Banca de QUALIFICAÇÃO: MARIA RAYANNE LIMA DE MORAES

Development and Characterization of Carbonaceous Nanomaterials based on citric acid and methylene blue for Photodynamic Application

Nanomaterials; Citric acid; Methylene blue; Photodynamic therapy; Spectroscopy; DCCR.

Since their discovery in 2004, carbonaceous nanomaterials have proven to be a promising option for applications in photosensitizing systems, with potential for application in photodynamic therapies. The combination of citric acid (CA), a promising precursor in the synthesis of these materials, with methylene blue (AM), known for its photosensitizing properties, provides new perspectives for the development of functional and stable nanomaterials.

In this study, nanomaterials composed of AC + AM were prepared by two different routes: in Route A, the reagents were simultaneously subjected to thermal decomposition; in Route B, citric acid was carbonized and subsequently added to the AM solution. An experimental design based on Central Composite Rotational Design (DCCR) 2³, totaling 17 experiments, was used to explore the synthesis variables (time, amount of citric acid and methylene blue).

Characterization included UV-Vis absorption spectroscopy, FTIR, Raman scattering and zeta potential determination. 

Spectroscopic analysis in the infrared region shows structural changes in AC/AM-based materials, with the main 

stretches remaining. UV-Vis analyzes showed changes in the absorption bands of methylene blue, 

suggesting molecular interactions in the conjugates. The zeta potential showed differences in colloidal stability, 

with values tending to higher values after conjugation, while the emission spectra showed the characteristic property

 of these carbonaceous materials, that is, the dependence of emission in relation to the excitation wavelength, with 

profiles that emit from blue to orange for the conjugates. The emission region presented by the 

AC/AM compounds prepared in this initial study is promising for use as photosensitizers for photodynamic action.