Development of Protein‐Loaded Layer‐by‐Layer Capsules Using Mesoporous Silica Particle Templates

Abstract This study explores protein‐loaded, semipermeable polymer capsules for potential applications in drug delivery and biomedical analytics. Several proteins were loaded into mesoporous silica particles and encapsulated by layer‐by‐layer (LbL) assembling of oppositely charged polyelectrolytes. The LbL capsules are characterized using confocal laser scanning microscopy (CLSM). A novel protocol for the removal of the silica core under mild conditions (e.g., pH 7, room temperature, low ionic strength) is developed, providing a less harsh approach than existing methods. The functionality of the encapsulated biomolecules after the dissolution of the silica core is shown. By adjusting the pore size corresponding to the protein molecular weight, a homogeneous biomolecule distribution within the silica templates and the LbL capsules is achieved. The LbL coating can be performed without penetration into the protein‐loaded cores, preventing complexation and inactivation of the biomolecules. To assess the functionality of the protein‐loaded capsules, assays are conducted using streptavidin – biotin interactions, and anti‐streptomycin antibodies (aSM‐1), which bind streptomycin. The activity of the encapsulated proteins and the permeability of the LbL membrane for low‐molecular compounds are confirmed. A homogeneous displacement immunoassay is created using different fluorescence labeled antibodies and streptomycin.