Bacteria collection using PS microspheres in an evaporating sessile droplet

Abstract

Detection and collection bacteria in medium are so important in environmental microbiology and food safety as well as in ocean engineering such as ballast water treatment system. However it is not easy to detect and to collect the bacteria in dilute solutions. We developed a simply method to collect bacteria (i.e. E-coli in this study) using non-functional and carboxyl-terminated polystyrene (PS) beads in an evaporating sessile droplet on hydrophilic surface (Fig. 1). For relatively high concentration of E-coli, the non-functional PS beads were used. E-coli were trapped between PS beads and liquid layer and then moved inward (Fig. 2a). Finally E-coli were concentrated near PS beads, making a ling-like pattern (Fig. 2b). For relatively low concentration of E-coli, the carboxyl-terminated PS beads were used. One cannot see the E-coli at low magnitude (Fig. 3a) and bottom-view (~2.5 &micro m from bottom) at high magnitude (Fig. 3b) while the PS beads are clearly recognized. However there are E-coli attached to PS beads (Fig. 3c). E-coli are likely to attach at carboxyl-terminated PS beads with covalent binding. The results indicate that we can detect and collect E-coli from dilute solution using carboxyl-functionalized PS beads in an evaporating sessile droplet.in dilute solutions. We developed a simply method to collect bacteria (i.e. E-coli in this study) using non-functional and carboxyl-terminated polystyrene (PS) beads in an evaporating sessile droplet on hydrophilic surface (Fig. 1). For relatively high concentration of E-coli, the non-functional PS beads were used. E-coli were trapped between PS beads and liquid layer and then moved inward (Fig. 2a). Finally E-coli were concentrated near PS beads, making a ling-like pattern (Fig. 2b). For relatively low concentration of E-coli, the carboxyl-terminated PS beads were used. One cannot see the E-coli at low magnitude (Fig. 3a) and bottom-view (~2.5 &micro m from bottom) at high magnitude (Fig. 3b) while the PS beads are clearly recognized. However there are E-coli attached to PS beads (Fig. 3c). E-coli are likely to attach at carboxyl-terminated PS beads with covalent binding. The results indicate that we can detect and collect E-coli from dilute solution using carboxyl-functionalized PS beads in an evaporating sessile droplet.