Abstract Quantum dots (QDs), nano-sized semiconductors, are one of the most important materials t... more Abstract Quantum dots (QDs), nano-sized semiconductors, are one of the most important materials that create a bridge between nanotechnology, and drug assay. Their unique photoluminescence and electronic properties including broad and continuous absorption spectra, narrow emission spectra from visible to near-infrared wavelengths, long light lasting, high brightness make them as some suitable probe materials in (bio)sensing or immunosensing platform. Quantum dots (QDs) are considered efficient fluorescent labels used in a drug delivery system for monitoring the metabolism process of drugs in the body owing to the unique physicochemical characteristics. They can also be developed for a variety of biomedical applications, such as disease detection, and fluorescent assays for drug discovery. This paper reviews the physical and chemical properties of QDs, their synthesis methods, surface modification and bioconjugation as well as some interesting examples of their recent applications in analytical chemistry, drug delivery, biosensing and immunoassay.
In this study, an electrochemical DNA biosensor was developed using a straightforward methodology... more In this study, an electrochemical DNA biosensor was developed using a straightforward methodology to investigate the interaction of indinavir with calf thymus double-stranded deoxyribonucleic acid (ct-dsDNA) for the first time. The decrease in the oxidation signals of deoxyguanosine (dGuo) and deoxyadenosine (dAdo), measured by differential pulse voltammetry, upon incubation with different concentrations of indinavir can be attributed to the binding mode of indinavir to ct-dsDNA. The currents of the dGuo and dAdo peaks decreased linearly with the concentration of indinavir in the range of 1.0–10.0 μg/mL. The limit of detection and limit of quantification for indinavir were 0.29 and 0.98 μg/mL, respectively, based on the dGuo signal, and 0.23 and 0.78 μg/mL, respectively, based on the dAdo signal. To gain further insights into the interaction mechanism between indinavir and ct-dsDNA, spectroscopic measurements and molecular docking simulations were performed. The binding constant (Kb) between indinavir and ct-dsDNA was calculated to be 1.64 × 108 M−1, based on spectrofluorometric measurements. The obtained results can offer insights into the inhibitory activity of indinavir, which could help to broaden its applications. That is, indinavir can be used to inhibit other mechanisms and/or hallmarks of viral diseases.
Abstract Graphene quantum dots (GQDs) functionalized with chitosan (GQDs-CS) were used for the fi... more Abstract Graphene quantum dots (GQDs) functionalized with chitosan (GQDs-CS) were used for the first time as a suitable nanostructured sensing film for efficient immobilization of methylene blue (MB) through amino-hydroxyl reaction to prepare a novel non-enzymatic hydrogen peroxide sensor using a glassy carbon electrode (GCE). The synthesized hybrid nanostructures were characterized by X-ray diffraction, field emission scanning electron microscopy, cyclic voltammetry, FT-IR, UV–vis, photoluminescence, and energy dispersive X-ray spectroscopy techniques. Cyclic voltammograms showed that the GQDs-CS/MB/GCE exhibited a significant electrocatalytic activity for the reduction of H 2 O 2 . The calculated k cat is 4.45 × 10 4 cm 3 mol −1 s −1 . The calibration graph for H 2 O 2 constructed by amperometry (−0.6 V vs. SCE) at the modified electrode showed two different linear ranges (1.0 × 10 −6 –2.9 × 10 −3 M and 2.9–11.78 mM) with a sensitivity of 10.115 μA/mM for the lower linear range and a calculated detection limit of 0.7 μM (S/N = 3). The response time of the sensor for H 2 O 2 detection was 3s. The electrochemical response of GQDs-CS/MB/GCE is not influenced by potential interferents (ascorbic and uric acids, dopamine, caffeine, glucose, and various inorganic salts). This modified electrode exhibited suitability for the non-enzymatic H 2 O 2 sensing in food and water samples.
In this work, immobilizing anti-GFAP antibodies via covalent attachment onto L-cysteine/gold nano... more 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...
A new label-free electrochemical immunosensor is constructed for the selective and sensitive dete... more A new label-free electrochemical immunosensor is constructed for the selective and sensitive determination of the clinically relevant biomarker receptor tyrosine kinase (AXL) in human serum. The disposable immunosensing platform is prepared by immobilization of the specific anti-AXL antibody onto amine functionalized graphene quantum dots (fGQDs)-modified screen-printed carbon electrodes (SPCEs). The affinity reactions were monitored by measuring the decrease in the differential pulse voltammetric (DPV) response of the redox probe Fe(CN). All the experimental variables involved in the preparation of the modified electrodes and in the immunosensor performance were optimized. The as prepared immunosensor exhibits an improved analytical performance with respect to other electrochemical immunosensors reported so far, with a wider range of linearity and a lower detection limit, 0.5 pg mL, which is more than one hundred thousand times lower than the established cut-off value for heart fai...
An immunosensor is a kind of affinity biosensor based on interactions between an antigen and spec... more An immunosensor is a kind of affinity biosensor based on interactions between an antigen and specific antigen immobilized on a transducer surface. Immunosensors possess high selectivity and sensitivity due to the specific binding between antibody and corresponding antigen, making them a suitable platform for several applications especially in the medical and bioanalysis fields. Electrochemical immunosensors rely on the measurements of an electrical signal recorded by an electrochemical transducer and can be classed as amperometric, potentiometric, conductometric, or impedimetric depending on the signal type. Among the immunosensors, electrochemical immunosensors have been more perfected due to their simplicity and, especially their ability to be portable, and for in situ or automated detection. This review addresses the potential of immunosensors destined for application in clinical analysis, especially cancer biomarker diagnosis. The emphasis is on the approaches used to fabricate ...
Environmental pollution has arisen from releasing pollutants into water sources in many parts of ... more Environmental pollution has arisen from releasing pollutants into water sources in many parts of the world, endangering human health and marine environments. Chemical discharge may come from various places, including wastewater treatment plants, agriculture, manufacturing, and stormwater overflows. As a result, monitoring pollution including, heavy metals, pesticides, toxic gases, and other contaminants in environmental samples such as water (e.g., groundwater, surface water, and drinking water), air, soil, and vegetables is critical to eliminating or reducing their risk and toxicity. Real-time analysis may also have an effect on reducing consumption of a variety of harsh chemicals and reagents, with the additional benefit of on-site contaminant composition assessment prior to discharge into the setting. Electrochemical biosensors have received a lot of interest in solving this issue as a result of recent technological breakthroughs. This review presents the types and properties of ...
Abstract Quantum dots (QDs), nano-sized semiconductors, are one of the most important materials t... more Abstract Quantum dots (QDs), nano-sized semiconductors, are one of the most important materials that create a bridge between nanotechnology, and drug assay. Their unique photoluminescence and electronic properties including broad and continuous absorption spectra, narrow emission spectra from visible to near-infrared wavelengths, long light lasting, high brightness make them as some suitable probe materials in (bio)sensing or immunosensing platform. Quantum dots (QDs) are considered efficient fluorescent labels used in a drug delivery system for monitoring the metabolism process of drugs in the body owing to the unique physicochemical characteristics. They can also be developed for a variety of biomedical applications, such as disease detection, and fluorescent assays for drug discovery. This paper reviews the physical and chemical properties of QDs, their synthesis methods, surface modification and bioconjugation as well as some interesting examples of their recent applications in analytical chemistry, drug delivery, biosensing and immunoassay.
In this study, an electrochemical DNA biosensor was developed using a straightforward methodology... more In this study, an electrochemical DNA biosensor was developed using a straightforward methodology to investigate the interaction of indinavir with calf thymus double-stranded deoxyribonucleic acid (ct-dsDNA) for the first time. The decrease in the oxidation signals of deoxyguanosine (dGuo) and deoxyadenosine (dAdo), measured by differential pulse voltammetry, upon incubation with different concentrations of indinavir can be attributed to the binding mode of indinavir to ct-dsDNA. The currents of the dGuo and dAdo peaks decreased linearly with the concentration of indinavir in the range of 1.0–10.0 μg/mL. The limit of detection and limit of quantification for indinavir were 0.29 and 0.98 μg/mL, respectively, based on the dGuo signal, and 0.23 and 0.78 μg/mL, respectively, based on the dAdo signal. To gain further insights into the interaction mechanism between indinavir and ct-dsDNA, spectroscopic measurements and molecular docking simulations were performed. The binding constant (Kb) between indinavir and ct-dsDNA was calculated to be 1.64 × 108 M−1, based on spectrofluorometric measurements. The obtained results can offer insights into the inhibitory activity of indinavir, which could help to broaden its applications. That is, indinavir can be used to inhibit other mechanisms and/or hallmarks of viral diseases.
Abstract Graphene quantum dots (GQDs) functionalized with chitosan (GQDs-CS) were used for the fi... more Abstract Graphene quantum dots (GQDs) functionalized with chitosan (GQDs-CS) were used for the first time as a suitable nanostructured sensing film for efficient immobilization of methylene blue (MB) through amino-hydroxyl reaction to prepare a novel non-enzymatic hydrogen peroxide sensor using a glassy carbon electrode (GCE). The synthesized hybrid nanostructures were characterized by X-ray diffraction, field emission scanning electron microscopy, cyclic voltammetry, FT-IR, UV–vis, photoluminescence, and energy dispersive X-ray spectroscopy techniques. Cyclic voltammograms showed that the GQDs-CS/MB/GCE exhibited a significant electrocatalytic activity for the reduction of H 2 O 2 . The calculated k cat is 4.45 × 10 4 cm 3 mol −1 s −1 . The calibration graph for H 2 O 2 constructed by amperometry (−0.6 V vs. SCE) at the modified electrode showed two different linear ranges (1.0 × 10 −6 –2.9 × 10 −3 M and 2.9–11.78 mM) with a sensitivity of 10.115 μA/mM for the lower linear range and a calculated detection limit of 0.7 μM (S/N = 3). The response time of the sensor for H 2 O 2 detection was 3s. The electrochemical response of GQDs-CS/MB/GCE is not influenced by potential interferents (ascorbic and uric acids, dopamine, caffeine, glucose, and various inorganic salts). This modified electrode exhibited suitability for the non-enzymatic H 2 O 2 sensing in food and water samples.
In this work, immobilizing anti-GFAP antibodies via covalent attachment onto L-cysteine/gold nano... more 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...
A new label-free electrochemical immunosensor is constructed for the selective and sensitive dete... more A new label-free electrochemical immunosensor is constructed for the selective and sensitive determination of the clinically relevant biomarker receptor tyrosine kinase (AXL) in human serum. The disposable immunosensing platform is prepared by immobilization of the specific anti-AXL antibody onto amine functionalized graphene quantum dots (fGQDs)-modified screen-printed carbon electrodes (SPCEs). The affinity reactions were monitored by measuring the decrease in the differential pulse voltammetric (DPV) response of the redox probe Fe(CN). All the experimental variables involved in the preparation of the modified electrodes and in the immunosensor performance were optimized. The as prepared immunosensor exhibits an improved analytical performance with respect to other electrochemical immunosensors reported so far, with a wider range of linearity and a lower detection limit, 0.5 pg mL, which is more than one hundred thousand times lower than the established cut-off value for heart fai...
An immunosensor is a kind of affinity biosensor based on interactions between an antigen and spec... more An immunosensor is a kind of affinity biosensor based on interactions between an antigen and specific antigen immobilized on a transducer surface. Immunosensors possess high selectivity and sensitivity due to the specific binding between antibody and corresponding antigen, making them a suitable platform for several applications especially in the medical and bioanalysis fields. Electrochemical immunosensors rely on the measurements of an electrical signal recorded by an electrochemical transducer and can be classed as amperometric, potentiometric, conductometric, or impedimetric depending on the signal type. Among the immunosensors, electrochemical immunosensors have been more perfected due to their simplicity and, especially their ability to be portable, and for in situ or automated detection. This review addresses the potential of immunosensors destined for application in clinical analysis, especially cancer biomarker diagnosis. The emphasis is on the approaches used to fabricate ...
Environmental pollution has arisen from releasing pollutants into water sources in many parts of ... more Environmental pollution has arisen from releasing pollutants into water sources in many parts of the world, endangering human health and marine environments. Chemical discharge may come from various places, including wastewater treatment plants, agriculture, manufacturing, and stormwater overflows. As a result, monitoring pollution including, heavy metals, pesticides, toxic gases, and other contaminants in environmental samples such as water (e.g., groundwater, surface water, and drinking water), air, soil, and vegetables is critical to eliminating or reducing their risk and toxicity. Real-time analysis may also have an effect on reducing consumption of a variety of harsh chemicals and reagents, with the additional benefit of on-site contaminant composition assessment prior to discharge into the setting. Electrochemical biosensors have received a lot of interest in solving this issue as a result of recent technological breakthroughs. This review presents the types and properties of ...
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