A carbonic anhydrase targeting agent represented by formula (I), or a salt thereof: wherein: CAB is a carbonic anhydrase binding moiety comprising (i) a sulfonamide and (ii) an aliphatic, aromatic or heteroaromatic moiety; Q is a substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, C 1 -C 18 alkyl, alkenyl, alkynyl, alkoxy, or thioalkyl group; or Q is absent; L 1 , L 2 , and L 3 each represent independently for each occurrence a bond or a linker moiety; W represents a benzo-condensed, a naphtho-condensed or a pyrido-condensed ring; X is, independently for each occurrence, C(CH 2 Y 1 )(CH 2 Y 2 ), O, S, or Se; Y 1 and Y 2 are independently hydrogen or a C 1 -C 20 aliphatic group, each of which is optionally substituted with L 3 -M; M, independently for each occurrence, is hydrogen or a chemical modifying moiety selected from the group consisting of a carboxylate, phosphonate, phosphate, iminodiacetate, alcohol, sulfonic acid, sulfonate, polysulfonate, cysteic acid, sulfonamide, sulfoxide, sulfone, ketone, ethylenediamine tetra-acetic acid, diethylenetriamine pentaacetic acid, tetra-azacyclododecane tetra-acetic acid, an amino acid or polyamino acid, oligo- or polyethylene glycol, amine, quaternary ammonium ion, a sugar, glucosamine, galactosamine, mannosamine, alkoxy polyethylene glycol, a branched polypropylene glycol, polypropylene glycol, a graft copolymer of poly-lysine and methoxypolyethyleneglycol, a peptide, a lipid, a fatty acid, palmitate, phospholipid, a phospholipid-PEG conjugate, a carbohydrate, an iron oxide nanoparticle, naphthylalanine, phenylalanine, 3,3-diphenylpropylamine, taurine, and a polycarboxylate; and the agent has a net negative charge ranging from -3 and -12 at neutral pH. CAB is a carbonic anhydrase binding moiety comprising (i) a sulfonamide and (ii) an aliphatic, aromatic or heteroaromatic moiety; Q is a substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, C 1 -C 18 alkyl, alkenyl, alkynyl, alkoxy, or thioalkyl group; or Q is absent; L 1 , L 2 , and L 3 each represent independently for each occurrence a bond or a linker moiety; W represents a benzo-condensed, a naphtho-condensed or a pyrido-condensed ring; X is, independently for each occurrence, C(CH 2 Y 1 )(CH 2 Y 2 ), O, S, or Se; Y 1 and Y 2 are independently hydrogen or a C 1 -C 20 aliphatic group, each of which is optionally substituted with L 3 -M; M, independently for each occurrence, is hydrogen or a chemical modifying moiety selected from the group consisting of a carboxylate, phosphonate, phosphate, iminodiacetate, alcohol, sulfonic acid, sulfonate, polysulfonate, cysteic acid, sulfonamide, sulfoxide, sulfone, ketone, ethylenediamine tetra-acetic acid, diethylenetriamine pentaacetic acid, tetra-azacyclododecane tetra-acetic acid, an amino acid or polyamino acid, oligo- or polyethylene glycol, amine, quaternary ammonium ion, a sugar, glucosamine, galactosamine, mannosamine, alkoxy polyethylene glycol, a branched polypropylene glycol, polypropylene glycol, a graft copolymer of poly-lysine and methoxypolyethyleneglycol, a peptide, a lipid, a fatty acid, palmitate, phospholipid, a phospholipid-PEG conjugate, a carbohydrate, an iron oxide nanoparticle, naphthylalanine, phenylalanine, 3,3-diphenylpropylamine, taurine, and a polycarboxylate; and the agent has a net negative charge ranging from -3 and -12 at neutral pH. <EOS>