A multi-walled carbon nanotube-zinc oxide nanofiber based flexible chemiresistive biosensor for malaria biomarker detection.

We report the fabrication of a flexible, lightweight and disposable multi walled carbon nanotube (MWCNT)-zinc oxide (ZnO) nanofiber based chemiresistive biosensor for label free detection of the malaria biomarker, histidine rich protein II (HRP2). The sensing platform is formed by depositing nanofibers in between the source and drain electrodes patterned on a thin, flexible polyethylene terephthalate (PET) substrate. MWCNT-ZnO nanofibers are synthesized via the electrospinning technique followed by a calcination process. This approach creates functional groups on the nanofiber surface that are used for the one step immobilization of HRP2 antibodies without further surface modification. The device exhibits a good sensitivity of 8.29 kΩ g-1 mL and a wide detection range of 10 fg mL-1-10 ng mL-1, and it is specific towards the targeted HRP2 biomarker. To the best of our knowledge, this is the first report on a flexible chemiresistive biosensor explored for the detection of the malaria biomarker and can be extended in the future to several other biomarker detection systems towards smart point-of-care (POC) diagnostics.

One step biofunctionalized electrospun multiwalled carbon nanotubes embedded zinc oxide nanowire interface for highly sensitive detection of carcinoma antigen-125.

Ovarian cancer is the most leading cause of cancer-related death in women . The carcinoma antigen-125, which is found on the surface of many ovarian cancer cells is known to be a gold standard clinical biomarker associated with life-threatening gynecological malignancy. In this work, we demonstrate a novel biosensor platform based on multiwalled carbon nanotubes embedded zinc oxide nanowire for the ultrasensitive detection of carcinoma antigen-125. Label free detection of the carcinoma antigen-125 was accomplished by differential voltammetry technique that demonstrated excellent sensitivity (90.14µA/(U/mL)/cm2) with a detection limit of 0.00113UmL-1 concentration. The fabricated immunosensor exhibits good performance with wider detection range (0.001UmL-1-1kUmL-1), reproducibility, selectivity, acceptable stability, and thus is a potential cost-effective methodology for point-of-care diagnosis. The multiwalled carbon nanotubes (MWCNTs) embedded highly oriented zinc oxide (ZnO) nanowires were synthesized by simple, low cost electrospinning technique. Compared to pure ZnO nanowires, electrochemical activity of MWCNTs embedded ZnO nanowires was found to be much higher. The calcination temperature was optimized to avoid any decomposition of the CNTs and to obtain multiwalled carbon nanotubes embedded highly crystalline ZnO nanowires. The salient feature of this biosensing platform is that one step calcination process is enough to create the functional groups on MWCNT-ZnO nanowire surface that are effective for the covalent conjugation of antibody without further surface modification. To the best of our knowledge, this is the first report on MWCNT-ZnO nanowire based immunosensor explored for the detection of cancer biomarker.