Presence Of Rhodamine Research Articles

Impact of Rhodamine B solution on charge carrier generation and photocatalytic performance in CdS/TiO2 heterostructures synthesized by CBD.

This article presents the study of Rhodamine B solution effects on the generation of charge carriers and the photocatalytic performance of CdS/TiO2 heterostructure films. CdS/TiO2 heterostructure films were synthesized using the chemical bath deposition technique (CBD). The structure and morphology of the heterostructures were studied by X-ray diffraction (XRD), and Scanning Electron Microscope (SEM), respectively. The optical properties of the CdS/TiO2 heterostructures were characterized using a UV–vis spectrophotometer. The results showed that the CdS/TiO2 optical band gap energy (Eg) was 2.75 eV, between the TiO2 band gap energy (3.38 eV) and the CdS band gap energy (2.57 eV). The electrochemical characterization indicated that the photocurrent of the CdS/TiO2 heterostructure decreased from 29 mA to 12.4 mA when the UV-vis light source was turned off. The density of charge carriers generated on the surface of the CdS/TiO2 was simulated employing the WXAMPS software. The results suggest that the thickness of the TiO2 layer should be optimized to allow the activation of CdS. Finally, this study concludes that the presence of rhodamine B in the solution attenuates light transmission and affects the generated electron-hole pairs, resulting in poor photocatalytic behavior.

Facile novel acid coprecipitation synthesis of BiPO4 polymorphs: Enhanced photocatalytic degradation of the antibiotic AMX and the dyes RhB, MB and MO

BiPO4 photocatalyst was synthesized by an acid coprecipitation route followed by heat treatments. The effect of the annealing process was correlated to the formation of BiPO4 polymorphs and the enhancement of photocatalytic activities. Bismuth phosphate calcined at 500 °C (BiP-500) showed the highest photocatalytic performance in the presence of Rhodamine B dye, due to the formation of both low-temperature monoclinic phase (LTMP) and high-temperature monoclinic phase (HTMP) on the one hand and the developed particle size on the other. The efficient photocatalyst was also used to photodegrade a wider range of organic pollutants: methylene blue, methyl orange and amoxicillin. The pH environment concerning the degradation of the anionic dye was studied and revealed increased activities in basic media. The radical superoxide species were highlighted as the major role in the photodegradation mechanism, according to the active radical species trapping experiments. Photoluminescence measurements performed under UV excitation revealed green and orange emissions with the greatest intensity in BiPO4 annealed at 400 and 450 °C.

Ultrafast removal of Cr(VI) ions using polyamine modified carbon nanotubes

• Polyamine modified carbon nanotubes (PA-CNTs) adsorbents were used for the removal hexavalent chromium from polluted water. • The maximum Cr(VI) adsoption capacity of PA-CNTs was 168.54 mg/g at 35 °C. • The fastest adsorption rate reached 95.0% removal within 3 min at pH 4. • The coexisting of Rhodamine B enhanced Cr(VI) adsorption by PA-CNTs. Hexavalent chromium (Cr(VI)) is a highly hazardous substance due to its carcinogenicity, mutagenicity, genotoxicity, and bioaccumulation through food chains. Therefore, how to remove Cr(VI) fastly is an important issue. Polyamine modified carbon nanotubes (PA-CNTs) were synthesized by leveraging a facile grafting condensation modification strategy to remove aqueous Cr(VI). The PA-CNTs was characterized by FTIR, XPS, TGA, SEM and TEM, respectively. The adsorption and desorption behavior of PA-CNTs to Cr(VI) was studied. The PA-CNTs showed an extremely fast Cr(VI) adsorption rate with 95% of Cr(VI) was removed within 3 min. In addition, the prepared PA-CNTs adsorbents displayed a maximum Cr(VI) adsorption capacity of 168.54 mg g −1 , benefiting from the newly introduced surface amine groups. The adsorption process is well described by the pseudo-second-order model. Significantly, the synthesized PA-CNTs adsorbents had a high Cr(VI) adsorption capacity of 392.78 mg g −1 in the presence of Rhodamine B, along with an excellent reusability. The enhanced Cr(VI) adsorption performance can be attributed to the strong electrostatic interactions, complexation, as well as oxidation–reduction between Cr(VI) and PA-CNTs.

Could Sterile Aedes albopictus Male Releases Interfere with Aedes aegypti Population in Reunion Island?

Simple SummaryThe Sterile Insect Technique consisting of inundative and repeated releases of sterile males that induce sterility in the wild population is currently tested as a new strategy to control Ae. albopictus. Considering that Ae. albopictus and Ae. aegypti thrive in sympatry in some regions, and that mating between both species is known to occur at low rates, we hypothesize that releasing millions of sterile male Ae. albopictus in could affect female Ae. aegypti reproduction. To study this potential mating interference, the newly established marking technique has been applied using the rhodamine B that is administered to males through sugar meal. It is internally incorporated into the mosquito’s male body and during mating, the rhodamine is transferred into the females. In laboratory-based experiments rhodamine marking proved to be a powerful means of detecting mating in females of both Aedes species, whatever the mating crosses between males and females. Some mated females were able to lay eggs, but all were not viable. However, despite the promiscuity of the adults in small experimental cages, 95% of the female Ae aegypti showed no evidence of insemination following mating with sterile male Ae. albopictus, suggesting that in the field, an inundative and repeated releases of sterile male Ae. albopictus will not influence the reproduction of female Ae aegypti.In Reunion Island, the feasibility of an Aedes albopictus control program using the Sterile Insect Technique (SIT) is studied. Because, in some regions, Ae. albopictus is living in sympatry with Aedes aegypti, the impact of releasing millions of sterile male Ae. albopictus on female Ae. aegypti reproduction needs to be assessed. Thus, to study the potential heterospecific matings, a marking technique using rhodamine B has been used. Rhodamine is given in solution to male mosquitoes to be incorporated into the male body and seminal fluid and transferred during mating into the bursa inseminalis and spermathecae of females. The presence of rhodamine in females occurred in 15% of cases when Ae. aegypti females were offered non-irradiated Ae. albopictus males, 5% when offered irradiated Ae. albopictus males and 18% of cases in the inverse heterospecific matings. Moreover, our results also showed that these matings gave few eggs but were not viable. Finally, the results showed that whatever the type of mating crosses, females in cages previously crossed with males of another species can re-mate with males of their species and produce an equivalent amount of egg compared to females only mated with conspecific males. Despite the promiscuity of the males and females in small cages for three days, heterospecific mating between sterile male Ae. albopictus and female Ae aegypti, 95% of the females have not been inseminated suggesting that in the field the frequency satyrization would be very low.

Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B

Polycrystalline bismuth phosphate BiPO4 was synthesized by solid-state reaction at different temperatures varying from 500 to 900 °C. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and Raman spectroscopy. The low-temperature phase of BiPO4 has monoclinic structure with a space group P21/n, and was transformed into the monoclinic phase P21/m with a slight distortion of monoclinic lattice when it was heated above 500 °C. The effect of the transformation on the structure, morphology and photocatalytic properties was examined. The photocatalytic activity of each sample, in presence of Rhodamine B (RhB) in aqueous solution, was carried out and analyzed under UV light irradiation. Photoexperiments showed that the material prepared at 500 °C is the best catalyst with degradation efficiency of the order of 96% after 12 min of reaction time under UV light irradiation. This high photocatalytic efficiency could be due to their structural and morphological changes. The photocatalytic degradation mechanism of RhB in the presence of the best photocatalyst BiP-500 °C is proposed. The stability of the catalyst was also examined by carrying out four successive tests of the degradation in the presence of BiP-500 °C. Total organic carbon (TOC) was used to further estimate the rate of mineralization in the presence of BiP-500 °C (83% TOC removal). Photoluminescence experiments performed under UV-laser light irradiation revealed emissions in the green-orange range, with optimal intensities for the mix systems observed at 550 °C.

Synthesis of Molecular Imprinted BiVO4 with Enhanced Adsorption and Photocatalytic Properties Towards Target Contaminants

Selective photocatalysis is a very promising direction to improve the activities of photocatalysts. Combining the technique of molecular imprinting (MIP) with heterogeneous photocatalysis can be an appealing approach to achieve our aim. Herein, using the MIP technique, the monoclinic MIP-BiVO4 was successfully synthesized by the presence of rhodamine B (RhB) during the hydrothermal synthesis. The synthesized MIP-BiVO4 possessed better adsorptive and photocatalytic activities than pristine BiVO4. RhB added in the synthesis process worked as a template and served a crucial role in the formation of the MIP-BiVO4 morphology. The photoelectrochemical analysis verified the superiority of MIP-BiVO4 sample in the transfer and separation of the electron–hole pairs. Holes played the most crucial role in the degradation of the pollutants. The effective approach combining MIP technique in the synthesis of photocatalysts would provide some guidance to selective photocatalysis field for designing and synthesizing highly efficient photocatalysts.

Preconcentration and ultrasensitive spectrophotometric estimation of tungsten in soils using polyurethane foam in the presence of rhodamine B: Kinetic and thermodynamic studies, and designing a simple automated preconcentration system

This work describes designing and using a simple automated preconcentration system for estimation of tungsten in soil spectrophotometrically. The preconcentration of tungsten is based upon the retention of ion associate of [RB+.HWO4-] inside a minicolumn packed with polyurethane foam. The retained ion associate is then automatically and quantitatively eluted by acetone. The tungsten concentration was estimated by measuring the absorbance of elution at 584 nm. The absorbance of elution follows Beer's law in concentration range of 0.5–100 µgL−1 with a detection limit of 0.09 µgL−1. The enhancement factor and relative standard deviation of proposed methodology were 50 and 1.7%, respectively. The system developed in this research is characterized by its low cost and high efficiency, as it uses low-cost PUF as a stationary phase and a few number of pumps and valves. On the other hand, the designed system can be used, in the future, with many detection techniques easily. The composition of the ion association formed between W(VI) ions and RB was calculated by continuous variation method (Job plot) to be 1:1 (W6+:RB). On the other hand, the ion associate in its solid state was synthesized and characterized using elemental analysis and ATR–FTIR technique. The retention of tungsten (VI) ions in the form of [RB+.HWO4-] ion association on the surface of PUFs was confirmed by SEM images and XRF spectra. Moreover, the kinetic and thermodynamic behaviors of the retention of [RB+.HWO4-] on the polyurethane foams were studied in detail. The kinetic models revealed that the retention of [RB+.HWO4-] on PUF surface obeys the pseudo-second-order reaction. The thermodynamic investigations confirmed that the adsorption of [RB+.HWO4-] on PUF surface was spontaneous at 298 K and the interaction between [RB+.HWO4-] and active sites available on PUF surface was physical and electrostatic in nature.

Laser-Induced Single-Molecule Extraction and Detection in Aqueous Poly(N-isopropylacrylamide)/1-Butanol Solutions.

We report photothermal phase separation of aqueous poly(N-isopropylacrylamide) (PNIPAM)/1-butanol (BuOH) solutions by focused 1064 nm laser irradiation and subsequent single microparticle formation in the solution. The single microparticle [diameter = ∼10 μm and volume = ∼picoliter (pL)] produced by laser irradiation was optically trapped by the incident 1064 nm laser beam, and this enabled us in situ Raman/fluorescence microspectroscopies of the particle. Raman spectroscopy demonstrated that the particle produced by laser irradiation was composed of PNIPAM and BuOH. In the presence of rhodamine B (RhB) in the solution, RhB was distributed from the water phase to the PNIPAM/BuOH microparticle produced by laser irradiation, as confirmed by fluorescence microspectroscopy. Laser-induced distribution/extraction of RhB to a single PNIPAM/BuOH microparticle was shown to be possible at the RhB concentration as low as 10-14 mol/dm3, where the RhB fluorescence intensity from the particle showed a step-by-step increase by every ∼3 min laser irradiation. This is the first demonstration of laser-induced simultaneous extraction and detection of single RhB molecules in solution.

The catalytic system ‘Rhodamine B/additive’ for the chemical fixation of CO2

Abstract The catalytic system ‘Rhodamine B/additive’ was introduced to promote the CO2 reactions. We synthesized various cyclic carbonates in good to excellent yields under the catalysis of rhodamine B and TBAB. A variety of 2-oxazolidinone derivatives were obtained in the presence of rhodamine B and DBU.

Identifikasi dan Penetapan Kadar Rhodamin B pada Eye Shadow secara Kromatografi Lapis Tipis dan Spektrofotometri Ultraviolet-Visible

Abstract
 Based on BPOM findings in 2016 there is still the presence of Rhodamin B which is used as one of the dyes in cosmetics. It causes irritation to the skin, respiratory tract and is carcinogenic. The purpose of this study to conduct an examination and determination of Rhodamin B in eye shadow in the Kalideres traditional market. The sample used for the research is eye shadow that is bought from cosmetics stores and cosmetic kiosks, which circulated in the Kalideres traditional market. The sample consist of five different brands based on three criteria is eye shadow which does not include the ingredients used, the writing in the packaging used a language other than Indonesia and does not have a permit number from BPOM. This research was conducted to identify the presence of Rhodamin B in eye shadow with KLT method ( thin layer chromatography), the eluent used is N-butanol, etil asetat, amoniac 25% (10 : 4 : 5) then detected with UV light 254 nm and determination of the content using UV-Vis spectrophotometry method at maximum wavelength 553 nm using as blank is methanol. The resulted was presence of Rhodamine B in sample code A and sample code D with the average value of Rhodamine B levels in the sample examined, the sample code A is 1,3063 mg/g and sample code D is 1,2564 mg/g.
 
 Keywords: Rhodamine B, Eye Shadow, KLT, Uv-Vis Spectrophotometry

Lipidated gemini peptide amphiphiles with enhanced loading capacity and cell membrane affinity for drug delivery

Lipidated peptide amphiphiles exhibit high affinity for plasma cell membranes, good cell internalization and improved stability against degradation, which make them attractive as a drug delivery system. However, low drug loading capacity limits their application for drug delivery. Herein, we developed a gemini peptide amphiphile with enhanced membrane activity and endosomal escape, containing dodecanoic acid hydrophobic tails at the N-terminus, rhodamine on the pendant chain and an active targeting peptide sequence (GRGDS). The presence of rhodamine not only provides high drug loading capability due to the π-π stacking interaction between camptothecin (CPT) and rhodamine, but also promotes peptide amphiphiles to form compact spherical micelles, as well as allows for fluorescence imaging. Single-molecule total internal reflection fluorescence microscopy investigation reveals gemini peptide amphiphile has higher affinity for plasma cell membranes than single-tail peptide amphiphile. Meanwhile, better cell internalization of gemini peptide amphiphile was confirmed by flow cytometry and confocal laser scanning microscopy. Moreover, CPT-loaded gemini peptide amphiphile induced enhanced cytotoxicity in cancer cells when compared to free CPT, indicating that lipidated peptide amphiphile with π-conjugates on the pendant chain and two hydrophobic tails can serve as a highly efficient drug delivery vehicle.

Kinetic fluorimetry for determination of bisphenol S in plastics based on its promoting effect on the Fenton process

The environmental contaminant bisphenol S (BPS) was determined by a kinetic fluorimetric method combined with Fenton process in the presence of rhodamine B (RhB). In acidic solution, the fluorescent RhB was oxidized by hydroxyl radical generated in Fenton process and produced fluorescence quenching, which was obviously accelerated by BPS added into the system. The decrease in fluorescence intensity (ΔF) was proportional to the concentration of BPS with the maximum excitation and emission wavelengths of 554 nm and 578 nm, respectively. Under the optimal conditions, the ΔF was good linear with the concentration of BPS over the range of 0.004–2.0 mg/L with a correlation coefficient of 0.9991. The detection limit of 0.73 μg/L was obtained for the determination of BPS by the proposed method. The general coexisting substances did not interfere to the reactions of BPS with Fenton reagent and RhB. The proposed method has been successfully applied to determine BPS migrated from plastic package with satisfactory results. This new method is environmentally friendly and easy to popularize.

Dual-emission carbon dots achieved by luminescence center modulation within one-pot synthesis for a fluorescent ratiometric probe of pH, Hg2+, and glutathione.

Dual-emission carbon dots were synthesized by one-pot hydrothermal pyrolysis of citric acid and polyethyleneimine in the presence of rhodamine B at 160°C for 5h. The carbon dots have an average diameter of 2.51nm with rhodamine moiety on their surface. Two emission bands centered at 447 and 581nm are exhibited in their fluorescence spectra excited at 360nm, and the former is sensitive while the latter is insensitive to Hg2+ and pH. Glutathione (GSH) can recover the fluorescence quenched by Hg2+. Therefore, the dual-emission carbon dots were developed as a fluorescent ratiometric probe employing the ratio of the two intensities at 447 and 581nm (RI447/I581) as the signal for the determinations of pH, Hg2+, and GSH. In the range of 5.0-10.0, a good linear relationship between RI447/I581 and pH was built with a regression equation of RI447/I581= 11.95-0.56 pH (R2= 0.998). In the range from 0.0 to 8.0μM, an excellent linear relationship between RI447/I581 and the concentration of Hg2+ was obtained with a calibration equation of RI447/I581= 6.2317-0.4458c (R2= 0.995) and a limit of detection (LOD) of 0.24μM. In the range from 1.0 to 10.0μM, a linear equation, RI447/I581= 1.9133-0.4157c (R2= 0.995), was calibrated between RI447/I581 and the concentration of glutathione with a LOD of 0.27μM. The recoveries for the determinations of Hg2+ and GSH in real samples were in the ranges of 94.6 to 103.8% and 94.3 to 104.2%, respectively. Graphical abstract Dual-emission carbon dots achieved by luminescence center modulation within one-pot synthesis for a fluorescent ratiometric probe of pH, Hg2+, and glutathione.

Role of thermal decomposition process in the photocatalytic or photoluminescence properties of BiPO4 polymorphs.

Thermal decomposition process was used to obtain modified photocatalytic and/or photoluminescence properties of bismuth phosphate polymorphs. The precursor BiPO4 , 0.7H2 O was synthesized by a coprecipitation route. The observed polymorphs were the hexagonal P31 21 hydrate phase BiPO4 , 0.7H2 O at 25°C, a mix system of hexagonal and monoclinic P21 /n phases at 200°C and 400°C, a mix system of monoclinic phases P21 /n and P21 /m at 600°C, and a unique monoclinic phase P21 /m at 900°C. The X-ray diffraction analyses allowed evidencing lattice deformations due to structural defects. The photocatalytic activities in the presence of rhodamine B in aqueous solution were determined using UV light irradiation. The best photocatalytic efficiencies were observed with the mix systems resulting from thermal decomposition at 400 and 600°C. Photoluminescence experiments performed under UV-laser light irradiation revealed unexpected emissions in the green-orange range, with optimal intensities for the mix systems observed at 400°C. The role of structural defects resulting from decomposition process is discussed. PRACTITIONER POINTS: Thermal decomposition is used to introduce structural defects in BiPO4 polymorphs The BiPO4 intermediate systems are used to photodegrade rhodamine B Active species trapping experiments are performed Photoluminescence experiments highlight green-orange emissions Structural defects are at the origin of this photoluminescence.

Uptake of ‘Eradicat’ feral cat baits by non-target species on Kangaroo Island

Abstract ContextPredation by feral cats (Felis catus) threatens a range of vertebrate species across Australia, and cat-free islands increasingly act as safe havens for biodiversity. A feral cat eradication program has begun on Kangaroo Island (4405km2) in South Australia, and poison baiting is likely to be one of the main methods used. Aims Here, we trial a non-toxic version of a cat bait, ‘Eradicat’, on western Kangaroo Island, to examine its potential impact on non-target species. MethodsNon-toxic baits containing the biomarker Rhodamine B were deployed across four sites in early August and late November in 2018, with bait take and consumption assessed both by remote cameras and by the presence of Rhodamine B in mammalian whisker samples taken post-baiting. Key resultsCats encountered baits on very few occasions and took a bait on only one occasion in August (<1% of 576 baits deployed). Non-target species accounted for over 99% of identifiable bait takes. In both seasons, >60% of all baits laid was taken by either the common brushtail possum (Trichosurus vulpecula), bush rat (Rattus fuscipes) or Australian raven (Corvus coronoides). In November, Rosenberg’s goanna (Varanus rosenbergi) and southern brown bandicoot (south-eastern subspecies; Isoodon obesulus obesulus), listed nationally as Endangered, also took baits (3% and 1% respectively). The Kangaroo Island dunnart (Sminthopsis fuliginosus aitkeni), listed nationally as endangered, approached a bait on only one occasion, but did not consume it. Evidence of bait consumption was visible in the whiskers of captured common brushtail possums (100% of post-baiting captured individuals in August, 80% in November), bush rats (59% in August and 50% in November), house mice (Mus musculus) (45% in November) and western pygmy-possums (Cercartetus concinnus) (33% in November). ConclusionsAlthough feral cat baiting has the potential to significantly benefit wildlife on Kangaroo Island, impacts on non-target species (particularly the bush rat and common brushtail possum) may be high. ImplicationsAlternative cat baits, such as those containing a toxin to which native species have a higher tolerance or that are less readily consumed by native wildlife, will be more appropriate.

Silk Fibroin‐Based Films Enhance Rhodamine 6G Emission in the Solid State: A Chemical–Physical Analysis of their Interactions for the Design of Highly Emissive Biomaterials

AbstractDescribed herein is the preparation of dye‐doped films employing silk fibroin (SF) as a biomaterial, capable of preserving the optical properties of the monomeric dye in the solid state, a critical requisite for optical and biolaser applications. A comprehensive physical–chemical characterization is reported for SF films doped with Rhodamine 6G, an ideal candidate for photonics and optoelectronics. Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD) and X‐Ray diffraction (XRD) provide information on SF secondary conformation in the presence of rhodamine. UV–vis absorption spectra and exciton CD inform on the structure of encapsulated rhodamine, while changes in dye photophysical properties illuminate the molecular mechanism of the involved host–guest interactions. SF host environment inhibits rhodamine dimer formation, indicating that SF is an optimum matrix to keep rhodamine essentially monomeric at concentrations as high as 7 mm in the film. The relevant optical properties of these films and the easiness of their preparation, make these systems optimal candidates for innovative photonic technologies.

FRET-Mediated Zn2+ Sensing in Aqueous Micellar Solution: Application in Cellular Imaging and Molecular Logic Gate

Forster (fluorescence) resonance energy transfer (FRET) is an excellent method in generating characteristic fluorescence signals between two light sensitive molecules in the 1–10 nm range. On the other hand, studies of Zn2+ detection and imaging are also important, as zinc is the second most abundant transition metal ion in the human body and is involved in many biological activities and neurological functions. This work is a superposition between these two realities, which demonstrates the excellent performance of 4-(pyridine-2-yl)-3H-pyrrolo [2, 3-c] quinoline (PPQ) as a FRET sensor for Zn2+, entrapped in aqueous micellar solution, in presence of Rhodamine B (RB)/Rhodamine 6G (R6G). We show that easy, superior detection and molecular imaging of Zn2+ becomes possible via FRET, as PPQ nonradiatively transfers its energy to R6G/RB, only when it binds with Zn2+, over important biological cations including Na+, K+, Ca2+, Mg2+. During FRET, the Forster radius (R0) between the donor (PPQ) and the acceptor (RB/R6G) is calculated to be ≈ 4 nm, when they are encapsulated in sodium dodecyl sulphate (SDS) micelles at pH 6. Moreover, on careful observation of the fluorescence behavior of PPQ, we also demonstrate that PPQ functions like a monomolecular circuit in an INHIBIT logic gate, based upon two chemical inputs from Zn2+ and Rhodamine.

Photocatalytic microreactors based on nano TiO 2 -containing clay colloidosomes

Abstract Photocatalytic microcompartments have attracted increasing interests in the field of photocatalytic degradation. This work focused on the construction and characterization of a novel photocatalytic microsystem comprising polydopamine-modified TiO2 nanoparticles (NPs) dispersed in clay-based colloidosomes, utilizing partially hydrophobic montmorillonite particles as building blocks for colloidosome membrane assembly. Assessment of photocatalytic activity was performed by photocatalytic degradation of methylene blue and rhodamine B, with the small molecule dyes decomposing within the compartmentalized microsystems. Encapsulation of TiO2 NPs within the clay colloidosomes enhanced the efficiency of photocatalytic degradation. The results showed a selective degradation of methylene blue in the presence of rhodamine B, with associated λMB/λRhB of 2.04. The present study indicates that photocatalytic semiconductor NPs encapsulated in clay colloidosomes form a promising microsystem with great potential for application in environmental remediation.

P173 The ART(EFACT) of multicolor flow cytometry. A case of mysterious CD3/CD19 double positive lymphocytes in the flow cytometry crossmatch (FCXM) assay

Aim Over the past 3 months we have been noticing an unusual population of CD3/CD19 double positive (DP) lymphocytes in some flowcytometry crossmatches (FCXM) performed in our HLA lab. Initially, the appearance of these unusual DP cells seemed random. However, upon careful review it was noted that the DP cells were seen only in reactions with the positive control sera and only when two recently trained techs were involved in setting up FCXM. Who was to blame? Methods FCXM were performed in 96-well trays according to the Halifax protocol. In house negative control (NC) and positive control (PC) sera were used in each FCXM. T/B cells were identified using mouse anti-CD3 PerCP(BD) and anti-CD19-PE (BD) mAbs respectively. Positive FCXM reactions were identified using polyclonal goat anti-human IgG-FITC (Jackson). FCXM were acquired on BD Canto II and analysed using Diva software. Results Fig. 1A illustrates a representative dot plot showing the unusual CD3/CD19 DPcell population observed with the PC sera in FCXM set up by one of the two recently trained technologists. This DP population appeared to be a result of CD3 + T cells shifting up on the PE (FL2) scale and is not seen with the NC sera (Fig. 1B) or any patient sera in the same FCXM. Repeat FCXM performed with identical reagents (including the PC) by a senior technologist did not reveal the DP cells. While direct observation did not identify any protocol deviations by the two junior technologists, it was noted that both individuals used red sharpies to mark the rims of the PC wells (blue for NC) in crossmatch trays (Fig. 1C). Further experiments showed that marking tray rims with red sharpies caused the appearance of the DP cells. Similar effect was seen with pink or purple sharpies but not when black, blue or green sharpies were used (Fig. 1D). This was attributed to the presence of Rhodamine B (fluorescence emission spectrum similar to PE) in the ink of red, pink and purple sharpies. Conclusions This report HIGHLIGHTS that even the best intentions can create strange and unexpected artefacts in FCXM. Download : Download high-res image (303KB) Download : Download full-size image

Low-Cost Plasmonic Carbon Spacer for Surface Plasmon-Coupled Emission Enhancements and Ethanol Detection: a Smartphone Approach

Surface plasmon-coupled emission (SPCE) has led to significant advancements in analytical techniques on account of its unique characteristics that include highly polarized photon-sorting ability. In this study, we report the use of a low-cost activated carbon as a plasmonic spacer in the SPCE substrate for achieving 30-fold enhancement in fluorescence emission. We extend the use of this spacer in the presence of Rhodamine B Base, a lactone dye as the sensing material for smartphone-based ethanol detection on the SPCE platform. Ethanol detection from 1 to 6% concentration highlights the potential use of this technique in monitoring fermentation processes.