Human Blood Serum Samples Research Articles

Investigation of Leptospirosis Agents in Cattle and Humans.

Leptospirosis, a global zoonotic disease, causes serious morbidity and mortality generally in low-income societies. This study aimed to investigate the prevalence of Leptospira serovars in cattle and high-risk human populations. This study investigated the presence of pathogenic Leptospira serogroups in the blood and kidney samples of cattle arriving at the Erzurum Meat and Milk Institution for slaughter between April and July, and between September and December 2022, and in the serum samples of humans. Kidney and serum samples from 289 cattle and serum samples from 100 individuals from at-risk occupational groups (58 farmers, 25 veterinarians and 17 butchers) were collected. As a control, 100 human blood samples were collected from civil servants who had no contact with animals. Microagglutination testing was used to investigate Leptospira serogroups in bovine sera, real-time polymerase chain reaction (PCR) for Leptospira DNA in kidney samples, and microagglutination testing and enzyme-linked immunosorbent assays for Leptospira antibodies in human blood serum samples. Microagglutination test in 4.5% of cattle; Leptospira DNA was positive in 0.7%. Six strains of Leptospira interrogans, two of Bratislava, one of Pomana and one of Icterohaemorrhagiae were found in cattle, as well as one strain of Leptospira kirschneri Dadas. In humans, two Icterohaemorrhagiae, one Hebdomadis and one Dadas serovar were detected in both the risk group and the control group. Using ELISA, antibody positivity was found to be 14.0% in the risk group and 11.0% in the control group. The seroprevalence of Leptospira spp. in cattle in Erzurum, Türkiye, is relatively high. In this region, the risk of encountering Leptospira in the normal population is as high as in the risk group.

A highly sensitive and selective molecularly imprinted sensor for the determination of atorvastatin

In this study, we developed a highly sensitive carbon paste sensor that combines a molecularly imprinted polymer (MIP) with specific recognition capabilities to monitor atorvastatin (ATV). In the MIP synthesis, designed especially for ATV, ethylene glycol dimethacrylate (EGDMA) was utilized as a cross-linking monomer and methacrylic acid (MAA) as a functional monomer. This non-covalent method made use of polymerization by free radicals. After that, this MIP was added to a carbon paste electrode (CPE), which served as both a selective detection element and a preconcentration agent for ATV analysis. The improved CPE was characterized using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). To investigate ATV, the anodic peak signal was assessed using square wave stripping voltammetry (SWSV).The calibration curve exhibited two linear regions encompassing dosages from 0.005 to 1 µM and 1 to 20 µM, with a 1.5 nM calculated detection limit. The designed MIP electrode was successfully utilized to assess ATV in tablet and human blood serum samples, demonstrating its usefulness in practical analysis.

Near-infrared photothermal lens as microfluidic analyzer for determination of phosphate in food and biological samples

In this work, photothermal lens spectrophotometer (PTLS) with crossed-beam configuration pumped by a laser diode (850 nm) was used for determination of soluble phosphorus exists mainly in the form of orthophosphate (PO43−) in nonalcoholic beverage and human blood serum samples. The determination was carried out after complexation reaction between blue molybdenum and phosphate in aqueous solution. UV–vis spectrophotometry was used by measuring absorption in the near infrared region (815 nm) for optimizing the complex formation time, concentrations of reducing agent and sulfuric acid. The UV–vis absorption measurements showed that the calibration curve was obtained in the concentration ranges of 0.5–80 mg L−1 with a linear correlation coefficient of 0.98 and a detection limit of 0.2 mg L−1. Then, PTLS at a wavelength of 850 nm after optimizing the device conditions (flow rate, excitation laser power and interrupting frequency) was used for phosphate determination. The calibration curve in the concentration range of 11–1000 µg L−1 has a correlation coefficient of 0.98 and a detection limit of 4 µg L−1. The achieved detection limit was about 50 times better than NIR absorption spectrometry using a conventional 1 cm sample cell. In PTLS with the 3 μL microfluidic cell experimental detectability amount of phosphate is 33 picogram, while in UV–vis-NIR method this amount is 1.5 µg.

Study on interaction with high-abundant blood proteins and identification of low-abundant proteins to 5-phenyl-1-(p-tolyl)-1 H-1,2,3-triazole by serum proteomics

In this study, a comprehensive investigation was undertaken to elucidate a simple triazole compound, 5-phenyl-1-(p-tolyl)-1 H-1,2,3-triazole (PPTT), its interactions with high-abundant proteins and identification of low-abundant proteins by serum proteomics. Employing a combination of spectroscopic techniques and computational chemistry, the interactions between PPTT and three high-abundance blood globular proteins, namely human serum albumin (HSA), human immunoglobulin G (HIgG), and hemoglobin (BHb), were explored, thereby ascertaining their binding constants and thermodynamic parameters at the molecular level. Subsequently, based on the differential proteomics, utilizing two-dimensional gel electrophoresis (2-DE) in conjunction with matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS), the research team isolated and identified differentially expressed low-abundance proteins in human blood serum samples following exposure to PPTT. The results showed that there were twenty highly expressed proteins identified from blood serum samples intervened by PPTT. Combining bioinformatics techniques, these proteins were classified, providing preliminary insights like preproprotein or precursors inhibiting the activity of elastase, defending and regulating the immune system, carrying lipid, and other functions into their biological functionalities. One of the differential proteins, apolipoprotein A-1 (ApoA-1) protein, was selected as a possible target to explore the mechanism of action of PPTT intervention on the related signaling pathways involved in human hepatocellular carcinomas(Hep G2) cells. These research findings offer scientifically sound guidance for further in-depth exploration, development, and application of the 1,2,3-triazole compound.

Novel application of carbon nanotube electrodes for electrochemical detection of amino acids in athlete’s biological samples

Understanding different physiological processes and spotting any health problems, especially in athletes, depend on tracking the quantities of amino acids in biological samples. This study looked at the creation of a unique electrochemical sensor for the sensitive and targeted identification of the necessary amino acid methionine in biological materials. Based on a modified glassy carbon electrode (GCE) surface, the sensor incorporated a tungsten disulfide (WS2) and carbon nanotube (CNT) nanocomposite. The improved electrical conductivity and catalytic activity of this material combination towards methionine oxidation led to its selection. The sensor that was created showed remarkable selectivity for methionine over other amino acids, along with a wide linear range of 5–1475 μM and a low detection limit of 10 nM. A relative standard deviation of 3.62 % was obtained across ten consecutive measurements, confirming the sensor's repeatability. The practical use of the CNTs-WS2/GCE sensor was verified by the detection of MTN in human blood serum, urine, and food samples. The recovery values ranged from 93.00 % to 99.40 %, and the relative standard deviation was less than 4.71 %. Based on these findings, we believe that our new CNTs-WS2/GCE sensor holds great potential for quick and precise methionine identification in biological samples from athletes.

Selective extraction of captafol from blood and river water samples using molecularly imprinted polymers

In this study, the captafol molecularly imprinted polymers were first prepared using the precipitation polymerization method, using captafol as the template molecule and acrylamide (Am) as the functional monomer. The synthesized polymers have spherical particles with a loose, porous surface, as determined through scanning electron microscopy. The polymer was analyzed using BET, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR). The polymers demonstrated a high adsorption efficiency of up to 90 % and specific recognition ability towards captafol, based on the results of the dynamic and static adsorption assays. The factors affecting MIPs’ binding efficiency were carefully optimized. Studies were established to analyze captafol in water and human blood serum samples under optimal conditions. Through adsorption kinetics, adsorption isotherms, and selectivity tests, this suggested approach demonstrated good MIP adsorption characteristics for captafol. The resulting Cap-MIPs showed notable selectivity for captafol as compared to folpet, high adsorption capacity (90 %), and good reusability, with the ability to reach adsorption equilibrium in less than 60 min. The results showed that the Cap-MIPs strategy exhibited high selectivity, good consistency, and high sensitivity, making it an efficient way to enrich and recognize captafol in a complex blood serum matrix.

Ultrasensitive tadalafil detection with eco-friendly CeO2/Al-pillared clay incorporated pencil graphite paste electrode

In this study, we have constructed a novel voltammetric sensor based on montmorillonite clay (MMT) incorporated with CeO2 nanoparticles using a composite graphite paste electrode as a cross linker (MMT-CeO2NPs/GPG-PE) for the trace determination of tadalafil (TAD) drug. The characterization of CeO2 nanoparticles has been conducted using various analytical techniques, including X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The morphology of the composite of CPG and MMT-CeO2NPs/CPG was elucidated through scanning electron microscopy (SEM). The newly developed sensor (MMT-CeO2NPs/CPG-PE) exhibited remarkable efficiency towards TAD oxidation using adsorptive stripping square-wave voltammetry (AdS-SWV) in Mcllvaine buffer solution (pH 8.0). A highly selective and sensitive method for TAD detection has been successfully applied based on MMT-CeO2NPs/CPG-PE, showing two different linear concentration ranges of 0.005−0.1 and 0.1–9.9 µM. The LOD and LOQ were determined to be 1.97 × 10−10 and 6.57 × 10−10 M, respectively, with a sensitivity of 3916 µA µM−1 cm−2. Interestingly, the sensing electrode exhibited excellent reproducibility, reusability, and stability even after 30 days. Moreover, the newly developed nano-sensor (MMT-CeO2NPs/CPG-PE) has been effectively utilized for the accurate detection of TAD in pharmaceutical formulations and spiked human blood serum and urine samples, demonstrating no interference from other substances.

Nanoengineered plasmonics-enhanced photothermal tags for sensitive detection of cardiac biomarker troponin I using lateral flow immunoassay

In recent years, photothermal lateral flow immunoassay (LFIA) has gained widespread use as a point-of-care testing (POCT) technique because of its cost-effective portable instrumentation and easy-to-handle procedures. However, developing a highly sensitive photothermal LFIA platform with high photothermal efficiency remains challenging. In this study, we developed a portable smartphone-based plasmonics-enhanced photothermal LFIA (PPh-LFIA) platform to improve the photothermal LFIA sensitivity by engineering plasmonic-active gold nanostars (GNS) having large-sized sharp branches. We investigated the photothermal effect using various GNS engineered to have different sizes and spike lengths of GNSs (GNS-1, GNS-2, GNS-3, and GNS-4) in order to exhibit optimal plasmonics properties. The results showed that the GNS-3 having a broad plasmon band with a plasmon maximum band at 995 nm exhibited the strongest photothermal efficiency (80 %). As a proof-of demonstration, we have employed GNS-3 for the detection of the cardiac biomarker, troponin I (cTnI), used as the model system. The results show high sensitivity with a detection limit (LOD) of 5.5 pg/mL, which was around 1000 times more sensitive than traditional colorimetric LFIA based on gold nanospheres (GNSP). To verify the applicability of the PPh-LFIA platform, cTnI was spiked into human blood serum samples, enabling the detection of cTnI with an LOD of 6.7 pg/mL. Overall, this study offers insights for nanoengineering and fine-tuning the GNS morphology to increase the photothermal efficiency, consequently improving the PPh-LFIA detection sensitivity, which makes it suitable for use as a sensitive and portable POCT tool.

Electrochemical sensor based on reduced graphene oxide paste electrode for detection of gemcitabine as a chemotherapy drug in breast cancer

The development of a precise and sensitive electrochemical sensor is essential in the field of medical diagnostics in order to identify gemcitabine, a chemotherapy drug that is commonly used to treat breast cancer. This work presents a novel electrochemical sensor based on a reduced graphene oxide (rGO) nanocomposite and a zirconium-based metal-organic framework (Zr-MOF) with terephthalic acid as a ligand. Gemcitabine (GEM), a chemotherapy medication used to treat breast cancer, is detected with remarkable sensitivity and selectivity by the Zr-MOF-rGO modified graphene paste electrode (GrPE) sensor. By combining the strong structure and active sites of Zr-MOF with the large surface area and electrical conductivity of rGO, the sensor's design maximizes electron transfer rates and GEM adsorption capacity. The sensor outperforms current GEM sensors with its wide linear detection range (0.5–490 μM) and low detection limit (0.008 μM). The sensor's long-term analytical applicability is confirmed by stability and reusability studies, which produced accuracy rates surpassing 94 % and RSD values below 4.21 % in recovery trials using spiked human blood serum and urine samples. Overall, the results of this investigation show that the Zr-MOF-rGO/GrPE electrode has the potential to be a useful platform for the detection of gemcitabine in patients with breast cancer.

Devoting turbidity measurements via absorptiometry: glutathione determination

The study included estimation of glutathione (GSH) as an important biomarker using turbidimetric method based on reaction of GSH with Ce(IV) in acidic medium to form turbid solution. More than twenty metal ions were used to test their interaction with GSH in acidic medium, it was obtained that only Ce(IV) forms turbid product. Instead of using turbidimeter to conduct measurements, a single beam spectrophotometer was used for this purpose. The measurements were studied at three wavelengths via 500, 700 and 900nm, but a near infrared wavelength, i.e. 900nm, shows the best results. In addition, the effect of temperature, time, type of acid, sequence addition as an optimum conditions required for the product to form were studied. Then the effect of the interferences was studied at two concentrations. A calibration curve in µg.mL-1 was constructed and its trending lies on points of concentrations ranged from 20 to 180µg.mL-1 with a correlation coefficient of 0.9994, and detection limit of 0.0005 µg.mL-1 and slope is (0.0014). The analytical method was applied on samples of human blood serum. The obtained results were compared with the results of the referenced (kit) method. The results obtained by the method followed, some of them were close and the others were far.

Rapid ultrasensitive and specific BNP biosensor with LED readout.

Biosensing for diagnostics has risen rapidly in popularity over the past decades. With the discovery of new nanomaterials and morphologies, sensitivity is being constantly improved enough for reliable detection of trace biomarkers in human samples, like serum or sweat. This precision has enabled detailed research on the efficacy of biosensors. However, current biosensors suffer from reduced speed of operation. To make better use of this sensitivity, the development of a conductometric biosensor with in-situ use of an Laser Emitting Device (LED) display can provide rapid determination of sample results, steadily pushing biosensors toward more clinical, point-of-care (POC) applications. In this research, a simple LED was used for facile optical determination and visual output of an ultrasensitive bio-signal amplification circuit was made to interface with a B-type Natriuretic Peptide (BNP) biosensor. Tuning circuit gain enables an elegant method for adjustable separation of concentrations into 3 discrete categories: sub-threshold, analog, and saturation regions. These regions corresponded to 0 < [C] < 500pg/mL (25, 100, 250pg/mL, LED off), 500 < [C] < 1000pg/mL (LED varying intensity), and 1000pg/mL < [C] (LED full intensity). System efficacy was tested using human blood serum samples from University of Pittsburgh Medical Center patients, which were able to be accurately detected and sorted for rapid low cost and power. determination without need for complex digital elements. Additional specificity testing suggests insignificant impact of non-target biomarkers.

Electrochemical sensing of cortisol by gold nanoparticle incorporated carboxylated graphene oxide based molecularly imprinted polymer

In this work, we report a simple electrochemical biosensor for cortisol (Cor) detection using a molecularly imprinted polymer (MIP). MIP was prepared by graft copolymerization method on allylated gold nanoparticle (Au) incorporated carboxylated graphene oxide (allylated Au/GO-COOH) polymerized along with the template molecule Cor. Cor is one of the important corticosteroid hormones in human physiology. Cor, the stress hormone, is a steroid hormone that comes under the class of glucocorticoid hormones and is produced as a part of our body’s stress response. This Cor imprinted polymer (Cor-MIP) was chosen to modify the working glassy carbon electrode surface. Thereby developing a highly selective and sensitive electrochemical biosensor. Electrochemical Impedance Spectroscopy and Cyclic Voltammetry explored the electrochemical properties of the developed electrochemical biosensor. The investigation reports from the electrochemical studies revealed that the current value increases proportionally with increasing concentration of Cor. This confirmed the excellent electrocatalytic activity of the prepared Cor-MIP based biosensor toward Cor. The nanomaterials as well as the electroactive sites on Cor-MIP together enhancing the electron transfer rate and lower detection. Differential Pulse Voltammetry is used to find the limit of detection and quantification, and were obtained as, 0.61 × 10−14 M and 2.02 × 10−14 M, respectively. With excellent specificity, stability, and selectivity, this newly developed electrochemical biosensor has been successfully used for Cor measurements in human blood serum samples.

Hybridization of 2D MnO2 and MoS2 via single-step microwave synthesis for trace-level detection of thrombin in simulated blood serum samples

Thrombin (THMB), a critical enzyme in the coagulation of blood, necessitates rapid and sensitive detection for assessing thrombotic disorders and cardiovascular health. Here, we demonstrate the trace-level detection of thrombin in simulated human blood serum samples by hybridization of 2D materials MnO2 and MoS2 modified nickel Foam (MnO2/MoS2/NF). MnO2/MoS2 hybrid is synthesized by a low-cost, and ultra-fast (within five minutes) solid-phase synthesis via microwave technique. Synthesized MnO2/MoS2 hybrid has been characterized by Transmission electron microscope (TEM) to know the microstructure of the hybrid. The crystalline nature of the material is confirmed by X-ray diffraction (XRD), Chemical fingerprint, and vibrational modes of the as-synthesized MnO2/MoS2 hybrid is examined using Raman spectroscopy (Raman, etc). The MnO2/MoS2/NF sensor demonstrates a wide linear range of detection varying from 10 fM to 50 nM with a superior sensitivity of 3.5 μA/nM/cm2 and a lower detection limit of 3.2 pM (LOD = 3 s/m). It is highly selective over other interfering species (IgG, BSA, Na2+, CA, and Urea). The standard addition method was employed to conduct real-time analysis of simulated blood serum samples using the DPV technique. The sensor demonstrated outstanding recovery percentages of ∼ 98 % to 102 %. The hybrid structure offers a greater number of active sites, employing the distinctive surface characteristics of both MnO2 and MoS2. This facilitates more efficient electrochemical reactions, crucial for sensitive Thrombin detection. Additionally, the 3D highly porous skeletal NF substrate ensures stability and enhances catalytic activity, while enabling rapid electron transfer, further boosting the sensor’s sensitivity. This work provides a rapid, cost-effective, and efficient solid-phase microwave synthesis method for obtaining MnO2/MoS2 hybrid material, thereby expanding its utility in detecting biological samples for clinical diagnosis and biomedical research purposes.

Label-free voltammetric screening of human blood serum

The current study presents a comprehensive voltammetric investigation into the direct analysis of untreated human blood serum in a phosphate buffer at an unmodified, graphite electrode by means of voltammetry. By employing advanced square-wave voltammetry at an edge plane pyrolytic graphite electrode (EPPGE), the basic principles were established for developing a sensitive, fast, simple, and label-free method for the simultaneous screening of uric acid, bilirubin, and albumin analytes that are present in human blood serum and are quite essential for rapid medical diagnostics. The electrochemical protocol utilizes the specific structural patterns of the EPPGE, the inherent redox and adsorption properties of the analysed analytes, and the sensitivity and rapidity of the employed advanced voltammetric technique. The methodology has been successfully applied for quantification of the considered analytes in a series of samples of human blood serum and was compared with the standard methods used in a clinical biochemical laboratory. This novel method represents a significant advancement towards the development of point-of-care devices aimed at swiftly and simultaneously quantifying uric acid, bilirubin, and albumin levels in human serum.

Gold nanoparticles assisted colorimetric sensing of paroxetine, duloxetine, and olanzapine in aqueous and micellar systems with improved sensitivity

The present study explored a rapid and facile colorimetric identification of two antidepressants (paroxetine and duloxetine) and one antipsychotic drug (olanzapine) in aqueous and micellar systems using citrate-stabilized gold nanoparticles (Cit-AuNPs). The sensing approach involved hydrogen bonding and electrostatic interactions on the surface of Cit-AuNPs. The attributes of Cit-AuNPs and their interactions with the drugs were probed using characterization techniques like UV–Vis spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta potential measurement, and Fourier-transform infrared spectroscopy (FT-IR). Various factors including the volume of Cit-AuNPs, pH, reaction time, surfactant concentration, and the sequence of addition of reagents were optimized to inspect their impacts on sensing results. Under optimized conditions, the probe showed good linearity for the three drugs at the nanomolar (nM) range. Consequently, the color of the Cit-AuNP solution transformed from red to royal purple and blue, which was visible to the naked eye and monitored by visible absorption spectra. This label-free optical detection approach could recognize paroxetine (Prx), duloxetine (Dlx), and olanzapine (Olz) in aqueous system at concentrations ranging from 1 to 17 nM with a limit of detection (LOD) of 0.312, 0.258, and 0.418 nM (S/N = 3), respectively. Meanwhile, the sensitivity was improved in the Triton X-100 (TX-100) micellar system with LOD of 0.029, 0.030, and 0.029 nM for Prx, Dlx, and Olz, respectively accompanied by a shift in the absorption bands. The micellar system contributes stability to the Cit-AuNP-drug complex. The devised colorimetric approach was convenient and did not require any complex equipment. It was efficaciously used to detect three drugs in pharmaceutical products, spiked human urine, and blood serum samples with satisfactory recoveries of 99.83–103.45% and RSD < 3.5%. Notably, the sensing assay demonstrated good selectivity for three drugs in the existence of commonly encountered foreign species and certain common drugs with a relative error below 3%. The results of the present study were statistically compared with reference methodology. The results were validated with no significant difference between the devised and reported approaches considering precision and accuracy, respectively.

A novel potentiometric screen-printed electrode based on crown ethers/nano manganese oxide/Nafion composite for trace level determination of copper ion in biological fluids.

Copper levels in biological fluids are associated with Wilson's, Alzheimer's, Menke's, and Parkinson's diseases, making them good biochemical markers for these diseases. This study introduces a miniaturized screen-printed electrode (SPE) for the potentiometric determination of copper(II) in some biological fluids. Manganese(III) oxide nanoparticles (Mn2O3-NPs), dispersed in Nafion, are drop-casted onto a graphite/PET substrate, serving as the ion-to-electron transducer material. The solid-contact material is then covered by a selective polyvinyl chloride (PVC) membrane incorporated with 18-crown-6 as a neutral ion carrier for the selective determination of copper(II) ions. The proposed electrode exhibits a Nernstian response with a slope of 30.2 ± 0.3mV/decade (R2 = 0.999) over the linear concentration range 5.2 × 10-9 - 6.2 × 10-3mol/l and a detection limit of 1.1 × 10-9mol/l (69.9ng/l). Short-term potential stability is evaluated using constant current chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). A significant improvement in the electrode capacitance (91.5 μF) is displayed due to the use of Mn2O3-NPs as a solid contact. The presence of Nafion, with its high hydrophobicity properties, eliminates the formation of the thin water layer, facilitating the ion-to-electron transduction between the sensing membrane and the conducting substrate. Additionally, it enhances the adhesion of the polymeric sensing membrane to the solid-contact material, preventing membrane delamination and increasingthe electrode's lifespan. The high selectivity, sensitivity, and potential stability of the proposed miniaturized electrode suggests its use for the determination of copper(II) ions in human blood serum and milk samples. The results obtained agree fairly well with data obtained by flameless atomic absorption spectrometry.

In situ anchored ternary hierarchical hybrid nickel@cobaltous sulfide on poly(3,4-ethylenedioxythiophene)-reduced graphene oxide for highly efficient non-enzymatic glucose sensing.

A ternary hierarchical hybrid Ni@CoxSy/poly(3,4-ethylenedioxythiophene)-reduced graphene oxide (Ni@CoxSy/PEDOT-rGO) is rationally designed and in situ facilely synthesized as electrocatalyst to construct a binder-free sensing platform for non-enzymatic glucose monitoring through traditional electrodeposition procedure. The as-prepared Ni@CoxSy/PEDOT-rGO presents unique hierarchical structure and multiple valence states as well as strong and robust adhesion between Ni@CoxSy/PEDOT-rGO and GCE. Profiting from the aforementioned merits, the sensing platform constructed under optimal conditions achieved a wide detection range (0.2μM ~ 2.0mM) with high sensitivity (1546.32 μA cm-2mM-1), a rapid response time (5s), an ultralow detection limit (0.094μM), superior anti-interference performance, excellent reproducibility and considerable stability. Furthermore, the sensor demonstrates an acceptable accuracy and appreciable recoveries ranging from 90.0 to 102.0% with less than 3.98% RSDin human blood serum samples, indicating the prospect of the sensor for the real samples analysis. It will provide a strategy to rationally design and fabricate ternary hierarchical hybrid as nanozyme for glucose assay.

MnO2 nanosheet quenched thulium doped photon-up conversion luminescent immunoprobe for the ‘turn-on’ detection of cardiac troponin T

A “turn-on” photon up conversion nano couple based on NaYF4: Yb, Tm UCNPs quenched with MnO2 nanosheet was developed for the rapid and selective detection of cTnT. Herein, MnO2 nanosheet hold on the surface of Antibody cTnT (Ab-cTnT) conjugated blue emitting up conversion nanoprobe (λem at 475 nm), which leads to quenching of fluorescence due to energy transfer from photon up conversion nanoparticles to MnO2 nanosheets. On introducing cTnT antigen to the system, the energy transfer process is hindered due to strong antigen -antibody interface on the surface. This in turn, influences the nano-couples positions and effectively separates up conversion nanoprobe from MnO2 nanosheets surface resulting in restriction to energy transfer process enabling fluorescence recovery. The developed probe shows a linear response towards cTnT in the range of 0.16–2.77 ng/mL with a Limit of Detection (LoD) of 0.025 ng/mL. The practical feasibility of the nanoprobe is performed with possible coexisting biomolecules. Biological study in human blood serum samples exhibited sufficient recovery percentage in the range of 92–103 % is obtained.

Aqueous phosphate detection in real samples using NIR-triggered Diamino Bis-Benzimidazoquinoline fluorescence sensor: An experimental and theoretical approach

The present work reports the design, synthesis, and sensing applications of Diamino bis-benzimidazoquinoline (DA-BISQ) derivatives. These compounds were synthesized in appreciable yield and characterized by FT-IR, 1H, and 13C NMR spectral and mass spectrometry. Optical studies revealed intriguing dual excitation properties: single excitations at λex 330-386 nm and double excitations at λex 660-772 nm in 10 % ethanol-water medium. The near-infrared excitation region λex 660-772 nm was particularly focused on the detection of F¯, Cl¯, Br¯, I¯, AcO ̄, ClO4¯, NO3¯, and HPO4¯ anions. Notably, selective fluorescence quenching "OFF" responses were observed for geometric anions like AcO¯, ClO4¯, NO3¯, and HPO4¯. Interestingly, the pyridine spacer-containing derivative 1c exhibited a unique fluorescence "OFF-ON'' response for the phosphate ion. Cyclic voltammetry titration further corroborated the binding affinity towards phosphate. To demonstrate practical applicability, a thin-film strip of receptor 1c was fabricated and tested for effective phosphate sensing in human blood serum samples. Density functional theory calculations were performed to elucidate the sensing mechanism with the phosphate anion. The combined experimental and theoretical results suggest an internal charge transfer process between the receptor and the anion.

Nanostructures of Prussian blue supported on activated biochar for the development of a glucose biosensor

This work emphasizes the utilization of biochar, a renewable material, as an interesting platform for anchoring redox mediators and bioreceptors in the development of economic, environmentally friendly biosensors. In this context, Fe(III) ions were preconcentrated on highly functionalized activated biochar, allowing the stable synthesis of Prussian blue nanostructures with an average size of 58.3 nm. The determination of glucose was carried out by indirectly monitoring the hydrogen peroxide generated through the enzymatic reaction, followed by its subsequent redox reaction with reduced Prussian blue (also known as Prussian white) in a typical electrochemical-chemical mechanism. The EDC/NHS (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-Hydroxysuccinimide) pair was employed for the stable covalent immobilization of the enzyme on biochar. The biosensor demonstrated good enzyme-substrate affinity, as evidenced by the Michaelis-Menten apparent kinetic constant (4.16 mmol L−1), and analytical performance with a wide linear dynamic response range (0.05–5.0 mmol L−1), low limits of detection (0.94 μmol L−1) and quantification (3.13 μmol L−1). Additionally, reliable repeatability, reproducibility, stability, and selectivity were obtained for the detection of glucose in both real and spiked human saliva and blood serum samples.