Development of theranostic hybrid nanoparticles for phototherapies

Treatment of bacterial infections, just like cancer is complicated. The effectiveness of traditional treatment methods is often poor. As an alternative, local phototherapies show great promise as a single modality or in combination with traditional therapies. This thesis describes a portfolio of superparamagnetic iron oxide (SPION), quantum dots (QD) and their combination, namely hybrid nanoparticles, as a new theranostic nanoparticle platform to deliver a combination of tracking/imaging and treatment, specifically, photodynamic therapy (PDT) and photothermal therapy (PTT) with enhanced efficiency. Both PTT and PDT and the treatment of cancer and bacterial infections are the targeted applications for such nanoparticles. A multitude of techniques is employed in the development of such theranostic hybrid nanoparticles considering translation to the clinic. Nanoparticles that can effectively convert light energy into heat are effective in PTT; but for PDT usually photosensitizers, PS, which produces toxic reactive oxygen species (ROS) upon excitation at a particular wavelength, are used. The combination of a PS with a nanoparticle capable of inducing PTT may provide improved therapeutic efficiency. 5-Aminolevulinic acid (ALA), a well-known and FDA-approved prodrug, is used as the, PS in this thesis. This thesis first describes the synthesis of high-quality SPION and Ag2S quantum dots, the formation of hybrid structures and the evaluation of their use as theranostics for imaging and enhanced PTT, thereafter. Yet, NIR-emitting and N-acetyl cystein-coated Ag2S quantum dots emerged as the most promising nanoparticle for imaging, PTT and were applied for the treatment of wound-related biofilm eradication in vivo, for the first time in the literature.