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Chemical Sensing with POF
Published in Marcelo Martins Werneck, Regina Célia da Silva Barros Allil, Plastic Optical Fiber Sensors, 2019
Filipa Sequeira, Rogério N. Nogueira, Lúcia Bilro
When the detection and monitoring of chemical species are foreseen, a finer analysis must be performed. If the target analyte has a characteristic absorption at a specific wavelength, the broad spectrum of the light that is transmitted will have a valley at the absorbed wavelength. A simple example will be given in order to clarify the procedures that can be used. Rhodamine B is commonly used as an indicator due to the characteristic absorption in the visible region and the fluorescence emission depending on the form that is used. In order to obtain the transmitted spectra after passing through a liquid sample, a white light source and a spectrometer can be used placing the sample in between; see Figure 11.6. The transmission spectra of water and a solution of rhodamine B isothiocyanate (ITC) in sodium hydroxide (NaOH, 0.01M) are depicted in Figure 11.7 as well as the respective calculated absorbance according to Equation 11.4. From the manufacturer it was expected a maximum absorption (λmax) at 555 nm.
Photonic-Crystal Fibers for Sensing Applications
Published in Krzysztof Iniewski, Ginu Rajan, Krzysztof Iniewski, Optical Fiber Sensors, 2017
Rhodamine is often used as a tracer dye, being extensively used in biotechnology applications such as fluorescence microscopy and flow cytometry. A double-clad PCF was used to detect fluorescence of a rhodamine 6G dye sample, showing enhanced detection efficiency [159]. Using a highly sensitive gold-coated side-polished D-shaped PCF, the fluorescence emission of rhodamine B was found to be enhanced through surface plasmon resonance technology [160]. Rhodamine B detection using a four-hole SCF with gold nanoparticles was presented, showing a large interaction volume between the excitation light and the nanoparticles [161]. By filling HC PCFs with aqueous solutions and using surface-enhanced Raman scattering (SERS), rhodamine 6G was detected with the lowest detectable concentration of 10−10 M [162]. Figure 6.14 illustrates a common setup for SERS detection. When comparing SC PCFs and three-hole SCFs, it was observed that the SCFs are more adequate for the purpose, demonstrating a sensitivity of 10−10 M to rhodamine 6G in an aqueous solution with only ∼7.3 μL of volume [163].
Chitosan nano-composites applications for water remediation
Published in Cogent Engineering, 2023
Ashwaq M. Alnemari, Moustapha E. Moustapha, Amr A. Hassan, Dina Salah
Xu and coworkers introduced a nanocomplex of gold nanoparticles/chitosan/graphene oxide/Fe3O2 to adsorb and detect Rhodamine from different samples such as tape water, wastewater, soft drinks, and eye shadow samples. Rhodamine is a fluorescent red pigment used in the food, textiles, cosmetics, pharmaceutical, plastic, leather industries, dyeing, and printing fields. It has some disadvantages to humans, animals, and the environment, as it irritates the skin, eyes, and respiratory system. Moreover, some tests proved its potential carcinogenicity and toxicity. The presented complex was synthesized by coating Fe3O4 nanoparticles with chitosan for its stability, then reacted with graphene oxide; afterward, the gold nanoparticles were added to the nanocomplex. The optimum adsorption and detection for Rhodamine were studied using magnetic solid-phase extraction and fluorescent techniques (Xu et al., 2019).
Polydiacetylene rhodamine-based colorimetric chemosensor for Au3+ detection
Published in Environmental Technology, 2022
Chatthai Kaewtong, Banchob Wanno, Wandee Rakrai, Audchara Saenkham, Sanguansak Sriphalang, Datchanee Pattavarakorn, Thawatchai Tuntulani, Buncha Pulpoka
Rhodamine dyes are often used as colorimetric and fluorescent probes. The higher absorption coefficient and broad fluorescence are shown in the visible region of the electromagnetic spectrum, high fluorescence quantum yield, and photostability [16]. Rhodamine derivatives have been acquired increasing interest in the design of chemosensors for metal ions. The non-fluorescent spirolactam of rhodamine derivatives can undergo a ring-opening of in the presence of metal ions to give rise the highly fluorescence emission and pink. In general, the chemical structure of rhodamine derivatives is unique, in which the carbonyl moiety in a spirolactone or spirolactam group of the structure backbone is converted to the exhibit a red change and strong fluorescence in acidic solution. Previous examinations indicated that an appropriate ligand on the spirolactam ring can induce colour and fluorescent change upon the addition of metal ions even though this process is rather dependent on the solvent system [17]. The development of rhodamine-based sensors for the cations and other analytes has acquired ever-increasing attention in areas, such as Pb2+, Cu2+, Hg2+, Fe3+, Cr3+, and so on [18,19].
A review on Rhodamine-based Schiff base derivatives: synthesis and fluorescent chemo-sensors behaviour for detection of Fe3+ and Cu2+ ions
Published in Journal of Coordination Chemistry, 2023
For the past few decades chemists, biologists, and researchers have sought fluorescent chemo-sensors. Such chemo-sensors are highly selective and specific for particular metal ions and can be used as diagnostic tools to detect different metal ions in living organisms as well as in environmental water bodies [24]. Iron and copper are essential micronutrients important for the human body and living organisms. Iron plays crucial roles in many biochemical processes, an imbalance of causes fatal diseases. In this review, we discuss Rhodamine Schiff bases, their synthesis, and their application as a sensor for detection of Fe and Cu ions in different sources, water, the human body, cancer cell, etc. Rhodamine is a heterocyclic organic dye that is a subgroup of triaryl-methane dyes and is a derivative of xanthene. Rhodamine 6G, Rhodamine 123, and Rhodamine B are important members of the Rhodamine family used primarily as dyes and inks. Since Rhodamine dyes show fluorescence, they are easily detectable with fluorometers. Rhodamine B is used for staining the cell and has great photostability, high emission wavelength and great quantum yields. Rhodamine conjugate Spiro-lactam is a nonfluorescent and colorless Rhodamine derivative, but as the ring opens it gives pink and strong fluorescent emission [25,26]. Due to good optical properties and switching nature of spirocyclic structure, Rhodamine derivatives are also used for designing different multidetector probes for detection of Cu2+ and Al3+ [27], Fe3+, Cr3+, Al3+ [28], etc. The sensing mechanism of Rhodamine is due to the opening of the spirolactam ring upon the combination with any metal ions. One of the challenges in the application of Rhodamine-based sensors is their poor water solubility and biocompatibility, which inhibits their application in biological and environmental samples [29]; they work in an organic solvent or a mixture of organic and water, but researchers have been able to develop Rhodamine-based sensors with better water solubility and biocompatibility [30].