Human Blood Serum Samples Research Articles

Synthesis of magnetic molecular imprinted polymer with a new functional monomer for dispersive micro solid phase extraction of captopril from wastewater and biological samples and determination by UV-Vis spectrophotometry

A magnetic molecularly imprinted polymer (MMIP) was fabricated for captopril by surface polymerization of Fe3O4@SiO2 nanoparticles using a new functional monomer of N-(allylcarbamothioyl)-2-chlorobenzamide. It was then employed as a selective nanosorbent for dispersive magnetic micro solid phase extraction (DM-μ-SPE) of captopril from biological and wastewater samples. To characterize the physicochemical properties of the MMIP, different analytical methods such as the vibrating sample magnetometer, field emission scanning electron microscopy, Brunauer-Emmett-Teller, and Fourier transform infrared spectroscopy were utilized. To gain the maximum extraction recovery of captopril, the influence of various operating conditions was investigated and experimental settingsoptimized. After the extraction step, the concentration of captopril was measured by UV-Vis spectrophotometer at 245 nm. The assessments demonstrated that the MMIP provides higher extraction efficiency in comparison to magnetic non-imprinted polymer, suggesting the establishment of selective recognition binding sites at the MMIP surface. The method depicted desirable figures of merit of a low detection limit of 0.16 μg L-1, a limit of quantification of 0.50 μg L-1, a linear dynamic range of 0.50-22.0 μg L-1, and an acceptable preconcentration factor of 333. The magnetic MIP was successfully employed for preconcentration and extraction of trace amounts of captopril in real samples, such as human blood serum, urine, and wastewater samples, with recoveries in the range 95.7 to 102.6% and relative standard deviations < 5%.

Quantitative evaluation of oxidative stress in terms of H2O2 in smokers and nonsmokers serum samples

The bimetallic Fe-Ni nanomaterial was synthesized by a modified co-precipitation method and characterized by various techniques. The results showed random morphology with a face-centered cubic structure with an average diameter of 60 nm. The cyclic voltammetry and amperometric techniques were used to analyze the oxidative stress caused by hydrogen peroxide. Different parameters were optimized including scan rate, pH, and concentration. The material showed promising performance in phosphate buffer of pH 7.2 for standard and serum with correlation coefficients of 0.9897 and 0.99054, respectively. The detection limit for hydrogen peroxide was 5.9 µM and 7.3 µM (n = 3) for standard and serum, respectively. Fe-Ni@GCE is selective towards hydrogen peroxide in the presence of interferences. The modified electrode is stable up to 50 hrs with a loss of 25% performance. The developed sensor is applied to evaluate the percentage recovery from human blood serum samples of smokers and non-smokers. A quantitative study is also performed using serum samples of smokers and nonsmokers. The results showed a positive association and higher H2O2 in smokers compared to nonsmokers. Smoking may be a critical factor in oxidative stress in smokers older than 30 years related to smoking compared to non-smokers of the same age group. It is expected that bimetallic Fe-Ni nanomaterial can be exploited to detect specific levels of hydrogen peroxide as biomarkers and monitor disease severity.

Promote the electrocatalytic activity through the assembly of hexagonal SnS2/C sphere nanocomposite for determination of the immunosuppressant drug azathioprine in biological samples

In modernized eras, enhanced growth of transplantation and the use of drugs are high. However, the overuse of immunosuppressant drugs is hazardous to human health. In particular, long-term use of azathioprine (ATN) causes heavy side effects on human health, therefore nanomolar detection and determination of ATN are essential. Herein, an efficient electrocatalyst of hexagonal tin sulfide incorporated carbon sphere (SnS2/C) nanocomposite was prepared by using the temperature and pressure maintained hydrothermal method. The prepared electrocatalyst was successfully characterized by using various spectra and microscopic techniques. The SnS2/C/GCE exhibits the well-resolved ATN reduction peak in the CV experiments, due to the synergetic effect between the hexagonal SnS2 and C sphere. In addition, SnS2/C/GCE exhibits two linear ranges of (0.001 – 104.7 µM and 121.8 – 1275 µM) and the low detection limit of 5.7 nM along with the higher sensitivity (0.4325 µA µM−1 cm−2). In addition to that, the constructed sensor delivers notable repeatability, reproducibility, and superior selectivity with the existence of metal ions, biological molecules, and nitro compounds, enabling the electrochemical detection of ATN. The fabricated, SnS2/C/GCE sensor was successfully applied to the real-time determination of ATN in biological human urine and blood serum samples with good recovery results. Based on this, SnS2/C is a portable electrocatalyst for sensing ATN for biological and clinical purposes.

Zinc Phosphate-Incorporated Niobium Carbide as an Effective Electrocatalyst for Ultrasensitive and Selective Monitoring of Monoamine Neurotransmitter

The earth-abundant, cost-effective, easier preparation of zinc phosphate eases its diverse implications in recent applications. We have synthesized two-dimensional niobium carbide (NbC)-encapsulated zinc phosphate Zn2P2O7. The physicochemical characteristics were determined, which demonstrate pure crystallinity and good integration of the composite samples. To improve and develop a sustainable environment, the Zn2P2O7/NbC composite will be an efficient material. The detection of pharmaceutical compounds is highly preferable in clinical approaches. The importance of serotonin (SER) has empowered sensor development with the fabricated Zn2P2O7-based electrode. The synergistic action prevailing in the composite material endowed the active sites with improved electrocatalytic activity. The increased addition of SER was acquired with two linear ranges from 0.019 to 563.68 μM. The lower detection limit was obtained as 0.0055 μM toward the exposed SER addition at a lower concentration, and the sensitivity was about 7.72 μA μM–1 cm–2. Analyses of other parameters such as repeatability, reproducibility, and stability indicate the excellent performance of the electrode. The presence of SER in human urine and blood serum samples can be identified very easily, and hence, analysis of real samples was performed. The as-obtained recovery results stated the excellent performance of the fabricated sensor.

Application of nitrogen-doped carbon particles modified electrode for electrochemical determination of tetrazepam as muscle relaxant drug

The objective of this work was to create a modified carbon paste electrode (N-CNP/CPE) with nitrogen-doped carbon nanoparticles for electrochemically detecting tetrazepam (TZ) as a muscle relaxant in samples of human blood serum. N-CNP was created using a microwave-assisted process, and N-CNP was applied to the CPE surface using an electrodeposition technique. N atoms were effectively doped within the carbon framework of CNP/CPE, according to the results of morphology and structure characterization using FE-SEM, XRD, and EDS analyses. Additionally, abundant and evenly distributed pores and a spherical structure of N-CNP were electrodeposited on the CPE surface. The electrochemical analyses' findings show that the N-CNP/CPE TZ sensor is sensitive and selective, with a broad linear range of 0–650 µg/mL and a sensitivity value of 0.29478 µA/µg.mL−1. The proposed TZ sensor's limit of detection was discovered to be a low value of 5 ng/mL, which was a relatively low value of LOD and a broad linear range compared to other TZ sensors. Results indicated acceptable recovery values (more than 98.53%) and appropriate precision (RSD less than 5.08%), as well as good agreement between the DPV measurements and ELISA technique, for the determination of TZ in prepared samples of blood serum from bodybuilding athletes. These results show that the TZ content of blood samples from athletes may be monitored using the N-CNP/CPE as a trustworthy TZ sensor.

Electrochemical Determination of Chloroquine Phosphate in Real Samples Using a Diresorcinate-1,10-phenanthrolinecobalt(II)-Modified Glassy Carbon Electrode.

Chloroquine phosphate (CQP) is used for malaria treatment. As it is facing increasing resistance, it needs continuous monitoring using sensitive and specific detection methods. In this work, a voltammetric sensor was prepared by electropolymerization of a diresorcinate-1,10-phenanthrolinecobalt(II) complex on a glassy carbon electrode (poly(DHRPCo)/GCE) which was followingly characterized. Compared with a bare GCE, CQP showed single well shaped irreversible oxidative peak at the poly(DHRPCo)/GCE. The peak current showed excellent linearity with CQP concentration in the range of 0.005-300.0 μm with a detection limit of 0.39 nm. The response of CQP at poly(DHRPCo)/GCE was not influenced by the presence of amoxicillin, ciprofloxacillin and paracetamol in addition to its high stability and reproducibility. It was applied for detection of CQP in various real samples, including three brands of tablets, human blood serum, and urine samples. The detected amount in tablets were in the range 98.4-103.2 % of their labeled value. Spike recovery results in human blood serum, urine, and tablet samples were 99.35-100.28 %, 99.03-100.32 %, and 98.40-100.41 %, respectively. Interference recovery results with less than 4.60 % error, the lower limit of detection and the wider dynamic range than most of the previously reported methods validate the potential applicability of the proposed method for CQP determination in various real samples with complex matrices.

Reduced Phosphorene Quantum Dot Incorporated Flexible Bio-Electronic Device for the Detection of Uric Acid in Real Media

Among all developed 2D materials, phosphorene is in notable demand in recent times due to its distinctive electrical performance in biomedical applications. Zero-dimensional phosphorene quantum dot semiconducting material is a promising candidate that initiated a platform for fabricating high-performance electrical biosensors. In this study, we have successfully developed the material reduced phosphorene quantum dots (rPhQDs) of an average size of 2.1–2.3 nm using a simple hydrothermal technique. This material can be utilized as an electrical bio-sensing platform to detect uric acid in aqueous media as well as in real samples such as human blood serum and artificial urine. Biodegradable polymer composites of rPhQDs show unique current–voltage properties. They can be used to fabricate electrical devices that selectively detect uric acid in human blood serum and urine samples in the linear range of 1–5 μM. The corresponding detection limits for aqueous media, human blood serum, and artificial urine are 0.809, 0.5292, and 1.065 μM, respectively. We have investigated the driving force responsible for this selective electrical sensing and found that improvement of ionic movement in the presence of analytes plays a prominent role that can be established by measuring the transport number of the nano-bio-composite film. The device has the potential for successful detection of uric acid quantities in human blood serum and artificial urine.

Green synthesis of cyclodextrin-capped AuNPs decorated on polystyrene microspheres for a furazolidone-responsive electrode

Herein, a glassy carbon electrode modified with polystyrene microspheres decorated with β-cyclodextrin-capped gold nanoparticles (denoted P/CD@AuNPs/GCE) was designed to scrutinize the electrochemical sensing behavior of furazolidone (FZ) for the first time. Various spectroscopic and microscopic techniques were applied to characterize the physiochemical attributes of the prepared P/CD@AuNPs. Compared to bare GCE, P/CD@AuNPs/GCE unveils higher peak currents with lower peak potentials. Due to the presence of a combination of monodispersed CD@AuNPs on the PS surface, it benefits from high electrical conductivity, ghost-guest interaction, and rapid electron transfer ability, thus warranting competent electrocatalytic performance. The sensor showed great sensitivity, wide linear range (0.05–715 μM), low limit of detection (2.03 nM), superior selectivity, good repeatability, and reproducibility (1.29%) toward FZ detection. The sensor was successfully validated on a real human blood serum sample, and excellent recovery values (90%−101.2%) were achieved. The devised sensor offers a competent and promising sustainable electrocatalyst for monitoring FZ in human blood serum.

Electrospun nanofibers for extraction of thymoquinone from Nigella-Stevia prior to detection using electrochemical biosensor based on GCE/rGO/CuO

Thymoquinone (TQ) is the main constituent of Nigella sativa that has some effects on the treatment of many illnesses such as cancer and kidney diseases. Electrospun nanofibers with polyvinyl chloride/ethylene vinyl acetate latex/electrochemically (reduced graphene oxide/polypyrrole)/Silybum marianum inflorescence extract (PVC/EVA/(rGO/Ppy)/SM) were first prepared, and then TQ was extracted from black seed with using these nanofibers as a sorbent. Finally, TQ was detected with the construction of a simple nonenzymatic electrochemical biosensor using copper (II) oxide nanoparticles/reduced graphene oxide/glassy carbon electrode (CuO/rGO/GCE). Factors affecting TQ adsorption/desorption, time and potential values for constructed biosensor were optimized by methods such as design-expert 12.0 and one-at-a-time (OAT). The morphology of PVC/EVA/(rGO/Ppy)/SM nanofibers and rGO/CuO nanocomposites was characterized. Finally, the electrochemical biosensor was put into human blood serum samples and the standard addition method was applied with the spike of TQ to them. The linear range and detection limit reached 50–1000 μM and 4.85 μM, respectively (S/N = 3).

3D printed microfluidic chemiluminescence PoC device with self-powering and integrated incubating system: Validation via ALP detection on disposable µPADs

Point-of-Care (PoC) devices have become the fundamental requirement for rapid diagnostics and quantitative analysis at locations convenient to patients. This work reports a fully portable, pocket-friendly, self-powering, and temperature-controlled 3D printed chemiluminescence (CL) device. Moreover, the CL device leveraged the omnipresent smartphone as a detector unit to capture the CL signals. The device also contains a removable magnetic locking smartphone holder, making it universal. Further, the CL device integrates a microfluidic µPAD based detection methodology to monitor the abnormal levels of crucial bio-analyte alkaline phosphatase (ALP). The alkaline phosphatase (ALP) hydrolysis reaction with l-Ascorbic acid 2 phosphate releases a by-product, ascorbic acid (AA). The produced AA is a radical scavenger that quenches the CL signal, thereby facilitating the detection of ALP. Excellent performance of the developed CL device was observed in detecting the ALP with good linearity ranging from 1 mU/L to 10 mU/L and a detection limit of 0.59 mU/L. Subsequently, the device was tested for real-time ALP detection in human blood serum samples. Interestingly, the obtained results were less than 7 % error, compared to clinical samples. The developed fully portable 3D printed CL device with integrated electronics can be a future benchmark for mass production of susceptible devices in detecting various analytes.

2‐(N‐Morpholino)ethanesulphonic acid mediated facile and rapid one‐pot synthesis of gold nanoparticles and its application for colorimetric detection of heparin in human serum

AbstractA facile and rapid method for one‐pot synthesis of gold nanoparticles (AuNPs) has been developed. It employed 2‐(N‐morpholino)ethanesulphonic acid (MES) to act as reducing agent, buffering agent, and capping ligand to perform the reduction of the gold precursor (HAuCl4) into AuNPs. The AuNPs were synthesized by a simple mixing of MES buffer (pH 6.0) and HAuCl4 solution under a vortex at room temperature, and the process was completed within 1 min, which not only significantly simplifies the preparation procedure without heating or cooling but also greatly shortens the reaction time. Moreover, a novel colorimetric approach for sensitive detection of heparin was fabricated based on the prepared AuNPs. The detection limit was determined to be 3.1 μg/ml (i.e., 0.465 U/ml) with a linear response range of 3.25–130 μg/ml. Additionally, the sensor was also successfully applied for the detection of heparin in human blood serum samples, demonstrating its potential applicability for disease diagnosis in the future.

Development of Polydiphenylamine@Electrochemically Reduced Graphene Oxide Electrode for the D-Penicillamine Sensor from Human Blood Serum Samples Using Amperometry.

D-penicillamine (PA) is a sulfur group-containing drug prescribed for various health issues, but overdoses have adverse effects. Therefore, regular, selective, and sensitive sensing is essential to reduce the need for further treatment. In this study, diphenylamine (DPA) was electropolymerized in an aqueous acidic medium. The PA detection sensitivity, selectivity, and limit of detection were enhanced by electropolymerizing DPA on an electrochemically reduced graphene oxide (ERGO)/glassy carbon (GC) surface. The formation of p-DPA and ERGO was investigated using various techniques. The as-prepared p-DPA@ERGO/GC revealed the excellent redox-active (N-C to N=C) sites of p-DPA. The p-DPA@ERGO/GC electrode exhibited excellent electrochemical sensing ability towards PA determination because of the presence of the -NH-functional moiety and effective interactions with the -SH group of PA. The p-DPA@ERGO/GC exhibited a high surface coverage of 9.23 × 10-12 mol cm-2. The polymer-modified p-DPA@ERGO/GC electrode revealed the amperometric determination of PA concentration from the 1.4 to 541 μM wide range and the detection limit of 0.10 μM. The real-time feasibility of the developed p-DPA@ERGO/GC electrode was tested with a realistic PA finding in human blood serum samples and yielded a good recovery of 97.5-101.0%, confirming the potential suitability in bio-clinical applications.

Application of nickel-doped graphene nanotubes to modified GCE as a sensitive electrochemical sensor for the antipsychotic drug clozapine in spiked human blood serum samples

Clozapine (CLZ) is one of the most vital medications for managing schizophrenia, and the timely measurement of CLZ levels has been recognized as an obstacle to the wider use of CLZ. Herein, for the first time, nickel-doped graphene nanotubes (Ni@GRNT) were used to construct an electrochemical CLZ sensor by drop coating Ni@GRNT suspension on a glassy carbon electrode. The Ni@GRNT was synthesized and characterized using X‐ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The electrochemical behavior and influence of different physicochemical factors of sensing electrodes were investigated by using cyclic voltammetry, EIS technique, and differential pulse voltammetry techniques. Also, the catalytic rate constant (kcat) and the transfer coefficient (α) were calculated. The modified electrode illustrated satisfactory linear range, detection limit (LOD), reusability, and reproducibility results. At optimal experimental conditions, measurements can be performed at a broad linear dynamic range of 0.3 nmol L−1–60.0 μmol L−1 CLZ and with a LOD of 0.1 nmol L−1. The sensitivity value was estimated to be 3.06 μA µmol L−1 cm−2. Ultimately, this platform was successfully used for CLZ sensing in spiked human blood serum and tablet samples with an accuracy of > 93%.Graphical abstract

Facile one-step synthesis of a niobium iron oxide based electrochemical transistor for rapid, label-free detection of folic acid in human blood serum samples

An inorganic electrochemical transistor to detect folic acid in human blood serum.

A bacterial cellulose-based LiSrVO4:Eu3+ nanosensor platform for smartphone sensing of levodopa and dopamine: point-of-care diagnosis of Parkinson's disease.

Among the catecholamines, dopamine (DA) is essential in regulating multiple aspects of the central nervous system. The level of dopamine in the brain correlates with neurological diseases such as Parkinson's disease (PD). However, dopamine is unable to cross the blood-brain barrier (BBB). Therefore, levodopa (LD) is used to restore normal dopamine levels in the brain by crossing the BBB. Thus, the control of LD and DA levels is critical for PD diagnosis. For this purpose, LiSr0.0985VO4:0.015Eu3+ (LSV:0.015Eu3+) nanoplates were synthesized by the microwave-assisted co-precipitation method, and have been employed as an optical sensor for the sensitive and selective detection of catecholamines. The synthesized LSV:0.015Eu3+ nanoplates emitted red fluorescence with a high quantum yield (QY) of 48%. By increasing the LD and DA concentrations, the fluorescence intensity of LSV:0.015Eu3+ nanoplates gradually decreased. Under optimal conditions, the linear dynamic ranges were 1-40 μM (R2 = 0.9972) and 2-50 μM (R2 = 0.9976), and the detection limits (LOD) were 279 nM, and 390 nM for LD and DA, respectively. Herein, an instrument-free, rapid quantification visual assay was developed using a paper-based analytical device (PAD) with LSV:0.015Eu3+ fixed on the bacterial cellulose nanopaper (LEBN) to determine LD and DA concentrations with ease of operation and low cost. A smartphone was coupled with the PAD device to quantitatively analyze the fluorescence intensity changes of LSV:0.015Eu3+ using the color recognizer application (APP). In addition, the LSV:0.015Eu3+ nanosensor showed acceptable repeatability and was used to analyze real human urine, blood serum, and tap water samples with a recovery of 96-107%.

Triple Amplification Ratiometric Electrochemical Aptasensor for CA125 Based on H-Gr/SH-β-CD@PdPtNFs

A triple-amplified and ratiometric electrochemical aptasensor for CA125 was designed based on hemin-graphene/SH-β-cyclodextrin@PdPt nanoflower (H-Gr/SH-β-CD@PdPtNF) composites and an exonuclease I (Exo I)-assisted strategy. In the nanocomposite, hemin acts as an internal reference signal owing to the reversible heminox/heminred pair. PdPtNFs can significantly improve the electron transfer rate. SH-β-CD can efficiently enrich quercetin probes through host-guest recognition and increase the second indicator signal. In the presence of CA125, due to the specific binding between the aptamer and CA125, the conformational change of dsDNA (designed by the CA125 aptamer and its complementary DNA) results in the release of quercetin embedded in dsDNA. Subsequently, the free quercetin and DNA fragments are enriched on the H-Gr/SH-β-CD@PdPtNF-modified electrode. Thus, an enhanced oxidation peak from quercetin (IQ) and a reduced peak from hemin (Ihemin) can indicate the same biological identification event. In addition, the recycling amplification of CA125 by Exo I can effectively assist the increase of the quercetin signal. The value of IQ/Ihemin is linear with the concentration of CA125 in the range from 6.0 × 10-4 to 1.0 × 103 ng/mL, and the limit of detection is 1.4 × 10-4 ng/mL. The recovery of CA125 in human blood serum samples was from 99.2 to 104.4%. The proposed sensor is sensitive and reliable, which provides an avenue for the development of triple amplification and ratiometric signal strategies for detecting tumor markers in clinical diagnostics.

In-situ construction of N and P doped hollow sphere carbon for electrochemical sensing of antibiotic drug from poultry sustenance

To develop a low-cost electrocatalyst with excellent performance for real time drug monitoring along with higher selectivity is yet challenging. Herein, N, P-hollow sphere carbon (NPSC) loaded with different amount of phytic acid content by single step in-situ polymerization technique is explored to modulate porous structure of carbon support. From the results, enhanced electrocatalytic performance towards the detection of nitrofurantoin (NFT) was gratified by the introduction of 0.6 g P loading with unique hollow shell morphology, large accessible surface area, abundant defect sites and high surface to volume ratio as well as synergy effect of N and P dopants. Boosted electrocatalytic activity of NPSC-0.6 altered working electrode can be employed to assay NFT with wide linear range from 1-2500 μM and ultra-low LOD of 0.036 µM along with appreciable sensitivity and superior stability over 95 %. Accordingly, this work will enrich the understanding of different amount of P loading on N-hollow sphere carbon for NFT detection over poultry sustenance and human blood serum samples. This work paves the way to design a low cost, high performance porous sensing material for the detection of poultry drug nitrofurantoin.

Metal-organic framework-assisted Co3O4/CuO@CoMnP with core-shell nanostructured architecture on Cu fibers for fabrication of flexible wire-typed enzyme-free micro-sensors

Flexible fiber-based sensors have recently received increasing interest for real-time monitoring personal health, owing to their small size, high flexibility, lightweight, and application potentials in next-generation wearable electronics. Herein, we report a flexible wire-typed micro-sensor based on CoMnP@Co3O4/CuO core–shell nanohybrid array on 1D Cu wire substrate for sensitive detection of glucose. The synthesis process involves in-situ growth of ZIF-67 rhombic dodecahedron on the surface of CuO nanotubes, followed by thermal annealing and electrodeposition of CoMnP nanoparticles to form core–shell nanostructured architectures. Benefiting from desirable hybrid nanostructures, the as-made binder-free fiber microelectrode exposes more electroactive sites for transport of ions and electrons during the catalytic process and provides strong adhesion between electroactive species and metal fiber substrate. As a glucose sensor, the CoMnP@Co3O4/CuO fiber microelectrode displays favorable analytical properties, including two linear dynamic ranges of 0.001 mM – 0.55 mM and 0.55 mM – 3.03 mM with the sensitivities of 2445 μA mM−1cm−2 and 1774 μA mM−1cm−2, respectively, fast response time (1.62 s), excellent selectivity toward glucose at the presence interfering substances, and a low detection limit of 11.42 μM (S/N = 3). Moreover, the proposed wire-typed micro-sensor was successfully applied for measurement of glucose in human blood serum and saliva samples. Taking advantage of the versatility of 1D metal fiber current collector, MOF-assisted strategy and transition metal phosphides, the presented protocol here can be extended to the construction of other wearable and implantable sensing micro-devices.

Ultrasensitive Determination of Glial-Fibrillary-Acidic-Protein (GFAP) in Human Serum-Matrix with a Label-Free Impedimetric Immunosensor

In this work, immobilizing anti-GFAP antibodies via covalent attachment onto L-cysteine/gold nanoparticles that were modified with screen-printed carbon electrodes (Anti-GFAP/L-cys/AuNps/SPCE) resulted in the development of a sensitive label-free impedance immunosensor for the detection of Glial Fibrillary Acidic Protein (GFAP). The immunosensor's stepwise construction was studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). L-cysteine was chosen as the linker between GFAP antibodies and Au NPs/SPCE because it enables the guided and stable immobilization of GFAP antibodies, thus resulting in increased immunosensor sensitivity. As a redox probe, 5 mM of [Fe(CN)6]3-/4- was used to measure the electron-transfer resistance (Ret), which was raised by the binding of antigens to the immobilized anti-GFAP on the surface of the modified electrode. A linear correlation between Rct and GFAP concentration was achieved under optimum conditions in the range of 1.0-1000.0 pg/mL, with an extraordinarily low detection limit of 51.0 fg/mL. The suggested immunosensor was successfully used to detect the presence of GFAP in human blood serum samples, yielding good findings. As a result, the proposed platform may be utilized to monitor central nervous system injuries.

Fluorescent copper conjugated curcumin cysteine nanoprobe for selective determination of Fe3+ and G-quadruplex DNA.

Thesynthesis of fluorescent copper-curcumin-cysteine (Cu-CC) as a sensing platformis reported. The synthesized probe has been confirmed by UV-visible spectroscopy, FT-IR, XRD, SEM, and TEM characterization techniques, respectively. The mechanistic aspects of selective sensing of Fe3+ and detection of different G-quadruplex DNA have been illustrated based on the "turn-off-on" concept of a regeneratable fluorescence sensing probe at λex 450nm. Interestingly, we have noticed a high selectivity to Fe3+ ion by the developed Cu-CC sensing probe in comparison withother metal ions. Furthermore, the restoration of fluorescence of the sensing probe in the presence of different DNA sequences is illustrating a cost-effective, convenient, and reliable detection methodology of DNA detection. It is highly sensitive for the determination of Pu27, promoter c-MYC quadruplex DNA in a wide linear range of 100-700nM having a detection limit of 13.1nM (RSD: 0.15%) and sensitivity of 37.2 cps/nM. Whereas, the Pu18 and H-telo telomeric DNA sequences are showing a narrow linear range, i.e., 10nM-200nM and 10nM-180nM, respectively. The real-world sample analysis performance of the regeneratable sensing probe for Pu27 DNA detection in fresh human blood serum samples is showing a satisfactory result.