Scheme 1


Scheme 1: Schematic diagram for the synthesis of iron oxide (IO), silica coated IO (SIO), E. coli antibody linked SIO nanoparticles (NPs), capture of E. coli and SERS in presence of colloidal Ag NPs (i) 10 N HCl and 1.5 M NaOH; 4M H₂O₂ 100^°C, 1h (ii) TEOS (2.26 or 1.13, or 0.56 mmol); 50 mL EtOH, 28- 30% NH₄OH (3.4 ml), RT., 16 h (iii) 0.1 M CNBr, 5 mM Na₂CO₃, CH₃CN RT. 15 min (iv) 0.1 mg/mL anti E. coli antibody, PBS (pH 7.2), 4^°C, 24 h (v) at rt., 30 min in PBS (pH 7.2) (vi) SERS measurement at 0.5, 1.5, 2.5, 4.5 and 22.5 h using 532 nm laser.

Scheme 1: Schematic diagram for the synthesis of iron oxide (IO), silica coated IO (SIO), E. coli antibody linked SIO nanoparticles (NPs), capture of E. coli and SERS in presence of colloidal Ag NPs (i) 10 N HCl and 1.5 M NaOH; 4M H₂O₂ 100^°C, 1h (ii) TEOS (2.26 or 1.13, or 0.56 mmol); 50 mL EtOH, 28- 30% NH₄OH (3.4 ml), RT., 16 h (iii) 0.1 M CNBr, 5 mM Na₂CO₃, CH₃CN RT. 15 min (iv) 0.1 mg/mL anti E. coli antibody, PBS (pH 7.2), 4^°C, 24 h (v) at rt., 30 min in PBS (pH 7.2) (vi) SERS measurement at 0.5, 1.5, 2.5, 4.5 and 22.5 h using 532 nm laser.