Role of Simulated Body Fluid in Biofilm Formation and Growth on a Polycarbonate Material

Abstract

Bacteria form biofilms to facilitate colonization, and biofilm formation on polymeric medical devices is a common cause of hospital-acquired infection. Simulated body fluid (SBF) is a supersaturated calcium-phosphate solution with ionic composition nearly equal to that of human blood plasma, and has been used to test the bioactivity of materials. The purpose of this work was to understand whether SBF influenced surface structure on bacterial adhesion and biofilm formation on polycarbonate, a polymer commonly used in medical devices. In this study, polycarbonate coupons were immersed in a SBF solution at 37 oC for 7 and 14 days and air-dried for 30 minutes, and compared with deionized water immersion. Colony biofilms of P. aeruginosa were then investigated by growing bacteria on top surface of immersed coupons for 24 and 48 hours, and observed by the quantitative assay (areal cell density) and visualized using a field emission scanning electron microscopy (FESEM). Results stated that a prolonged immersion time of coupons in deionized water enhanced biofilm growth. Immersion in SBF for a period of 14 days showed a significant reduction in the viability following 24 hours of incubation compared to that in deionized water incubated for 48 hours. FESEM further demonstrated that P. aeruginosa had a tendency to form biofilm on a polycarbonate substrate, and was able to develop biofilms on both the SBF and deionized water. Significant cell clusters and bacterial adhesion was observed at 48-hour incubation. These insights can potentially assist in the establishment of infection and colonization of this opportunistic pathogen, and will aid the development of strategies to prevent biofilm formation.