Hybrids of a Genetically Engineered Antibody and a Carbon Nanotube Transistor for Detection of Prostate Cancer Biomarkers

Abstract

We developed a novel detection method for osteopontin (OPN), a new biomarker for prostate cancer, by attaching a genetically engineered single chain variable fragment (scFv) protein with high binding affinity for OPN to a carbon nanotube field-effect transistor (NTFET). Chemical functionalization using diazonium salts is used to covalently attach scFv to NT-FETs, as confirmed by atomic force microscopy, while preserving the activity of the biological binding site for OPN. Electron transport measurements indicate that functionalized NT-FET may be used to detect the binding of OPN to the complementary scFv protein. A concentration-dependent increase in the source-drain current is observed in the regime of clinical significance, with a detection limit of approximately 30 fM. The scFv-NT hybrid devices exhibit selectivity for OPN over other control proteins. These devices respond to the presence of OPN in a background of concentrated bovine serum albumin, without loss of signal. Based on these observations, the detection mechanism is attributed to changes in scattering at scFv protein-occupied defect sites on the carbon nanotube sidewall. The functionalization procedure described here is expected to be generalizable to any antibody containing an accessible amine group, and to result in biosensors appropriate for detection of corresponding complementary proteins at fM concentrations.

Silicon Nanowire Biosensor for Highly Sensitive and Multiplexed Detection of Oral Squamous Cell Carcinoma Biomarkers in Saliva

“…4 Many researchers have achieved early diagnosis of cancer by studying biomarkers. 5 Several OSCC biomarkers in body fluids are found to be involved in the development of cancer in its early stage.…”

Scalable, non-invasive glucose sensor based on boronic acid functionalized carbon nanotube transistors

“…8 Nanotube-based glucose sensors have been demonstrated using a variety of techniques; 9 however, the sensitivity of nanotube FETs to the local charge environment suggests that this modality could potentially attain the lowest detection limits. 10,11 The prevalence of boronate anions created from bound glucose molecules is expected to modulate the electronic transport properties of the FET in a concentration-dependent manner. Carbon nanotube-based sensors with sensitivity equal to or greater than commercially available enzyme-based immunoassays would then potentially be useful for glucose monitoring in bodily fluids other than blood, such as saliva, eliminating the need for daily, uncomfortable finger pricking.…”

Immunoassay for troponin I using a glassy carbon electrode modified with a hybrid film consisting of graphene and multiwalled carbon nanotubes and decorated with platinum nanoparticles

“…The n = 0.23 found in the present case corresponds to a negative cooperativity, which indicates the binding of cTnI to more than one anti-cTnI at the bioelectrode surface [36]. This may be due to the inhibition of multiple cTnI molecules binding to small aggregates or clusters of anti-cTnI due to steric hindrance [37]. Fig.6b shows the calibration curve of the bioelectrode representing a linear relationship between the change in charge transfer resistance (ΔR et = (R et ) after immunoreaction -(R et ) control ) and the cTnI concentration over the range of 1.0 pg mL −1 to 10 ng mL −1 and can be represented by Eq.…”