Optically improved aluminum oxide membrane through electroless Ni modification

An optically improved fluid filter for localization and microscopic imaging was prepared by electroless deposition of nickel–boron (Ni–B) nanoparticle structures in the approximately 0.2 um channel walls of alumina-based Anopore™ fluid filter membranes. The relatively simple, two-step membrane modification process of Pd catalyst addition followed by aqueous Ni–B deposition increases filter optical absorption by more than three orders of magnitude. The resulting black membrane retains its original flow properties but has approximately 98% less autofluorescence compared with the unmodified membrane (dark field illuminated at 488 nm) and has a significant reduction in fluorescence signal from non-specifically bound species.