Protein-building molecular recognition sites by layer-by-layer molecular imprinting on colloidal particles

In this paper, we report a layer-by-layer (LbL) molecular imprinting strategy for constructing molecular recognition sites at the surface of colloidal silica particles by glutaraldehyde (GA)-mediated covalent assembly of gelatin protein in aqueous media. Accompanying the repeated coating of gelatin at the amine-capped silica particles, 2,4,6-trinitrotoluene (TNT) templates were synchronously imprinted into the formed gelatin shells by the charge-transfer interaction between the electron-deficient aromatic rings of TNT and the electron-rich amino groups of gelatin chains. The effective molecular recognition sites generated at the protein interlayers of gelatin shells of monodisperse silica@gelatin particles, and the rebinding TNT capacities changed nonlinearly with the layer number of imprinted gelatin. Three layers of imprinted gelatin produced the largest imprinting factor of approximately 3.0, which is explained by the covalent assembly mechanism. The imprinting protocol is applicable to a broad range of biomaterials (such as proteins, enzymes, chitosan and biopolymers) for imprinting various molecules in aqueous media. Therefore, these results reported here will open a new window of interest in the exploration of novel molecular recognition systems for application in chemosensors, selective separation, and drug screening and release.