Conjugate of biotin-modified dimer and phthalocyanine dye

A complex comprising (a) a compound represented by the following formula (1) or a salt thereof:

• wherein
• X represents a substituent having a hydrophilic group, a cationic group or an amino group at the terminus thereof, or —OH,
• X1a, X1b, X2a and X2b each independently represent O or NH,
• Y1 and Y2 each independently represent C or S,
• Z1 and Z2 each independently represent O, S or NH,
• V1 and V2 each independently represent S or S+—O−,
• n1 and n2 each independently represent an integer of 0 or 1,
• L1 and L2 each independently represent a divalent linking group,
• L3 represents a trivalent linking group,
• L4, L5, and L6 each independently represent a divalent linking group, and (b) a conjugate of mutant streptavidin, comprising a molecular probe conjugated to mutant streptavidin.