Stochastic and potentiometric microsensors based on porphyrins and polymeric surfactants such as polysodium N-undecanoyl-L-leucylvanilate and polysodium N-undecanoyl-L-vanilate were developed for enantioselective assay of pipecolic acid. The matrices used for the design of the stochastic sensors were diamond paste and graphite paste, while the matrix used for the design of potentiometric sensors was carbon paste. The response characteristics of the microsensors were determined for the enantiomers of pipecolic acid. The response characteristics, selectivity, and enantioselectivity studies proved that the proposed microsensors can be used for clinical enantioanalysis of pipecolic acid in biological fluids, e.g., urine and whole blood.
Disposable sensors are essential for biomedical analysis. Therefore, paper based sensors may became a good alternative to expensive tools and methods used to date in clinical laboratories. New stochastic sensors based on carbon thin films deposited on adsorbent and glossy papers modified with nanostructured material such as 5,10,15,20-tetraphenyl-21H,23H-porphyrin were proposed. Carcinoembryonic antigen-a biomarker very often used for cancer diagnosis as well as for follow up of cancer treatment, was selected as model analyte. Qualitative and quantitative assay was performed using the new proposed sensors. The sensors can be used as disposable sensors for biomedical analyses with high reliabilities.
Maltodextrin with dextrose equivalence between 4 and 7 was proposed for the design of a multimode sensor. The multimode term was introduced for the sensors that can be used in more than one electrochemical method. The selection of the materials was based on its nanostructure nature (for stochastic mode), and its catalytic activity (for amperometric mode). The qualitative analysis was performed using the stochastic mode, while the quantitative analysis of the antigens was performed using both stochastic and amperometric modes. The biomarkers specific for hepatitis B and breast cancer were determined directly from the biological fluids (e.g., whole blood). The response characteristics of the new multimode sensors for CA15-3, and hepatitis B biomarkers (HBV antigen and D-pipecolic acid) (linear concentration ranges, limits of determination) as well as their recovery tests performed using whole blood samples proved that they can be used for screening tests of whole blood with high reliability.
Engineered nanoporous gold microspheres were designed and used as new materials for stochastic microsensors. Carcinoembryonic antigen was used as model analyte to prove the stochastic sensing capabilities of the new material. A new sensor based on gold particles was used for the assay of the carcinoembryonic antigen in biological fluids. Stochastic sensing was used to determine the antigen in the samples. The working concentration range of the stochastic microsensor (1.6 Â 10 À8 to 1.6 Â 10 À5 mg mL À1 ) as well as its sensitivity (3.0 Â 10 3 s mg mL À1 ) and limit of quantification (16 ng mL À1 ) made possible its reliable utilization for screening tests of whole blood samples for the carcinoembryonic antigen.
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