High-performance liquid chromatography coupled to enzyme-amplified biochemical detection for the analysis of hemoglobin after pre-column biotinylation

A nanolayered structure for sensitive detection of hemoglobin concentration using surface plasmon resonance

The objective of the proposed work is to design a biosensor that monitors hemoglobin (Hb) concentration using the combination of nanolayer, i.e., barium titanate (BaTiO3) and antimonene based on surface plasmon resonance (SPR) technique. Antimonene is used here as bio-recognition element (BRE) layer to attach the Hb analyte through physical adsorption due to its hydrophilic nature, higher adsorption energy and larger active surface area. The use of BaTiO3 adlayer (7 nm) just before antimonene is to enhance the refractive index (RI) sensitivity up to 1.90 times for the proposed SPR biosensor. The reason behind sensitivity enhancement is its high dielectric constant which enhances the electromagnetic field with in analyte medium. The performance of the biosensor is demonstrated with performance parameters namely sensitivity, detection accuracy (DA), figure of merit (FOM) and resolution. The proposed biosensor has potential to achieve much higher performance in terms of RI sensitivity of 303.83°/RIU, FOM of 50.39 RIU-1 and resolution of 0.021 g/l in comparison with reported biosensors in the literature for detection of Hb concentration. Thus, based on the obtained results one can say that the proposed work unlocks a reliable sensing in the field of medical science to detect hemoglobin-related diseases in human being.

Tannic Acid Capped Copper Nanoclusters as a Cost-Effective Fluorescence Probe for Hemoglobin Determination

For the first time, we report on a copper nanoclusters based fluorescence sensor for hemoglobin (Hgb). The aggregation-induced quenching of tannic acid capped copper nanoclusters' (TACuNCs) fluorescence by a Hgb-H₂O₂ mixture that mimics the Fenton's reagent is used here for the selective determination of Hgb. It is possible to effectively determine Hgb using this sensitive and cost-effective sensor in the linear range of 5.0 × 10^-8 to 4.0 × 10^-9 M with a detection limit of 5.6 × 10^-10 M. The practical utility of the sensor is evident from the good recovery values obtained from Hgb spiked with artificial blood serum.

Portable Instrument for Hemoglobin Determination Using Room-Temperature Phosphorescent Carbon Dots

A portable reconfigurable platform for hemoglobin determination based on inner filter quenching of room-temperature phosphorescent carbon dots (CDs) in the presence of H₂O₂ is described. The electronic setup consists of a light-emitting diode (LED) as the carbon dot optical exciter and a photodiode as a light-to-current converter integrated in the same instrument. The reconfigurable feature provides adaptability to use the platform as an analytical probe for CDs coming from different batches with some variations in luminescence characteristics. The variables of the reaction were optimized, such as pH, concentration of reagents, and response time; as well as the variables of the portable device, such as LED voltage, photodiode sensitivity, and adjustment of the measuring range by a reconfigurable electronic system. The portable device allowed the determination of hemoglobin with good sensitivity, with a detection limit of 6.2 nM and range up to 125 nM.

A persistent luminescence-based label-free probe for the ultrasensitive detection of hemoglobin in human serum

Hemoglobin (Hb) plays an important role in oxygen carriage for mammals, which is also a typical biomarker for certain diseases. Although numerous methods had been developed for the detection of Hb in red blood cells, analytical technology for the monitoring of low-abundance Hb in serum or plasma is still a challenge. Herein, persistent luminescence nanoparticles (PLNPs) with strong near-infrared (NIR) emission character behaving as a label-free probe for the highly sensitive and selective detection of Hb were developed. Further studies revealed that the sensing mechanism should be attributed to the Hb-induced dynamic quenching process. Moreover, the nanoprobe showed high selectivity to Hb against the common existing substances in human serum and a linear response to Hb ranging from 1 to 50 nM with an extremely high limit of detection (LOD) of 0.13 nM. Finally, applicability of the proposed probe for the detection of Hb in human serum samples was validated.

Ternary Emission of a Blue-, Green-, and Red-Based Molecular Imprinting Fluorescence Sensor for the Multiplexed and Visual Detection of Bovine Hemoglobin

A novel ternary-emission fluorescence sensor was proposed by post-imprinting mixing blue-/green-/red-emission bovine hemoglobin (BHb) imprinted polymers (b-MIPs, g-MIPs, and r-MIPs) at a proper ratio and realized the multiplexed and visual detection of BHb. The three MIPs were individually embedded with blue-emission 7-hydroxycoumarin, green-emission CdTe quantum dots (QDs), and red-emission CdTe/ZnS QDs. Upon interaction with BHb within 8 min, the fluorescence of CdTe and CdTe/ZnS QDs were simultaneously turned off, whereas the 7-hydroxycoumarin turned on the fluorescence intensity. Thereupon, the ratiometric fluorescence intensity of the ternary emission linearly varied within 0.025-3 μM BHb, accompanying the profuse fluorescence color evolution from yellowish green to yellow to salmon to plum to purple to finally blue. In comparison with the dual- or single-emission sensor, the ternary-emission fluorescence MIPs sensor provided a wider color variation covering the green-red-blue window for accurate naked-eye determination of BHb, as well as a lower detection limit down to 7.8 nM and a higher imprinting factor of 15.2. Moreover, the satisfactory recoveries of 99.25-111.7% in determining the spiked BHb in bovine urine samples, as well as the optical stability and post-imprinting construction convenience, indicated that the developed tricolor-emission fluorescence MIPs sensor provided an ideal alternative for rapid, sensitive, and visual determination of proteins in complicated samples.

Hemoglobin detection using curcumin nanoparticles as a colorimetric chemosensor

This article presents a simple and efficient measurement system for quantitative sensing of blood hemoglobin (Hgb) using curcumin nanoparticles (CURNs).

Facile synthesis of N-acetyl-L-cysteine capped CdHgSe quantum dots and selective determination of hemoglobin

Using N-acetyl-L-cysteine (NAC) as a stabilizer, well water-dispersed, high-quality and stable CdHgSe quantum dots were facilely synthesized via a simple aqueous phase method. The as-prepared NAC capped CdHgSe quantum dots were thoroughly characterized by fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. A novel method for the selective determination of hemoglobin (Hb) was developed based on fluorescence quenching of the NAC capped CdHgSe quantum dots. A number of key factors including pH value of phosphate buffer solution, quantum dots concentration, the adding sequence of reagents and reaction time that influence the analytical performance of the NAC capped CdHgSe quantum dots in Hb determination were investigated. Under the optimal experimental conditions, the change of fluorescence intensity (ΔI) was linearly proportional to the concentration of Hb in the range of 4.0×10(-9)-4.4×10(-7) mol L(-1) with a detection limit of 2.0×10(-9) mol L(-1). The developed method has been successfully employed to determine Hb in human urine samples.

New Fluorimetric Determination of Hemoglobin Used as a Substitute of Mimietic Peroxidase

Hemoglobin (Hb) could be used as a substitute of peroxidase in the catalytic oxidation of tetra-substituted amino aluminum phthalocyanine (TAA1Pc) by H2O2. We found that the fluorescence of TAA1Pc (a red-region fluorescent dye with a maximum excitation wavelength at 606 nm and a maximum emission wavelength at 673 nm) could significantly be quenched by H2O2 in the presence of Hb. The value of F0/F (where the relative fluorescence intensity of blank solution and that of the sample solution containing Hb were given by F0 and F, respectively) is linearly related to the concentration of Hb. Based on this, a novel fluorimetric method was developed for the determination of Hb in aqueous solution. Under optimal conditions, Hb could be determined in the concentration range of 5 x 10(-11) - 12 x 10(-8) mol L(-1) with a detection limit of 1.5 x10(-11) mol L(-1). The relative standard deviation of ten replicate measurements was 1.95% for solution containing 1 x10(-9 ) mol L(-1) Hb. The proposed method has been applied to the analysis of Hb in human blood and the results were in good agreement with those reported by a hospital laboratory. So this is a new, high sensitive and precise fluorescence quenching method to determine Hb.

On-Line Continuous-Flow, Multi-Protein Biochemical Assays for the Characterization of Bioaffinity Compounds Using Electrospray Quadrupole Time-of-Flight Mass Spectrometry

The applicability of a homogeneous on-line continuous-flow, multi-protein biochemical assay was demonstrated for the interaction between fluorescein-biotin and streptavidin and for digoxin and anti-digoxigenin using electrospray quadrupole time-of-flight mass spectrometry (Q-TOF MS). In the on-line continuous-flow biochemical MS-based system several receptors (e.g., streptavidin and anti-digoxigenin, respectively) were allowed to react with corresponding reporter ligands (e.g.,fluorescein-biotin and digoxin, respectively). The methodology presented allows the simultaneous measurement of affinity and molecular mass of an active compound. By using automated MS and MS-MS switching functions of the Q-TOF, structure information is obtained allowing the characterization of bioactive compounds. No cross-reactivities were observed between the two model systems fluorescein-biotin/streptavidin and digoxin/anti-digoxigenin.

Use of bioaffinity interactions in electrokinetically controlled assays on microfabricated devices

In this contribution, the role of bioaffinity interactions on electrokinetically controlled microfabricated devices is reviewed. Interesting applications reported in the literature include enzymatic assays, where enzyme and enzyme inhibition kinetics were studied, often in combination with electrophoretic separation. Attention is paid towards developments that could lead to implementation of electrokinetically controlled microdevices in high-throughput screening. Furthermore, enzyme-facilitated detection in combination with electrophoretic separation on microdevices is discussed. Various types of immunoassays have been implemented on the microchip format. The selectivity of antibody-antigen interaction has been exploited for the detection of analytes in complex sample matrices as required, for example, in clinical chemistry. Binding kinetics as well as stoichiometry were studied in chip-based assays. Automated mixing protocols as well as the demonstration of a parallel immunoassay allow implementation of microdevices in high-throughput screening. Furthermore, demonstration of immunoassays on cheap polymeric microdevices opens the way towards the fabrication of disposable devices, a requirement for commercialization and therefore for application in routine analyses.

Continuous-flow, on-line monitoring of biospecific interactions using electrospray mass spectrometry

A continuous-flow analytical screening system is presented using electrospray mass spectrometry to measure the interaction of biologically active compounds with soluble affinity proteins. The biochemical detection system is based on a solution-phase, homogeneous assay. In a first step, compounds to be screened (e.g., biotinylated compounds, concentration range 10-1,000 nmol/L) are injected into a continuous-flow reaction system and allowed to react with the affinity protein (e.g., streptavidin, concentration range 3-48 nmol/L). Subsequently, a reporter ligand (fluorescein-labeled biotin 96 nmol/L) is added to saturate the remaining free binding sites of the affinity protein and the concentration of unbound reporter ligand is measured using electrospray MS in the selectedion monitoring mode. The presence of active compounds in the sample results in an increase of the concentration of unbound reporter ligands. The feasibility of a homogeneous MS-based biochemical assay is demonstrated using streptavidin/biotin and anti-digoxigenin/digoxin as model systems. Compared to radioactive or fluorescence-based biochemical assays, the present assay format does not require the synthesis and purification of labels. Various analytical conditions were investigated to determine the ability of MS to measure the biochemical interactions. The availability of a single ligand that can be detected at 10-50 nmol/L concentrations by electrospray MS is sufficient to set up the biochemical assay. For the biospecific interactions studies, detection limits of 10-100 nmol/L were obtained.

Detection of biological toxins on an active electronic microchip

An electric-field-driven assay for fluorescein-labeled staphylococcal enterotoxin B and cholera toxin B was developed on an active electronic microchip. An array of microlocations was transformed into an immunoassay array by electronically biasing electrodes at each microlocation to attract biotinylated capture antibodies. The electric field generated on the array directed the transport, concentration, and binding of biotinylated capture antibodies to streptavidin-coated microlocations. Subsequently, solutions of fluorescein-labeled staphylococcal enterotoxin B and fluorescein-labeled cholera toxin B were electronically addressed to the assay sites by an applied electric field. Each toxin was specifically bound to microlocations containing the appropriate capture antibody with little nonspecific binding to assay sites lacking the appropriate capture antibody. It was possible to detect both toxins from a mixture in a single electronic addressing step; detection was accomplished after a 1-min application of the electric field followed by washing. The ability to perform a rapid, electric field-mediated immunoassay for multiple analytes may provide an advantage over existing approaches.