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A protein amino acid, phenylalanine-based bolaamphiphile 1 containing a centrally located oligomethylene group has been found to be a hydrogelator at nearly physiological pH (pH 6.5−7.2) in the presence of divalent metal salts (such as MnCl₂, CoCl₂, CuSO₄, and NiCl₂) on sonication. Other structurally related synthetic bolaamphiphiles 2−4 do not form hydrogels under similar conditions. The metallo-hydrogels have been characterized using transmission electron microscopic (TEM) studies and FT-IR studies. TEM study of these metallo-hydrogels indicates a network of nanofibrilar morphology that might be responsible for gelation. The pH sensitivity of these metallo-hydrogels can be potentially utilized for entrapment and slow release of biologically important molecules. It has been demonstrated that one of these gels entraps and slowly releases vitamin B₁₂ molecules depending upon the pH of the medium …