The antihypertensive effect of Alizarin is achieved by activating VEGFR2/eNOS pathway, attenuating oxidative stress-induced mitochondrial damage and premature senescence.

The primary and initial manifestations of hypertension encompass arterial hypoelasticity and histiocyte senescence. Oxidative stress plays a pivotal role in the progression of senescence. Elevated intracellular oxidative stress levels will directly induce cell damage, disrupt normal physiological signal transduction, which can cause mitochondrial dysfunction to accelerate the process of senescence. Alizarin, an anthraquinone active ingredient isolated from Rubia cordifolia L., has a variety of pharmacological effects, including antioxidant, anti-inflammatory and anti-platelet. Nevertheless, its potential in lowering blood pressure (BP) and mitigating hypertension-induced vascular senescence remains uncertain. In this study, we used spontaneously hypertensive rats (SHR) and human umbilical vein endothelial cells (HUVECs) to establish a model of vascular senescence in hypertension. Our aim was to elucidate the mechanisms underpinning the vascular protective effects of Alizarin. By assessing systolic blood pressure (SBP) and diastolic blood pressure (DBP), H&E staining, SA-ß-Gal staining, vascular function, oxidative stress levels, calcium ion concentration and mitochondrial membrane potential, we found that Alizarin not only restored SBP and increased endothelium-dependent relaxation (EDR) in SHR, but also inhibited oxidative stress-induced mitochondrial damage and significantly delayed the vascular senescence effect in hypertension, and the mechanism may be related to the activation of VEGFR2/eNOS signaling pathway.

A facile synthesis of water-soluble copper nanoclusters as label-free fluorescent probes for rapid, selective and sensitive determination of alizarin red.

Copper nanoclusters (FA@CuNCs) emitting blue fluorescence were successfully developed via a one-pot technique. In this method, the copper chloride, folic acid and hydrazine hydrate were applied as a precursor, protective agent and reducing agent, respectively. The absorption, fluorescence excitation and emission spectra of FA@CuNCs were carried out by using ultraviolet-visible and fluorescence spectrometry, respectively. The morphology, particle size, functional groups, oxidation states of elements of FA@CuNCs were discussed via using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The stability of FA@CuNCs was studied under various conditions, such as storage time at 25 ℃, ultraviolet radiation time, sodium chloride solutione and pH. The FA@CuNCs displayed blue fluorescence under the excitation wavelength of 361 nm, and the fluorescence quantum yield was 7.45 %. As a result of the inner filter effect, the alizarin red could significantly weaken the blue fluorescence of FA@CuNCs. Thus, the as-prepared FA@CuNCs could be utilized as fluorescence nanosensors for the trace determination of alizarin red. This platform suggested an excellent linear range for alizarin red varying from 0.5 to 200 µM with a fitting coefficient of 0.9955. The detection limit was calculated to be 0.064 µM in the light of the 3b/k (b and k refer to the standard deviation and slope of fitted curve, respectively). Furthermore, the as-developed FA@CuNCs could be used to detect the alizarin red in real samples and for the sensing of temperature.

Vanadium and strontium co-doped hydroxyapatite enriched polycaprolactone matrices for effective bone tissue engineering: A synergistic approach.

Scientific research targeted at enhancing scaffold qualities has increased significantly during the last few decades. This emphasis frequently centres on adding different functions to scaffolds in order to increase their usefulness as instruments in the field of regenerative medicine. This study aims to investigate the efficacy of a multifunctional sustainable polymer scaffold, specifically Polycaprolactone (PCL) embedded with hydroxyapatite co-doped with vanadium and strontium (HVS), for bone tissue engineering applications. Polycaprolactone was used to fabricate the scaffold, while hydroxyapatite co-doped with vanadium and strontium (HVS) served as the nanofiller. A thorough investigation of the physicochemical and biological characteristics of the HVS nanofiller was carried out using cutting-edge techniques including Dynamic Light Scattering (DLS), and X-ray Photoelectron Spectroscopy (XPS) and in vitro cell studies. A cell viability rate of more than 70 % demonstrated that the synthesised nanofiller was cytotoxic, but in an acceptable range. The mechanical, biological, and physicochemical properties of the scaffold were extensively evaluated after the nanofiller was integrated. The water absorption characteristics of scaffold were enhanced by the addition of HVS nanofillers, leading to increased swelling, porosity, and hydrophilicity. These improvements speed up the flow of nutrients and the infiltration of cells into the scaffold. The scaffold has been shown to have important properties that stimulate bone cell activity, including better biodegradability and improved mechanical strength, which increased from 5.30 ± 0.37 to 10.58 ± 0.42 MPa. Further, its considerable antimicrobial qualities, blood-compatible nature, and capacity to promote biomineralization strengthen its appropriateness for usage in biomedical applications. Mainly, enhanced Alkaline phosphatase (ALP) activity, Alizarin Red Staining (ARS) activity, and excellent cell adhesive properties, indicating the outstanding osteogenic potential observed in rat bone marrow-derived stromal cells (rBMSC). These combined attributes highlight the pivotal role of these nanocomposite scaffolds in the field of bone tissue engineering.

A sensitive and selective voltammetric method for the detection of pyrogallol in tomato and water samples using platinum electrode modified with alizarin red S film.

In contrast to the hyperactive platinum electrode, ARS modified platinum electrode presents a remarkable inertness toward adsorption and surface processes and lends it for further voltammetric applications. Measuring pyrogallol levels in samples is significant for assessing their antioxidant activity, which is crucial for understanding their potential health benefits and ability to combat oxidative stress. In addition, the excess consumption of pyrogallol can have significant negative effects on human health. A voltammetric sensor has been developed for the determination of pyrogallol using ARS modified platinum electrode. The electrode was prepared by electrodeposition of alizarin red S on a platinum electrode using cyclic voltammetry with a potential scan range of - 0.4 to 1.2 V against an Ag/AgCl quasi reference electrode for 60 cycles as optimum number of cycles. The modified electrode was characterized by CV and SEM techniques. This modified alizarin red S platinum electrode showed remarkable electrocatalytic performance and stability, resulting in a significant increase in pyrogallol oxidation current by 11.05% compared to the pyrogallol oxidative current at the unmodified platinum electrode. A well-defined oxidation peak was observed at ~ 0.40 V. The sensor exhibited a low limit of detection (LOD) of 0.28 µM and a linear standard curve covering the ranges of 1.0-40 µM and 0.01-10.0 mM pyrogallol. Extensive studies were performed to evaluate possible interferences from various organic and inorganic compounds and yielded satisfactory results that confirm the selectivity of the developed sensor for pyrogallol determination. In addition, the ARS-Pt electrode provided consistently reliable results for the accurate detection of pyrogallol in water and tomato samples.

Ammonia-Responsive Colorimetric Film of Phytochemical Formulation (Alizarin) Grafted onto ZIF-8 Carrier with Poly(vinyl alcohol) and Sodium Alginate for Beef Freshness Monitoring.

In this study, we devised a photothermally stable phytochemical dye by leveraging alizarin in conjunction with the metal-organic framework ZIF-8 (AL@ZIF-8). The approach involved grafting alizarin into the microporous structure of ZIF-8 through physical adsorption and hydrogen-bonding interactions. AL@ZIF-8 significantly enhanced the photostability and thermostability of alizarin. The nanoparticles demonstrate substantial color changes in various pH environments, showcasing their potential for meat freshness monitoring. Furthermore, we introduced an intelligent film utilizing poly(vinyl alcohol)-sodium alginate-AL@ZIF-8 (PA-SA-ZA) for detecting beef freshness. The sensor exhibited a superior water contact angle (52.34°) compared to the alizarin indicator. The color stability of the film was significantly enhanced under visible and UV light (ΔE < 5). During beef storage, the film displayed significant color fluctuations correlating with TVB-N (R2=0.9067), providing precise early warning signals for assessing beef freshness.

A novel dual-channel cassava starch/polyvinyl alcohol-based film for visual monitoring of shrimp freshness.

In this study, the polyvinylpyrrolidone-alizarin nanoparticles (PVP-AZ NPs) with favorable water dispersion and the carbon quantum dots (RQDs) with aggregate induced emission effect were synthesized to construct an eco-friendly film for food freshness monitoring. The introduction of PVP-AZ NPs and RQDs enhanced the network structure and thermal stability of the cassava starch/polyvinyl alcohol film, and reduced its crystallinity and light transmittance via non-covalent binding with the film-forming matrix. The developed film exhibited visually recognizable colorimetric and fluorescent responses to ammonia at 0.025-25 mg/mL, and it can be reused at least 6 times. Practical application experiment proved that the film, as an indicator label, can achieve accurate, real-time, and visual dynamic monitoring of the freshness of shrimp stored at 25 °C, 4 °C, and - 20 °C under daylight (orange yellow to purple) and UV light (red to blue). The integration of multivariate detection technology can eliminate the interference of external factors by self-correction to improve sensitivity and reliability, which provides a reference for the development of other food quality and safety monitoring platforms.

A novel and efficient voltammetric sensor for the simultaneous determination of alizarin red S and tartrazine by using poly(leucine) functionalized carbon paste electrode.

In the current work, a rapid, selective, and sensitive technique was developed for the detection of Alizarin Red S (ARS) by applying poly leucine modified carbon paste electrode (PLMCPE). Electrochemical impedance spectroscopy (EIS) and Scanning electron microscopy (SEM) were utilized to study the surface morphology of unmodified carbon paste electrode (UMCPE) and PLMCPE. The active surface area for UMCPE and PLMCPE was found to be 0.0012 cm2 and 0.0026 cm2 respectively. The electrochemical response of ARS at UMCPE and PLMCPE was analyzed using cyclic voltammetry (CV) in the potential window of 0.4 to 1.0 V. The cyclic voltammogram obtained for varying the pH of 0.2 M phosphate buffer (PB) solution showed maximum current for the oxidation of ARS at pH 6.5. The electrochemical reaction of ARS was found to be irreversible and adsorption controlled. The effect of variation of concentration of ARS on the oxidation peak current was evaluated using CV and linear scan voltammetry (LSV). A linear relationship between the concentration variation and current was obtained in the linear range of 1.5 µM-3.5 µM and 0.2 µM-5.0 µM for CV and LSV respectively. The limit of detection (LOD) of 0.68 µM for the CV method and 0.29 µM for the LSV method was exhibited by the developed sensor. The simultaneous study of ARS along with tartrazine (TZ) showed good selectivity for ARS. The interferents of foreign molecules showed no effect on the selectivity of the electrode. The applicability of PLMCPE on real samples gave good recovery ranging from 97.46-101.2%; hence, the sensor can be utilized on real samples. The developed sensor has good stability and sensitivity.

Adjusting UV-Vis Spectrum of Alizarin by Insertion of Auxochromes.

First synthesized in 1868, alizarin became one of the first synthetic dyes and was widely used as a red dye in the textile industry, making it more affordable and readily available than the traditional red dyes derived from natural sources. Despite extensive both experimental and computational analyses on the electronic effects of substituents on the shape of the visible spectrum of alizarin and alizarin Red S, no previous systematic work has been undertaken with the aim to fine tune the dominant absorption region defining its color by introducing other electron-withdrawing or electron-donor groups. For such, we have performed a comprehensive study of electronic effects of substituents in position C3 of alizarin by means of a time dependent DFT approach. These auxochromes attached to the chromophore are proven to alter both the wavelength and intensity of absorption. It is shown that the introduction of an electron-donor group in alizarin causes the transition bands to be significantly red-shifted whereas electron-withdrawing groups cause a minor blue-shifting.

In vitro determination of osteo-adipogenic lineage choice of bone marrow stromal/stem cells (BMSCs).

Bone marrow stromal/stem cells (BMSCs) are primitive and heterogeneous cells that can be differentiated into osteoblasts, adipocytes and other subsets. Their bone-fat lineage commitment is responsible for the homeostasis of bone marrow microenvironment. However, there are little effective methods and evidence to simultaneously visualise the lineage commitment of BMSCs. Here we provide a bivalent differentiation medium that can enable BMSCs differentiation into osteoblasts and adipocytes in vitro, and establish a method to simultaneously distinguish osteoblasts or adipocytes from the heterogeneous BMSCs based on Alizarin red S and Oil red O staining, which have been used for detection of specific mineralized nodules and lipid droplets, respectively. This assay provides a specifically simple but effective and low-cost method to evaluate the efficiency of osteo-adipogenic (OA) allocation of BMSCs.►Researchers can utilize the bivalent differentiation medium to evaluate the efficiency of osteogenic and adipogenic differentiation of BMSCs in vitro.

Protective effect of alizarin on vascular endothelial dysfunction via inhibiting the type 2 diabetes-induced synthesis of THBS1 and activating the AMPK signaling pathway.

BACKGROUND: In this study, we investigated the protective effects of alizarin (AZ) on endothelial dysfunction (ED). AZ has inhibition of the type 2 diabetes mellitus (T2DM)-induced synthesis of thrombospondin 1 (THBS1). Adenosine 5'-monophosphate- activated protein kinase (AMPK), particularly AMPKα2 isoform, plays a critical role in maintaining cardiac homeostasis. PURPOSE: The aim of this study was to investigate the ameliorative effect of AZ on vascular injury caused by T2DM and to reveal the potential mechanism of AZ in high glucose (HG)-stimulated human umbilical vein endothelial cells (HUVECs) and diabetic model rats. STUDY DESIGN: HUVECs, rats and AMPK-/- transgenic mice were used to investigate the mitigating effects of AZ on vascular endothelial dysfunction caused by T2DM and its in vitro and in vivo molecular mechanisms. METHODS: In type 2 diabetes mellitus rats and HUVECs, the inhibitory effect of alizarin on THBS1 synthesis was verified by immunohistochemistry (IHC), immunofluorescence (IF) and Western blot (WB) so that increase endothelial nitric oxide synthase (eNOS) content in vitro and in vivo. In addition, we verified protein interactions with immunoprecipitation (IP). To probe the mechanism, we also performed AMPKα2 transfection. AMPK's pivotal role in AZ-mediated prevention against T2DM-induced vascular endothelial dysfunction was tested using AMPKα2-/- mice. RESULTS: We first demonstrated that THBS1 and AMPK are targets of AZ. In T2DM, THBS1 was robustly induced by high glucose and inhibited by AZ. Furthermore, AZ activates the AMPK signaling pathway, and recoupled eNOS in stressed endothelial cells which plays a protective role in vascular endothelial dysfunction. CONCLUSIONS: The main finding of this study is that AZ can play a role in different pathways of vascular injury due to T2DM. Mechanistically, alizarin inhibits the increase in THBS1 protein synthesis after high glucose induction and activates AMPKα2, which increases NO release from eNOS, which is essential in the prevention of vascular endothelial dysfunction caused by T2DM.

Innovative modification of cellulose fibers for paper-based electrode materials using metal-organic coordination polymers.

Cellulosic paper-based electrode materials have attracted increasing attention in the field of flexible supercapacitor. As a conductive polymer, polyaniline exhibits high theoretical pseudocapacitive capacitance and has been applied in paper-based electrode materials along with cellulose fibers. However, the stacking of polyaniline usually leads to poor performance of electrodes. In this study, metal-organic coordination polymers of zirconium-alizarin red S and zirconium-phytic acid are applied to modulate the polyaniline layer to obtain high-performance cellulosic paper-based electrode materials. Zirconium hydroxide is firstly loaded on cellulose fibers while alizarin red S and phytic acid are introduced to regulate the morphology of polyaniline through doping and coordination processes. The results show that the introduction of dual coordination polymers is effective to regulate the morphology of polyaniline on cellulose fibers. The performances of the paper-based electrode materials, including electrical conductivity and electrochemistry, are apparently improved. It provides a promising strategy for the potential development of economical and green electrode materials in the conventional paper-making process.

Alizarin-embedded γ-cyclodextrin-based metal-organic framework in a methylcellulose/polyvinyl alcohol film for maintaining and monitoring grass carp freshness.

Multifunctional packaging films that monitor and maintain fish freshness hold significant potential for use in the food industry. This study introduces a multifunctional intelligent packaging film comprising alizarin (ALI)-embedded cubic γ-cyclodextrin metal-organic frameworks (γ-CD-MOFs) (denoted as γ-CD-MOFs@ALI) in a methylcellulose/polyvinyl alcohol (MP)-based matrix to achieve colorimetric monitoring and enhanced preservation of fish freshness. The MP/γ-CD-MOFs@ALI reveals a rapid color transition in 3 min from yellow color progressively darkens to purple as the pH increases from 2.0 to 10.0. And it is proved that the as-prepared film owns high antibacterial activity against Gram-positive bacteria (S. aureus), impressive ABTS+ radical scavenging rates of 85.54 ± 1.25 %, and effective ALI sustained-release properties. The intelligent packaging film exhibits an excellent colorimetric response to total volatile basic nitrogen and provides exceptional freshness preservation performance, effectively prolonging the shelf life of Ctenopharyngodon idella (grass carp) under 25 °C to 42 h.

A Prenyltransferase Participates in the Biosynthesis of Anthraquinones in Rubia cordifolia.

Anthraquinones constitute the largest group of natural quinones, which are used as safe natural dyes and have many pharmaceutical applications. In plants, anthraquinones are biosynthesized through two main routes: the polyketide pathway and the shikimate pathway. The latter primarily forms alizarin-type anthraquinones, and the prenylation of 1,4-dihydroxy-2-naphthoic acid is the first pathway-specific step. However, the prenyltransferase responsible for this key step remains uncharacterized. In this study, the cell suspension culture of Madder (Rubia cordifolia), a plant rich in alizarin-type anthraquinones, was discovered to be capable of prenylating 1,4-dihydroxy-2-naphthoic acid to form 2-carboxyl-3-prenyl-1,4-naphthoquinone and 3-prenyl-1,4-naphthoquinone. Then, a candidate gene belonging to the UbiA superfamily, R. cordifolia  dimethylallyltransferase 1 (RcDT1), was shown to account for the prenylation activity. Substrate specificity studies revealed that the recombinant RcDT1 recognized naphthoic acids primarily, followed by 4-hydroxyl benzoic acids. The prenylation activity was strongly inhibited by 1,2- and 1,4-dihydroxynaphthalene. RcDT1 RNA interference significantly reduced the anthraquinones content in R. cordifolia callus cultures, demonstrating that RcDT1 is required for alizarin-type anthraquinones biosynthesis. The plastid localization and root-specific expression further confirmed the participation of RcDT1 in anthraquinone biosynthesis. The phylogenetic analyses of RcDT1 and functional validation of its rubiaceous homologs indicated that DHNA-prenylation activity evolved convergently in Rubiaceae via recruitment from the ubiquinone biosynthetic pathway. Our results demonstrate that RcDT1 catalyzes the first pathway-specific step of alizarin-type anthraquinones biosynthesis in R. cordifolia. These findings will have profound implications for understanding the biosynthetic process of the anthraquinone ring derived from the shikimate pathway.

Brownmillerite Calcium Ferrite, a Promising Perovskite-Related Material in the Degradation of a Tight Dye under Ambient Conditions.

Evaluation of effective and low-cost materials as catalysts to combat the threat of pollution is a significant and growing trend. With this aim, we have synthesized calcium ferrite brownmillerite by wet preparation approach as a catalyst for pollution. The structural analysis is established by the X-ray diffraction of Ca2 Fe2 O5 , whereas the tetrahedral and octahedral sites band stretching for ferrite specimen has been deduced using FTIR. The bandgap energy has been estimated by the Tauc relation (2.17 eV). Ca2 Fe2 O5 brownmillerite exhibits a BET surface area of 10 m2 /g and a BJH pore volume of 0.121 cm3 /g with the average particle size of 70 nm. Importantly, the alizarin Red S dye degradation has been studied using the prepared ferrite catalyst, under dark ambient conditions and without the presence of any acidic or basic additives. Degradation is also supported by both FTIR and TOC analysis. Surface properties of brownmillerite Ca2 Fe2 O5 have been characterized using electronic spectroscopy and CO2 temperature programmed desorption (TPD) analysis and revealed that the basic surface of brownmillerite Ca2 Fe2 O5 offers active sites that are suitable for degradation processes. All results show that the preparation of brownmillerite Ca2 Fe2 O5 via the Pechini method is suitable to produce fine surfaces and pores with nanosized particles.

Controlling pH-Sensitive Chemical Reactions Pathways with Light - a Tale of Two Photobases: an Arrhenius and a Brønsted.

Light-gated chemical reactions allow spatial and temporal control of chemical processes. Here, we suggest a new system for controlling pH-sensitive processes with light using two photobases of Arrhenius and Brønsted types. Only after light excitation do Arrhenius photobases undergo hydroxide ion dissociation, while Brønsted photobases capture a proton. However, none can be used alone to reversibly control pH due to the limitations arising from excessively fast or overly slow photoreaction timescales. We show here that combining the two types of photobases allows light-triggered and reversible pH control. We show an application of this method in directing the pH-dependent reaction pathways of the organic dye Alizarin Red S simply by switching between different wavelengths of light, i. e., irradiating each photobase separately. The concept of a light-controlled system shown here of a sophisticated interplay between two photobases can be integrated into various smart functional and dynamic systems.

Gallic acid induces osteoblast differentiation and alleviates inflammatory response through GPR35/GSK3ß/ß-catenin signaling pathway in human periodontal ligament cells.

BACKGROUND AND OBJECTIVE: Gallic acid (GA) possesses various beneficial functions including antioxidant, anticancer, anti-inflammatory as well as inhibiting osteoclastogeneis. However, effects on osteogenic differentiation, especially in human ligament periodontal (hPDL) cells, remain unclear. Thus, the aim of this study was to evaluate the function of GA on osteogenesis and anti-inflammation in hPDL cells and to explore the involved underlying mechanism. METHODS: Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) treatment was used as a model for periodontitis. ROS production was determined by H2DCFDA staining. Trans-well and wound healing assays were performed for checking the migration effect of GA. Alizarin red and alkaline phosphatase activity (ALP) assays were performed to evaluate osteogenic differentiation. Osteogenesis and inflammatory-related genes and proteins were measured by real-time PCR and western blot. RESULTS: Our results showed that GA-treated hPDL cells had higher proliferation and migration effect. GA inhibited ROS production-induced by Pg-LPS. Besides, GA abolished Pg-LPS-induced inflammation cytokines (il-6, il-1ß) and inflammasome targets (Caspase-1, NLRP3). In addition, GA promoted ALP activity and mineralization in hPDL cells, lead to enhance osteoblast differentiation process. The effect of GA is related to G-protein-coupled receptor 35 (GPR35)/GSK3ß/ß-catenin signaling pathway. CONCLUSION: GA attenuated Pg-LPS-induced inflammatory responses and periodontitis in hPDL cells. Taken together, GA may be targeted for therapeutic interventions in periodontal diseases.

Two-Dimensional Amorphous Titanium Dioxide/Silver (TiO2/Ag) Nanosheets as a Surface-Enhanced Raman Spectroscopy Substrate for Highly Sensitive Detection.

For the purpose of investigating the chemical enhancement of amorphous semiconductors as well as increasing the sensitivity of the surface-enhanced Raman spectroscopy (SERS) substrate, titanium dioxide (TiO2) precursors were calcined at different temperatures to generate crystallized TiO2 (c-TiO2) and amorphous TiO2 (a-TiO2) nanosheets, respectively. Afterward, a two-dimensional (2D) a-TiO2/Ag nanosheet SERS substrate was successfully fabricated using electrostatic interaction between a-TiO2 and Ag nanoparticles. In order to demonstrate a greater SERS sensitivity on a-TiO2/Ag compared to either c-TiO2 or Ag nanoparticles alone, the SERS probe molecules rhodamine 6G (R6G) and malachite green (MG) were utilized. Based on the results of SERS detections for probe molecules and contaminants, it demonstrates that a-TiO2/Ag nanosheets produce highly sensitive and repeatable Raman signals. The detectable concentration limits for R6G and MG were found to be 10-11 M and 10-10 M, respectively. And it has been determined that the system exhibits an enhancement factor (EF) of up to 1 × 108. The limit of detection for 4-mercaptobenzoic acid and alizarin red can both reach 1 × 10-8. Furthermore, a finite-difference time-domain simulation is performed in order to evaluate the magnetic field strength generated by Ag nanoparticles. As a result of the simulation, it is evident that the actual EF is smaller than the calculated one, leading support to the view that a-TiO2 nanosheets have a beneficial effect on the chemical enhancement of SERS.

Staining protocols affect use of otolith to estimate the demography of the damselfish sergeant major (Abudefduf vaigiensis).

This study assessed the otolith (sagittae, lapilli, and asterisci) increment deposition rate in the range-shifting damselfish, A. vaigiensis, using different concentrations of Alizain Red S and evaluated the impact of staining on increment width. Daily increment deposition was verified in all otolith types and presented clearer fluorescent markings in the lapilli and sagittae than the asterisci, with high stain concentration showing the best clarity. Higher stain concentrations were found to decrease increment width, suggesting care is needed when using stained otoliths as a proxy for growth for this species.

Simultaneous detection of norepinephrine and 5-hydroxytryptophan using poly-alizarin/multi-walled carbon nanotubes-graphene modified carbon fiber microelectrode array sensor.

Multi-walled carbon nanotubes, graphene and alizarin polymer composites coated carbon fiber microelectrode array sensor (p-AZ/MWCNT-GR/CFMEA) was constructed and used for the simultaneous detection of norepinephrine (NE) and 5-hydroxytryptophan (5-HT). The morphology and structural characteristics of sensor are characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Its electrochemical behavior has been studied with cyclic voltammetry and electrochemical impedance spectroscopy. The sensor exhibits excellent electrochemical activity for the oxidation of NE and 5-HT, two well separated oxidation peaks with the peak potential difference of 220 mV are observed on the cyclic voltammogram. NE and 5-HT both show two electrons and two protons electrochemical reaction on the p-AZ/MWCNT-GR/CFMEA. Under the optimized experiment conditions, the linear ranges of the sensor for NE and 5-HT are 0. 08- 8 µM and 0. 1-20 µM with detection limits of 4. 22 nM and 14. 2 nM (S/N = 3), respectively. In addition, the microsensor array show good reproducibility, stability and selectivity for the determination of NE and 5-HT. Finally, the p-AZ/MWCNT-GR/CFMEA is applied to the simultaneous detection of NE and 5-HT in human serum samples and macrophages.

Espial: Electrochemical Soil pH Sensor for In Situ Real-Time Monitoring.

We present a first-of-its-kind electrochemical sensor that demonstrates direct real-time continuous soil pH measurement without any soil pre-treatment. The sensor functionality, performance, and in-soil dynamics have been reported. The sensor coating is a composite matrix of alizarin and Nafion applied by drop casting onto the working electrode. Electrochemical impedance spectroscopy (EIS) and squarewave voltammetry (SWV) studies were conducted to demonstrate the functionality of each method in accurately detecting soil pH. The studies were conducted on three different soil textures (clay, sandy loam, and loamy clay) to cover the range of the soil texture triangle. Squarewave voltammetry showed pH-dependent responses regardless of soil texture (while electrochemical impedance spectroscopy's pH detection range was limited and dependent on soil texture). The linear models showed a sensitivity range from -50 mV/pH up to -66 mV/pH with R2 > 0.97 for the various soil textures in the pH range 3-9. The validation of the sensor showed less than a 10% error rate between the measured pH and reference pH for multiple different soil textures including ones that were not used in the calibration of the sensor. A 7-day in situ soil study showed the capability of the sensor to measure soil pH in a temporally dynamic manner with an error rate of less than 10%. The test was conducted using acidic and alkaline soils with pH values of 5.05 and 8.36, respectively.