A new fluorescence probe for detection of Cu+2 in blood samples: Circuit logic gate.

A Fluorescence probe was designed based on 8-hydroxyquinoline chitosan silica precursor (HQCS) for selective detection of Al3+, Cu2+. The HQCS has no observable fluorescence signal, but after the addition of Al3+, a huge fluorescence signal appeared, and the selective quenching was absorbed after the addition of Cu2+. The effect of other different cations, including Cu2+, Mg2+, Ca2+, Pb2+, Zn2+, Hg2+, Ag+, Fe3+, and K+ was studied. The addition of Cu2+ to the probe (HQCSAL) decreased the fluorescence very repeatable, and the variation of the fluorescence vs. Cu2+ was monotonic and linear. Therefore, the prepared probe was used to determine Cu2+ ions in real samples. The mechanism of fluorescence variation by adding cations to the probe solution was studied using the Stern-Volmer equation. Under the optimum conditions, the linear range and detection limit were 3.5-31 µM and 1 µM, respectively. The probe accuracy on the copper determination in the blood and tap waters was comparable to the ICP-OES results. The circuit logic gate mimic was designed for the fluorescence behavior of the probe constituents.

Hypozincemia in COVID-19 Patients Correlates With Stronger Antibody Response.

Zinc ion as an enzyme cofactor exhibits antiviral and anti-inflammatory activity during infection, but circulating zinc ion level during Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is unclear. This study aimed to evaluate serum zinc ion level in Coronavirus Disease 2019 (COVID-19) patients and healthy subjects, as well as its correlation with antibodies against SARS-CoV-2. 114 COVID-19 patients and 48 healthy subjects (38 healthy volunteers and 10 close contacts of patients with COVID-19) were included. Zinc ion concentration and levels of antibodies against SARS-CoV-2 Spike 1 + Spike 2 proteins, nucleocapsid protein, and receptor-binding domain in serum were measured. Results showed that the concentration of zinc ion in serum from COVID-19 patients [median: 6.4 nmol/mL (IQR 1.5 - 12.0 nmol/mL)] were significantly lower than that from the healthy subjects [median: 15.0 nmol/mL (IQR 11.9 - 18.8 nmol/mL)] (p < 0.001) and the difference remained significant after age stratification (p < 0.001) or when the patients were at the recovery stage (p < 0.001). Furthermore, COVID-19 patients with more severe hypozincemia showed higher levels of IgG against the receptor-binding domain of SARS-CoV-2 spike protein. Further studies to confirm the effect of zinc supplementation on improving the outcomes of COVID-19, including antibody response against SARS-CoV-2, are warranted.

Evaluation of a New Automated Routine Measurement for Serum Adjusted Ionized Calcium (at pH 7.4) in Patients Suspected of Calcium Metabolic Disease.

BACKGROUND: Total calcium is a less accurate test in predicting ionized calcium (Ca2+) in patients suspected of calcium metabolic disease. Nevertheless, total calcium continues to be used as routine measurement instead of adjusted Ca2+ (at pH 7.4). In the current study we evaluate a new multichannel instrument, the ISE Module E1200 for adjusted Ca2+ (at pH 7.4), containing three different ion-selective electrode (ISE) units. METHODS: Serum from 1350 patients was compared to the ABL835 flex and KoneLab. Total calcium was also evaluated on the Dimension Vista 1500 system. Correlations between instruments were assessed by Deming regression and degree of agreement by Cohen's kappa (κ). RESULTS: Analytical imprecisions for the three ISE units for adjusted Ca2+ (at pH 7.4) was between 0.36% and 2.52%, and for pH between 0.32% and 3.24%. Results were comparable for each ISE unit (r = 0.797-0.917; all P < 0.0001) and in high-throughput settings (r = 0.871; P < 0.0001). The degree of agreement between instruments was moderate to good (κ = 0.52-0.77). In contrast, there was a very poor agreement (κ = -0.14) for total calcium with discrepancy in 53.4% of the samples. CONCLUSIONS: The new ISE Module E1200 is comparable with the ABL835 flex and KoneLab 30i and therefore may be used for routine analysis of serum adjusted Ca2+ (at pH 7.4). The measured adjusted Ca2+ (at pH 7.4) was less comparable with very poor agreement to total calcium measured on the Dimension Vista 1500 system.

A highly sensitive DNAzyme-based SERS biosensor for quantitative detection of lead ions in human serum.

Lead ions (Pb2+), one form of the toxic heavy metal, have drawn significant attention due to their harmful effects on human health and the environment. Although many analytical techniques have been developed over the past few decades, the development of a sensitive, selective, and rapid method to detect Pb2+ remains a challenge. In this work, we developed a sensitive surface-enhanced Raman scattering (SERS) biosensor for highly sensitive detection of Pb2+ by using DNAzyme-modified Fe3O4@Au@Ag nanoparticles (Fe3O4@Au@Ag NPs). Firstly, the thiolated 5'-Cy3 DNA probe was modified on the surface of Fe3O4@Au@Ag NPs, which hybridized with the Pb2+-specific DNAzyme to form a SERS biosensor, and the Cy3 labels were used to detect Pb2+. In the presence of Pb2+, the DNAzyme cleaves the Cy3-labeled DNA probe, leading to the release of Cy3-labeled DNA probe from the Fe3O4@Au@Ag NPs. Therefore, the Raman intensity of the Cy3 labels decreases. The proposed biosensor exhibited excellent linearity in the range from 0.01 to 1.0 nM, with a limit of detection for Pb2+ of 5 pM. It features superior selectivity to Pb2+ over other interfering metal ions and good application in the determination of Pb2+ in tap water and human serum samples. The SERS biosensor provides a novel' simple and sensitive method for detection of Pb2+ and sheds new light on the design and synthesis of analogous SERS biosensors for the detection of other heavy metal ions.

Retinal-based polyene fluorescent probe for selectively detection of Cu2+ in physiological saline and serum.

Retinal is a flexible natural chromophore and widely present in organisms. The slender conjugated polyene structure retinal is conducive to entering protein structure. In this work, a novel turn-on fluorescent probe for Cu2+ based on retinal and phenylenediamine was designed and synthesized. The probe achieved recognition of copper ions in human serum complex protein environment. Furthermore, the high sensitivity, selectivity for Cu2+ and the sensing mechanism was also investigated.

Assessment of preeclampsia risk by use of serum ionized magnesium-based equation.

BACKGROUND: Preeclampsia is a common medical complication in pregnancy. It has been reported to be associated with decreased serum magnesium levels. However, there has not been evidence demonstrating utilization of change in magnesium for prediction of preeclampsia. The purpose of this study was to develop magnesium fraction-based equations which took other significant clinical risk factors into consideration for prediction of preeclampsia. METHODS: We collected serum total and ionized magnesium ionized magnesium levels from 84 pregnant women diagnosed with preeclampsia after week 20 of pregnancy. The ionized magnesium fraction was then calculated by the percentage ratio of ionized and total magnesium level. RESULTS: Sixty-four (76.19%) women had normal pregnancy and 20 (23.81%) developed preeclampsia. The ionized magnesium fraction was significantly lower in preeclampsia group (23.95 ± 4.7% vs. 26.28 ± 2.3%, p = .04). Additionally, lower ionized magnesium fraction (24.67%), teenage and elderly primigravida were significantly associated with preeclampsia (OR = 4.41, 95% CI: 1.46-13.40, OR = 5.47, 95% CI: 1.85-35.42 and OR = 11.11, 95% CI: 1.09-113.78, respectively). Consequently, we attempted to develop ionized magnesium fraction-based equations calculate risk scores for preeclampsia. The area of ROC for predictive accuracy of the model was 0.77 (p < .001) and ROC suggested that the score of 0.27 would be a threshold for screening preeclampsia with 70% sensitivity and 81% specificity. CONCLUSIONS: Ionized magnesium fraction may have been appropriate for screening of preeclampsia. We suggested blood testing on total and ionized magnesium concentrations as well as calculation of ionized magnesium fraction in addition to routine antenatal care for better screening of the disease.

Click chemistry-mediated cyclic cleavage of metal ion-dependent DNAzymes for amplified and colorimetric detection of human serum copper (II).

The determination of the level of Cu2+ plays important roles in disease diagnosis and environmental monitoring. By coupling Cu+-catalyzed click chemistry and metal ion-dependent DNAzyme cyclic amplification, we have developed a convenient and sensitive colorimetric sensing method for the detection of Cu2+ in human serums. The target Cu2+ can be reduced by ascorbate to form Cu+, which catalyzes the azide-alkyne cycloaddition between the azide- and alkyne-modified DNAs to form Mg2+-dependent DNAzymes. Subsequently, the Mg2+ ions catalyze the cleavage of the hairpin DNA substrate sequences of the DNAzymes and trigger cyclic generation of a large number of free G-quadruplex sequences, which bind hemin to form the G-quadruplex/hemin artificial peroxidase to cause significant color transition of the sensing solution for sensitive colorimetric detection of Cu2+. This method shows a dynamic range of 5 to 500 nM and a detection limit of 2 nM for Cu2+ detection. Besides, the level of Cu2+ in human serums can also be determined by using this sensing approach. With the advantages of simplicity and high sensitivity, such sensing method thus holds great potential for on-site determination of Cu2+ in different samples. Graphical abstract Sensitive colorimetric detection of copper (II) by coupling click chemistry with metal ion-dependentDNAzymes.

Polyacrylamide-phytic acid-polydopamine conducting porous hydrogel for rapid detection and removal of copper (II) ions.

In this work, a conducting porous polymer hydrogel-based electrochemical sensor has been developed for rapid detection of copper (II) ions (Cu2+). The polymer (termed as PAAM/PA/PDA) hydrogel is prepared through multi-interactions of the monomers dopamine (DA), acrylamide (AAM) and phytic acid (PA) under mild ambient conditions: the AAM polymerizes through free-radical polymerization, DA occurs poly coupling reaction, and PA crosslinks polydopamine (PDA) and polyacrylamide (PAAM) by hydrogen bonds. The three dimensional (3D) network nanostructured PAAM/PA/PDA hydrogel not only provides a large surface area for increasing the amount of immobilized molecules/ions, but also exhibits a good conductivity. The PAAM/PA/PDA hydrogel-based electrochemical sensor exhibits a low detection limit (1nmolL-1, S/N=3) and wide linear range (from 1nmolL-1 to 1µmolL-1) for Cu2+ detection in aqueous samples. Furthermore, the Cu2+ can be sensitively detected by the electrochemical sensor in different sample matrices, indicating that the electrochemical sensor could be used to monitor Cu2+ with reasonable assay performance in practical samples. The PAAM/PA/PDA hydrogel also exhibits a good capacity to remove Cu2+(231.36±4.70mgg-1), which is superior to those of other adsorption materials reported in the literature. The facile synthesized PAAM/PA/PDA hydrogel provides a novel and regenerable platform for monitoring and removing Cu2+ in real samples.

Plasmon enhanced photoelectrochemical sensing of mercury (II) ions in human serum based on Au@Ag nanorods modified TiO2 nanosheets film.

Taking advantages of the monodisperse TiO2 nanosheets (NSs) with high active crystal face exposure and the tunable localized surface plasmon resonance (LSPR) properties of Au@Ag nanorods (NRs), this study demonstrated that TiO2 NSs film with trace amount of Au@Ag NRs modification possess a strong enhancement of photocurrent response, which was remarkably inhibited with the addition of mercury (II) ions (Hg(2+)). Based on the selective decrease of photocurrent with the addition of Hg(2+), a simple photoelectrochemical (PEC) sensor has been assembled. The PEC sensor exhibits wide linear range (0.01-10nM), low detection limit (2.5 pM), satisfying selectivity, reproducibility and acceptable stability for Hg(2+) detection. The feasibility of this method for practical application in human serum has been evaluated and the result was satisfactory. This PEC sensing method would provide a potential application for Hg(2+) detection in clinical diagnosis.

Changes in Some Divalent Cations Concentrations In An Experimental Rat Model of Gentamicin-Induced Acute Renal Failure.

Aim: The changes in divalent cations concentration were assessed in and experimentally gentamicin-induced renal failure in white Wistar rats. Material and Methods: The white male Wistar rats were distributed into 4 groups of 7 animals each and were treated intraperitoneally as follows: Group I (Control): distilled water in a volume of 0.5ml/100g rat/day for10 days; Group II (Ge): gentamicin 80 mg/kbw/day for 7 days; Group III (Ge+Zn): gentamicin 80 mg/kbw/day for 7 days and ZnCl2 5 mg/kbw/day for 10 days prior to administration of Ge and then another 7 days simultaneously with Ge administration; Group IV (Zn): ZnCl2 5 mg/kbw/day for 17 days. Before starting the experiment (I0) and at 3, 7 and 10 days after the first Ge administration, magnesium, copper and zinc plasma concentrations and urinary magnesium levels were determined. Results: Zn administration significantly decreased (p<0.001) plasma Mg concentrations in Ge+Zn group compared to Ge group after 7 days in the experiment, and induced a lower urinary elimination of Mg in Ge+Zn group (p<0.05) than in Ge group (p<0.01). Also, Zn induced a slight augmentation of Cu concentration in Ge+Zn group (p<0.05) compared to Ge group after 7 and 10 days. Conclusions: The variation in divalent cation concentrations in the context of renal diseases may be helpful for an early diagnosis and effective alternative therapeutic measures.

Buccal Cell Cytokeratin 14 Correlates with Multiple Blood Biomarkers of Alzheimer's Disease Risk.

Mild cognitive impairment (MCI) may reflect early stages of neurodegenerative disorders such as Alzheimer's disease (AD). Our hypothesis was that cytokeratin 14 (CK14) expression could be used with blood-based biomarkers such as homocysteine, vitamin B12, and folate to identify individuals with MCI or AD from the Australian Imaging, Biomarkers and Lifestyle (AIBL) flagship study of aging. Buccal cells from 54 individuals were analyzed by a newly developed method that is rapid, automated, and quantitative for buccal cell CK14 expression levels. CK14 was negatively correlated with plasma Mg²âº and LDL, while positively correlated with vitamin B12, red cell hematocrit/volume, and basophils in the MCI group and positively correlated with insulin and vitamin B12 in the AD group. The combined biomarker panel (CK14 expression, plasma vitamin B12, and homocysteine) was significantly lower in the MCI (p = 0.003) and AD (p = 0.0001) groups compared with controls. Receiver-operating characteristic curves yielded area under the curve (AUC) values of 0.829 for the MCI (p = 0.002) group and 0.856 for the AD (p = 0.0003) group. These complex associations of multiple related parameters highlight the differences between the MCI and AD cohorts and possibly an underlying metabolic pathology associated with the development of early memory impairment. The changes in buccal cell CK14 expression observed in this pilot study supports previous results suggesting the peripheral biomarkers and metabolic changes are not restricted to brain pathology alone in MCI and AD and could prove useful as a potential biomarker in identifying individuals with an increased risk of developing MCI and eventually AD.

Coumarine-imino-C2-glucosyl conjugate as receptor for Cu(2+) in blood serum milieu, on silica gel sheet and in Hep G2 cells and the characterization of the species of recognition.

A coumarine-imino-C2-glucosyl conjugate (L) was synthesized and characterized. The conjugate L is found to recognize Cu(2+) in aqueous HEPES buffer by exhibiting a 95% fluorescence quenching in pH range 7-10 even in the presence of several biologically and ecologically relevant metal ions. Fluorescence on-off behavior has been clearly demonstrated on the basis of the binding variability of Cu(2+) to L. The binding has been elicited through the changes observed in fluorescence, absorption, ESI-MS and (1)H NMR titrations. All the other thirteen metal ions studied did not show any change in the fluorescence emission. These ions do not interfere with the recognition of Cu(2+) by L. The structural features of [CuL]2 complex in both the isomeric forms were established by DFT computational calculations. The utility of L has been demonstrated by showing its sensitivity toward Cu(2+) on a thin layer of silica gel. The L gives sensitive fluorescence signals for Cu(2+) even in blood serum and exhibits appropriate fluorescence responses in living cells.

DIVALENT CATIONS PROFILE IN PATIENTS WITH LIVER CIRRHOSIS AND VARICEAL BLEEDING.

AIM: The objective of this study is to evaluate divalent cations serum levels (magnesium, zinc, copper) in liver cirrhossis and one of its major complication (variceal bleeding). MATERIAL AND METHODS: A prospective case-control study including 60 patients with liver cirrhosis complicated with variceal bleeding admitted to the Emergency Department, and 35 subjects without liver cirrhosis which served as group control. Serum concentrations of zinc, copper and magnesium were determined using atomic absorption spectrophotometer. RESULTS: The concentration of magnesium was significantly lower between patients with liver cirrhosis (11.6 ± 2.77mg/l) vs group control study (17.7 = 3.86 mg/l) (p < 0.001), regarding decreased magnesium levels and the presence of complications as hepatic encephalopathy, ascites (Child C class). Serum concentrations of zinc were decreased (0.77 ± 0.35 mg/l) compared to control group (p < 0.001) in patients with liver cirrhosis and variceal bleeding. Serum levels of copper were increased (1.69 ± 0.722 mg/l) compared to control group in patients with liver cirrhosis and variceal bleeding and are also correlated with serum albumin levels (p < 0.001, Pearson coefficient r-0.631). CONCLUSIONS: Variceal bleeding in patients with liver cirrhosis is associated to important imbalances in blood concentrations of zinc, copper and magnesium.

Colorimetric detection of copper(II) ion using click chemistry and hemin/G-quadruplex horseradish peroxidase-mimicking DNAzyme.

G-quadruplex-forming sequence can be formed through a copper(I) ion (Cu(+))-catalyzed click chemistry between azide- and alkyne-modified short G-rich sequences in aqueous solution, eliminating immobilization and washing steps of conventional assays. The source for Cu(+) was generated from the reduction of Cu(2+) with the reductant of sodium ascorbate. In the presence of hemin and K(+), the self-assembly of hemin/G-quadruplex structure has the activity of horseradish peroxidase (HRP), which can catalyze its colorless substrate tetrazmethyl benzidine (TMB) into a colored product. Hence, the concentration of Cu(2+) can be evaluated visually for qualitative analysis according to the color change of the solution, and the optical density (OD) value of the resulting solution at 450 nm was also recorded using a microplate reader for quantitative analysis.

Ionized vs serum calcium in the diagnosis and management of primary hyperparathyroidism: which is superior?

BACKGROUND: The diagnosis of primary hyperparathyroidism (PHPT) is based on the presence of an elevated serum calcium level. The study objective was to compare ionized calcium levels to serum calcium levels with respect to parathyroid hormone level (PTH) and several patient outcomes. METHODS: The study population comprised a retrospective cohort of 268 patients with PHPT who underwent primary parathyroidectomy. Serum calcium levels were compared with ionized calcium levels regarding their association with PTH level, presence of multiglandular disease, adenoma size, and extent of neck exploration. RESULTS: Serum calcium level was correlated with ionized calcium level (R(2) = .68, 95% confidence interval [CI], .56 to .79; P < .0001) and PTH was associated with both serum (R(2) = .19; 95% CI, .04 to .33; P = .012) and ionized (R(2) = .23; 95% CI, .07 to .38; P = .004) calcium levels. Ionized calcium level was a more sensitive indicator of PHPT because there was a greater incidence of ionized calcium being elevated without concordant serum calcium elevation than vice versa (P < .0001). Ionized calcium was also more linearly associated with adenoma size than was serum calcium (P = .0001). There were no differences between serum and ionized calcium levels in predicting the presence of multiglandular disease or the extent of neck dissection. CONCLUSIONS: Serum calcium level is an appropriate first-line biochemical test for the diagnosis of PHPT. However, ionized calcium measurements may provide additional benefit in certain cases of PHPT because it is correlated with PTH level and adenoma size, and it may be a more sensitive marker of disease severity than serum calcium.

Fluorescence switch on-off-on receptor constructed of quinoline allied calix[4]arene for selective recognition of Cu2+ from blood serum and F- from industrial waste water.

A novel PET with ICT based substituted calix[4]arene fluroionophore was synthesized and used for detection of Cu(2+) and F(-) by emission spectra. The detection limit of the synthesized receptor was found to be 4.16 nM for Cu(2+) and 2.15 nM for F(-). Moreover, this probe has been applied for recognition of Cu(2+) in blood serum and F(-) from waste water.

Ablation of the Kell/Xk complex alters erythrocyte divalent cation homeostasis.

XK is a putative transporter of unknown function that is ubiquitously expressed and linked through disulfide bonds to Kell protein, an endothelin-3 (ET-3)-converting enzyme. We generated three knockout (KO) mice that lacked either Xk, Kell or both proteins and characterized erythrocyte cation levels, transport and hematological parameters. Absence of Xk or Kell was accompanied by changes in erythrocyte K(+), Mg(2+), Na(+) and Ca(2+) transport that were associated with changes in mean cellular volume and corpuscular hemoglobin concentration mean. Baseline Ca(2+)-ATPase activity was undetected in erythrocytes from all three mouse types but was restored upon pre-incubation with ET-3. Consistent with these alterations in Ca(2+) handling, we observed increased Gardos channel activity in Kel and Xk KO mice. In addition Kel deletion was associated with increased Mg(2+) permeability while Xk deletion blocked Na/Mg exchanger activity. Our results provide evidence that cellular divalent cation regulation is functionally coupled to the Kell/XK system in erythrocytes and loss of this complex may contribute to acanthocytosis formation in McLeod syndrome.

An ICT based "turn on/off" quinoline armed calix[4]arene fluoroionophore: its sensing efficiency towards fluoride from waste water and Zn2+ from blood serum.

A novel structurally simple calix[4]arene appended 8-amidoquinoline linked conjugate was synthesized and has been used as a turn-on fluorescence probe for Zn(2+) and turn off fluorescence probe for F(-). Moreover, this probe has been applied for Zn(2+) detection in blood serum upto 8.7 µM and fluoride detection upto 22 nM in waste water samples, using emission spectra.

Correlation of divalent cat ions (Ca++, Mg++) and serum renin in pateints of essential hypertension.

OBJECTIVE: To evaluate the serum status of Divalent Cat ions (Ca++ and Mg++) in hypertensive subjects along with correlation of Cat ions with serum Renin in all subjects. METHODS: Conducted at the Biochemistry Department of the Basic Medical Sciences Institute (BMSI), Jinnah Postgraduate Medical Centre, Karachi, the case control study comprised 75 subjects. Of the total, 40 were patients of essential hypertension while 35 were normal healthy subjects. The serum level of Divalent Cat ions was measured by spectrometry, Renin by RIA, and other biochemical parameters such as glucose, urea and creatinine were estimated by chemical methods. RESULTS: Serum calcium was significantly high (p < 0.001) while magnesium was significantly low (p < 0.001) in the hypertensives. Similarly, calcium had significant positive correlation (r value 0.576 and 0.593) while magnesium had significant negative correlation (r value -0.746 and -0.743) with systolic and diastolic blood pressure. The glucose, urea and creatinine were observed to be insignificant when compared to normotensive subjects. In addition, Renin has a positive correlation (r value 0.559 and 0.444) with systolic and diastolic blood pressure respectively. CONCLUSION: Elevated calcium and depressed magnesium are linked with hypertension, while among the hypertensives, Renin levels need to be closely observed.