Conjugation of superparamagnetic iron oxide nanoparticles and curcumin: association of photodynamic therapy and magnetic hyperthermia

Author(s)

Willian Max Oliveira de Souza de Santana

• Document type: Master's Dissertation
• Press: Araraquara. 2019-06-19.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Química. Araraquara
• Defense date: 2019-05-07
• Advisor: Celso Valentim Santilli

Abstract

The incidence of cutaneous infections caused by bacteria resistant to conventional antibiotic treatment has become a major public health problem. Some alternative therapeutic approaches have been proposed, among them antimicrobial photodynamic therapy (aPDT) and magnetic hyperthermia (MH). The aPDT involves the generation of reactive oxygen species (ROS) by using the combination of light, molecular oxygen and a photosensitizing agent (PS), and MH promotes temperature increase of an anatomic region by subjecting superparamagnetic iron oxide nanoparticles (SPIONPs) to an alternating magnetic field (AMF). The PS of choice for this study was curcumin (CUR), widely used in aPDT, but still has its photoactivity strongly affected in aqueous media due to the tendency of aggregation. In order to solve this problem and to promote the improvement of the administration of CUR, we propose the combination of CUR and SPIONPs of maghemite in a single material. Therefore, the objective of this work was to synthesize a SPIONPs-curcumin conjugate (Magh-CUR) and, mediated by the aPDT, to evaluate it against Staphylococcus aureus in the planktonic phase. This magnetic material was prepared by an alkaline coprecipitation method followed by a conjugation step with CUR. The conjugates were characterized by X-ray diffraction, electron transmission microscopy, zeta potential, infrared spectroscopy with Fourier transform, thermogravimetry, magnetometry, MH assays. The characterizations showed that the Magh-CUR had spheroid forms with sizes of ~ 15 nm and the conjugation was due to strong interactions between the CUR keto-enol group and the iron ions on the surface of the SPIONPs. In addition, the conjugates showed high heating power under CMA and photodynamic action when irradiated with blue LEDs light. In the microbiological experiments of aPDT it was shown that the conjugate can promote total reduction of the bacterial load in a low dose of light. The in vitro release assays of the conjugates showed that the release of CUR was dependent on temperature. In this way, the Magh-CUR conjugates are interesting materials for biological applications, since they allow to associate the aPDT with MH and drug delivery of the CUR in the same material. (AU)

• FAPESP's process: 17/07822-7 - Conjugation of superparamagnetic nanoparticles of iron oxide and curcumin: association of photodynamic therapy and magnetic hyperthermia
• Grantee: Willian Max Oliveira de Souza de Santana
• Support Opportunities: Scholarships in Brazil - Master