A nanoemulsion comprising an oil phase dispersed in an aqueous phase, at least one peptide surfactant and at least one polypeptide surfactant; wherein: i) the at least one peptide surfactant comprising the amino acid sequence: X 1 -(a b c d d' e f g) n -X 2 wherein n is an integer from 2 to 12; amino acid residues a and d are hydrophobic amino acid residues; amino acid residue d' is absent or is a hydrophobic amino acid residue; at least one of residues b and c and at least one of residues e and f are hydrophilic amino acid residues and the other of amino acid residues b and c and e and f are any amino acid residue; amino acid residue g is any amino acid residue; X 1 is absent, an N-terminal capping group, or an amino acid residue or a peptide of 2 to 10 amino acid residues optionally capped with an N-terminal capping group; and X 2 is absent, a C-terminal capping group, or an amino acid residue or a peptide of 2 to 10 amino acid residues optionally capped with a C-terminal capping group; and ii) the at least one polypeptide surfactant comprising at least two peptides having a-helical propensity linked by a linking sequence of 3 to 11 amino acid residues, wherein each peptide having a-helical propensity comprises the amino acid sequence: (t u v w w' x y z) m wherein m is an integer from 2 to 12; amino acid residues t and w are hydrophobic amino acid residues; amino acid residue w' is absent or is a hydrophobic amino acid residue; at least one of residues u and v and at least one of residues x and y are hydrophilic amino acid residues and the other of amino acid residues u and v and x and y are any amino acid residue; and amino acid residue z is any amino acid residue. i) the at least one peptide surfactant comprising the amino acid sequence: X 1 -(a b c d d' e f g) n -X 2 wherein n is an integer from 2 to 12; amino acid residues a and d are hydrophobic amino acid residues; amino acid residue d' is absent or is a hydrophobic amino acid residue; at least one of residues b and c and at least one of residues e and f are hydrophilic amino acid residues and the other of amino acid residues b and c and e and f are any amino acid residue; amino acid residue g is any amino acid residue; X 1 is absent, an N-terminal capping group, or an amino acid residue or a peptide of 2 to 10 amino acid residues optionally capped with an N-terminal capping group; and X 2 is absent, a C-terminal capping group, or an amino acid residue or a peptide of 2 to 10 amino acid residues optionally capped with a C-terminal capping group; and wherein n is an integer from 2 to 12; amino acid residues a and d are hydrophobic amino acid residues; amino acid residue d' is absent or is a hydrophobic amino acid residue; at least one of residues b and c and at least one of residues e and f are hydrophilic amino acid residues and the other of amino acid residues b and c and e and f are any amino acid residue; amino acid residue g is any amino acid residue; X 1 is absent, an N-terminal capping group, or an amino acid residue or a peptide of 2 to 10 amino acid residues optionally capped with an N-terminal capping group; and X 2 is absent, a C-terminal capping group, or an amino acid residue or a peptide of 2 to 10 amino acid residues optionally capped with a C-terminal capping group; and ii) the at least one polypeptide surfactant comprising at least two peptides having a-helical propensity linked by a linking sequence of 3 to 11 amino acid residues, wherein each peptide having a-helical propensity comprises the amino acid sequence: (t u v w w' x y z) m wherein m is an integer from 2 to 12; amino acid residues t and w are hydrophobic amino acid residues; amino acid residue w' is absent or is a hydrophobic amino acid residue; at least one of residues u and v and at least one of residues x and y are hydrophilic amino acid residues and the other of amino acid residues u and v and x and y are any amino acid residue; and amino acid residue z is any amino acid residue. wherein m is an integer from 2 to 12; amino acid residues t and w are hydrophobic amino acid residues; amino acid residue w' is absent or is a hydrophobic amino acid residue; at least one of residues u and v and at least one of residues x and y are hydrophilic amino acid residues and the other of amino acid residues u and v and x and y are any amino acid residue; and amino acid residue z is any amino acid residue.