ABSTRACT
This chapter focuses on methods in aminolevulinic acid (ALA) -based photodynamic therapy and photodetection, adapting concepts of controlled drug delivery in order to overcome problems associated with the poor bioavailability of ALA. Conventional treatment strategies in oncology-related fields range from surgery to radiation therapy to chemotherapy. Chemotherapy based on the systemic or regional administration of cytotoxic agents is often impeded by the lack of specificity of the drug for neoplastic tissue. Tumor cell heterogeneity and inhomogeneous blood vessel distribution in the tumor mass may result in cancerous cells that become resistant to a particular chemotherapeutic drug, leading to single- or multiple-drug resistance. An attractive and innovative alternative to the conventional therapies of cancer is based on the systemic or topical administration of a photoactive compound, which preferentially accumulates in neoplastic tissue. The interaction with light of an appropriate wavelength, results either in clear fluorescence demarcation or in destruction of tissue laden with the photoactive compound.
