Two three-dimensional (3D) stochastic microsensors based on immobilization of protoporphyrin IX (PIX) in single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) decorated with copper (Cu) and gold (Au) nanoparticles were designed and used for the molecular recognition of isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2) in biological samples (brain tumor tissues, whole blood). The linear concentration ranges obtained for the molecular recognition and quantification of IDH1 and IDH2 were: IDH1 (1 × 10-5-1 × 102 ng mL-1) and IDH2 (5 × 10-8 - 5 × 102 ng mL-1). The limits of quantification obtained using the proposed microsensors were: 10 fg mL-1 for IDH1 and 5 × 10-3 fg mL-1 for IDH2. The highest sensitivities were obtained for the microsensor based on MWCNT. High recoveries versus enzyme-linked immunosorbent assay (ELISA) standard method were recorded for the assays of IDH1 and IDH2, all values being higher than 99.00%, with relative standard deviations (RSD) lower than 0.10%.
Keywords: carbon nanotubes; isocitrate dehydrogenase 1; isocitrate dehydrogenase 2; stochastic microsensors.