Methods for manufacturing phthalocyanine dye conjugates and stable conjugates

Provided are methods for manufacturing a conjugate containing a phthalocyanine dye, including methods that include one or more steps of preparing or producing the conjugate, formulating the conjugate and packaging the conjugate. In some aspects, the manufacturing methods result in the generation of a stable conjugate. Also provided are stable phthalocyanine dye conjugates, compositions and articles of manufacture containing the stable conjugates, and methods for their administration to subjects for photoimmunotherapy. In some embodiments, the phthalocyanine dye conjugates are conjugated to a targeting molecule, such as an antibody, that targets the conjugate to a cell or pathogen, such as by binding to a cell surface protein.