An optical probe is presented comprising at least one fluorophore connected to at least one quencher by an enzyme cleavable peptide sequence； the or each fluorophore being substantially fluorescently quenched by the at least one quencher when connected to the enzyme cleavable peptide sequence； the or each fluorophore is separated from the at least one quencher when the enzyme cleavable peptide sequence of the at least one probe element is cleaved； and the enzyme cleavable peptide sequence is selectively cleavable by one or more matrix metalloproteinase (MMP). Methods of use of the optical probe are also presented.
