Immobilization of bacteriophages on gold surfaces for the specific capture of pathogens

Techniques for the chemical attachment of wild-type bacteriophages onto gold surfaces and the subsequent capture of their host bacteria have been developed. The surfaces were modified with sugars (dextrose and sucrose) as well as amino acids (histidine and cysteine) to facilitate such attachment. Non-specific attachment was prevented by using bovine serum albumin as blocking layer. Surfaces modified with cysteine (and cysteamine) followed by activation using 2% gluteraldehyde resulted in an attachment density of 18 ± 0.15 phages/μm². This represented a 37-fold improvement compared to simply applying physisorption. Subsequently, the phage immobilized surfaces were exposed to the host E. coli EC12 bacteria and capture was confirmed by fluorescence microscopy. We obtained a bacterial capture density of 11.9 ± 0.2/100 μm², a 9-fold improvement when compared to those on physically adsorbed phages. The specificity of recognition was confirmed by exposing similar surfaces to three strains of non-host bacteria. These negative control experiments do not show any bacterial capture. In addition, no capture of the host was observed in the absence of the phages.