Amanda Jalihal

Fӧrster resonance energy transfer (FRET)-based systems are widely applicable in many areas of interest. In this study, a novel FRET-based ionic material (IM) was synthesized by pairing carbazole imidazolium cation (CI+) with fluorescein anion (Fl2-) through a simple ion-exchange method. The resulting IM ([CI]2[Fl]) was converted into an ionic nanoparticle (INP) in aqueous media for practical use for bioimaging application. The photophysical properties of the parent dyes, [CI]2[Fl], and INP were studied in detail. All FRET parameters were calculated in the synthesized material. [CI]2[Fl] exhibited a significant spectral overlap integral and an ideal theoretical FRET distance. The presence of the FRET mechanism was verified by the observed decrease in donor fluorescence lifetime and a moderate FRET efficiency in [CI]2[Fl]. The INP formed from [CI]2[Fl] was evaluated for use as a fluorescent pH probe and bioimaging agent. FRET efficiency of INP is calculated in a series of pH studies which indicates the highest efficiency at physiological pH. Whereas no FRET phenomenon is observed in highly acidic and basic conditions. The pH-dependent photophysical properties of [CI]2[Fl] are monitored and allow for the potential application as a fluorescent probe for the detection of acidic tissues in biological systems. The FRET-capable INP showed superior bioimaging capability in vitro as compared to the parent dye.

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells to operate efficiently. Traditionally, platinum (Pt) catalysts are often utilized as they exhibit a highly efficient ORR with low overpotential values. However, Pt is an expensive and precious metal, posing economic problems for commercialization. Herein, advances in carbon-based catalysts are reviewed for their application in ORRs due to their abundance and low-cost syntheses. Various synthetic methods from different renewable sources are presented, and their catalytic properties are compared. Likewise, the effects of heteroatom and non-precious metal doping, surface area, and porosity on their performance are investigated. Carbon-based support materials are discussed in relation to their physical properties and the subsequent effect on Pt ORR performance. Lastly, advances in fuel cell electrolytes for various fuel cell types are presented. This review aims to provide valuable insight into current challenges in fuel cell performance and how they can be overcome using carbon-based materials and next generation electrolytes.

Herein, an ionic material (IM) with Förster Resonance Energy Transfer (FRET) characteristics is reported for the first time. The IM is designed by pairing a Nile Blue A cation (NBA⁺) with an anionic near-infrared (NIR) dye, IR820⁻, using a facile ion exchange reaction. These two dyes absorb at different wavelength regions. In addition, NBA⁺ fluorescence emission spectrum overlaps with IR820⁻ absorption spectrum, which is one requirement for the occurrence of the FRET phenomenon. Therefore, the photophysical properties of the IM were studied in detail to investigate the FRET mechanism in IM for potential dye sensitized solar cell (DSSCs) application. Detailed examination of photophysical properties of parent compounds, a mixture of the parent compounds, and the IM revealed that the IM exhibits FRET characteristics, but not the mixture of two dyes. The presence of spectator counterion in the mixture hindered the FRET mechanism while in the IM, both dyes are in close proximity as an ion pair, thus exhibiting FRET. All FRET parameters such as spectral overlap integral, Förster distance, and FRET energy confirm the FRET characteristics of the IM. This article presents a simple synthesis of a compound with FRET properties which can be further used for a variety of applications.