The authors made a copper-containing MOF loaded with diphenylalanine
(DPA) peptides. When the MOFs are placed in an EDTA solution, EDTA
chelates copper out of the MOF, releasing DPA in a controlled
unidirectional manner. The DPA self-assembles at the MOF/water interface
into a region of lower surface tension. The MOFs then move away from
the self-assembled DPA toward the region of higher surface tension, as
per the Marangoni Effect. MOF lifetime and velocity increase with
increasing DPA loading.