Abstract: Texaphyrins are provided for use as radiation sensitizers. Advantageous properties of texaphyrins for use as a radiation sensitizer include: i) a low redox potential which allows radiation-induced hydrated electrons to flow to texaphyrin rather than neutralizing hydroxyl radicals, allowing hydroxyl radicals to cause cellular damage, ii) a relatively stable texaphyrin radical that reacts readily to covalently modify neighboring molecules causing further cellular damage, iii) intrinsic biolocalization, and iv) indifference to the presence or absence of O.sub.2. These properties allow texaphyrins to be particularly effective for treating the hypoxic areas of solid neoplasms. Methods of treatment for an individual having a neoplasm or atheroma include the use of a texaphyrin as a radiation sensitizer and as an agent for photodynamic tumor therapy, or the use of a texaphyrin for internal and for external ionizing radiation. Novel texaphyrins are provided.

Abstract: The invention is directed to a method of incorporating expanded porphyrins, and particularly of incorporating a sapphyrin or a texaphyrin, before, during, or after chemical synthesis of an oligomer to form an expanded porphyrin-oligonucleotide conjugate, and particularly a sapphyrin- or texaphyrin-oligonucleotide conjugate. This method includes reacting derivatized nucleotides and a sapphyrin or a texaphyrin in a desired order in an automated or manual DNA synthesizer having a solid support to form a sapphyrin- or a texaphyrin-oligonucleotide conjugate.