Screen-Printed Sensors Modified with Nafion and Mesoporous Carbon for Electrochemical Detection of Lead in Blood.

Lead (Pb) has long been acknowledged as a systemic toxicant, with pronounced health impacts observed even at low exposure levels, particularly in children. Adverse effects include diminished cognitive function, altered behavior, and developmental delays. Consequently, it is imperative to conduct regular monitoring of Blood Lead Levels (BLLs). In this work, we report on an electrochemical sensor based on screen-printed carbon electrode (SPCE) coated with Nafion and mesoporous carbon (MC). The sensor system uses simple sample preparation (acidification and dilution of whole blood), minimal sample volume (a few blood drops, 200 µl), and swift time-to-results (1 h). A limit of quantitation (LOQ) of 0.3 µg dL-1 Pb was achieved in whole blood. To demonstrate the practical utility of our sensor system, we evaluated its performance in the analysis of blood samples collected from children (n = 25). Comparative analysis with the laboratory-based gold standard method of inductively coupled plasma mass spectrometry (ICP-MS) demonstrated approximately 77% accuracy and 94% precision. We anticipate that our approach will serve as a valuable tool for more frequent BLL monitoring, particularly in communities where access to laboratory testing is impractical or expensive.

Fluorescent/Colorimetric Dual-Mode Discriminating Gln and Val Enantiomers Based on Carbon Dots.

Discrimination and quantification of amino acid (AA) enantiomers are particularly important for diagnosing and treating diseases. Recently, dual-mode probes have gained a lot of research interest because they can catch more detecting information compared with the single-mode probes. Thus, it is of great significance to develop a dual-mode sensor realizing AA enantiomer discrimination conveniently and efficiently. In this work, carbon dot L-TCDs were prepared by N-methyl-1,2-benzenediamine dihydrochloride (OTD) and l-tryptophan. With the assistance of H2O2, L-TCDs show an excellent discrimination performance for enantiomers of glutamine (Gln) and valine (Val) in both fluorescent and colorimetric modes. The fluorescence enantioselectivity of Gln (FD/FL) and Val (FL/FD) is 5.29 and 4.13, respectively, and the colorimetric enantioselectivity of Gln (ID/IL) and Val (IL/ID) is 13.26 and 3.42, individually. The chiral recognition mechanism of L-TCDs was systematically studied. L-TCDs can be etched by H2O2, and the participation of AA enantiomers results in different amounts of the released OTD, which provides fluorescent and colorimetric signals for identifying and quantifying the enantiomers of Gln and Val. This work provides a more convenient and flexible dual-mode sensing strategy for discriminating AA enantiomers, which is expected to be of great value in facile and high-throughput chiral recognition.

Electrochemical Determination of Manganese in Whole Blood with Indium Tin Oxide Electrode.

In this work, we demonstrate accurate and precise measurement of manganese (Mn) concentration in human whole blood with indium tin oxide (ITO) electrode using square wave stripping voltammetry. While an essential trace metal for human health, elevated levels of Mn due to environmental or occupational exposure have been associated with severe neuromotor dysfunction characterized by parkinsonism and cognitive dysfunction making the monitoring of Mn in whole blood necessary. Pediatric populations are particularly susceptible to Mn given their developing brain and potential long-term impacts on neurodevelopment. The current gold standard for whole blood Mn measurements is by ICP-MS, which is costly and time consuming. The electrochemical detection with ITO working electrode in this work showed a limit of detection of 0.5 µg l-1 and a linear range of 5 to 500 µg l-1, which encompasses the physiological Mn levels in human whole blood (5-18 µg l-1). Our results of Mn measurement in whole blood show an average precision of 96.5% and an average accuracy of 90.3% compared to ICP-MS for both the normal range (5-18 µg l-1) and the elevated levels (>36 µg l-1) that require medical intervention. These results demonstrate the feasibility of Mn measurements in human blood with electrochemical sensors.

Validation of Electrochemical Sensor for Determination of Manganese in Drinking Water.

Manganese (Mn) is an essential nutrient for metabolic functions, yet excessive exposure can lead to neurological disease in adults and neurodevelopmental deficits in children. Drinking water represents one of the routes of excessive Mn exposure. Both natural enrichment from rocks and soil, and man-made contamination can pollute groundwater that supplies drinking water for a substantial fraction of the U.S. population. Conventional methods for Mn monitoring in drinking water are costly and involve a long turn-around time. Recent advancements in electrochemical sensing, however, have led to the development of miniature sensors for Mn determination. These sensors rely on a cathodic stripping voltammetry electroanalytical technique on a miniaturized platinum working electrode. In this study, we validate these electrochemical sensors for the determination of Mn concentrations in drinking water against the standard method using inductively coupled plasma mass spectrometry (ICP-MS). Drinking water samples (n = 78) in the 0.03 ppb to 5.3 ppm range were analyzed. Comparisons with ICP-MS yielded 100% agreement, ∼70% accuracy, and ∼91% precision. We envision the use of our system for rapid and inexpensive point-of-use identification of Mn levels in drinking water, which is especially valuable for frequent monitoring where contamination is present.

Development and application of a microfabricated multimodal neural catheter for neuroscience.

We present a microfabricated neural catheter for real-time continuous monitoring of multiple physiological, biochemical and electrophysiological variables that are critical to the diagnosis and treatment of evolving brain injury. The first generation neural catheter was realized by polyimide-based micromachining and a spiral rolling packaging method. The mechanical design and electrical operation of the microsensors were optimized and tailored for multimodal monitoring in rat brain such that the potential thermal, chemical and electrical crosstalk among the microsensors as well as errors from micro-environmental fluctuations are minimized. In vitro cytotoxicity analyses suggest that the developed neural catheters are minimally toxic to rat cortical neuronal cultures. In addition, in vivo histopathology results showed neither acute nor chronic inflammation for 7 days post implantation. The performance of the neural catheter was assessed in an in vivo needle prick model as a translational replica of a "mini" traumatic brain injury. It successfully monitored the expected transient brain oxygen, temperature, regional cerebral blood flow, and DC potential changes during the passage of spreading depolarization waves. We envisage that the developed multimodal neural catheter can be used to decipher the causes and consequences of secondary brain injury processes with high spatial and temporal resolution while reducing the potential for iatrogenic injury inherent to current use of multiple invasive probes.

Highly accurate thermal flow microsensor for continuous and quantitative measurement of cerebral blood flow.

Cerebral blood flow (CBF) plays a critical role in the exchange of nutrients and metabolites at the capillary level and is tightly regulated to meet the metabolic demands of the brain. After major brain injuries, CBF normally decreases and supporting the injured brain with adequate CBF is a mainstay of therapy after traumatic brain injury. Quantitative and localized measurement of CBF is therefore critically important for evaluation of treatment efficacy and also for understanding of cerebral pathophysiology. We present here an improved thermal flow microsensor and its operation which provides higher accuracy compared to existing devices. The flow microsensor consists of three components, two stacked-up thin film resistive elements serving as composite heater/temperature sensor and one remote resistive element for environmental temperature compensation. It operates in constant-temperature mode (~2 °C above the medium temperature) providing 20 ms temporal resolution. Compared to previous thermal flow microsensor based on self-heating and self-sensing design, the sensor presented provides at least two-fold improvement in accuracy in the range from 0 to 200 ml/100 g/min. This is mainly achieved by using the stacked-up structure, where the heating and sensing are separated to improve the temperature measurement accuracy by minimization of errors introduced by self-heating.

[Regulatory effect of leonurus extracts on hyperuricemia in rats].

In this study, SD rats were orally administrated with oteracil potassium (300 mg . kg-1 . d-1 ) to prepare the hyperuricemia model, and divided into normal, model, Allopurinol, LE high dosage, middle dosage and low dose (200, 100, 50 mg . kg-1 . d-1) groups. The rats were orally administrated with test drugs 1 hour later after being orally administrated with Oteracil potassium. After 7 days, serum uric acid, serum creatinine, uric acid and expression of relevant transporters in kidney were tested to study the regulatory effect of leonurus extracts on serum uric acid, renal function and relevant transporters in kidney of rats with hyperuricemia. Compared with the model group, the leonurus extract group could significantly down-regulate serum uric acid and creatinine levels of rats with hyperuricemia, and increase the urine uric acid level. Meanwhile, leonurus extracts could notably down-regulate the mRNA expressions of urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9), up-regulate the mRNA expressions of organic cation transportanter (OCT) and Carnitine transporter (OCTN) and promote the excretion of uric acid of kidney.

Bioactive protopanaxatriol type saponins isolated from the roots of Panax notoginseng (Burk.) F. H. Chen.

Seven new protopanaxatriol type saponins, 20S-sanchirhinosides A1 (1), A2 (2), A3 (3), A4 (4), A5 (5), and A6 (6), and sanchirhinoside B (7) were obtained as minor constituents from the root extract of Panax notoginseng (Burkill, F. H. Chen), which showed protection effects against antimycin A induced mitochondrial oxidative stress. Their structures were elucidated by chemical and spectroscopic methods (IR, HRESI-TOF-MS, 1D and 2D NMR). Among them, compounds 4, 6 and 7 showed significant protective effects against antimycin A-induced L6 cell injury.

Determination of Mercury with a Miniature Sensor for Point-of-care Testing.

In developing countries, subsistence gold mining entails mixing metallic mercury with crushed sediments to extract gold. In this approach, the gold-mercury amalgam is heated to evaporate mercury and obtain gold. Thus, the highly volatile mercury can be absorbed through inhalation, resulting in adverse health effects. Urinalysis can be used to detect mercury, which is excreted in urine and feces, and correlate exposure with toxic effects. The current gold standard analytical methods are based on fluorescence or inductively coupled plasma mass spectrometry methods, but are expensive, time consuming, and are not easily accessible in countries where testing is needed. In this work, we report on a miniature electrochemical sensor that can rapidly detect mercury in urine at levels well below the US Biological Exposure Index (BEI) limit of 50 ppb (µg/L). The sensor is based on a thin-film gold electrode and anodic stripping voltammetry electroanalytical approach. The sensor successfully detected mercury at trace levels in urine, with a limit of detection of ~15 ppb Hg in the linear range of 20-80 ppb. With the low-cost disposable sensors and portable instrumentation, it is well suited for point-of-care applications.

Brain temperature measurement: A study of in vitro accuracy and stability of smart catheter temperature sensors.

The injured brain is vulnerable to increases in temperature after severe head injury. Therefore, accurate and reliable measurement of brain temperature is important to optimize patient outcome. In this work, we have fabricated, optimized and characterized temperature sensors for use with a micromachined smart catheter for multimodal intracranial monitoring. Developed temperature sensors have resistance of 100.79 ± 1.19Ω and sensitivity of 67.95 mV/°C in the operating range from15-50°C, and time constant of 180 ms. Under the optimized excitation current of 500 µA, adequate signal-to-noise ratio was achieved without causing self-heating, and changes in immersion depth did not introduce clinically significant errors of measurements (<0.01°C). We evaluated the accuracy and long-term drift (5 days) of twenty temperature sensors in comparison to two types of commercial temperature probes (USB Reference Thermometer, NIST-traceable bulk probe with 0.05°C accuracy; and IT-21, type T type clinical microprobe with guaranteed 0.1°C accuracy) under controlled laboratory conditions. These in vitro experimental data showed that the temperature measurement performance of our sensors was accurate and reliable over the course of 5 days. The smart catheter temperature sensors provided accuracy and long-term stability comparable to those of commercial tissue-implantable microprobes, and therefore provide a means for temperature measurement in a microfabricated, multimodal cerebral monitoring device.

Micromachined lab-on-a-tube sensors for simultaneous brain temperature and cerebral blood flow measurements.

This work describes the development of a micromachined lab-on-a-tube device for simultaneous measurement of brain temperature and regional cerebral blood flow. The device consists of two micromachined gold resistance temperature detectors with a 4-wire configuration. One is used as a temperature sensor and the other as a flow sensor. The temperature sensor operates with AC excitation current of 500 µA and updates its outputs at a rate of 5 Hz. The flow sensor employs a periodic heating and cooling technique under constant-temperature mode and updates its outputs at a rate of 0.1 Hz. The temperature sensor is also used to compensate for temperature changes during the heating period of the flow sensor to improve the accuracy of flow measurements. To prevent thermal and electronic crosstalk between the sensors, the temperature sensor is located outside the "thermal influence" region of the flow sensor and the sensors are separated into two different layers with a thin-film Copper shield. We evaluated the sensors for accuracy, crosstalk and long-term drift in human blood-stained cerebrospinal fluid. These in vitro experiments showed that simultaneous temperature and flow measurements with a single lab-on-a-tube device are accurate and reliable over the course of 5 days. It has a resolution of 0.013 °C and 0.18 ml/100 g/min; and achieves an accuracy of 0.1 °C and 5 ml/100 g/min for temperature and flow sensors respectively. The prototype device and techniques developed here establish a foundation for a multi-sensor lab-on-a-tube, enabling versatile multimodality monitoring applications.

Automatic Microtitrator for Small Volume Samples.

Electroanalytical sensors for point-of-care biomedical or point-of-use environmental sample analysis are gaining popularity due to low limits of detection, ease of miniaturization, convenience, and ability to work with small sample volumes. Since pH must be tightly controlled for optimum electrochemical performance, adjustment of pH in these samples is often a necessity. Yet manual titration is time-consuming and can be especially challenging for small volumes. End point determination can also be difficult. Current commercial automatic pH titrators are generally designed for large volume (>1 mL) batch titrations, while the existing microvolume titrators are semiautomatic at best, still relying on multiple manual steps. To address the gap, we developed an automatic microtitration system suitable for small volume samples. The system was validated using digested whole blood microsamples, successfully demonstrating accurate and rapid pH adjustment for samples as small as 100 µL. The simple modular construction of the system makes it compatible with acid washing for trace metal detection and other cleaning or sample preparation steps. The electrochemical detection of manganese heavy metal in blood at the parts per billion level showed no detectable contamination induced by the system. Ultimately, our simple, accurate, user-friendly automatic microtitration system can be used in the pH adjustment of microvolume samples and can potentially be extended to other pH end point analysis.

One-Pot Synthesis of Dual-Responsive Hyperbranched Polymeric Prodrugs Using an All-in-One Chain Transfer Monomer.

Over the past decades, tremendous progress has been advanced in the preparation of hyperbranched polymers (HPs), especially for the one-pot synthesis of segmented HPs by using self-condensing vinyl polymerization based on controlled living radical polymerization techniques. However, the fabrication of hyperbranched polymeric prodrugs (HPPs) still requires multistep postpolymerization conjugations, which generally suffer from low and uncontrolled conjugation efficacy of drug molecules due to the steric hindrance, low yields because of multistep synthesis, and scale-up difficulties attributed to batch-to-batch variations. To further address these issues and provide a highly straightforward and robust strategy toward HPPs, we reported in this study the one-pot preparation of dual-responsive hyperbranched polymeric prodrugs (DRHPPs) using an all-in-one chain transfer monomer that integrates a drug molecule with both acidic pH- and reduction-sensitive links. The resulting DRHPPs with precisely regulated drug loading content and great therapeutic efficacy offered a highly promising platform for efficient anticancer drug delivery.

Peanut arachidin-1 enhances Nrf2-mediated protective mechanisms against TNF-α-induced ICAM-1 expression and NF-κB activation in endothelial cells.

Arachidin-1 [trans-4-(3-methyl-1-butenyl)-3,5,3',4'-tetrahydroxystilbene] is a polyphenol produced by peanut kernels during germination. The aim of the present study was to investigate the mechanism underlying the anti-inflammatory effect of arachidin-1 in endothelial cells (ECs). The results of cell adhesion and western blotting assays demonstrated that arachidin-1 attenuated tumor necrosis factor (TNF)-α-induced monocyte/EC adhesion and intercellular adhesion molecule-1 (ICAM-1) expression. Arachidin-1 was demonstrated to exert its inhibitory effects by the attenuation of TNF-α-induced nuclear factor-κB (NF-κB) nuclear translocation and inhibitor of κB-α (IκBα) degradation. Furthermore, arachidin-1 upregulated nuclear factor-E2-related factor-2 (Nrf-2), a known mediator of phase II enzyme expression, and increased the transcriptional activity of antioxidant response element. Transfection of ECs with Nrf-2 siRNA blocked the inhibitory effect of arachidin-1 on ICAM-1 expression, NF-κB nuclear translocation and IκBα degradation. In addition, arachidin-1 induced the expression of the phase II enzymes thioredoxin-1, thioredoxin reductase-1, heme oxygenase-1, glutamyl-cysteine synthetase and glutathione S-transferase. Following arachidin-1 pretreatment, the H2O2-induced generation of reactive oxygen species was reduced. Therefore, the present results indicate that arachidin-1 suppresses TNF-α-induced inflammation in ECs through the upregulation of Nrf-2-related phase II enzyme expression.

Lycopene inhibits ICAM-1 expression and NF-κB activation by Nrf2-regulated cell redox state in human retinal pigment epithelial cells.

AIMS: Age-related macular degeneration (AMD) is one of the most common diseases leading to blindness in elderly people. The progression of AMD may be prevented through anti-inflammation and antioxidation in retinal pigment epithelium (RPE) cells. Lycopene, a carotenoid, has been shown to possess both antioxidative and anti-inflammatory properties. This research was conducted to detail the mechanisms of these effects of lycopene-treated RPE cells. MAIN METHODS: We exposed ARPE-19 cells to TNFα after pretreatment with lycopene, and measured monocyte adhesion, ICAM-1 expression, NF-κB nuclear translocation, and transcriptional activity. Cell viability was assayed with Alamar Blue. The cell redox state was tested by glutathione (GSH) and reactive oxygen species (ROS) levels. The importance of the Nrf2 pathway was tested in nuclear translocation, promoter reporter assay, and siRNA. KEY FINDINGS: Lycopene could reduce TNF-α-induced monocyte adhesion and H2O2- induced cell damage in RPE cells. Furthermore, lycopene inhibits ICAM-1 expression and abolishes NF-κB activation for up to 12h in TNFα-treated RPE cells. Lycopene upregulates Nrf2 levels in nuclear extracts and increases the transactivity of antioxidant response elements. The use of Nrf2 siRNA blocks the inhibitory effect of lycopene in TNF-α-induced ICAM-1 expression and NF-κB activation. Glutamate-cysteine ligase (GCL) is the rate-limiting enzyme in the de novo synthesis of GSH. We found that lycopene increases intracellular GSH levels and GCL expression. Following lycopene treatment, TNF-α-induced ROS production was abolished. SIGNIFICANCE: The Nrf2-regulated antioxidant property plays a pivotal role in the anti-inflammatory mechanism underlying the inhibition of NF-κB activation in lycopene-treated ARPE-19 cells.

Single probe for real-time simultaneous monitoring of neurochemistry and direct-current electrocorticography.

We report a novel single neural probe for real-time simultaneous monitoring of multiple neurochemicals and direct-current electrocorticography (DC-ECoG). A major advance of this probe is the inclusion of two iridium oxide reference electrodes to improve sensor accuracy. The ECoG reference electrode is identical to the ECoG recording electrodes to significantly improve DC stability, while the reference for electrochemical sensors has 10-fold lower polarization rate to minimize the small current-induced drift in the reference electrode potential. In vitro, the single probe selectively measured oxygen (r(2)=0.985 ± 0.01, concentration range=0-60 mmHg, limit of detection=0.4 ± 0.07 mmHg) and glucose (r(2)=0.989 ± 0.009, concentration range=0-4mM, limit of detection=31 ± 8 µM) in a linear fashion. The performance of the single probe was assessed in an in vivo needle prick model to mimic sequelae of traumatic brain injury. It successfully monitored the theoretically expected transient brain oxygen, glucose, and DC potential changes during the passage of spreading depolarization (SD) waves. We envision that the developed probe can be used to decipher the cause-effect relationships between multiple variables of brain pathophysiology with the high temporal and spatial resolutions that it provides.

Evaluation of microelectrode materials for direct-current electrocorticography.

OBJECTIVE: Direct-current electrocorticography (DC-ECoG) allows a more complete characterization of brain states and pathologies than traditional alternating-current recordings (AC-ECoG). However, reliable recording of DC signals is challenging because of electrode polarization-induced potential drift, particularly at low frequencies and for more conducting materials. Further challenges arise as electrode size decreases, since impedance is increased and the potential drift is augmented. While microelectrodes have been investigated for AC-ECoG recordings, little work has addressed microelectrode properties for DC-signal recording. In this paper, we investigated several common microelectrode materials used in biomedical application for DC-ECoG. APPROACH: Five of the most common materials including gold (Au), silver/silver chloride (Ag/AgCl), platinum (Pt), Iridium oxide (IrOx), and platinum-iridium oxide (Pt/IrOx) were investigated for electrode diameters of 300 µm. The critical characteristics such as polarization impedance, AC current-induced polarization, long-term stability and low-frequency noise were studied in vitro (0.9% saline). The two most promising materials, Pt and Pt/lrOx were further investigated in vivo by recording waves of spreading depolarization, one of the most important applications for DC-ECoG in clinical and basic science research. MAIN RESULTS: Our experimental results indicate that IrOx-based microelectrodes, particularly with composite layers of nanostructures, are excellent in all of the common evaluation characteristics both in vitro and in vivo and are most suitable for multimodal monitoring applications. Pt electrodes suffer high current-induced polarization, but have acceptable long-term stability suitable for DC-ECoG. Major significance. The results of this study provide quantitative data on the electrical properties of microelectrodes with commonly-used materials and will be valuable for development of neural recordings inclusive of low frequencies.

Hypoglycemic activity evaluation and chemical study on hollyhock flowers.

Hollyhock (Althaea rosea (Linn.) Cavan) belongs to Althaea genus, Malvaceae family, is a perennial garden plant distributed throughout the world in warm temperate and tropical regions, which was used as anti-diabetes ingredient in traditional Chinese medicine. In the process of our research, ethanolic extract of hollyhock flower (HFE) was found to decrease serum triglyceride and glucose levels significantly in KK-A(y) mice after oral administration for 8weeks. Meanwhile, gene expressions on AMPK, IRS2, PI3K, AKT and GLUT4 in liver were remarkably up-regulated. Three new dihydroflavonol glycosides, named as roseaflavanonolosides A (1), B (2), and C (3), together with two known ones were obtained from HFE. Their structures were elucidated by chemical and spectroscopic methods. Hepatic cell glucose uptake experiment was performed using 2-NBDG as a glucose uptake indicator. At the dosage of 20µg/mL for 1-5, the glucose uptake increasing level was nearly 30%-40% in HepG2 cells. We partly revealed the glucose metabolism regulation effect may relate to dihydroflavonols in hollyhock flower.

Excretion of tectoridin metabolites in rat urine and bile orally administrated at different dosages and their inhibitory activity against aldose reductase.

This study investigated the urinary and biliary excretion of tectoridin, a major active isoflavonoid found in the flowers of Pueraria thomsonii Benth. and the rhizomes of Belamcanda chinensis (L.) DC. Using UHPLC/Q-TOFMS, seven glucuronides and/or sulfated metabolites and four Phase I metabolites were simultaneously quantified in rat urine after oral administration of tectoridin at 100 and 200 mg/kg. Over a 72-h period, 14.2% and 14.7% of the tectoridin were excreted as eleven metabolites in urine, among which, two major metabolites tectorigenin-7-O-ß-D-glucuronide (Te-7G) and tectorigenin accounted for 5.5-5.5% and 4.3-4.4%. Furthermore, the cumulative excretion of four glucuronides and sulfated metabolites in bile accounted for 7.3% and 3.9% of the dose within 60 h, among which, Te-7G and tectorigenin-7-O-glucuronide-4'-O-sulfate (Te-7G-4'S) accounted for 2.3-3.0% and 1.4-3.9%, respectively. The results indicate that the urine was the primary elimination route, and glucuronidation after deglycosylation at C-7 position was the major metabolic pathway of tectoridin in vivo. Moreover, the inhibitory activities of tectoridin and its five metabolites on rat lens aldose reductase were confirmed (IC50: 1.4-15.5 µM), whereas irisolidone-7-O-glucuronide (Ir-7G) and irisolidone showed little activity.

Acute and long-term toxicity of mango leaves extract in mice and rats.

The acute toxicity of mango leaves extract (MLE) at the maximal dose (18.4 g/kg) was studied in ICR mice and no abnormalities were detected during the experiment. The long-term studies at various doses of MLE (100 mg/kg, 300 mg/kg, and 900 mg/kg) in SD rats for 3 consecutive months revealed that, compared with the control group, rats in MLE treated groups showed slight body weight increase and higher fat weight; the serum TG and CHOL levels and the epididymis weight of male rats were a little higher; the serum K(+) level of female rats was on the low side but the weights of liver, kidney, and adrenal gland were on the high side. In addition to this, no other obvious abnormalities were detected.