Variation Of Fluorescence Intensity Research Articles

Evaluation and optimization of measurement conditions for heavy ions with fluorescent nuclear track detectors.

In applying fluorescent nuclear track detectors for heavy ion measurement, the fluorescence intensity directly influences linear energy transfer (LET) estimation. However, the conventional analysis highly depends on the analyzed depth and the reference frames from the optical readout. To improve the accuracy of measurements of heavy ions, the gradient of intensity and moving average fluorescence intensity were acquired and calculated to optimize the measurement conditions. The results indicate that the intensity gradient is an alternative quantity to discriminate ions with different LET, and the moving average fluorescence intensity is readily differentiated among individual ions without overlapping values in fluorescence intensity. The scanned range of 25-45μm is suggested to be the most suitable depth for measurement. To exclude the impact of the variation in fluorescence intensity on evaluation, it is recommended to use the quantities calculated in moving averages with depth in the future.

No two clones are alike: characterization of heterologous subpopulations in a transgenic cell line of the model diatom Phaeodactylum tricornutum

BackgroundConjugation-based episome delivery is a highly efficient method used to transfer DNA into the diatom Phaeodactylum tricornutum, facilitating the production of recombinant proteins and high-value metabolites. However, previous reports have indicated phenotypic heterogeneity among individual cells from clonally propagated exconjugant cell lines, potentially affecting the stability of recombinant protein production in the diatom.ResultsHere, we characterized the differences between subpopulations with distinct fluorescence intensity phenotypes derived from a single exconjugant colony of P. tricornutum expressing the enhanced green fluorescent protein (eGFP). We analyzed the expression cassette sequence integrity, plasmid copy number, and global gene expression. Our findings reveal that lower copy numbers and the deletion of the expression cassette in part of the population contributed to low transgene expression. Gene co-expression analysis identified a set of genes with similar expression pattern to eGFP including a gene encoding a putative Flp recombinase, which may be related to variations in fluorescence intensity. These genes thus present themselves as potential candidates for increasing recombinant proteins production in P. tricornutum episomal expression system.ConclusionsOverall, our study elucidates genetic and transcriptomic differences between distinct subpopulations in a clonally propagated culture, contributes to a better understanding of heterogeneity in diatom expression systems for synthetic biology applications.

A-173 Evaluation of Artificial Intelligence (AI)-assisted Flow Cytometry Analysis for Plasma Cell Neoplasms

Abstract Background Flow cytometry plays a critical role in diagnosing hematologic disorders, yet manual analysis is time-consuming and prone to variability. Significant advancements in artificial intelligence (AI) within healthcare have occurred in recent years. Previously, we developed and evaluated an AI-assisted automated system for diagnosing acute leukemia. This study aims to assess the effectiveness of the AI system in diagnosing plasma cell neoplasms. Methods A total of 76 bone marrow samples were analyzed using a panel of antibodies (CD38, CD56, CD138, Kappa, and Lambda) to determine plasma cell percentages and immunophenotype. All samples were used for initial diagnosis of plasma cell neoplasm or therapeutic monitoring. Manual analysis using Kaluza™ software served as the gold standard. The same flow cytometry data was processed by the AI software (DeepFlow™) for comparison. Pearson correlation coefficients were used to compare AI and manual analysis for diagnosis and plasma cell count. Results Among the 76 cases, manual analysis identified 57 positive cases for monoclonal plasma cells (36 cases of CD38+/CD138+/Kappa+ and 21 cases of CD38+/CD138+/Lambda+), with 89% showing aberrant CD56 expression. AI identified 49 monoclonal cases, missing 8 cases with low plasma cell levels (<0.07%) or brighter fluorescence. AI accurately matched 97% of immunophenotypes with manual analysis. Pearson correlation coefficients demonstrated excellent correlation (r=1.0) between manual and AI plasma cell percentages. Furthermore, AI has also enhanced laboratory efficiency, reducing analysis time per case from 10 minutes with manual methods to just 3 minutes with AI analysis. Conclusions This study shows promise for AI-assisted flow software in diagnosing plasma cell neoplasms. AI has enhanced operational efficiency by reducing the manual processing and analysis time. Further training is needed to improve the identification of variations in fluorescence intensity and low plasma cell levels.

HYDROTHERMAL SYNTHESIS OF NITROGEN-DOPED CQDS OF RUBUS NIVEUS LEAVES FOR FLUORESCENT pH SENSING AND PHOTOCATALYTIC APPLICATIONS

The development of a fluorescent pH sensor and the treatment of wastewater with nanoparticles are both critical topics. The variation in pH impacts the morphology and subsequent properties of the nanoparticles, which are used for their utilization in various fields and the second one gives a better treatment approach for industrial waste entities. The present study examines the effects of these variables on the biologically produced nitrogen-doped carbon quantum dots (NCQDs). Hydrothermal process was performed for the synthesis of the same by using Rubus-niveus leaf extract as a precursor. The UV-Vis spectroscopy analysis shows absorption spectra in the wide range of 200 nm to 800 nm and shows prominent peaks at 236 nm and 392 nm, respectively. Further, the direct energy band gap of 3.65eV was analysed for NCQDs. The SEM image shows flower-shaped particles, and FT-IR analysis indicates the existence of amide, CHO, N-H, and C-N functional groups. XRD pattern showed that the surface morphology of NCQDs is amorphous in nature. A good response was found in the variation of fluorescence intensity with the pH values, confirming the possibility of NCQDs serving as pH sensors. Rhodamine-B (Rh-B) dye's reaction kinetics was revealed for the purpose of analyzing the potential of NCQDs for the degradation of commercial dyes and found to be followed by pseudo-first order kinetics with the correlation coefficient of 0.80.

An all-in-one smartphone-assisted ratiometric fluorescent device for visual and quantitative detection of glutathione

The daily consumption of foods abundant in Glutathione (GSH) can be supplemented to maintain the homeostasis of GSH in human health and alleviate pathologies resulting from abnormal GSH levels. The fluorescence-based visual determination of GSH has gradually attracted the attention of researchers due to its robust performance and versatile implementation. However, the current GSH visual strategy primarily relies on variations in fluorescence intensity at a single emission wavelength, which poses challenges for naked-eye and portable readout, as well as distorted signals caused by complex matrix effects in real samples. Herein, a ratiometric fluorescence sensor based on carbon dots (CDs) combined with an all-in-one 3D-printed smartphone-based device was successfully developed for low-cost, visual and rapid detection of GSH without the need for an external excitation light source. The ratiometric fluorescent materials were synthesized by conjugating blue carbon dots (B-CDs) with yellow carbon dots (Y-CDs) through the utilization of selected Cu2+ ions. The resulting mechanism demonstrated that the coordination interaction between Cu2+ and residual aromatic amino groups in Y-CDs (Y-CDs-Cu2+) contributed to a newly emitted peak at 580 nm, thereby inducing fluorescence resonance energy transfer from B-CDs to Y-CDs-Cu2+. A linear correlation was found between GSH concentrations and R/B values in the range of 10–100 μM, with a limit of detection observed at 4.8 μM. By utilizing this portable device in combination with RGB analysis, the quantitative detection of GSH can be achieved even in complex food matrices such as tomatoes and grapes. The universality of this all-in-one device was further validated by pre-spraying CDs onto a paper strip for visual measurement of GSH. This work offers a portable, visual, and accessible approach to evaluating food safety and nutrition, thereby demonstrating significant economic value and holding profound implications for human health.

The Midas Touch by Internal Stimuli: Activatable Luminogens with Near‐Infrared Aggregation‐Induced Emission for Potent Bioimaging and Theranostics

AbstractAs a modality of optical imaging, fluorescence imaging of biochemical analytes holds significant potential in the field of disease diagnosis and therapy. However, the non‐responsive fluorophores are not able to selectively and sensitively detect lesions, resulting in a poor signal‐to‐background ratio and compromised accuracy. The utilization of activatable sensors, in contrast, is capable of effectively overcoming these limitations by displaying variations in fluorescence intensity and spectral wavelength in response to physiological parameters. Aggregation‐induced emission luminogens (AIEgens), particularly those emitting fluorescence in the near‐infrared (NIR, 700–1700 nm) window, have practical application prospects in disease theranostics due to their excellent photostability, deeper penetration depth, and enhanced fluorescence intensity in physiological environments. In this review, an overview of the advancements in research on NIR AIEgens for internal stimuli‐activated diagnosis and treatment of diseases is provided. The design principles of responsive NIR AIEgens and their biomedical applications are exemplified with representative examples, categorized based on the type of stimuli. Finally, the review concludes with a brief discussion of the challenges, opportunities, and future prospects of activatable NIR AIEgens in the field of disease photo theranostics.

Amyloidogenesis of SARS-CoV-2 delta plus and omicron variants receptor-binding domain (RBD): impact of SUMO fusion tag.

The RBD of SARS-CoV-2 mediates viral entry into host cells by binding to the host receptor ACE2. SARS-CoV-2 infection is linked to various health issues resembling amyloid-related problems, persuading us to investigate the amyloidogenicity of the SARS-CoV-2 spike RBD. The FoldAmyloid program was used to assess the amyloidogenic propensities in the RBD of Delta Plus and RBD of the Omicron variant, with and without the SUMO tag. After the expression of RBDs, purification, and dialysis steps were performed, subsequently the ThT assay, FTIR, and TEM were employed to check the RBD ability to form fibrils. The ThT assay, TEM, and FTIR revealed the ability of RBD to self-assemble into β-sheet-rich aggregates (48.4% β-sheet content). Additionally, the presence of the SUMO tag reduced the formation of RBD amyloid-like fibrils. The amyloidogenic potential of Omicron RBD was higher than Delta Plus, according to both in silico and experimental analyses. The SARS-CoV-2 RBD can assemble itself by forming aggregates containing amyloid-like fibrils and the presence of a SUMO tag can significantly decrease the formation of RBD amyloid-like fibrils. In silico analysis suggested that variation in the ThT fluorescence intensity of amyloid accumulations in the two SARS-CoV-2 strains arises from specific mutations in their RBD regions.

Static pressure response model of fluorescent pressure-sensitive film for underwater surface pressure measurement

The fluorescent pressure-sensitive film (FPSF) is a non-contact, deformation-based optical pressure sensor with high spatial resolution. The pressure response principle of FPSF is to convert pressure change into variations in fluorescent intensity through the deformation of fluorescent microspheres embedded within the film. To quantitatively analyze the pressure–deformation–intensity mechanism, a static pressure response model was established in this study. First, a finite element model was developed to predict the deformation of microspheres within the film under pressure. Second, the deformation-induced variation in fluorescent intensity was modeled with consideration of the light path blockage effect. The pressure calibration curve of the FPSF predicted by the proposed model was noted to be consistent with the experimental results of underwater calibration. In addition, the relationship between pressure sensitivity and the structural parameters of the FPSF were investigated using the pressure response model.

PH Sensitivity of YFPs is Reduced Upon AlphaRep Binding: Proof of Concept in Vitro and in Living Cells.

Yellow fluorescent proteins (YFPs) are commonly used in biology to track cellular processes, particularly as acceptors in experiments using the Förster Resonant Energy Transfer (FRET) phenomenon. However, their fluorescence intensity is strongly pH-dependent, limiting their utility in acidic environments. Here, we explore the pH sensitivity of YFPs upon binding with an artificial repeat protein (αRep) both in vitro and in living cells. We show that αRep binds to Citrine, with high affinity in the nanomolar range at physiological and acidic pHs, leading to increased thermal stability of the complex. Moreover, αRep binding reduces Citrine's pKa by 0.75 pH units, leading to a decreased sensitivity to pH fluctuations. This effect can be generalized to other YFPs as Venus and EYFP in vitro. An efficient binding of αRep to Citrine has also been observed in living cells both at pH 7.4 and pH 6. This interaction leads to reduced variations of Citrine fluorescence intensity in response to pH variations in cells. Overall, the study highlights the potential of αReps as a tool to modulate the pH sensitivity of YFPs, paving the way for future exploration of biological events in acidic environments by FRET in combination with a pH-insensitive cyan donor.

Dual-Function Wearable Hydrogel Optical Fiber for Monitoring Posture and Sweat pH.

In recent years, wearable devices have been widely used for human health monitoring. Such monitoring predominantly relies on the principles of optics and electronics. However, electronic detection is susceptible to electromagnetic interference, and traditional optical fiber detection is limited in functionality and unable to simultaneously detect both physical and chemical signals. Hence, a wearable, embedded asymmetric color-blocked optical fiber sensor based on a hydrogel has been developed. Its sensing principle is grounded in the total internal reflection within the optical fiber. The method for posture sensing involves changes in the light path due to fiber bending with color blocks providing wavelength-selective modulation by absorption changes. Sweat pH sensing is facilitated by variations in fluorescence intensity triggered by sweat-induced conformational changes in Rhodamine B. With just one fiber, it achieves both physical and chemical signal detection. Fabricated using a molding technique, this fiber boasts excellent biocompatibility and can accurately discern single and multiple bending points, with a recognition range of 0-90° for a single segment, a detection limit of 0.02 mm-1 and a sweat pH sensing linear regression R2 of 0.993, alongside great light propagation properties (-0.6 dB·cm-1). With its extensive capabilities, it holds promise for applications in medical monitoring.

Silica-supported indole derived fluorometric chemosensor for the selective detection of Ag+ ions in aqueous solution

A novel organic-inorganic hybrid nanomaterial-based fluorescent chemosensor was synthesized by functionalizing rice husk-derived nanosilica with 3-(aminopropyl)triethoxysilane (APTES) and then grafting it with para-aminobenzoic acid, benzaldehyde, and indole organic moieties, respectively, to detect Ag+ ions in the aqueous medium. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), fluorescence spectroscopic techniques, and thermogravimetric analysis (TGA) were used to characterize the synthesized material. The synthesized ligand showed highly selective and sensitive fluorescence-enhanced, "Turn-ON" chemosensor activity towards Ag+ ions at an excitation wavelength of 355 nm, with observable variations in fluorescence intensity compared to other metal ions. The detection limit for Ag+ was 1.94 × 10−4 M, and the limit of quantification was calculated as 6.49 × 10−4 M. These findings suggest that the silica-supported indole derivative (Indole-APTES@nanosilica) can be utilized as a sensitive and selective, Turn-ON fluorometric chemosensor for detecting Ag+ ions.

Visualizing dynamic interactions between mitochondria and lysosomes in living cells using novel pH-sensitive fluorescent probes in dual-channel

The neutral fluorescent probes 1a-1c based on D-π-A-π-D structure, with benzopyranoquinoline as the fluorophore and the electron-donating groups at both ends, were developed, which emitted dual-channel fluorescence in different pH environments. Among them, probe 1a with both N,N-diethyl group and morpholine ring as electron-donating groups exhibited the best fluorescence performance, showing a red shift of 85 nm in dual emission at 505 nm and 590 nm, and a Stokes shift of 95 nm in both channels. The neutral 1a displayed green fluorescence specifically targeting mitochondria, while the protonated form 1a+H+ resulting in red fluorescence localized in lysosomes. The ability to distinguish healthy and pathological cells such as cancer or inflammation could be achieved by observing the differences in red fluorescence within lysosomes. Probe 1a could migrate and retarget between mitochondria and lysosomes, and it was discovered by the physiological effects of chloral hydrate experiments. In addition, the dynamic changes in morphology and movement of mitochondria and lysosomes during cellular autophagy through the variation of fluorescence intensity in green and red channels induced by rapamycin and starvation conditions had been investigated deeply.

Hexagonal Boron Nitride Spacers for Fluorescence Imaging of Biomolecules

AbstractFluorescence imaging is an invaluable tool to investigate biomolecular dynamics, mechanics, and interactions in aqueous environments. Two‐dimensional materials offer large‐area, atomically smooth surfaces for wide‐field biomolecule imaging. Despite the success of graphene for on‐chip biosensing and biomolecule manipulation, its strong fluorescence‐quenching properties pose a challenge for biomolecular investigations that are based on direct optical readouts. Here, we employ few‐layer hexagonal boron nitride (hBN) as a precisely tailorable fluorescence spacer between labelled lipid membranes and graphene substrates. By stacking high‐quality hBN crystals in the 10–20 nm thickness range on monolayer graphene, we observe distance‐dependent fluorescence intensity variations. Remarkably, with hBN spacers as thin as 20 nm, the fluorescence intensity is comparable to bare SiO2/Si substrates, while the intensity was reduced to 60 % and 80 % with ~10 nm and ~16 nm hBN thicknesses respectively. We confirm that pre‐determined hBN thicknesses can be employed to control the non‐radiative energy transfer properties of graphene, with fluorescence quenching following a d−4 distance‐dependent behaviour. This seamless integration of electronically active and dielectric van der Waals materials into vertical heterostructures enables multifunctional platforms addressing the manipulation, localization, and visualization of biomolecules for fundamental biophysics and biosensing applications.

The Brown Sugar Mediated Carbon Quantum Dots as a Novel Fluorescence Sensor for Sensitive Detection of Gentamicin and Its Application in Foods.

In this work, a novel fluorescence sensing strategy was proposed for the detection of gentamicin based on fluorescent carbon quantum dots (CQDs) and gold nanoparticles (AuNPs). Herein, the CQDs were green-synthesized for the first time via a one-step hydrothermal method utilizing brown sugar as the precursor. In the presence of citrate-stabilized AuNPs, the fluorescence of CQDs was quenched efficiently. Gentamicin, on the other hand, had a higher affinity for AuNPs and was able to compete with CQDs for a preferential binding to AuNPs, which ultimately led to the aggregation of AuNPs and freeing of CQDs in solution, causing the fluorescence recovery of CQDs. Based on the above phenomenon, the concentrations of gentamicin could be ascertained by detecting the variations in fluorescence intensity of CQDs. This sensing strategy exhibited excellent selectivity in various antibiotics. At the same time, the method displayed outstanding sensitivity for gentamicin, which was successfully applied to real samples detection.

Dual-signal readout sensing of ATP content in single dental pulp stem cells during differentiation via functionalized glass nanopipettes

Adenosine triphosphate (ATP) is regarded as the “energy currency” in living cells, so real-time quantification of content variation of intracellular ATP is highly desired for understanding some important physiological processes. Due to its single-molecule readout ability, nanopipette sensing has emerged as a powerful technique for molecular sensing. In this study, based on the effect of targeting-aptamer binding on ionic current, and fluorescence resonance energy transfer (FRET), we reported a dual-signal readout nanopipette sensing system for monitoring ATP content variation at the subcellular level. In the presence of ATP, the complementary DNA-modified gold nanoparticles (cDNAs-AuNPs) were released from the inner wall of the nanopipette, which leads to sensitive response variations in ionic current rectification and fluorescence intensity. The developed nanopipette sensor was capable of detecting ATP in single cells, and the fluctuation of ATP content in the differentiation of dental pulp stem cells (DPSCs) was further quantified with this method. The study provides a more reliable nanopipette sensing platform due to the introduction of fluorescence readout signals. Significantly, the study of energy fluctuation during cell differentiation from the perspective of energy metabolism is helpful for differentiation regulation and cell therapy.

Hydrogel coatings on universal medical devices with water-responsive Janus adhesion and acidity-triggered transformation for adaptive antibacterial treatment and fluorescence diagnosis

Hydrogel coatings of catheters have attracted extensive attention in the field of medical devices due to its hydrophilicity and softness, while scarcities of Janus adhesion, adaptive antibacterial property, and real-time disease monitoring restricted their clinical translational applications. Herein, a novel hydrogel coating with water-responsive Janus adhesion and acidity-triggered transformation was fabricated for antibacterial treatment and fluorescence diagnosis of catheters-associated infections. First, a sufficient adhesion strength of 44.6 ± 1.9 kPa effectively prevented shedding of the hydrogel coating during catheterization, and meanwhile a super-lubricated layer with an extremely-low coefficient of friction of about 0.03 was formed to reduce friction pain in an aqueous microenvironment. Furthermore, size and fluorescence intensity of chitosan/bovine serum albumin-gold nanoparticles within the hydrogel were varied with pH due to acidity-triggered transformation, where an adaptive release of antibacterial nanoparticles was achieved to reduce biofilms formation and alleviate inflammation degree synergistically. More importantly, such antibacterial treatment was monitored in real-time dependent on an on–off variation of fluorescence intensity. Overall, amounts of in-vitro and in-vivo results performed in rabbit urinary tract infection model and porcine tracheal intubation model fully suggested our newly-synthesized hydrogel coating on universal medical devices showed a promising potential for integrated diagnosis and treatment of catheters-associated infections.

CellBoost: A pipeline for machine assisted annotation in neuroanatomy

One of the important yet labor intensive tasks in neuroanatomy is the identification of select populations of cells. Current high-throughput techniques enable marking cells with histochemical fluorescent molecules as well as through the genetic expression of fluorescent proteins. Modern scanning microscopes allow high resolution multi-channel imaging of the mechanically or optically sectioned brain with thousands of marked cells per square millimeter. Manual identification of all marked cells is prohibitively time consuming. At the same time, simple segmentation algorithms to identify marked cells suffer from high error rates and sensitivity to variation in fluorescent intensity and spatial distribution.We present a methodology that combines human judgement and machine learning that serves to significantly reduce the labor of the anatomist while improving the consistency of the annotation.As a demonstration, we analyzed murine brains with marked premotor neurons in the brainstem. We compared the error rate of our method to the disagreement rate among human anatomists. This comparison shows that our method can reduce the time to annotate by as much as ten-fold without significantly increasing the rate of errors. We show that our method achieves significant reduction in labor while achieving an accuracy that is similar to the level of agreement between different anatomists.

A wireless fluorescent flexible force sensor based on aggregation-induced emission doped liquid crystal elastomers.

Flexible strain sensors have drawn a lot of interest in various applications including human mobility tracking, rehabilitation/personalized health monitoring, and human-machine interaction, but suffer from interference of electromagnetic (EM). To overcome the EM interference, flexible force sensors without sensitive electronic elements have been developed, with drawbacks of bulky modules that hinders their applications in remote measurement with power-free environment. Therefore, it is highly desirable to fabricate a compact wireless flexible force sensor but it is still a challenge. Here, we demonstrate a fluorescent flexible force sensor based on aggregation-induced emission (AIE) doped liquid crystal elastomer (LCE) experimentally. The proposed force sensor film can be used to measure force through the variation of fluorescent intensity induced by the extension or contraction of LCE film, which leads to reduce or increase of the aggregation degree of AIE molecules within. This compact wireless force sensor features lightweight, low-cost, high flexibility, passivity and anti-EM interference, which also enables the naked eye observation. The proposed sensor provides inspiration and a platform for a new concept of non-contact detection, showing application potential in human-friendly interactive electronics and remote-control integration platform.

Preparation of Artemisia sphaerocephala Krasch. gum gel and ammonia fluorescence response mechanism based on peeling-off reaction

The release of hazardous NH3 toxic gas poses a significant threat to both the environment and human health, necessitating the development of materials capable of detecting NH3. This research focuses on the design of a fluorescent gel derived from the peeling-off reaction of Artemisia sphaerocephala Krasch. gum (ASKG). The variations in fluorescence intensity were examined for gels produced under different conditions of pH and adsorption capacity of NH3. The fluorescence response mechanism concerning NH3 and pH value was investigated through analysis of fluorescent lifetime, FT-IR, X-ray XPS, and GPC. Dextran was employed to validate this mechanism. The ASKG gel exhibited a rapid response to NH3 gas, and the fluorescence intensity demonstrated a linear correlation with the cumulative adsorption of NH3 gas. Pseudo-first-order kinetics was applied to analyze the adsorption system of the ASKG gel, revealing a maximum adsorption capacity of 0.03476 g/g for NH3. The practical application of the ASKG gel was demonstrated through a fish spoilage experiment.

Protein – Metal ion Interaction: A Spectroscopic Study

This study reports on the spectroscopic interaction studies of mercuric chloride LYZ. The quencher concentration was maintained in the range of 0–6.25 µM. At the studied concentration range (10-6 M), LYZ did not have any variation in fluorescence intensity. Increase in LYZ concentration to 10-3 M showed a decrease in the fluorescence intensity due to the involvement of nucleophilic functional group. The fluorescence of LYZ was quenched to a large extent depending on the protein solution pH (2.2, 4.5, and 7.4).At all the studied pH, emission spectra showed blue shift. The onset and the shift varied with solution pH. Stern-Volmer analysis showed a three stage transition At pH 7.4, the presence of HgCl2 did not have much influence on the amide bands. But at pH 4.5, the amide I band showed a shift to lower wavenumber These confirmed that the quenching takes place through both static and energy transfer processes.