The porin MspA from Mycobacterium smegmatis has many unique properties, one being that it is the longest and the most stable porin identified to date. It is formed by supramolecular interaction of eight identical monomers of 184 amino acid residues (m = 20,000 Da). With dimensions of approx 10 nm in length and a diameter ranging from 1 nm (constriction zone) to 4.8 nm (opening of the MspA-goblet), it is ideal for bio-nanotechnological applications. The porin possesses a hydrophobic docking zone, which enables it to reconstitute not only in lipid membranes, but also in numerous artificial (mono)membranes and hydrophobic, water-soluble polymer layers. Furthermore, we demonstrate here the design and proof-of-principle of an MspA porin-based biosensor for the TB-antibiotic isoniazid. © 2008 Humana Press Inc.