Fluorescence Emission Peak Research Articles

Spectrofluorometric quantitative analysis of aripiprazole based on quenching of natural derived carbon quantum dots in spiked human plasma

Autism spectrum disorder is a significant concern worldwide, particularly in Middle Eastern countries. Aripiprazole, a psychiatric medicine that works as a partial agonist at D2 receptors, is often used for autism-related behavior issues in children. Monitoring the therapy of aripiprazole could enhance the safety and effectiveness of treatment for autistic individuals. The purpose of this study was to develop a highly sensitive and environmentally friendly method for analysis of aripiprazole in plasma matrix. To achieve this, water-soluble N-carbon quantum dots were produced from a natural green precursor, guava fruit, and used in fluorescence quenching spectroscopy to determine the presence of aripiprazole. The synthesized dots were analyzed and characterized using transmission electron microscopy and Fourier transform infrared spectroscopy, and they showed a strong fluorescence emission peak at 475 nm. The proposed method was validated according to ICH M10 guidelines and was shown to be highly sensitive, allowing for nanoscale determination of aripiprazole in plasma matrix. Additionally, the method was compared to a previously reported spectrophotometric method, and it was found to be more sensitive and consistent with the principles of green analytical chemistry.

A novel dual-mode sensing strategy for the determination of 1,4-dithiothreitol based on tannic acid stabilized copper nanocluster

In this paper, a novel sensing strategy with both ratiometric fluorescence and colorimetric responses towards 1,4-dithiothreitol (DTT) was developed based on tannic acid-templated copper nanoclusters (TA-CuNCs). The one-step reduction approach was utilized to obtain TA-CuNCs with the fluorescence emission peak located at 436 nm. Through the catalytic oxidation of Cu2+, o-phenylenediamine (OPD) could be converted to 2,3-diaminophenazine (DAP) with an obvious fluorescence signal at 557 nm. Additionally, the obtained yellow DAP showed a clear absorption peak at 420 nm, DAP could cause a significant fluorescence quenching of TA-CuNCs on account of inner-filter effect (IFE). The oxidation process between Cu2+ and OPD could be largely prevented by 1,4-dithiothreitol (DTT), whose sulfhydryl groups bound to Cu2+, and the fluorescence intensity of DAP was diminished, whereas the fluorescence of the TA-CuNCs was restored. The ratiometric fluorescence signal and absorbance intensity changed with the concentration of DTT in the linear ranges of 5–45 μM and 5–40 μM, respectively. And the limits of detection (LOD) for two modes were found to be 2.98 and 2.03 μM, respectively. Furthermore, the dual-mode assay method was used for the determination of DTT accurately and reliably in human serum samples.

A novel reaction-based ratiometric fluorescent probe with large Stokes shift for the detection of Hg2+ in river sample

Based on Hg2+-promoted desulfurization-hydrolysis of the diphenylphosphinothioate moiety, a novel ratiometric fluorescent probe 1 for Hg2+ using hemicyanine as the fluorophore was designed and synthesized. In sensing of Hg2+, the maximum fluorescence emission and absorption peaks of 1 shifted from 450 nm to 504 nm and from 351 nm to 376 nm, respectively, accompanied by color change from colorless to green under illumination with a 365 nm UV lamp. 1 not only exhibited remarkable change in the ratios of both absorbance (A376 nm/A351 nm) and fluorescence intensity (F504 nm/F450 nm), but also had large Stokes shift, fast response, excellent sensitivity, and high selectivity for Hg2+. Furthermore, 1 was successfully applied for Hg2+ detection in river water sample.

Multiplicity of solvent environments in lipid bilayer revealed by DAS deconvolution of twin probes: Comparative method of Laurdan and Prodan

Laurdan and Prodan were designed for the evaluation of the surrounding hydration state. When inserted into lipid bilayer systems, both probes are located at different positions and their fluorescence properties are drastically varied, depending on their surrounding environment. In this study, a novel method using the above fluorescence probes was proposed on the basis of fluorescence lifetime (τ) and emission peak (λ), called as τ vs. λ plot, determined by global analysis of their multiple fluorescence decays and deconvolution of these decay-associated spectra. According to the evaluation of τ vs. λ plot, the existence of multiple fluorescence components in the membrane was revealed. In addition, their fluorescence distribution properties, described on τ vs. λ plot, of each probe tended to correspond to the phase state and vertical direction of the lipid membrane. To assess the contribution of environmental effect to each distribution, we defined the region in the τ vs. λ plot, which was modeled from a series of solvent mixtures (hexane, acetone, ethanol and water) to emulate the complex environment in the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine bilayer system. The distributions of fluorescence components of Laurdan and Prodan in lipid membranes were classified into each solvent species, and Prodan partition into bulk water was distinguished. The sensitivity of Prodan to the phase pretransition of the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine bilayer system was also observed in increasing the temperature. Noticeably, most of the fluorescence components was assigned to the solvent model, except for a single component that has longer lifetime and shorter emission wavelength. This component was dominant in solid-ordered phase; hence, it is assumed to be a specific component in lipid membranes that cannot be represented by solvents. Although these are still qualitative analytical methods, the unique approach proposed in this study provides novel insights into the multi-focal property of the membrane.

Synthesis of a water-stable fluorescence CsPbBr3 perovskite by dual-supersaturated recrystallization method and tuning the fluorescence spectrum for selective detection of folic acid

As an excellent fluorescent material, cesium lead halide perovskite nanocrystals (PNCs) is rarely used for analytical purposes because the PNCs are unstable in polar solvents, especially water. Developing a new synthesis method to prepare water-stable PNCs makes it promising for the detection of analytes in aqueous solutions. Herein, by using the solubility difference of the precursors in different solvents, we successfully synthesized water-stable CsPbBr3 PNCs by a dual-supersaturated recrystallization method at room temperature. We also found that the fluorescence of the as-prepared CsPbBr3 PNCs could be quenched by some small organic molecules, such as folic acid (FA) and dopamine (DA). By using a chloride-induced anion exchange reaction method, the fluorescence emission peak of the CsPbBr3 PNCs could be tuned from 518 to 418 nm and the emission color changed from green to blue. The blue emission chloride-exchanged PNCs have a good selectivity for only FA and a good linear relationship is established between the fluorescence quenching rate of the PNCs and concentration of FA from 10.0 to 140.0 μM, with a limit of detection (LOD) of 0.9 μM. This work expanded the applications of PNCs in the field of analytical chemistry and also proposed a new strategy for improving selectivity by tuning the emission spectrum of a fluorescent probe.

A Ratiometric Fluorescence Biosensor for Detection of Alkaline Phosphatase Via an Advanced Chemometric Model.

In this paper, a ratiometric fluorescence biosensor was introduced for alkaline phosphatase (ALP) detection based on 2-aminopurine (2-Amp) and thioflavin T (ThT)-G-quadruplex system. We designed a special DNA (5'-AGGGTTAGGGTTAGGGTTAGGGAAA/i2-Amp/AAAA-PO4-3', AP) modified with a phosphate moiety at the 3'-end, G-quadruplex at the 5'-end, and a fluorophore (2-Amp) in the middle. In the absence of ALP, the G-rich AP strand could be prone to fold into G-quadruplex structures in the presence of K+. Then, ThT combined with G-quandruplex, resulting in the enhancement of fluorescence emission peak at 485 nm. However, ALP-mediated hydrolysis of the 3'-phosphoryl end promoted the cleavage of AP by the exonuclease I (Exo I), releasing 2-Amp which displayed a strong fluorescence emission peak at 365 nm. Moreover, the quantitative fluorescence model (QFM) was derived for the analysis of the fluorescence measurements obtained by the proposed ratiometric fluorescent biosensor. With the aid of the advanced model, the proposed ratiometric fluorescent biosensor possessed satisfactory results for the detection of ALP in the human serum samples, with accuracy comparable to that of the reference method-the commercial ALP assay kit. Under the optimized experimental conditions, this method exhibited good selectivity and higher sensitivity, and the detection limit was found to be as low as 0.017 U/L. Therefore, it is reasonable to expect that the method had a great potential to detect ALP quantitatively in clinical diagnosis.

UHPLC-MS/MS-based lipidomics for the evaluation of the relationship between lipid changes and Zn-protoporphyrin formation during Nuodeng ham processing

The effects of changes in lipids on the formation of Zn-protoporphyrin (ZnPP) during the processing of Nuodeng ham were analyzed using a lipidomics approach based on UHPLC-MS/MS. The Nuodeng ham samples had a strong fluorescence emission peak at 590 nm, and the fluorescence intensity increased with the processing time. Lipid profiles were mainly affected by processing time. A total of 5 lipid classes were detected, of which glycerophospholipids (GP) and glycerolipids (GL) were the most abundant lipids. Fifty differential lipid compounds were screened, which were mainly GP and GL. Correlation analysis showed that 13 differential lipid compounds were significantly positively correlated with ZnPP content, and they contained more linoleic acid and oleic acid branch chains. Meanwhile, all triglycerides (TG) were negatively correlated with heme content, and they were enriched in stearic acid and palmitic acid branch chains. These findings can deepen the understanding of the relationship between ZnPP and lipids.

Synthesis, Optical, spectral and hardness properties of the novel Crystal: L-Arginium 5-Sulfosalicylate

An organic crystal L-Arginium 5-Sulfosalicylate (A5SA) was created by a slow evaporation method. The X-ray diffraction (XRD) analysis confirmed the novel cell parameters, a = 12.60 Å, b = 7.18 Å, c = 15.12 Å. The UV absorbance spectrum has a low cut-off wavelength at 243 nm. Optical bandgap of the crystal is 5.10 eV which matches with the Tauc’s Plot. The fluorescence emission peak at 609 nm shows that the crystal emits orange luminescence. Fourier Transform Infrared (FTIR) and Raman (FT-Raman) analyses were used to analyse the spectrum investigations. The microhardness test confirmed that the grown crystal belongs to soft material category.

Molecularly designed and synthesized of bright blue nitrogen-doped lignin-derived carbon dots applied in printable anti-counterfeiting

With the increased demand for green and sustainable development, the research of advanced biomass-based carbon dots (CDs) has drawn growing attention. Herein, a one-step green solvent integration strategy-assisted solvothermal method to preparing CDs from hydrolyzed lignin and ethylenediamine (EDA) in formamide (FA) was developed. The Schiff reaction between FA and EDA contributes to the formation of -C-N groups, further inducing the high photoluminescence quantum yield (up to 42.69 %)，obviously higher than NCDs prepared in H2O, EtOH and DMF systems (corresponding to H-NCDs, E-NCDs and D-NCDs, respectively). The analysis of structure, composition, photoluminescence (PL) behaviors and DFT calculations showed that F-NCDs have main blue fluorescent emission peak from 410 to 455 nm under 330–390 nm excitation due to the small sp2 structure in carbon core, and the large sp2 conjugated clusters and CO group related surface states leaded to the long wavelength emission. The F-NCDs with excellent optical properties was further used for preparing fluorescent film and invisible anti-counterfeiting ink, which exhibited outstanding fluorescence even at different temperatures and aging times. We provided a facile way for green facile preparation of lignin-based CDs and their sustainable anti-counterfeiting application.

Morphological and lipid metabolism alterations in macrophages exposed to model environmental nanoplastics traced by high-resolution synchrotron techniques.

The release of nanoplastics (NPs) in the environment is a significant health concern for long-term exposed humans. Although their usage has certainly revolutionized several application fields, at nanometer size, NPs can easily interact at the cellular level, resulting in potential harmful effects. Micro/Nanoplastics (M/NPs) have a demonstrated impact on mammalian endocrine components, such as the thyroid, adrenal gland, testes, and ovaries, while more investigations on prenatal and postnatal exposure are urgently required. The number of literature studies on the NPs' presence in biological samples is increasing. However, only a few offer a close study on the model environmental NP-immune system interaction exploited by advanced microscopy techniques. The present study highlights substantial morphological and lipid metabolism alterations in human M1 macrophages exposed to labeled polypropylene and polyvinyl chloride nanoparticles (PP and PVC NPs) (20 μg/ml). The results are interpreted by advanced microscopy techniques combined with standard laboratory tests and fluorescence microscopy. We report the accurate detection of polymeric nanoparticles doped with cadmium selenide quantum dots (CdSe-QDs NPs) by following the Se (L line) X-ray fluorescence emission peak at higher sub-cellular resolution, compared to the supportive light fluorescence microscopy. In addition, scanning transmission X-ray microscopy (STXM) imaging successfully revealed morphological changes in NP-exposed macrophages, providing input for Fourier transform infrared (FTIR) spectroscopy analyses, which underlined the chemical modifications in macromolecular components, specifically in lipid response. The present evidence was confirmed by quantifying the lipid droplet (LD) contents in PP and PVC NPs-exposed macrophages (0-100 μg/ml) by Oil Red O staining. Hence, even at experimental NPs' concentrations and incubation time, they do not significantly affect cell viability; they cause an evident lipid metabolism impairment, a hallmark of phagocytosis and oxidative stress.

Green synthesis of biomass derived carbon dots via microwave-assisted method for selective detection of Fe3+ ions in an aqueous medium

Heavy metal ion represents the most serious issues to the environment and human beings. Detection and removal of heavy metal ions in the water bodies are essential. Generally, carbon dots are used as a good fluorescence sensor to sense heavy metal ions. In the present study, Papaya seeds are successfully modified into water-soluble carbon dots by one-step microwave-assisted method. Synthesised carbon dots average size was about 1.45 nm with spherical shape analysed by HRTEM and the presence of decorated functional groups was analysed by FTIR. Papaya seeds carbon dots (PPYCDs) emit bright blue colour under UV radiation. PPYCDs emits a fluorescence emission peak at 405 nm with an excitation wavelength of 335 nm. PPYCDs have the greatest quenching efficiency with Fe3+ ions and display a rapid and good sensitivity due to the decorated functional groups present on them. The Fe3+ ions detection limit was about 2.35 μMol and these ecofriendly carbon dots being synthesised by a simple procedure without any complicated instrumentation and toxic reagents, paves a way for the sensor applications effectively.

Computational identification of key residues regulating fluorescence emission in a red/green cyanobacteriochrome.

Cyanobacteriochromes (CBCRs) are linear tetrapyrrole bilin-binding photoreceptors of cyanobacteria that exhibit high spectral diversity, gaining attention in optogenetics and bioimaging applications. Several engineering studies on CBCRs were attempted, especially for designing near-infrared (NIR) fluorescent proteins with longer fluorescence wavelengths. However, despite continuous efforts, a key component regulating fluorescence emission property in CBCRs is still poorly understood. As a model system, we focused on red/green CBCR Slr1393g3, from the unicellular cyanobacterium Synechocystis sp. PCC 6803 to engineer Pr to get far-red light-emitting property. Energy profiling and pairwise structural comparison of Slr1393g3 variants effectively reveal the mutations that are critical to the fluorescence changes. H497 seems to play a key role in stabilizing the chromophore environment, especially the α3 helix, while H495, T499, and Q502 are potential key residues determining fluorescence emission peak wavelength. We also found that mutations of α2 and α4 helical regions are closely related to the chromophore binding stability and likely affect fluorescence properties. Taken together, our computational analysis suggests that the fluorescence of Slr1393g3 is mainly controlled by the stabilization of the chromophore binding pocket. The predicted key residues potentially regulating the fluorescence emission property of a red/green CBCR will be advantageous for designing improved NIR fluorescent protein when combined with in vitro molecular evolution approaches.

Design and Analysis of Rapid Production Single Wall Carbon Nanotube Sensor Platforms

Single-wall carbon nanotubes (SWNT) have a strong and stable near-infrared (nIR) signal and can interact with target analytes selectively, even at the single molecule level, to alter fluorescence intensity and/or emission peak wavelength. SWNT have been employed as nIR optical sensors for detecting a variety of analytes. However, high cost, long fabrication time, and poor fluorescence yield limit the current methods for immobilizing SWNT sensors on solid substrates. Recently, our group reported a protocol for SWNT immobilization resulting in high fluorescence yield, signal longevity, fluorescence distribution, and quick sensing response time. However, it takes 5 days to fabricate these sensor arrays. We have improved our previously reported protocol to immobilize SWNT sensors with a method that takes only 2 days, results in a platform with similar surface morphology, and has a higher fluorescence intensity than the previous platforms without sacrificing the sensing capabilities.

Multi-colorful ratio fluorescent biosensing of β-glucosidase activity based on the rapidly synthetic gold nanoclusters

Given the undeniable importance of robust analysis of β-glucosidase (β-GLU) activity in clinical diagnosis and therapeutics applications, in this work, a multi-colorful ratio fluorescent assay for monitoring β-GLU activity by applying gold nanoclusters (AuNCs) as the probes was proposed. The AuNCs were prepared via a convenient chemical reduction procedure within 15 min at 70 °C. In the catalytic system of enzymatic substrate 3-indoxyl-β-D-glucopyranoside (IDG) and β-GLU, the generations of hydrogen peroxide (H2O2) and fluorescent indoxyl oxidation product (op-ID) were demonstrated. The generated op-ID exhibited a fluorescence emission peak at 478 nm, and H2O2 quenched the fluorescence of AuNCs at 645 nm, forming a typical ratio fluorescence and multiple fluorescence color change responses to β-GLU. The ratio sensing platform determined β-GLU activity with a limit of detection (LOD) as low as 0.051 U/L. Further, β-GLU activity could also be detected in real human serum samples using the prepared biosensor. This sensing strategy was also used to construct a simple and low-cost hydrogel kit for portable monitoring of β-GLU activity, holding great potential for point-of-care testing of β-GLU-related clinical investigation.

Design of two different functional molecular logic devices based on hybrid fluorescence resonance­electron exchange energy transfer

Faster and more convenient construction of different functional multi-input–multi-output molecular logic devices has become a current research hotspot. In this study, a complex was synthesized using bovine serum albumin (BSA) and hydrazide dihydroxydisalicylaldehyde by a combinatorial approach. Then, the interaction mechanism was investigated by fluorescence spectroscopy and molecular simulation. Both methods revealed that the interaction between BSA and hydrazide dihydroxydisalicylaldehyde mainly occurred at site I of BSA. The main types of interactions included hydrogen bonding and van der Waals forces. Based on hybridized fluorescence resonance and electron exchange energy transfer, the complex generated two fluorescence emission peaks. Then, a digital comparator and a molecular logic circuit were designed using different metal ions or pH to modulate the output signals. Notably, the apparent increase in the fluorescence lifetime of the donor serves as an important basis for electron exchange between the donor and the acceptor.

Smartphone-Enabled Fluorescence and Colorimetric Platform for the On-Site Detection of Hg2+ and Cl- Based on the Au/Cu/Ti3C2 Nanosheets.

Smartphone-assisted fluorescence and colorimetric methods for the on-site detection of Hg2+ and Cl- were established based on the oxidase-like activity of the Au-Hg alloy on the surface of Au/Cu/Ti3C2 NSs. The Au nanoparticles (NPs) were constructed via in-situ growth on the surface of Cu/Ti3C2 NSs and characterized by different characterization techniques. After the addition of Hg2+, the formation of Hg-Au alloys could promote the oxidization of o-phenylenediamine (OPD) to generate a new fluorescence emission peak of 2,3-diaminopenazine (ADP) at 570 nm. Therefore, a turn-on fluorescence method for the detection of Hg2+ was established. As the addition of Cl- can influence the fluorescence of ADP, the fluorescence intensity was constantly quenched to achieve the continuous quantitative detection of Cl-. Therefore, a turn-off fluorescence method for the detection of Cl- was established. This method had good linear ranges for the detection of Hg2+ and Cl- in 8.0-200.0 nM and 5.0-350.0 µM, with a detection limit of 0.8 nM and 27 nM, respectively. Depending on the color change with the detection of Hg2+ and Cl-, a convenient on-site colorimetric method for an analysis of Hg2+ and Cl- was achieved by using digital images combined with smartphones (color recognizers). The digital picture sensor could analyze RGB values in concentrations of Hg2+ or Cl- via a smartphone app. In summary, the proposed Au/Cu/Ti3C2 NSs-based method provided a novel and more comprehensive application for environmental monitoring.

Synthesis of Fluorescent Carbon Dots from Soybean Residuals Using Hydrothermal Method

Soybean residuals are biowaste composed of carbon chains and amine groups bounded in peptide linkages. The component was identified through FTIR analysis which showed the vibration of the diamide bond (N=C=N) at wave number 2132cm-1. Owing to the existence of these components, soybean has the potential to be used as a precursor to synthesize carbon nano-material, such as Carbon Dots (C - Dots). In this study, the synthesis of C - Dots material from soybean residuals was carried out using the facile hydrothermal method at a temperature of 200 oC for 6 hours. Afterward, the as-synthesized C - Dots were analyzed for their optical property, structure, and morphology. Based on the analysis of the UV - Vis and photoluminescent spectra, C - Dots exhibited absorbance peaks of 292 nm and 301 nm in the UV light region, and fluorescence emission peaks of 468 nm, with blue luminescence characteristics. The observation was supported by the morphological analysis using the HR - TEM, C - Dots exist in a spherical shape with an average particle size of 3.467 nm and a lattice distance of 0.363 nm. Besides, the C - Dots exhibited a good quantum yield of 28.15 %. From the results of the analysis, it is known that the synthesis of C - Dots material has been successfully carried out with particle size < 10 nm.

SMART RHESINs-Superparamagnetic Magnetite Architecture Made of Phenolic Resin Hollow Spheres Coated with Eu(III) Containing Silica Nanoparticles for Future Quantitative Magnetic Particle Imaging Applications.

Magnetic particle imaging (MPI) is a powerful and rapidly growing tomographic imaging technique that allows for the non-invasive visualization of superparamagnetic nanoparticles (NPs) in living matter. Despite its potential for a wide range of applications, the intrinsic quantitative nature of MPI has not been fully exploited in biological environments. In this study,a novel NP architecture that overcomes this limitation by maintaining a virtually unchanged effective relaxation (Brownian plus Néel) even when immobilized is presented. This superparamagnetic magnetite architecture made of phenolic resin hollow spheres coated with Eu(III) containing silica nanoparticles (SMART RHESINs)wassynthesized and studied. Magnetic particle spectroscopy (MPS) measurements confirm their suitability for potential MPI applications. Photobleaching studies show an unexpected photodynamic due to the fluorescence emission peak of the europium ion in combination with the phenol formaldehyde resin (PFR). Cell metabolic activity and proliferation behavior are not affected. Colocalization experiments revealthe distinct accumulation of SMART RHESINs near the Golgi apparatus. Overall, SMART RHESINs show superparamagnetic behavior and special luminescent properties without acute cytotoxicity, making them suitable for bimodal imaging probes for medical use like cancer diagnosis and treatment. SMART RHESINs have the potential to enable quantitative MPS and MPI measurements both in mobile and immobilized environments.

A near-infrared AIEE fluorescent chemosensor for Cu2+ through an IPT process

A near-infrared AIEE fluorescent chemosensor 2-(2-(4-(((3-methyl-5-oxo-1- phenyl-4,5-dihydro-1H-pyrazol-4-yl)methylene)amino)styryl)-4H-chromen-4-ylidene)malono- nitrile (HL1) was synthesized. In DMSO solution, HL1 showed fluorescence emission at 570 nm, and the fluorescence emission peak red shifted to 675 nm with the addition of H2O, which was attributed to the tautomerism of ketone (K) and enol (E) caused by intramolecular proton transfer (IPT) and aggregation-induced emission enhancement (AIEE). For comparison, 2-(2-(4-(((1-phenyl-1H-pyrazol-4-yl)methylene)amino)styryl)-4H-chromen-4-ylidene)malononitrile (HL) without CO was synthesized. The results show that HL cannot coordinate with metal ions due to the absence of CO, but AIEE effect also exists. The sensor HL1 can coordinate with Cu2+ to cause fluorescence quenching in the near-infrared region, and the fluorescence intensity recovered after the addition of Na2EDTA, indicating that the probe HL1 can reversibly recognize Cu2+. Job's curve showed that the stoichiometric ratio of HL1 to Cu2+ was 1:1, and the detection limit for Cu2+ could reach at 4.68 × 10-8·mol•L-1 level. The experimental results are verified by theoretical calculation. In addition, the probe HL1 can be used to detect Cu2+ in actual drinking water.

Ziziphus spina-christi Leaf-Derived Carbon Dots as a Fluorescence Nanosensor to Evaluate Rifaximin Antibacterial via Inner Filter Effect: Greenness and Whiteness Studies

Rifaximin (RFX) is a non-absorbable antibiotic with broad-spectrum efficacy. It treats travelers’ diarrhea, irritable bowel syndrome, non-systematic bacterial diarrhea, bowel infections, overgrowth syndrome, and enteric infections. In this work, carbon dots prepared from Ziziphus spina-christi leaves’ powders are utilized as a green fluorometric biosensor for the assessment of RFX. The morphological lineaments of the prepared carbon dots were recognized by using TEM and SEM techniques. The prepared carbon dots manifest a fluorescence emission peak at 432 nm after an excitation fluorescence peak at 366 nm. The absorbance band of RFX (absorbance peaks at 370 nm and 443 nm) could be thoroughly overlapped with fluorescence excitation/emission bands of the produced carbon dots. A fluorometric tool has been designed and validated for the evaluation of RFX reliant on the inner filter effect methodology, in which the produced carbon dots act as an inner filter effect fluorophore and RFX as an inner filter effect absorber. The quenching degree in the fluorescence activity of the prepared carbon dots depended on the concentration of RFX. The analytical parameters were checked and directed for successfully applied assessment of RFX concentration in different pharmaceutical formulations. The proposed tool’s greenness and eco-friendliness profile was evaluated using the most recent greenness assessment tool, which is the complementary green analytical procedure index (Complex-GAPI) and the Analytical GREEnness metric (AGREE). Additionally, using the recently released White Analytical Chemistry (WAC) tool, the whiteness characteristic—which indicated the method’s sustainability—was investigated.