Synthesis and Characterization of Nickel Oxide Nanostructures for Electrochemical Analysis of Methotrexate

Metal oxide nanoparticles have found numerous applications in different fields. In this paper, the preparation of nickel oxide nanostructures is given. The nanostructures were synthesized by using the hydrothermal method. The characterization was done with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The newly synthesized nanostructures were utilized as a modifier of the working electrode, i.e., glassy carbon electrode (GCE). The modified GCE exhibited an excellent response towards methotrexate (MTX) anticancer drug. The modified GCE, as compared to bare GCE, showed an increased response towards MTX. In this study, BrittonRobinson buffer (BRB) was selected as a supporting electrolyte having pH 5. By using electrochemical impedance spectroscopy (EIS), the method was found linear in the range of 5-40 µM with a limit of detection and quantification values of 2.4 µM and 7.28 µM, respectively. The method developed by this way was successfully applied for the analysis of MTX from injection formulations. The interference studies were also carried out to check the method's selectivity.

No Diagnostic Utility of Zero Heparin Control Buffer in Serotonin Release Assay: Findings from a Validation Study

Background: Heparin induced thrombocytopenia (HIT) is a rare immune mediated complication that is triggered in a subset of patients temporal to therapeutic heparin exposure. Laboratory testing is based on screening for the presence of serum anti-PF4 antibodies using sensitive solid-phase immunoassays. If antibodies are detected, functional testing to demonstrate the platelet activating properties and heparin dependence of these immune complexes is then performed. Previous studies have reported possible clinical utility in identifying non heparin dependent platelet activating antibodies using a buffer control with zero heparin in the serotonin release functional assay (SRA). These reports suggested a correlation between reactivity in the zero heparin buffer control and pathogenicity of HIT antibodies which may define a subtype of HIT, referred to as autoimmune HIT. We aimed to investigate the utility of zero heparin buffer control as a part of an inhouse validation study of a mass spectrometry-coupled SRA (Mayo-SRA). Methods: Three hundred archived serum samples were tested using anti-PF4 IgG antibody enzyme-linked immunosorbent assay (ELISA; Immucor Diagnostics, GA, USA). SRA was preformed on all samples using Mayo-SRA and reference 14C SRA methods. Zero heparin control buffer was included in the Mayo-SRA assay. Serotonin release >20% in the low dose heparin (0.1U/mL, LDH) and ELISA optical density (OD) >0.4 were considered positive. Drug interference studies were performed by spiking known SRA-positive samples with increasing concentrations of unfractionated heparin (UFH), low molecular weight heparin (LMWH) or fondaparinux in the LDH and zero heparin SRA. The clinical 4T score was calculated retrospectively calculated for all patients. Results: Of the 300 tested samples, 57 were anti-PF4 ELISA positive. 33 of the 57 samples were positive using the reference 14C SRA method. Whereas 43 samples were positive by Mayo-SRA assay. Three additional samples were positive by Mayo-SRA, but negative by both screening anti-PF4 ELISA and the reference SRA method (Fig- 1A). Lastly, 13 samples were anti-PF4 ELISA positive, but SRA negative by both methods in comparison. Interestingly, 44 of 46 (95%) samples interpreted positive by LDH were also interpreted positive (serotonin release >20%) under zero heparin conditions. These included the 3 samples that were positive by Mayo-SRA but negative by both screening anti-PF4 ELISA and the reference SRA. The overall % serotonin release using zero heparin control was significantly lower (P= 0.003, paired Student T-test) compared to LDH (Fig-1B). In addition, zero heparin followed a similar pattern as LDH, with highest levels at ELISA OD units >2 (Fig-1C). Strikingly, drug interference studies showed artifactual serotonin release in the zero heparin reaction, which was not detected in the absence of spiked drugs. For UFH, serotonin release in zero heparin control occurred at very low spiked concentrations, ≥0.063 U/mL. LMWH and fondaparinux spiking experiments also displayed similar zero heparin serotonin release patterns (Fig-1D). Of note, none of these interferences were detected in UFH spiked SRA-negative samples (data not shown). Conclusion: Contrary to prior results suggesting that less than 50% of LDH SRA positive samples are also positive in the zero heparin SRA, our results show high zero heparin SRA positivity rate of >95%. Zero heparin SRA showed a pattern with highest levels at ELISA OD units >2 suggesting that reactivity in this condition is a function of antibody strength rather than a qualitative difference (i.e. "autoimmune" HIT antibodies vs "non-autoimmune" HIT antibodies). In addition, contamination of patient sera with small amounts of remnant heparin can significantly impact platelet activation in the zero heparin SRA test. Thus, zero heparin SRA positive results may be artifactual and represent residual heparin contained in the patient sample. Figure legend: Fig-1A. Scatter plots of SRA positive samples grouped by 4T scores. Red dots are Mayo-SRA only positive samples. Fig-1B and Fig-1C. Scatter plots of % serotonin release of Mayo-SRA positive samples at LDH (circles) vs. zero heparin buffers (squares), and grouped by ELISA OD values, respectively. Fig-1D. % Serotonin release of known SRA-positive samples spiked with increasing concentrations of UFH, LMWH, or fondaparinux at LDH (white) or zero heparin buffers (red). Figure 1 Figure 1. Disclosures Pruthi: CSL Behring: Honoraria; Genentech: Honoraria; Bayer Healthcare AG: Honoraria; HEMA Biologics: Honoraria; Instrumentation Laboratory: Honoraria; Merck: Honoraria. Padmanabhan: Veralox Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Using Graphene-Based Biosensors to Detect Dopamine for Efficient Parkinson’s Disease Diagnostics

Parkinson’s disease (PD) is a neurodegenerative disease in which the neurotransmitter dopamine (DA) depletes due to the progressive loss of nigrostriatal neurons. Therefore, DA measurement might be a useful diagnostic tool for targeting the early stages of PD, as well as helping to optimize DA replacement therapy. Moreover, DA sensing appears to be a useful analytical tool in complex biological systems in PD studies. To support the feasibility of this concept, this mini-review explores the currently developed graphene-based biosensors dedicated to DA detection. We discuss various graphene modifications designed for high-performance DA sensing electrodes alongside their analytical performances and interference studies, which we listed based on their limit of detection in biological samples. Moreover, graphene-based biosensors for optical DA detection are also presented herein. Regarding clinical relevance, we explored the development trends of graphene-based electrochemical sensing of DA as they relate to point-of-care testing suitable for the site-of-location diagnostics needed for personalized PD management. In this field, the biosensors are developed into smartphone-connected systems for intelligent disease management. However, we highlighted that the focus should be on the clinical utility rather than analytical and technical performance.

Laser-Induced Graphene-Based Enzymatic Biosensor for Glucose Detection

Laser-induced graphene (LIG) has recently been receiving increasing attention due to its simple fabrication and low cost. This study reports a flexible laser-induced graphene-based electrochemical biosensor fabricated on a polymer substrate by the laser direct engraving process. For this purpose, a 450 nm UV laser was employed to produce a laser-induced graphene electrode (LIGE) on a polyimide substrate. After the laser engraving of LIGE, the chitosan–glucose oxidase (GOx) composite was immobilized on the LIGE surface to develop the biosensor for glucose detection. It was observed that the developed LIGE biosensor exhibited good amperometric responses toward glucose detection over a wide linear range up to 8 mM. The GOx/chitosan-modified LIGE biosensor showed high sensitivity of 43.15 µA mM−1 cm−2 with a detection limit of 0.431 mM. The interference studies performed with some possible interfering compounds such as ascorbic acid, uric acid, and urea exhibited no interference as there was no difference observed in the amperometric glucose detection. It was suggested that the LIGE-based biosensor proposed herein was easy to prepare and could be used for low-cost, rapid, and sensitive/selective glucose detection.

Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters

This paper presents a novel procedure for the treatment of contaminated water with high concentrations of nitrates, which are considered as one of the main causes of the eutrophication phenomena. For this purpose, magnetic nanoparticles functionalized with silver (Fe3O4@AgNPs) were synthesized and used as an adsorbent of nitrates. Experimental conditions, including the pH, adsorbent and adsorbate dose, temperature and contact time, were analyzed to obtain the highest adsorption efficiency for different concentration of nitrates in water. A maximum removal efficiency of 100% was reached for 2, 5, 10 and 50 mg/L of nitrate at pH = 5, room temperature, and 50, 100, 250 and 500 µL of Fe3O4@AgNPs, respectively. The characterization of the adsorbent, before and after adsorption, was performed by energy dispersive X-ray spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller analysis and Fourier-transform infrared spectroscopy. Nitrates can be desorbed, and the adsorbent can be reused using 500 µL of NaOH solution 0.01 M, remaining unchanged for the first three cycles, and exhibiting 90% adsorption efficiency after three regenerations. A deep study on equilibrium isotherms reveals a pH-dependent behavior, characterized by Langmuir and Freundlich models at pH = 5 and pH = 1, respectively. Thermodynamic studies were consistent with physicochemical adsorption for all experiments but showed a change from endothermic to exothermic behavior as the temperature increases. Interference studies of other ions commonly present in water were carried out, enabling this procedure as very selective for nitrate ions. In addition, the method was applied to real samples of seawater, showing its ability to eliminate the total nitrate content in eutrophized waters.

Do Cross-Language Script Differences Enable Bilinguals to Function Selectively When Speaking in One Language Alone?

The present study examined the role of script in bilingual speech planning by comparing the performance of same and different-script bilinguals. Spanish-English bilinguals (Experiment 1) and Japanese-English bilinguals (Experiment 2) performed a picture-word interference task in which they were asked to name a picture of an object in English, their second language, while ignoring a visual distractor word in Spanish or Japanese, their first language. Results replicated the general pattern seen in previous bilingual picture-word interference studies for the same-script, Spanish-English bilinguals but not for the different-script, Japanese-English bilinguals. Both groups showed translation facilitation, whereas only Spanish-English bilinguals demonstrated semantic interference, phonological facilitation, and phono-translation facilitation. These results suggest that when the script of the language not in use is present in the task, bilinguals appear to exploit the perceptual difference as a language cue to direct lexical access to the intended language earlier in the process of speech planning.

Exploration of a Molecularly Imprinted Polymer (MIPs) as an Adsorbent for the Enrichment of Trenbolone in Water

The presence of endocrine disruptors in surface waters can have negative implications on wildlife and humans both directly and indirectly. A molecularly imprinted polymer (MIP) was explored for its potential to enhance the UV-Vis determination of trenbolone in water using solid-phase extraction (SPE). The synthesized MIP was studied using Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM). Using the MIP resulted in a preconcentration and enrichment factor of 14 and 8, respectively. Trenbolone binding on the MIP was shown to follow a Langmuir adsorption and had a maximum adsorption capacity of 27.5 mg g−1. Interference studies showed that the MIP selectivity was not compromised by interferences in the sample. The MIP could be recycled three times before significant loss in analyte recovery.

Validation of Soluble Fms-Like Tyrosine Kinase-1 (sFlt-1) and Placental Growth Factor (PlGF) Assays on Cobas e602 System

Background Preeclampsia is a leading hypertensive disorder in pregnant women. The angiogenic biomarkers, soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) ratio, have been shown to be associated with diagnosis and prediction of preeclampsia. The objective of this study is to validate the analytical performance of sFlt-1 and PlGF on the Cobas e602 system (Roche Diagnostics Corporation). Method Intra-day and inter-day precisions for both sFlt-1 and PlGF assays were assessed using quality control materials provided from Roche Diagnostics. The accuracies for both assays were assessed by running 60 patient samples, which have been previously analyzed on the Elecsys 411 analyzer (Roche Diagnostics Corporation) at the Beth Israel Deaconess Medical Center. Linearity studies for both assays were performed using patient plasma spiked with recombinant sFlt-1 and PlGF proteins (R&D systems). Hemolysis, icterus, lipemia and biotin interference studies were performed by spiking hemolysate, bilirubin, intralipid or biotin into either pooled patient plasma with detectable levels of sFlt-1 and PlGF or otherwise, patient plasma spiked with recombinant sFlt-1 and PlGF proteins. Results Total precisions for both assays demonstrated CVs of <5.0%. The sFlt-1 and PlGF assays demonstrated analytical measuring ranges of 3060,000 pg/mL and 79,000 pg/mL, respectively (r2 > 0.98). Lower limit of quantitation (10% CV) was 30 pg/mL for sFlt-1 and 7 pg/mL for PlGF, respectively. Interference studies showed sFlt-1 and PlGF were not significantly affected by hemolysis up to H-indices of 500 and 1000 respectively; both assays were not affected by bilirubin up to an I-index of 60, and lipemia up to an L-index of 2800. Biotin at concentrations >30 ng/mL caused significant negative bias for both sFlt-1 and PlGF assays. Comparison studies showed the following: Cobas e602 sFLT-1 = 1.09 [Elecsys 411 sFLT-1] +203 (r2=0.97, Sy/x=1234, n=58); Cobas e602 PlGF = 1.10 [Elecsys 411 PlGF] +47 (r2=0.99, Sy/x=22.1, n=58); Cobas e602 sFLT-1/PlGF ratio = 0.94 [Elecsys 411 sFLT-1/PlGF ratio] +3.5 (r2=0.91, Sy/x=50, n=58). Conclusion sFlt-1 and PlGF measured on Roche Diagnostics Cobas e602 system demonstrated excellent analytical performance and are acceptable for clinical use once approved in the US.