A peptide dendrimer that comprises a branched core, and a plurality of fibrinogen-binding peptides separately covalently attached to the branched core, wherein the branched core comprises either: from two to ten multi-functional amino acid residues, wherein each fibrinogen-binding peptide is separately covalently attached to a multi-functional amino acid residue of the branched core; a plurality of multi-functional amino acid residues, wherein one or more fibrinogen-binding peptides are separately covalently attached to each of at least two adjacent multi-functional amino acid residues of the branched core; a plurality of multi-functional amino acid residues, wherein two or more fibrinogen-binding peptides are separately covalently attached to at least one of the multi-functional amino acid residues of the branched core; a plurality of multi-functional amino acid residues, wherein two or more multi-functional amino acid residues are covalently linked through a side chain of an adjacent multi-functional amino acid residue; or a single multi-functional amino acid residue, and a fibrinogen-binding peptide is separately covalently attached to each functional group of the multi-functional amino acid residue; wherein the multi-functional amino acid residues comprise tri- or tetra-functional amino acid residues, or are tri- and tetra-functional amino acid residues, or the single multi-functional amino acid residue is a tri- or tetra-functional amino acid residue; wherein the tri-functional amino acid residues comprise a central carbon atom bearing an amino group, a carboxyl group and a side chain bearing a further functional group, and the tetra-functional amino acid residues comprise a central carbon atom bearing an amino group, a carboxyl group and a side chain bearing a further two functional groups. from two to ten multi-functional amino acid residues, wherein each fibrinogen-binding peptide is separately covalently attached to a multi-functional amino acid residue of the branched core; a plurality of multi-functional amino acid residues, wherein one or more fibrinogen-binding peptides are separately covalently attached to each of at least two adjacent multi-functional amino acid residues of the branched core; a plurality of multi-functional amino acid residues, wherein two or more fibrinogen-binding peptides are separately covalently attached to at least one of the multi-functional amino acid residues of the branched core; a plurality of multi-functional amino acid residues, wherein two or more multi-functional amino acid residues are covalently linked through a side chain of an adjacent multi-functional amino acid residue; or a single multi-functional amino acid residue, and a fibrinogen-binding peptide is separately covalently attached to each functional group of the multi-functional amino acid residue; wherein the multi-functional amino acid residues comprise tri- or tetra-functional amino acid residues, or are tri- and tetra-functional amino acid residues, or the single multi-functional amino acid residue is a tri- or tetra-functional amino acid residue; wherein the tri-functional amino acid residues comprise a central carbon atom bearing an amino group, a carboxyl group and a side chain bearing a further functional group, and the tetra-functional amino acid residues comprise a central carbon atom bearing an amino group, a carboxyl group and a side chain bearing a further two functional groups.