Results: Figure 3. a) Fluorescence spectra of SNP-NH 2 at different irradiation times for the excitation wavelength λ exc = 330 nm. b) Fluorescence enhancement (λ exc = 330 nm; λ obs = 399 nm) with and without SNP-NH 2, Absorbance (NMB) = 0,55. c) UV-Vis of supernatant and solution without SNP-NH 2. Figure 4. a) Fluorescence spectra of SNP-OH at different irradiation times for the excitation wavelength λ exc = 330 nm. b) Fluorescence enhancement (λ exc = 330 nm; λ obs = 399 nm) with and without SNP-OH, Absorbance (NMB) = 0,53. c) UV-Vis of supernatant and solution without SNP-OH. Study of a furyl vinyl naphthoxazole derivate as fluorescent probe on silica nanoparticles for monitoring singlet oxygen Ignacio Chi Durán 1, Antonio L. Zanocco 1 1 Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas Universidad de Chile, Santiago, Chile. Background: Reactive oxygen species (ROS), such as 1 O 2, can be created as the result of 3 O 2 interacting with an electronically excited molecule. This ROS has great importance because it can cause oxidative stress in living organisms that can lead to death. Photodynamic therapy (PDT) is a promising new modality for cancer treatment and other skin diseases. This involves the combination of a photosensitizing agent and light of an appropriate wavelength to generate singlet oxygen in situ. This ROS leads to irreversible celullar damage and causes cell death. The photosensitizer has a higher affinity for the tumoral than healthy cell, thus the singlet oxygen concentration is major in the tumoral cell. However, if the healthy cell has a high concentration of singlet oxygen can damage it, leading to mutations and possibly cancer. Therefore, the participation of singlet oxygen in this and others photochemical processes justify its detection and quantification studies. The molecule (E)-2-(2-(furan-2-yl)vinyl)naphtho[1,2-d]oxazole (FVNAFTOX) has been reported as a successful probe for monitoring singlet oxygen with high selectivity and sensibility. It shows enhancement factors for fluorescence up to 300- fold higher than the control samples and negligible self-sensitization effects. However, its low water solubility makes it difficult to employ this probe in biological systems. On the other hand, the silica nanoparticles (SNP) can enhance the FVNAFTOX concentration because the high surface area leads to adsorpt a large quantity of this probe. Figure 1. a) FVNAFTOX reaction with singlet oxygen. b) Fluorescence spectra at different irradiation times for the excitation wavelength λ exc = 330 nm. c) Fluorescence enhancement (λ exc = 330 nm; λ obs = 399 nm) with different absorbances of NMB. Method: A mixture of FVNAFTOX 1,41·10 -3 M in ethanol with 9,3 mg SNP was stirred for 48 hours at room temperature. This solution was diluted 10-fold in the photolysis cell and NMB was used as photosensitizer at a concentration of 4,8 ·10 -6 M (A = 0,54). The photolysis system consists of a lamp of 50W to 7 cm photolysis cell and FH 500 nm filter. UV-Vis absorption and fluorescence emission spectra were taken after each photolysis for the solution with and without SNP. The adsorption of FVNAFTOX on SNP was determinated by absorbance measurement of the supernatant concentration after centrifugation. The diameter and zeta-potential was obtained by dynamic and electrophoretic light scattering measurement. a) b)c) Download me! goo.gl/AK34d1 Silica nanoparticles used in this work: SNP-NH 2 SNP-OH Figure 4. Summary of physical data about silica nanoparticles used in this work. SNP-NH 2 SNP-OH Diameter (nm)161,4141,4 PdI0,070,10 Zeta-Potential (mV)+46,1+21,5 % FVNAFTOX adsorpted22 ± 319 ± 5 Conclusions: The adsoption of FVNAFTOX is major on SNP-NH 2 than SNP-OH. Probably the highly polar surface on SNP-OH References: 1 Ruiz-González, R., Zanocco, R., Gidi, Y., Zanocco, A. L., Nonell, S., & Lemp, E. (2013). Naphthoxazole-based singlet oxygen fluorescent probes. Photochemistry and Photobiology, 89(6), 1427–1432. doi: /php a) Figure 2. Adsorption of FVNAFTOX on SNP and enhancement of the fluorescent emission after photolysis process.