Carbon Dot Nanoparticles

Bacterial infection is a global burden, killing one in every eight people worldwide, primarily due to antibiotic resistance. Pseudomonas aeruginosa is one of the top five bacteria responsible for around 7.7 million fatalities caused by bacterial infections. P. aeruginosa secretes biofilm, a biological substance with viscoelastic characteristics to avoid antimicrobial treatments particularly, in chronic and serious wound infections. In the bid to create topical treatments, we investigated the mechano-active potentials of cellulase-based carbon dots as a therapeutic agent against P. aeruginosa biofilm where we envisage the retaining of the cellulase hydrolytic activity in the cellulase-based carbon dots. Cellulase is a glycoside hydrolase that has already been shown to be effective in causing biofilm dispersal as well as reduction in biofilm stiffness and elasticity. The cellulase carbon dots were synthesized using the microwave while citric acid carbon dots (CA-CDs) were hydrothermally synthesized to serve as non-protein-based carbon dots and then characterized for surface properties, size, elemental compositions, and fluorescence profile. P. aeruginosa biofilms were grown in a microfluidic environment for 24 hours and then treated with these carbon dots at a range of concentrations. Using microrheology, it was seen that biofilms treated with cellulase-based carbon dots were more viscous and less stiff compared to those treated with citric acid-based carbon dots. This appears to be because the cellulase carbon dots impact PSL within the biofilm based on microrheology studies examining bacteria strains with specific EPS components removed. This is consistent with the impact of molecular cellulase on biofilms. In general, initial studies suggest that the cellulase-based carbon dots have the potential to act as an excellent multi-antibiofilm therapeutic in the future.