Sensitive detection of proteins and bacteria is of central importance in biomedical research, with applications to elucidating disease pathways, immunology, medical diagnostics, systems biology, functional proteomics, and new drug development. Highly selective and sensitive binding-assay arrays are increasingly important in light of emerging areas of biomedical science and intensified world bioterrorism. Sensitive, rapid, specific, multiple detection of proteins, bacteria and toxins in biological and environmental samples is critically important for public health. The broad, long term goals of this proposal are to develop highly sensitive micro- and nano-biosensor arrays for proteins and bacteria using patterned single-walled carbon nanotubes (SWNTs) and biomolecule recognition elements. Major specific applications include simultaneous measurement of suites of protein biomarkers in serum for early cancer detection. Single walled carbon nanotubes (SWNTs) with approximately 1.4 nm diameters have the world's highest conductivity per unit mass and have excellent potential for electrical sensing of biomolecules. We have assembled approximately 30 nm long carbon nanotubes standing in 20-200 nm diameter bundles called SWNT forests with electrical links to conductive surfaces. These high surface area, patternable, conductive nanostructures provide new opportunities for highly sensitive biosensor arrays. In this project, we combine nanotube electrical transduction with specific molecular recognition of antibodies for proteins and bacteria. SWNTs as molecular wires will shuttle electrons vectorially between enzyme labels at their tips and external electrical connections. We focus here on peroxidase-linked amperometric immunoassays, in which enzyme catalyzed reduction of H2O2 provides electrical signals transmitted via SWNTs. In preliminary work, we attached antibodies to SWNT forests and achieved detection of several antigens in the ng/mL range and below. Using newly developed conjugates of nanotubes, peroxidases and secondary antibodies (Ab2) with high label-to-Ab2 ratios with the SWNT immunosensors, we recently detected prostate specific antigen (PSA) in human serum at 0.01 ng/mL (0.25 Fmol/mL), a detection limit better than the best commercial assays for PSA. Ultra-low NSB combined with conductive polymer wiring of nanotube junctions, along with multi-enzyme label strategies, promise the highest possible sensitivity. Thus, we will optimize the new Ab2 nanoconjugates, explore conductive polymer wiring strategies, and eliminate non-specific binding (NSB) of interferences via competitively adsorbed protein/surfactant additives and synthesis of novel low NSB organic surfaces on nanotube ends. Finally, we will integrate optimized fabrication/detection approaches into multi-analyte sensor arrays utilizing patterned SWNT-antibody assemblies. In addition to achieving our specific aims, this project should provide fundamental guidance for fabrication of sensitive microarray devices for a wide variety of biomedical applications.

National Institute of Health (NIH)
National Institute of Environmental Health Sciences (NIEHS)
Research Project (R01)
Project #
Application #
Study Section
Enabling Bioanalytical and Biophysical Technologies Study Section (EBT)
Program Officer
Balshaw, David M
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Connecticut
Schools of Arts and Sciences
United States
Zip Code
Sharifi, R; Abanulo, D C; Papadimitrakopoulos, F (2013) Isotopically induced variation in the stability of FMN-wrapped carbon nanotubes. Langmuir 29:7209-15
Croce Jr, Robert A; Vaddiraju, SanthiSagar; Kondo, Jun et al. (2013) A miniaturized transcutaneous system for continuous glucose monitoring. Biomed Microdevices 15:151-60
Croce Jr, Robert A; Vaddiraju, Santhisagar; Papadimitrakopoulos, Fotios et al. (2012) Theoretical analysis of the performance of glucose sensors with layer-by-layer assembled outer membranes. Sensors (Basel) 12:13402-16
Chai, Hongmei; Liu, Hongyun; Guo, Xihong et al. (2012) Long Distance Electron Transfer Across >100 nm Thick Au Nanoparticle/Polyion Films to a Surface Redox Protein. Electroanalysis 24:1129-1140
Rusling, James F (2012) Nanomaterials-based electrochemical immunosensors for proteins. Chem Rec 12:164-76
Ju, Sang-Yong; Abanulo, Darlington C; Badalucco, Christopher A et al. (2012) Handedness enantioselection of carbon nanotubes using helical assemblies of flavin mononucleotide. J Am Chem Soc 134:13196-9
Malhotra, Ruchika; Patel, Vyomesh; Chikkaveeraiah, Bhaskara V et al. (2012) Ultrasensitive detection of cancer biomarkers in the clinic by use of a nanostructured microfluidic array. Anal Chem 84:6249-55
Tang, Chi K; Vaze, Abhay; Rusling, James F (2012) Fabrication of immunosensor microwell arrays from gold compact discs for detection of cancer biomarker proteins. Lab Chip 12:281-6
Chikkaveeraiah, Bhaskara V; Soldà, Alice; Choudhary, Dharamainder et al. (2012) Ultrasensitive nanostructured immunosensor for stem and carcinoma cell pluripotency gatekeeper protein NANOG. Nanomedicine (Lond) 7:957-65
Venkatanarayanan, Anita; Crowley, Karl; Lestini, Elena et al. (2012) High sensitivity carbon nanotube based electrochemiluminescence sensor array. Biosens Bioelectron 31:233-9

Showing the most recent 10 out of 51 publications