Fluorescent Reaction Research Articles

An Acid-Activatable Fluorescent Probe for Sulfur Dioxide in Traditional Chinese Medicines and Living Cells.

Excessive sulfur dioxide (SO₂) disturbs physiology of lysosomes causing diseases and threatening human health. A fluorescent probe has been regarded as one of the most attractive approaches, which is compatible with living cells and possesses high sensitivity. However, most of fluorescent probes' reaction sites are activated before they reach the destination. In this work, an acid-activatable fluorescent probe PT1 was synthesized, characterized, and used for SO2 detection. The introduction of oxazolines in PT1 enables the intelligent response of probe to release the activation stie for SO2 derivatives through Michael addition upon exposure to acid. In vitro studies showed a remarkable selectivity of PT1 to SO₂ derivatives than other biothiols with a limit of detection as low as 62 nM. By using this acidic pH-controlled fluorescence responsiveness to SO₂, precise spatiotemporal identification of lysosomal SO2 fluctuations has been successfully performed. Furthermore, probe PT1 can be applied for monitoring SO₂ derivatives in traditional Chinese medicines.

Probing Phoretic Transport of Oxidative Enzyme-Bound Zn(II)-Metallomicelle in Adenosine Triphosphate Gradient via a Spatially Relocated Biocatalytic Zone.

Although cellular transport machinery is mostly ATP-driven and ATPase-dependent, there has been a recent surge in understanding colloidal transport processes relying on a nonspecific physical interaction with biologically significant small molecules. Herein, we probe the phoretic behavior of a biocolloid [composed of a Zn(II)-coordinated metallomicelle and enzymes horseradish peroxidase (HRP) and glucose oxidase (GOx)] when exposed to a concentration gradient of ATP under microfluidic conditions. Simultaneously, we demonstrate that an ATP-independent oxidative biocatalytic product formation zone can be modulated in the presence of a (glucose + ATP) gradient. We report that both directionality and extent of transport can be tuned by changing the concentration of the ATP gradient. This diffusiophoretic mobility of a submicrometer biocolloidal object for the spatial transposition of a biocatalytic zone signifies the ATP-mediated functional transportation without the involvement of ATPase. Additionally, the ability to analyze colloidal transport in microfluidic channels using an enzymatic fluorescent product-forming reaction could be a new nanobiotechnological tool for understanding transport and spatial catalytic patterning processes. We believe that this result will inspire further studies for the realization of elusive biological transport processes and target-specific delivery vehicles, considering the omnipresence of the ATP-gradient across the cell.

Robust and low-cost open-source device for detecting infectious microorganisms by loop-mediated isothermal amplification

Loop-Mediated Isothermal Amplification (LAMP) is a useful technique for detecting infectious microorganisms in human fluids since it performs similarly to conventional PCR, the results are obtained faster and no thermocyclers or complex devices are required. Since only two isothermal blocks (95 °C to lyse cells and 65 °C for DNA amplification) are needed, LAMP is particularly suited for applications in Low- and Middle-Income Countries (LMICs). To validate such assumption, we first designed and tested Arduino-controlled LAMP thermoblocks to process a considerable number of samples simultaneously with a low-energy consumption to enable routine use under worst-case conditions (no main power source and low ambient temperatures).The thermoblocks were tested when battery-powered at temperature down to 5 °C, showing high stability in well temperatures (<0.8 °C). The charge required for both thermoblocks to simultaneously achieve the target temperatures after switching on and to keep their working temperatures were 4.1 A·h and 2.4 A·h/h, respectively. Second, we implemented a low-cost viewer with LEDs and filters to detect the fluorescent LAMP reaction. All the components required for the instrument are for general purpose and readily available by e-commerce. Thus, the LAMP device allows for considerable autonomy by using a typical car battery in rural and itinerant healthcare or field hospitals in LMICs, even under difficult environmental conditions.

Encapsulated inorganic pigments in epoxy composite microspheres using emulsion synthesis

Inorganic pigments are a commonly used colorant with various applications and promising prospects. However, the implement of organic pigments is hindered by poor dispersion stability in coatings due to non-uniform morphology and size. Herein, encapsulated pigments of Cobalt Chrome Green CoCr2O4 (PG 26), Cobalt Blue CoAl2O4 (PB 28), Titanium Chrome Yellow TiCrSbO6 (PB 24) in epoxy microspheres are obtained via an oil-in-water emulsion polymerization. The morphology, particle size, thermal properties, glass transition temperature (Tg) and color performance of the composite microspheres were characterized by different analytical techniques. The average particle size varied with pigments types and loadings. When the content of CoCr2O4 and CoAl2O4 is in the range of 15 wt%-30 wt%, and TiCrSbO6 content is between 15 wt%-25 wt%, the composite microspheres exhibit a narrow particle size distribution, regular morphology, and smooth surface. The size followed the rule of CoAl2O4/epoxy (20–26 μm) > CoCr2O4/epoxy (14-16μm) > TiCrSbO6/epoxy (6–9 μm). Besides, according to the aggregation-induced emission (AIE) principle, the relationship between fluorescence intensity and reaction time was investigated, thus deducing the curing process of the epoxy groups with m-xylenol dimethylamine (MXDA). The kinds of three inorganic fillers exhibit varying effects on the diffusion process of MXDA. TiCrSbO6 promotes the progress of the epoxy-amine curing reaction. Notably, CoCr2O4 microspheres exhibited stable green value (a*) and color saturation (C*), TiCrSbO6 microspheres showed increased yellow value (b*) and saturation (C*), and CoAl2O4 microspheres enhanced blue value (b*) with minimal change in lightness (L*). Overall, this study provides a comprehensive understanding of the properties of inorganic pigment/epoxy composite microspheres and highlights their potential for improved dispersion stability in coating applications.

Screening the Performance of a Reverse Osmosis Pilot-Scale Process That Treats Blended Feedwater Containing a Nanofiltration Concentrate and Brackish Groundwater.

A two-stage pilot plant study has been completed that evaluated the performance of a reverse osmosis (RO) membrane process for the treatment of feedwater that consisted of a blend of a nanofiltration (NF) concentrate and brackish groundwater. Membrane performance was assessed by monitoring the process operation, collecting water quality data, and documenting the blended feedwater's impact on fouling due to microbiological or organic means, plugging, and scaling, or their combination. Fluorescence and biological activity reaction tests were used to identify the types of organics and microorganisms present in the blended feedwater. Additionally, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to analyze suspended matter that collected on the surfaces of cartridge filters used in the pilot's pretreatment system. SEM and EDS were also used to evaluate solids collected on the surfaces of 0.45 µm silver filter pads after filtering known volumes of NF concentrate and RO feedwater blends. Water quality analyses confirmed that the blended feedwater contained little to no dissolved oxygen, and a significant amount of particulate matter was absent from the blended feedwater as defined by silt density index and turbidity measurements. However, water quality results suggested that the presence of sulfate, sulfide, iron, anaerobic bacteria, and humic acid organics likely contributed to the formation of pyrite observed on some of the membrane surfaces autopsied at the conclusion of pilot operations. It was determined that first-stage membrane productivity was impacted by the location of cartridge filter pretreatment; however, second-stage productivity was maintained with no observed flux decline during the entire pilot operation's timeline. Study results indicated that the operation of an RO process treating a blend of an NF concentrate and brackish groundwater could maintain a sustainable and productive operation that provided a practical minimum liquid discharge process operation for the NF concentrate, while the dilution of RO feedwater salinity would lower overall production costs.

Visual fluorescence detection kit for Cr (VI) based on biological matrix-derived carbon dots and assisted for AA

In this study, a novel green donkey-hide gelatin carbon dots (D-CDs) were synthesized by hydrothermal method and a portable detector based on Cr (VI) fluorescent test strips was prepared. The synthesized D-CDs exhibited bright blue fluorescence which was used for the detection of Cr (VI) and ascorbic acid (AA). It still exhibited high sensitivity and acceptable selectivity under high concentration of other interfering ions. The morphology and elemental characteristics of D-CDs were characterized. Meanwhile, the “on-off” quenching mechanism of Cr (VI) on D-CDs was studied by ultraviolet-visible absorption spectra, fourier transform infrared spectroscopy and fluorescence spectra. Then a D-CDs/Cr (VI) fluorescence sensing platform was constructed, and reopened by AA, thus eliciting an “on-off-on” fluorescence reaction. Under the optimal conditions, the fluorescence intensity was quenched significantly with the increase of Cr (VI) concentration and restored by the good reducibility of ascorbic acid (AA), with the linear ranges of 0.5–400 μM and 1–400 μM, respectively. The detection limits of Cr (VI) and AA can be as low as 0.08 μM and 0.14 μM. Consequently, it has low toxicity and can be successfully used as a fluorescent probe to determine Cr (VI) in river water and AA in fruits with satisfactory results. It not only lays a foundation for the development of fluorescence sensor in the field of environment and food, but also provides a good application prospect for its detection of heavy metal ions and AA.

Analysis of optical properties and response mechanism of H2S fluorescent probe based on rhodamine derivatives

H2S plays a crucial role in numerous physiological and pathological processes. In this project, a new fluorescent probe, SG-H2S, for the detection of H2S, was developed by introducing the recognition group 2,4-dinitrophenyl ether. The combination of rhodamine derivatives can produce both colorimetric reactions and fluorescence reactions. Compared with the current H2S probes, the main advantages of SG-H2S are its wide pH range (5–9), fast response (30 min), and high selectivity in competitive species (including biological mercaptan). The probe SG-H2S has low cytotoxicity and has been successfully applied to imaging in MCF-7 cells, HeLa cells, and BALB/c nude mice. We hope that SG-H2S will provide a vital method for the field of biology.

Exploring a new format of thermophoretic measurement – Stop-flow microscale thermophoresis in the narrow-bore transparent capillary

The classic format of the microscale thermophoresis technique (MST) requires the use of disposable glass capillaries. Their total capacity significantly exceeds the volume of the sample used directly in the thermophoretic measurement. An alternative approach that allows for reducing the consumption of sample, reagents and elimination of waste is the use of narrow-bore capillaries, commonly applied in the capillary electrophoresis technique (CE), in combination with injecting sample segment of a reduced length. This article presents the first-ever use of a transparent and flexible narrow-bore capillary for this purpose, which is much easier to handle than a regular non-transparent silica capillary. In this approach, it is possible to perform thermophoretic analysis with a small sample volume, which is delivered to the detection site using pressure-induced flow, or electrophoretically – while simultaneously performing electrophoretic separation. We focused primarily on the former approach, called Transparent Capillary Stop-Flow MicroScale Thermophoresis (TCSF-MST). Its potential was demonstrated in systems presenting the original use of the thermophoresis phenomenon: monitoring the progress of the fluorescent derivatization reaction, determining the critical micellization concentration of a surfactant, and quantitative analysis of fluorophores based on the internal standard method. The obtained results suggest that the new format can be considered an interesting alternative to the traditional MST methodology, and also seems consistent with the idea of “​​green” and “white” analytical chemistry.

Rapid and portable quantification of HIV RNA via a smartphone-enabled digital CRISPR device and deep learning

For the 29.8 million people in the world living with HIV/AIDS and receiving antiretroviral therapy, it is crucial to monitor their HIV viral loads. To this end, rapid and portable diagnostic tools that can quantify HIV RNA are critically needed. We report herein a rapid and quantitative digital CRISPR-assisted HIV RNA detection assay that has been implemented within a portable smartphone-based device as a potential solution. Specifically, we first developed a fluorescence-based reverse transcription recombinase polymerase amplification (RT-RPA)-CRISPR assay that can efficiently detect HIV RNA at 42 °C. We then implemented this assay within a commercial stamp-sized digital chip, where RNA molecules were quantified as strongly fluorescent digital reaction wells. The isothermal reaction condition and the strong fluorescence in the digital chip simplified the design of thermal and optical modules, allowing us to engineer a palm-size device measuring 70 × 115 × 80 mm and weighing less than 0.6 kg. We also capitalized the smartphone by developing a custom app to control the device, perform the digital assay, and capture fluorescence images throughout the assay using the smartphone's camera. Moreover, we trained and verified a deep learning-based algorithm for analyzing fluorescence images and identifying positive digital reaction wells with high accuracy. Using our smartphone-enabled digital CRISPR device, we successfully detected as low as 75 copies of HIV RNA in just 15 min, showing its potential toward monitoring of HIV viral loads and aiding the global effort to combat the HIV/AIDS epidemic.

Determination of glucose oxidase activity by tyrosine fluorescence spectrophotometry

A novel Fe2+/Tyr/H2O2 fluorescence reaction system has been established for the purpose of analyzing glucose oxidase activity. This system involves the catalysis of glucose oxidase on glucose to produce H2O2, which in turn oxidizes tyrosine to a highly fluorescent substance under the catalysis of Fe2+. The fluorescence intensity is subsequently employed to ascertain the enzymatic activity of glucose oxidase. The enzymatic oxidation reaction and tyrosine fluorescence reaction conditions were optimized based on the H2O2 standard curve equation. Direct fluorescence spectrophotometry was used to determine the activity range and detection limit of glucose oxidase, which were found to be 7.00 × 10−5–7.00 × 10−2 U/mL and 3.36 × 10−5 U/mL (Enzyme-like activity is 6.72 × 10−4 U/mL, The enzyme reaction time is 5 min), respectively, with a relative standard deviation of less than 3.2 %. This method has been successfully applied to determine the activity of glucose oxidase in food additives, with a recovery rate ranging from 96.00 % to 102.0 %.

Role of connexin 43 in a rat model of periodontitis-induced renal injury.

This study aims to investigate the role of gap junction mediated by connexin 43 (Cx43) in renal injury induced by periodontitis in rats. Twelve SPF-grade Wistar male rats were divided into a control group and a periodontitis group by using a completely random number table method, with six rats in each group. The control group rats were not treated, while the periodontitis group rats were subjected to wire ligation of the neck of their bilateral maxillary first molars to construct a periodontitis model. After 8 weeks of modeling, the rats were examined for clinical indicators of the periodontium. micro-CT scanning of the maxilla reconstructed its 3D structure and analyzed the absorption of alveolar bone. Histopathological changes in periodontal and renal tissues were detected. MitoSOX red reagent was used to determine reactive oxygen species (ROS) content in renal tissues. A biochemical reagent kit was used to detect serum oxidative stress biomarkers. Real-time fluorescent quantitative-polymerase chain reaction (qRT-PCR) was employed to determine Cx43, nuclear factor kappa-B (NF-κB) , interleukin (IL)-1β, IL-6, BCL2-Associated X (Bax), B-lymphomatoma-2 gene (Bcl-2), and Caspase-3 mRNA were determined. Western blot analysis was used to detect Cx43, NF-κB, IL-1β, Bax, Bcl-2 and Caspase-3 protein. micro-CT 3D reconstruction showed significant bone resorption of the first molar alveolar bone in the periodontitis group rats and decreased height of the alveolar ridge. The distance from the enamel cementum boundary to the top of the alveolar ridge in the periodontitis group was significantly higher than that inthe control group. The histopathological results showed a large number of inflammatory cells that infiltrated the periodontal tissue of the periodontitis group, and the alveolar bone was significantly absorbed. Rats in the periodontitis group also exhibited mild thickening of the glomerular basement membrane, dilation of the Bowman's capsule, and destruction of the brush-like edge of the renal tubules in the renal tissue. The MitoSOX red staining results showed a significant increase in ROS content in the renal tissue of the periodontitis group. The biochemical test results showed that the levels of superoxide dismutase and glutathione in the serum of rats with periodontitis decreased, while that of malondialdehyde increased. The results of qRT-PCR and Western blot showed that the expression levels of Cx43, IL-1β, IL-6, Bax, Caspase-3 mRNA and Cx43, IL-1β, NF-κB, Bax, Caspase-3 proteins in the periodontitis group significantly increased compared with those in the control group, while the expression levels of Bcl-2 mRNA and protein decreased. Periodontitis may activate NF-κB signaling molecules by upregulating the expression of Cx43 in rat kidney tissues, leading to increased levels of inflammation and apoptosis and ultimately inducing kidney injury.

Development of time-resolved fluoroimmunoassay with enhanced fluorescence reaction for the quantitation of atezolizumab in plasma.

Atezolizumab (ATZ) is a human monoclonal antibody, which has been granted multiple approvals from the US Food and Drug Administration (FDA) for the immunotherapy of different types of cancer. This study describes the prototype of a time-resolved fluoroimmunoassay (TRFIA) for the quantitation of ATZ in plasma. The assay involved the non-competitive binding of ATZ to its specific antigen [programmed death-ligand 1 (PD-L1) protein]. The immune complex formed on the inner surface of the assay plate wells was quantified by anti-human secondary antibody labeled with a chelate of europium-ethylenediaminetetraacetic acid. The enhanced fluorescence signal was generated by an enhanced fluorescence solution composed of thenoyltrifluoroacetone, trioctylphosphine oxide, and Triton X-100. The conditions of the TRFIA were refined, and its optimum procedures were established. The assay was validated in accordance with the immunoassay validation guidelines, and all the validation parameters were acceptable. The working range of the assay was 20-1000 pg mL-1, and its limit of quantitation was 20 pg mL-1. The assay was applied to the quantitation of ATZ in plasma samples with satisfactory accuracy and precision. The proposed TRFIA has significant benefits over the existing methodologies for the quantitation of ATZ in clinical settings.

Nomogram based on multimodal magnetic resonance combined with B7-H3mRNA for preoperative lymph node prediction in esophagus cancer.

Accurate preoperative prediction of lymph node metastasis (LNM) in esophageal cancer (EC) patients is of crucial clinical significance for treatment planning and prognosis. To develop a clinical radiomics nomogram that can predict the preoperative lymph node (LN) status in EC patients. A total of 32 EC patients confirmed by clinical pathology (who underwent surgical treatment) were included. Real-time fluorescent quantitative reverse transcription-polymerase chain reaction was used to detect the expression of B7-H3 mRNA in EC tissue obtained during preoperative gastroscopy, and its correlation with LNM was analyzed. Radiomics features were extracted from multi-modal magnetic resonance imaging of EC using Pyradiomics in Python. Feature extraction, data dimensionality reduction, and feature selection were performed using XGBoost model and leave-one-out cross-validation. Multivariable logistic regression analysis was used to establish the prediction model, which included radiomics features, LN status from computed tomography (CT) reports, and B7-H3 mRNA expression, represented by a radiomics nomogram. Receiver operating characteristic area under the curve (AUC) and decision curve analysis (DCA) were used to evaluate the predictive performance and clinical application value of the model. The relative expression of B7-H3 mRNA in EC patients with LNM was higher than in those without metastasis, and the difference was statistically significant (P < 0.05). The AUC value in the receiver operating characteristic (ROC) curve was 0.718 (95%CI: 0.528-0.907), with a sensitivity of 0.733 and specificity of 0.706, indicating good diagnostic performance. The individualized clinical prediction nomogram included radiomics features, LN status from CT reports, and B7-H3 mRNA expression. The ROC curve demonstrated good diagnostic value, with an AUC value of 0.765 (95%CI: 0.598-0.931), sensitivity of 0.800, and specificity of 0.706. DCA indicated the practical value of the radiomics nomogram in clinical practice. This study developed a radiomics nomogram that includes radiomics features, LN status from CT reports, and B7-H3 mRNA expression, enabling convenient preoperative individualized prediction of LNM in EC patients.

DNA nanoflowers encapsulating horseradish peroxidase as a signal amplification tag for rapid diagnosis in cytology specimens

Rapid analysis of cytology samples obtained by minimally invasive sampling is essential in clinical diagnosis, yet existing diagnostic methods are often cumbersome and time-consuming. To rapidly detect the scanty number of cells in specimens, a multifunctional detection probe based on DNA nanoflower structure was prepared in this study, which possesses both signal output capability of fluorescence and oxidation reaction (colorimetric assay) for ultra-sensitive cancer cell detection. Firstly, DNA nanoflowers encapsulating horseradish peroxidase (HRP-DNA Nanoflowers, HDFs) were prepared by the rolling circle amplification (RCA) reaction and then hybridized with the aptamers labeled with fluorophores to construct the multivalent aptamer HDFs (Multi-Aptamer-HDFs) with fluorescence effect and efficient cancer cell targeting. The Multi-Aptamer-HDFs probe can be used to detect fresh clinical cytology specimens directly for fluorescence observation with sensitivity and specificity of 88.64%, and 84.85%, respectively. In addition, Multi-Aptamer-HDFs has peroxidase activity due to the encapsulation of HRP, which can catalyze the oxidation of substrates such as ABTS and DAB for color development. Therefore, we applied Multi-Aptamer-HDFs to one-step staining of clinical cytology cell blocks with a sensitivity of 88.41% and a specificity of 83.33%, which required fewer steps and reagents with a significantly shorter time required for immunocytochemical staining. The multifunctional probe, Multi-Aptamer-HDFs, prepared in this study is expected to be better applied in the rapid cellular analyses and one-step immunostaining, which is expected to provide a new means for rapid on-site assessment and on-site preliminary diagnosis.

Fluorometric “AND” logic gate for detection of tyramine and tyrosinase based on in-situ formation of silicon-containing nanoparticles

BackgroundTyramine is an important index of food freshness degree, and tyrosinase that can specifically oxidized monophenolamine to catecholamine plays a crucial part in the occurrence and development of melanin-related skin diseases. Therefore, it is crucial to develop sensitive and efficient methods for the detection of tyramine and tyrosinase. ResultsIn this work, encouraged by tyrosinase-triggered specific oxidation of tyramine to dopamine and the unique fluorescent reaction between dopamine and amino silane, we have developed a one-step synthetic strategy of silicon containing nanoparticles (Si CNPs) for “turn-on” detection of tyramine and tyrosinase. The Si CNPs formed with thoroughly studied mechanism exhibit uniform structure and robust yellow-green fluorescence. The low detection limits for tyramine (1.87 μM) and tyrosinase (0.0029 U/mL) demonstrate admirable sensitivity outstripping most methods. The proposed assay achieves satisfactory results in the determination of tyramine and tyrosinase activity in real samples. Furthermore, we leverage this new fluorescent assay to enable the fabrication of an “AND” Boolean logic gate. SignificanceThe entire process can be completed at easily available temperature and pressure with rapid response, convenient operation and visual observation. This fluorescent assay featured with excellent sensitivity, selectivity and stability has considerable prospects in the application of biosensors and disease diagnosis.

The Usage of an AMCA-Modified Aptamer Facilitates the Rapid Detection of Vibrio vulnificus

Background: Vibrio vulnificus can cause serious infections in human beings associated with the consumption of raw oysters or cuts exposed to seawater. The traditional method for culturing V. vulnificus is time-consuming and has a high failure rate. Objectives: This study aims to detect V. vulnificus using an AMCA-modified specific DNA aptamer. Methods: Common pathogenic microorganisms present in the seawater of the Fujian Sea area were collected, cultured, and identified. The samples were found to contain mainly V. vulnificus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, V. alginolyticus, V. parahaemolyticus, and V. cholerae. AMCA was conjugated with 5’ ends of the aptamer using N-hydroxysuccinimide ester (NHS ester) to target V. vulnificus and produce a fluorescent signal upon binding. The aptamer was screened and optimized for rapid detection of V. vulnificus. We collected the 50 bacterial strains isolated from clinical secretion samples and used a fluorescence microscope to determine whether the sample contained V. vulnificus or not. We compared these results with those obtained from VITEK MS (considered the gold standard) to test the sensitivity and specificity of the AMCA-modified aptamer using IBM SPSS Statistics 22. Results: In this experiment, the sensitivity and specificity of the modified aptamer for detecting V. vulnificus were determined to be 100% [95% CI (0.39, 1)] and 93.4% [95% CI (0.81, 0.98)], respectively. The positive predictive value was 57% [95% CI (0.20, 0.88)], and the negative predictive value was 100% [95% CI (0.89, 1)]. These findings indicate that V. vulnificus specimens can be rapidly detected via fluorescence reaction within 30 minutes. Conclusions: Our results suggest that this modified DNA aptamer has the potential to be used for diagnosing V. vulnificus. Further research is needed to explore the application of aptamers in pathogen infections.

Cold-Pressed Okra Seed Oil Byproduct as an Ingredient for Muffins to Decrease Glycemic Index, Maillard Reaction, and Oxidation.

This study aimed to investigate the effects of adding cold-pressed okra seed oil byproduct (OSB) to the muffin formulation, as a partial substitute for wheat flour, on the nutritional, physicochemical, rheological, textural, and sensory properties of muffins. The carbohydrate, protein, oil, moisture, and ash contents of OSB were 44.96, 32.34, 10.21, 7.51, and, 4.98%, respectively, indicating that OSB was rich in protein and carbohydrate. All muffin samples showed a shear thinning behavior, indicating that the viscosity of all samples decreased with increasing shear rate. The frequency sweep test showed that all samples showed viscoelastic solid-like structure [G' (storage modulus)> G″ (loss modulus)]. The K' values (between 66.45 and 139.14) were higher than the K″ values (between 36.62 and 80.42) for all samples. The result was another indication of the viscoelastic solid characteristic of the samples. In our study, it was found that the fluorescence of advanced Maillard products and soluble tryptophan index decreased with increasing amount of OSB, indicating that OSB addition led to a decrease in the amount of fluorescent Maillard reaction (MR) products. The fortified muffins with more than 10% OSB had a reduced estimated glycemic index (GI) significantly in comparison with control muffin samples (p < 0.05). The induction period (IP) values of the muffin samples containing OSB (between 11:57 and 15:15 h/min) were higher than the IP value of the control sample (10:50 h/min), indicating that OSB improved the oxidative stability of the muffin samples. The addition of OSB has shown no negative effect on sensory attributes considering texture, mouth fell, odor, and taste. This study suggested that the addition of OSB in muffins could improve rheological properties and oxidative stability and decrease GI and the amount of MR products without negative impact on sensory properties.

Clinical Application of Quantitative Light-Induced fluorescent(QLF) device in the Diagnosis of cracked teeth

As social interest in health increases, interest in oral health and preservation of natural teeth are also increasing. The hard tissues in the oral cavity undergo physical changes as age increases. One of the changes is the progress of tooth cracks in natural or restored teeth. These cracks are commonly encountered in daily clinicalpractice but often confuse the operator due to its difficulties in diagnosis and therapeutic access. Diagnosing acracked tooth has been a chanllenge to dental clinicians. For the diagnosis of a cracked tooth, the quantitative light-induced fluorescent (QLF) device, which is capable of detecting fluorescent reactions of the tooth with visible light (405nm), has been introduced as one of the methods for observing tooth cracks. Specific metabolites of microorganisms that penetrate through the crack’s line react with specific autofluorescence to 405nm visible light emitted from the QLF device. These fluorescent image provided by the QLF helps to observe the location of the crack during the diagnosis of a cracked tooth and helps the patient’s dental record. The QLF images provided a magnified image as well as a fluorescent im-age that could identify the location of the crack existing outside the tooth, around the restoration, and inside the cavity after removal of the restoration by a simple process of capturing images. This report shows the process of diagnosis of a cracked tooth using a QLF device by observing three separate cases which can help clinicians to understand this process.

A dual-function chromogenic and fluorogenic benzofurazan probe for plazomicin and its innovative utility for development of two microwell assays with high throughput for analysis of drug substance and pharmaceutical formulations.

Plazomicin (PLZ) is a novel aminoglycoside which has been recently approved by The US Food and Drug Administration for the treatment of complicated urinary tract infections including acute pyelonephritis, caused by certain Enterobacteriaceae, in adult patients with limited or no options for alternative treatment. This study focuses on the development of microwell-based photometric and fluorometric assays for the quantitative determination of PLZ in its bulk drug substance and commercial pharmaceutical formulations (Zemedri® injections). Both assays utilize the dual-function chromogenic and fluorogenic properties of the 4-fluoro-7-nitrobenzofurazan (NBD-F) probe. The reaction between PLZ and NBD-F, conducted in a borate buffer at pH 8, resulted in the formation of a colored and fluorescent reaction product. The product exhibited maximum light absorption at 473 nm and emitted fluorescence at 541 nm when excited at 473 nm. Factors influencing the reaction between PLZ and NBD-F were thoroughly investigated, and optimal conditions were determined. Under the optimized reaction conditions, calibration curves were generated to establish the relationship between absorbance and fluorescence intensities of the reaction product with the corresponding PLZ concentrations. The absorbance-concentration relation was linear in a PLZ concentration range of 20-800 μg mL-1 with a limit of quantitation of 25 μg mL-1, while the fluorescence-concentration relation was linear in the concentration range of 0.05-1.5 μg mL-1 with a limit of quantitation of 0.08 μg mL-1. Both assays underwent validation and were successfully applied to the quantitation of PLZ in its bulk drug substance and pharmaceutical formulations (injections) with satisfactory accuracy and precision. The eco-friendliness/greenness assessment of the assays demonstrated that both assays comply with the requirements of green analytical chemistry approaches. Furthermore, the proposed microwell assay plates allowed for the simultaneous handling of numerous samples with micro-volumes, enabling high-throughput analysis. In conclusion, this study represents the first evaluation of NBD-F as a dual-function probe for the microwell-based photometric and fluorometric determination of PLZ. The developed assays serve as valuable analytical tools for the quality control of PLZ's bulk drug substance and pharmaceutical formulations.

Gold nanocluster aggregates-phenol derivative system constructed by van der Waals for ratiometric fluorescence detection of dopamine, norepinephrine, and resorcinol

Here, we synthesized gold nanocluster aggregates (GNCA) and constructed a gold nanocluster aggregates-phenol derivative system based on van der Waals for ratiometric fluorescence detection of dopamine (DA), norepinephrine (NE), and resorcinol (Rs), respectively. Novel fluorescent GNCA were rapidly prepared by one-pot method in an alkaline environment regulated by PEI instead of NaOH. PEI wrapped around and connected gold nanoclusters to form GNCA with long fluorescence lifetime and high fluorescent stability. Additionally, Rs was adsorbed on the surface of GNCA via van der Waals to develop the GNCA-Rs system. When NE and DA were introduced to the GNCA-Rs system, two new fluorescence peaks at 513 nm and 474 nm appeared, owing to the fluorescent polycondensation reaction of Rs with NE and DA, respectively. Thus, non-enzymatic fluorescence detections of NE and DA were achieved. When the GNCA-Rs system was used as a fluorescent probe, the linear detection ranges of NE and DA were 0.01–400.0 μM and 0.001–400.0 μM respectively, with detection limits (LOD) of 78.0 nM and 3.0 nM. The high sensitivity was attributed to physical adsorption based on van der Waals interactions and polycondensation processes. Similarly, van der Waals developed a GNCA-DA system with remarkable sensitivity (LOD=1.4 nM) for the detection of Rs. In this study, we not only proposed an efficient approach for constructing fluorescent probes, but also presented a novel strategy for the detection of catecholamines.