Described herein are compositions and methods for the immobilization of passenger molecules in a dense matrix of ADP-ribose within the vault particle. The present disclosure also describes a method for altering the physicomechanical properties (e.g. density, compressive strength, electrostatic properties, etc.) of packaged vaults for enhanced stability and/or downstream functionality. In addition, the present disclosure also describes compositions and methods for altering amino acid sequence of the vault protein in the vault particle by amino acid mutation, amino acid insertion and/or amino acid deletion to package passenger molecules and/or to target vault particles to specific receptors or ligands.
