Smart bio-nano interface derived from zein protein as receptors for biotinyl moiety

Proteinaceous, tunable nanostructures of zein (prolamine of corn) were developed as biotinyl-specific receptors using a molecular imprinting technique. Sacrificial templates, such as latex beads (LB3) and anodized alumina membrane (AAM), have been used to control nanostructural patterns in biotin-imprinted zein (BMZ). Briefly, a methanolic solution of the zein-biotin complex was drop cast upon a self-organized LB3 and AAM templates on Au/quartz surfaces. Subsequent dissolution of these sacrificial templates affords highly oriented, predetermined, and uniformly grown hyperporous (300 nm) and nanowires (150 nm) motifs of zein (BMZ-LB3 and BMZ-AAM), as shown by scanning electron microscopy (SEM). Selective extraction of biotin molecular template cast-off site-selective biotin imprints within these zein nanostructures complementary to biotinyl moieties. Alternatively, biotin-imprinted zein nanoparticles (BMZ-Np) and thin film (BMZ-MeOH) were prepared by coacervation and drop casting methods, respectively. Density functional theoretical (DFT) studies reveal strong hydrogen-bonded interaction of biotin with serine and glutamine residues of zein. Quartz crystal microbalance (QCM) studies show remarkable sensitivity of the hyperporous-BMZ-LB3 and nanowires of BMZ-AAM towards biotin derivative (biotin methyl ester) by five (24.75 ± 1.34 Hz/mM) and four (18.19 ± 0.75 Hz/mM) times, respectively, higher than the BMZ-MeOH. Enhanced permeability features of the zein nanostructures, when templated with LB3, enable the QCM detection of biotin- or its derivatives down to 12.9 ng mL^-1 from dairy products (Kefir). The outcome of this study shall be a key aspect in interfacing biological materials with micro-/nano-sensors and electronic devices for detecting pertinent analytes using sustainably developed biopolymer-based nanostructures.