Real-time polarimetric biosensing using macroporous alumina membranes

We report the first demonstration of real-time biosensing in free standing macroporous alumina membranes. The membranes with their 200 nm diameter pores are ideal candidates for biosensing applications where fast response times for small sample volumes are needed as they allow analytes to flow through the pores close to the bioreceptors immobilized on the pores walls. A bulk refractive index sensitivity of 5.2x10(-6) refractive index units was obtained from signal responses to different concentrations of NaCl solutions flowing through the pores. Finally, after functionalizing the alumina pore surfaces with an epoxysilane and then spotting it with beta-Lactoglobulin protein, the interactions between the beta-lactoglobulin and rabbit anti-beta-lactoglobulin, as well as the interaction between the rabbit anti-beta-lactoglobulin and a secondary antibody anti-rabbit Immunoglobulin G were monitored in real-time.