Early detection of pathogens requires methods that are fast, selective, sensitive and affordable. We report the development of a biosensor with high sensitivity and selectivity based on the low-cost preparation of organosiloxane (OSX) polymers imprinted with -GFP (green fluorescent protein). OSX polymers with high optical transparency, no cracking, and no shrinkage were prepared by varying several parameters of the sol-gel reaction. The unique shape and chemical fingerprint of the targeted inactivated -GFP were imprinted into bulk polymers by replication imprinting where the polymer solution was dropcast onto a bacteria template that produced a replica of the bacterial shape and chemistry on the polymer surface upon removal of the template. Capture performances were studied under non-laminar flow conditions with samples containing inactivated -GFP and compared to inactivated -GFP. Capture selectivity ratios are dependent on the type of alkoxysilanes used, the HO:silane molar ratio, and the polymerization temperature. The bacteria concentration in suspension ranged from ~6 × 10 to 1.6 × 10 cells/mL. -imprinted OSX polymers with polyethylene glycol (PEG) differentiated between the targeted bacterium , and non-targeted bacteria and native -GFP, achieving selectivity ratios up to 4.5 times higher than polydimethylsiloxane (PDMS) and OSX polymers without PEG.