No abstract

Excessive production of reactive oxygen species can lead to alteration of cellular functions responsible for many diseases including cardiovascular, neurodegenerative, cancer, and aging. Hydroxyl radical is a short-lived radical which is considered very aggressive due to its high reactivity towards biological molecules. In this study, a COumarin-NEutral Red (CONER) nanoprobe was developed for the detection of hydroxyl radical based on the ratiometric fluorescence signal between 7-hydroxy coumarin 3-carboxylic acid and neutral red dyes. Biocompatible poly-lactide-co-glycolide (PLGA) nanoparticles containing encapsulated neutral red were produced using a coumarin 3-carboxylic acid conjugated poly(sodium N-undecylenyl-Nε-lysinate) (C3C-poly-Nε-SUK) as moiety reactive to hydroxyl radicals. The response of the CONER nanoprobe was dependent on various parameters such as reaction time and nanoparticle concentration. The probe was selective for hydroxyl radicals as compared with other reactive oxygen species including O 2 •− , H 2 O 2 , 1 O 2 , and OCl −1 . Furthermore, the CONER nanoprobe was used to detect hydroxyl radicals in vitro using viable breast cancer cells exposed to oxidative stress. The results suggest that this nanoprobe represents a promising approach for the detection of hydroxyl radicals in biological systems.

Porphyrin-based GUMBOS and nanoGUMBOS were synthesized for potential application as improved photosensitizing materials. In this study, porphyrin dyes [meso-tetra(4-carboxyphenyl)porphine (TCPP) and zinc(II) meso-tetra(4-carboxyphenyl)porphine (Zn-TCPP)] were selected as anions, and trihexyltetradecylphosphonium (P66614) was employed as a cation. The resulting [P66614] 4 [TCPP] and [P66614] 4 [Zn-TCPP] GUMBOS (group of uniform materials based on organic salts) provided high photostability and excellent thermal stability for these compounds. NanoGUMBOS, i.e., nanomaterials derived from GUMBOS, were synthesized using reprecipitation and ion association methods. The surface charges of these nanoparticles were tuned from positive to negative through use of an ion association synthetic method without the need for additives or stabilizers. When compared to the parent dyes, nanoGUMBOS exhibited excellent photodynamic properties for potential applications as photosensitizers. Evaluation of the electrochemical properties of these GUMBOS suggest that these compounds can be applied as photosensitizers in optoelectronic devices such as dye-sensitized solar cells.

A novel approach for tuning spectral properties, as well as minimizing aggregation, in zinc porphyrin and zinc phthalocyanine-based compounds is presented. Particular emphasis is placed on use of these compounds as photosensitizers in photodynamic therapy (PDT). To accomplish this aim, a bulky hydrophobic cation, trihexyltetradecylphosphonium, is paired with anionic porphyrin and phthalocyanine dyes to produce a group of uniform materials based on organic salts (GUMBOS) that absorb at longer wavelengths with high molar absorptivity and high photostability. Nanoparticles derived from these GUMBOS possess positively charged surfaces with high zeta potential values, which are highly desirable for PDT. Upon irradiation at longer wavelengths, these GUMBOS produced singlet oxygen with greater efficiency as compared to the respective parent dyes.

Energy relay dyes based on GUMBOS displayed improved characteristics in comparison to respective parent dyes including solubility and solar efficiency.