Maltoheptaose Promotes Nanoparticle Internalization by Escherichia coli

Abstract

Nanoparticles conjugated with D-maltoheptaose (G7) showed a striking increase in the surface adherence and internalization by E. coli. This applies to silica nanoparticles (SNP), magnetic nanoparticles (MNP), silica-coated magnetic nanoparticles (SMNP) and silica-coated quantum dots (SQDs) ranging from a few to over a hundred nanometers in size, as well as wild type E. coli ATCC 33456, ORN 178, ORN 208 with the maltodextrin transport channel and the LamB mutant JW 3392-1 (Fig. 1). TEM images including the thin section samples revealed the uptake of nanoparticles in cell walls and inside the cytoplasm (Fig. 2). Unfunctionalized nanoparticles and nanoparticles functionalized with β-cyclodextrin (CD) showed little or no binding to the E. coli cell surface, and no obvious internalization of the nanoparticles was observed. D-Mannose-functionalized nanoparticles bound to the pili of E. coli ORN 178 through the well-known Man-binding lectin (FimH) rather than cell internalization. Surface ligands that can improve the uptake of nanomaterials to bacterial cells should provide a powerful means of targeting a payload delivery to a potential disease causing strain. Work is underway to develop nanomaterial delivery systems for multidrug resistance bacteria.