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A novel, simple and highly sensitive spectrofluorimetric approach has been developed and validated for the first time for determination of berotralstat through derivatization reaction using fluorescamine as a fluorescent probe. The reaction was carried out in buffered medium at pH 7.5, using a borate buffer. After being illuminated at 390 nm, the fluorescence intensity of the resulting product was measured at 480 nm. The proposed approach demonstrated linearity within the concentration range of 100 to 1000 ng mL − 1 . LOD and LOQ are 6.98 and 26.36 ng mL − 1 , respectively. Pharmaceutical capsules of berotralstat were successfully evaluated in addition to spiked biological fluid. The statistical data has been validated in accordance with ICH criteria. Additionally, it was applied to examine the content uniformity in accordance with US Pharmacopeia requirements. Furthermore, the results of the ecology scale scores indicated that the analytical process involved was green.

The studies on the behavior of Auramine O (AuO) at the water–air interface and in the bulk phase of the aqueous solution of Kolliphor® ELP (ELP) and Kolliphor® RH 40 (RH40) and their mixture were based on the results obtained from the measurements of the contact angle of water, formamide and diiodomethane on the polytetrafluoroethylene covered by the AuO layer, the surface tension of the aqueous solution of AuO, AuO + ELP, AuO + RH40, AuO + ELP + RH40, density and fluorescence intensity. Based on the obtained results, it was possible to determine components and parameters of the AuO surface tension, concentration and composition of the mixed monolayer, including AuO, ELP and RH40, as well as that of the mixed micelles, and to determine the Gibbs standard free energy of adsorption, micellization and AuO solubilization. The obtained results also showed that surface tension isotherms of the studied solutions can be described by the Szyszkowski equation and the exponential function of the second order and predicted by the Fainerman and Miller equation. In addition, the mixed surface layer composition can be predicted based on the contribution of the components of this layer to the water surface tension reduction.

Abstract A universal enzyme strand (E-DNA) recyclable L-histidine (L-His), melamine (MA), and cisplatin (CP) biosensor was fabricated on the basis of a target-specific RNA-cleaving DNAzyme with specific auramine O (AuO) dye instead of thioflavin T. In this strategy, the substrate strand (S-DNA) of the RNA-cleaving site was constructed as an intramolecular stem-loop structure, and a GT-rich sequence was imprisoned in the double-stranded stem which inhibits the formation of stable G-quadruplex (G4cpx) with AuO. The presence of L-His initiates a catalytic reaction for cleaving the RNA site of the S-DNA hydrolytically releasing the GT-rich portion, which subsequently combines with AuO and forms a G4cpx for enhanced fluorescent signal. The subsequent addition of MA uncoils the G4cpx to form T-MA-T dsDNA, or addition of CP unwound the G4cpx to form CP-DNA leading to an intensive decrease of AuO emission. Remarkably, the liberated L-His can ultimately cause several rounds of cleavage, and the liberated E-DNA can catalyze the subsequent reaction with the other S-DNA. The use of L-His and E-DNA repeatedly induces S-DNA cleavage and intensifies the emission signal. The results show that the proposed biosensor is extremely sensitive to L-His, MA, and CP with a detection limit of 0.98, 10, and 3.4 nM respectively. To the best of our knowledge, the utilization of AuO as the G4cpx inducer and stabilizer for L-His, MA, and CP detection in real milk and urine samples has never been reported.

Background Fluorochrome smear microscopy is the method recommended for the direct examination of clinical samples for mycobacteria. However, no studies to date have comprehensively assessed the diagnostic utility of this method using auramine O stain for detecting non-tuberculous mycobacteria (NTM) versus Mycobacterium tuberculosis complex (MTBC) in adult samples. Hence, this study aimed to investigate the diagnostic utility of auramine O smear microscopy (AOSM) for detecting NTM versus MTBC in adult samples, using mycobacterial culture as the reference standard. Methods This was a 5-year retrospective study conducted in a tertiary academic medical centre in Malaysia. Adult samples tested with both AOSM and mycobacterial culture from 1 January 2018 to 31 December 2022 were included in the analysis. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) with 95% confidence intervals (CI) were calculated using Open Epi Version 3.01. Results Of 12 016 adult samples that underwent both AOSM and mycobacterial culture, 19.0% ( n  = 2 288) were culture positive. NTM and MTBC accounted for 50.2% ( n  = 1 149) and 49.8% ( n  = 1 139) of the mycobacterial isolates, respectively. The diagnostic utility of AOSM for detecting NTM versus MTBC was 2.4% (95% CI 1.6%-3.5%) versus 53.6% (95% CI 50.6%-56.5%) for sensitivity, 93.8% (95% CI 93.3%-94.2%) versus 99.1% (95% CI 98.9%-99.3%) for specificity, 4.0% (95% CI 2.8%-5.8%) versus 86.4% (95% CI 83.8%-88.7%) for PPV and 90.1% (95% CI 90.0%-90.2%) versus 95.3% (95% CI 95.0%-95.6%) for NPV. Conclusions The diagnostic utility of AOSM was limited by poor sensitivity and PPV for NTM, and by poor sensitivity for MTBC. A positive AOSM result was a much more reliable indicator of the presence of MTBC than of NTM. In settings with a higher burden of TB than NTM disease, AOSM-positive patients with a clinical history suggestive of TB disease should be considered for TB treatment initiation while awaiting culture confirmation. In contrast, AOSM-positive patients whose clinical history is not strongly suggestive of TB—or is suggestive of NTM disease—should undergo additional testing using alternative methods, such as rapid molecular assays, that can reliably detect and distinguish between MTBC and NTM while awaiting culture confirmation.

Microscopy-based tuberculosis (TB) diagnosis i.e. Ziehl-Neelsen screening still remains the primary diagnostic method in resource poor and high TB burden countries, however this method has poor sensitivity (~60%). Bringing three million TB patients who are left undiagnosed under the treatment has been a major focus as part of END-TB strategy across the world. We have developed a portable set-up called ‘SeeTB’ that converts a bright-field microscope into fluorescence microscope (FM) with minimal interventions. SeeTB, a total internal reflection-based fluorescence excitation system allows visualization of auramine-O stained bacilli efficiently with high signal-to-noise ratio. Along with the device, we have developed a sputum-processing reagent called ‘CLR’ that homogenizes and digests the viscous polymer matrix of sputum. We have compared the performance of SeeTB system in 237 clinical sputum samples along with FM, GeneXpert and liquid culture. In comparison with culture as gold standard, FM has sensitivity of 63.77% and SeeTB has improved sensitivity to 76.06%. In comparison with GeneXpert, FM has sensitivity of 73.91% while SeeTB has improved sensitivity to 85.51%. However, there is no significant change in the specificity between FM and SeeTB system. In short, SeeTB system offers the most realistic option for improved TB case identification in resource-limited settings.

The dyes Auramine and Auramine O are used in several industrial products, despite the scarce information regarding their ecotoxicity. The aim of the present study was to assess the acute and chronic toxicity of both dyes to aquatic organisms from different trophic levels ( Raphidocelis subcapitata , Daphnia similis , Hydra attenuata , and Danio rerio ) and calculate their predicted non-effect concentrations (PNEC). Auramine and Auramine O induced toxicity to all selected test organisms with L(E)C50 values ranging from 300 to 4800 ug/L. Both dyes induced inhibition in the growth rate of exposed algae, negatively affecting the reproduction of D. similis and induced deformities in H. attenuata (clubbed tentacles and shortened tentacles) and D. rerio (edemas, tail malformation and delay in yolk sac absorption). PNEC values of 0.92 μg/L and 4.0 μg/L were obtained for Auramine and Auramine O, respectively, based on results of the most sensitive test system (algae). Test results were analyzed using the Criteria of Reporting and Evaluating Ecotoxicity Data (CRED), confirming their reliability and relevance. Thus, PNEC values can be used in future risk assessments of those substances in freshwater systems.

A clay-based adsorbent (CBA) was purified from a sustainable precursor (raw clay, RC), which was obtained from the Amazon region in Brazil. The CBA was characterized using X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Brunauer-Emmet-Teller surface area (S BET , RC = 23.386 m 2 .g −1 , CBA = 33.020 m 2 .g −1 ), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), thermogravimetric analysis (TGA), cation exchange capacity (CEC, CBA = 44.75 cmol/kg), and point of zero charge analyses ( pH PZC , CBA = 2.20). Subsequently, CBA was used to adsorb basic yellow 2 (BY2) dye from aqueous solutions. A CBA dosage (1 g/L), initial concentration of dye ( C 0  = 15 mg/L), and pH (5.6) were ideal conditions for the BY2 dye removal of ~ 98%. The BY2 kinetics was better represented by the pseudo-first-order (PFO) model while the BY2 equilibrium was well represented by the Sips model, with a maximum adsorption capacity of q ms  = 18.04 mg/g at 28 °C. The negative values of ΔG° and ΔH° showed that the studied process is spontaneous and exothermic, while the values of isosteric heat ( ∆H st , -16 to -20 kJ/mol) suggest a predominance of physical interactions. The molecular chemical reactivity of BY2 was investigated using quantum chemical descriptors calculated based on Density Functional Theory (DFT) optimization of the dye molecule, and the results revealed a large energy gap value (4.3900 eV) and considerable chemical hardness (η = 2.1950 eV). Therefore, the correlation between DFT and experimental results consistently sustains that BY2 dye tends to be adsorbed on the CBA surface by electrostatic interactions, thus, this is the possible adsorption mechanism of this process. Graphical Abstract

Diagnosis of leprosy mainly relies on clinical examination due to the inconsistent sensitivity and poor reproducibility of the current laboratory tests. Utilisation of alternative methods to the standard Ziehl Neelsen (ZN), Fite-Faraco (FF) and Haematoxylin and Eosin (H&E) staining procedures may eventually improve leprosy diagnosis. In this comparative study, the performance of the fluorescent Auramine O (AO) staining and polymerase chain reaction (PCR) was assessed with different skin samples using a combination of ZN, FF and H&E staining as the gold standard. AO, ZN, FF, H&E and PCR tests were performed on slit skin smears (SSS) and/or punch biopsies collected from 141 clinically confirmed leprosy cases and 28 non-leprosy skin samples. DNA was extracted from punch biopsies using two different methods with or without mechanical lysis. Sensitivities were 87.6%, 59.3% and 77% for H&E, ZN and FF, respectively, whereas it reached 65.5% and 77.9% for AO in SSS and tissue sections and 91.1% for PCR in tissue samples. Morover, samples with low bacillary index, sensitivity of AO staining (61.8%) was similar to FF (60%, p>0.05) and lower than PCR (86.6%, p<0.05). Sensitivity of PCR also increased (96.8%, p<0.05) when mechanical lysis was used during DNA extraction compared to enzymatic treatment alone (84.6%). Our results showed that for diagnostic purposes, analysis of skin section is more sensitive than SSS, especially for samples with low bacillary load. AO staining on SSS and tissue sections was not significantly better than other routine diagnostic tests but considerably more user friendly. The sensitivity of PCR was higher than current standard methods and increased when combined with more efficient DNA extraction using mechanical and chemical lysis. Therefore, we recommend AO staining for the diagnosis of leprosy in lower health facilities such as health centres and district hospitals and PCR diagnosis at referral level and research centres.

Background. Fluorescence microscopy offers well-described benefits, compared with conventional light microscopy, for the evaluation of sputum smear samples for tuberculosis. However, its use in resource-limited settings has been limited by the high cost of the excitatory light source. We evaluated the diagnostic performance of fluorescence microscopy, using novel light-emitting diode (LED) technology as an alternative to the conventional mercury vapor lamp (MVP). Methods. Routinely collected sputum specimens from persons suspected to have tuberculosis who attended community clinics were stained with auramine O and were evaluated using 2 different excitatory light sources (MVP and LED); these specimens were then Ziehl-Neelsen stained and reexamined using light microscopy. Two microscopists independently evaluated all smears. Bacterial culture provided the gold standard. Results. Of the 221 sputum specimens evaluated, 36 (16.3%) were positive for Mycobacterium tuberculosis by culture. Sensitivity and specificity documented for the different modalities were 84.7% and 98.9%, respectively, for the LED assessment; 73.6% and 99.8%, respectively, for the MVP assessment; and 61.1% and 98.9%, respectively, for light microscopy. Κ values for interreader variation were 0.87 for the LED assessment, 0.79 for the MVP assessment, and 0.77 for light microscopy. The mean time to read a negative smear was 1.4 min with fluorescence microscopy and 3.6 min with light microscopy, reflecting a time savings of 61% with fluorescence microscopy. Conclusion. LED fluorescence microscopy provides a reliable alternative to conventional methods and has many favorable attributes that facilitate improved, decentralized, diagnostic services.

The presence of dyes and heavy metals in water sources as pollutants is harmful to human and animal health. Therefore, this study aimed to evaluate the efficacy of zinc ferrite (ZnFe O ) nanoparticles (ZF-NPs) due to their outstanding properties including cost-effectiveness, availability, and applicability for removal of auramine O (AO), methylene blue (MB), and Cd (II). The effect of the main operating parameters such as AO concentration, MB concentration, Cd (II) concentration, adsorbent amount, solution pH, and sonication time was optimized by the response surface methodology (RSM). Optimal conditions were obtained at adsorbent amount of 0.25 g, pH = 6, sonication time of 15 min, and concentration of 15 mg L , and more than 91.56% were removed from all three analytes. The adsorption of AO, MB, and Cd (II) onto ZF-NPs followed pseudo-second-order kinetics and the equilibrium data fitted well with Langmuir isotherm. The maximum adsorption capacities of ZF-NPs for AO, MB and Cd (II) were as high as 201.29 mg g , 256.76 mg g and 152.48 mg g , respectively. Also, the reuse of the adsorbent was investigated, and it was found that the adsorbent can be used for up to five cycles. Based on the results of interference studies, it was found that different ions do not have a significant effect on the removal of AO, MB, and Cd (II) in optimal conditions. The ZF-NPs was investigated successfully to remove AO, MB, and Cd (II) from environmental water samples. The results of this study showed that ZF-NPs can be used as a suitable adsorbent to remove AO, MB, and Cd (II) from aqueous solution.