Carbon Nanotubes and Gold Nanoparticles

Gold nanoparticles have a wide array of applications including molecular diagnosis, imaging, bioinformatics, and targeting therapy [147]. Early and accurate detection of cancer is very important so that proper or personalized medication can be administered. Gold nanoparticle—based calorimetric assay has been developed by Medley et al. for the detection of cancer cells [148]. The assay involves aptamer-conjugated gold nanoparticles. When gold NPs bind to targeted cancer cells, a distinct color change will appear, whereas control noncancerous cells remain unchanged [148]. Aptamer-based biobarcode assays for the detection of Cyt c released from apoptotic cells have been investigated [149]. Sensitivity and specificity of the assay enabled differentiation between cancer and noncancer cells depending on the aptamer used [148]. Kah et al. applied gold nanoparticles with surface modification for early detection of oral cancer [150]. The nanoparticles conjugated to antiepidermal growth factor receptor produced an optical contrast that could differentiate between cancer and normal cells [150]. Furthermore, spectrum analysis from self-enhanced Raman scattering of gold nanoparticles showed a distinct difference between normal saliva and saliva obtained from patient with cancer [150]. These results demonstrate the feasibility of early diagnosis of oral cancer.

Graphene CNT aptasensor was adapted for cardiac myoglobin biomarker by Kumal et al. The aptamer-functionalized nanotube revealed a substantial increase in signal response with a detection limit of around 0.3 ng/mL [151]. This assay can be utilized for the diagnosis of myoglobin screening in patients [151]. SWCNT-based transparent immunosensor has been developed as the biomarker osteopontin (OPN) for the detection of prostate cancer [152]. Monoclonal antibodies specific for OPN were covalently immobilized on the SWCNT with various channel lengths (2, 5, and 10 pm) [152]. Studies indicate that immunosensors were specific for OPN in phosphate buffer saline. Human serum from 1 pg/mL to 1 pg/mL as well as BSA protein with a detection limit of 0.3 pg/mL were detected [152].

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