Ultra-Sensitive Detection of Proteins Using Chemically Modified Nanoporous PVDF Membrane with Attenuated Near IR Autofluorescence

We report the lowest autofluorescent nanoporous polyvinylidene fluoride (PVDF) membranes exhibit near infra-red (NIR) emission properties for western blot detection of high and low molecular weight proteins. The design involves post modification of PVDF membranes by an alkali treatment that reduces the native of PVDF at 450–520 nm. The background fluorescence of these modified membranes is eight times lower than the commercial available PVDF membranes and displayed NIR emission at 750 nm. Imparted alkene conjugated double bonds in the polymeric backbone by alkali treatment causes the NIR emission in the modified PVDF membranes and this translates improvement in detection of, in particular, high molecular weight proteins (130 kDa) compared to traditional western blot. To validate the pore size effect, two different pores sized (∼100 nm and ∼0.8 μm) PVDF membranes were prepared, surface modified and subjected for protein profiling. High linearity was achieved in detection of high molecular weight proteins and significant protein binding was noticed for the alkali treated membranes of ∼∼100 nm size. The methodology permits the design of modified PVDF membranes with lesser pore size could be an alternative for existing membranes with minimal autofluorescence for efficient and quick detection of high molecular weight proteins.