Sensitive biological detection based on Langmuir--Blodgett films prepared from diluted silica suspensions

Abstract

Self-assembled three-dimensional (3-D) colloidal crystals have been extensively utilized in nanolithography for fabricating a wide spectrum of functional periodic nanostructures for important technological applications. Here a simple and versatile way is reported using silica colloids to prepare close-packed particle multilayers by the Langmuir--Blodgett technique to create highly ordered 3-D colloidal crystals with unusual nanoarrays on a large variety of substrates. Successive deposition of monolayers using amphiphilic molecules in this approach allows control of the layer thickness, particle size, and especially packing structure of them in each layer. It has been demonstrated that the Langmuir--Blodgett film's transparency and high antiglare optical properties are preserved even after multiple colloidal particle transfers on both straight and curved surfaces. The surface prepared by the Langmuir--Blodgett technique shows remarkable sensitivity for potential biodetection applications. These colloidal templated films have an optical response time of less than 40 s against essential bioproduct vapors. It is shown that the results are consistent with the Kelvin equation (ln P/P$_{o}=-$2 Vl $\gamma $/rRT) when the liquid water layer is getting thicker.