Application of solutions of Rhodamine B in dosimetry

Design of a prodrug photocage for cancer cells detection and anticancer drug release

Developing probes for simultaneous diagnosis and killing of cancer cells is crucial, yet challenging. This article presents the design and synthesis of a novel Rhodamine B fluorescence probe. The design strategy involves utilizing an anticancer drug (Melphalan) to bind with a fluorescent group (HRhod-OH), forming HRhod-MeL, which is non-fluorescent. However, when exposed to the high levels of reactive oxygen species (ROS) of cancer cells, HRhod-MeL transforms into a red-emitting Photocage (Rhod-MeL), and selectively accumulates in the mitochondria of cancer cells, where, when activated with green light (556 nm), anti-cancer drugs released. The Photocage improve the efficacy of anti-cancer drugs and enables the precise diagnosis and killing of cancer cells. Therefore, the prepared Photocage can detect cancer cells and release anticancer drugs in situ, which provides a new method for the development of prodrugs.

Effect of gamma rays on Zn/Cu doped strontium borate glass system for dosimetric applications

Two alkali strontium borate glasses containing Cu2+ or Zn2+ ions (0.15 mol%) has been prepared by melting annealing method. Some of the glasses dosimetric measurements have been performed; they were checked by ultraviolet-visible light measurement showing the specific peaks of Cu+/Cu2+ and Zn2+ ions. Upon γ-rays, glasses are sensitive to the absorbed dose in the range 0.4–15 kGy, revealing their light absorption. A gradual decrease in optical absorbance and DC electrical conductivity was detected with progressive irradiation. While a gradual increase in optical energy bandgap (Eopt) and electron paramagnetic resonance (EPR) was observed. The presence of transition metal ion (TM) with their variable configurations helps to trap the radiolytic electrons or holes during the color center recovery rates. UV–Vis and EPR dosimetric characteristics have high color stability with excellent short and long-term stability revealing their possible use as glass dosimeters in medical sterilization and food irradiation processing.

Variation in dose response of three dosimetry systems based on diphenyl thiocarbazone

Three different dosimetry systems were prepared based on diphenyl thiocarbazone (DTH) dye: polymer films made with, poly(vinyl alcohol), DTH liquid dosimeter and DTH gel dosimeter. All the systems received several gamma doses. The three systems were analyzing by UV–Vis spectrophotometery before and after irradiation. The effective dose range in the linear part of these systems is between 1–10 kGy, 0.3–2 kGy, and 50–200 Gy. The dose range of these three dosimeters relies on the concentration of DTH. The radiation chemical yield (G-value) was determined for the three prepared dosimeters, and all three radiation dosimeters were examined before and after irradiation.

Dosimetric characterization of a Nickel complex for routine use in radiation processing

In this paper, the dosimetric characteristics of a colored metal complex solution were investigated. Nickel nitrate hexahydrate and 1,5-diphenylcarbazone were made as a liquid solution chemical dosimeter at three concentrations with an inexpensive and simple synthesis for use in gamma irradiation in the range of 20-1000 Gy. The maximum absorbance was observed spectrophotometrically at a maximum wavelength of 530 nm. The paper presents the dosimeter response, radiation chemical yield (G(x)), stability, and repeatability. The results showed that this solution is suitable for use in routine dosimetry in the 20-1000 Gy range.

A microfluidic dosimetry cell to irradiate solutions with poorly penetrating radiations: a step towards online dosimetry for synchrotron beamlines

Synchrotron radiation can induce sample damage, whether intended or not. In the case of sensitive samples, such as biological ones, modifications can be significant. To understand and predict the effects due to exposure, it is necessary to know the ionizing radiation dose deposited in the sample. In the case of aqueous samples, deleterious effects are mostly induced by the production of reactive oxygen species via water radiolysis. These species are therefore good indicators of the dose. Here the application of a microfluidic cell specifically optimized for low penetrating soft X-ray radiation is reported. Sodium benzoate was used as a fluorescent dosimeter thanks to its specific detection of hydroxyl radicals, a radiolytic product of water. Measurements at 1.28 keV led to the determination of a hydroxyl production yield, G(HO.), of 0.025 ± 0.004 µmol J-1. This result is in agreement with the literature and confirms the high linear energy transfer behavior of soft X-rays. An analysis of the important parameters of the microfluidic dosimetry cell, as well as their influences over dosimetry, is also reported.

Fluorescence emission quenching of RdB fluorophores in attendance of various blood type RBCs based on Stern-Volmer formalism

In this work, the optical properties of Rhodamine B (RdB) are investigated in the attendance of various red blood cells (RBCs). RdB fluorophores, as biological markers, is excited using SHG-CW Nd:YAG laser at 532 nm. In fact, the addition of biomolecules of interest to the reference fluorophore notably changes the fluorescence properties of the suspension. Here, laser induced fluorescence (LIF) spectrophotometry based on Stern-Volmer quenching formalism and field emission scanning electron microscope (FESEM) are employed here. According to the given fluorescence spectra, the spectral shift of emissions as well as quenching coefficients are assessed subsequently. The Stern-Volmer formalism is used to determine the quenching coefficients. In fact, RdB + RBCs suspensions contain a plenty of bioconjugates leading to the signal reduction and notable red shift in RdB fluorescence emissions. Furthermore, it is demonstrated that the positive blood type RBCs exhibit the higher quenching coefficients and the larger red shifts against those of negative blood types. This mainly arises from the nature of specific sugar antigens available on the RBC membranes as to N-acetylgalactosamine and galactose attached to the O-antigen terminal would enhance further quenching of the species. Moreover, a significant correlation appears between Stern-Volmer coefficients and the corresponding RBCs. In fact, distinct discrepancy takes place in quenching coefficients in terms various positive/negative blood types to envisage a facile method of blood typing.

Insight in to sunlight-driven rapid photocatalytic degradation of organic dyes by hexacyanoferrate-based nanoparticles

Release of colouring agents into the environment alarms the need to design a cheap, quick and safe process. Owing to environmental safety concern, synthesis of two metal hexacyanoferrates (MHCFs) based on cadmium (CdHCF) and manganese (MnHCF) was carried out using natural plant extract of Azadirachta indica and water as a solvent. Synthesized MHCFs were utilized for the removal of an acid dye (fuchsin acid, FA) and a xanthenes dye (rhodamine B, RB). The reactions were optimized at various conditions of dye concentration, catalyst dose, reaction pH, time and source of light. The MHCFs showed excellent results with both the dyes within very limited span of time (2 h). Consequently, 98% of FA and 97% of RB were degraded with 10 mg of CdHCF, at neutral pH and under sunlight. The degradation process followed the first-order reaction kinetics having t_1/2 around 0.3 min. The MHCFs exhibited difference of only little percentage in degradation owing to a very slight difference between their surface areas (CdHCF: 54.1 m² g^-1; MnHCF: 49.7 m² g^-1). The synthesised nanocatalysts were stable as indicated by their higher negative zeta potential values. The adsorption of dyes was found to be maximum with CdHCF having X_m value 19.69 mg g^-1 and 18.15 mg g^-1 for FA and RB, respectively. Photocatalytic degradation involved the main role of hydroxyl radical as indicated by decline in activity of nanocatalyst in the presence of scavengers. All in all, this study presents highly active nanomaterials with higher surface area, stability and semiconducting properties under natural conditions.

Possible use of tetrabromophenolphthalein ethyl ester as a liquid dosimeter

Aqueous solution of pH indicator dye tetrabromophenolphthalein ethyl ester containing chloral hydrate was studied for its possibility to be used as a liquid dosimeter. The useful measuring range was found to be (0.5–2 kGy) depending on the concentration of both dye and chloral hydrate added. The system has good stability before and after irradiation under different storage conditions. A comparison study between direct irradiation of the dye containing chloral hydrate and indirect method that executed through avoiding exposure of the dye to irradiation and irradiate the chloral hydrate only followed by outputs for interaction with dye was investigated seeking to extend the dose range up to 5 kGy.

Exploring polyvinyl alcohol – nickel sulphate composite film for absorbed dose monitoring

In the current study, we employ the polyvinyl alcohol doped with nickel sulphate (PVA-Ni+2) as a new film for monitoring the absorbed dose in radiation processing facility. The effect of irradiation doses on the structure of PVA-Ni+2 composite films was analyzed through Fourier transform infrared and X-ray diffraction techniques. The PVA-Ni+2 composite films have a response curve that extends from 5 to 60 kGy and labeling character figured through color change from pale green to intense purple color on exposing to gamma photons. Although the films are dose rate dependent, the films have excellent post stability.

A Fast and Simple Qualitative Method for Screening Oleaginous Yeasts on Agar

Finding new oleaginous yeasts is of great interest due to their many important applications. Currently available screening procedures are time-consuming, and most of these require liquid cultures. In this work, a new, fast, economical, and simple qualitative method for screening oleaginous yeasts was developed. The fluorescent dye, Rhodamine B, was selected because its fluorescence is directly correlated to lipid content, and no additional steps or special equipment are needed. This method only requires growing the yeasts on dyed agar plates. Under visible light, it is easy to observe that nonpigmented oleaginous yeasts become colored, whereas non-oleaginous yeasts remain uncolored. The developed method is also useful for improving medium composition in specific applications. Moreover, it was also adapted to use alternative carbon sources, such as lignocellulosic materials and glycerol. The developed method was applied to screen 124 recently isolated nonpigmented yeasts on three different carbon sources, namely, glucose, glycerol, and agave bagasse hydrolysate. Five strains were selected as good lipid producers on all tested carbon sources and accumulated over 48% lipids. Furthermore, the assay was adapted to screen reddish-pigmented yeasts. Considering all the above, the developed method has a wide range of applications in the field of microbial oils.

Evaluation of fluorescent dye degradation indirectly induced by x-ray ionizing radiation

This work evaluated the fluorescent dye degradation indirectly induced by ionizing radiation with high energy photons (50 keV). Aqueous gels of agarose with low concentrations of Rhodamine 6G and Fluorescein were submitted to doses of x-ray radiation up to 200 Gy. The dye degradation was analyzed by fluorescence spectroscopy, using an excitation light-emitting diode with a peak wavelength of 462 nm. A rate equation model of fluorophores and radicals' species populations was developed to describe the degradation time behavior of the fluorescent solutions. The model suggests fluorescent dyes should be used in dosimetry.