John Carruthers

Nanomonitors: Protein Biosensors for Rapid Analyte Analysis

A technology for electrical detection of proteins has been developed using electrical conductance measurements. It is based on developing high density, low-volume multiwell plate devices. The scientific core of this technology lies in integrating nanoporous membranes with microfabricated chip platforms. This results in the conversion of individual pores into wells of picoliter volume. Specific antibodies are localized and isolated into individual wells. The formation of the antibody-antigen binding complex occurs in individual wells. The membrane allows for robust separation among individual wells. This technology has the capability to achieve near real-time detection with improved sensitivity and selectivity.

Electrical Immunoassays toward Clinical Diagnostics: Identification of Vulnerable Cardiovascular Plaque

A technology for electrical detection of protein biomarkers has been developed. It is based on developing high-density, low-volume multiwell plate devices. The scientific core of this technology lies in integrating nanoporous membranes with microfabricated chip platforms. This results in the conversion of individual pores into wells of picoliter volume. Specific antibodies are localized and isolated into individual wells. The formation of the antibody–antigen-binding complex occurs in individual wells. The membrane allows for robust separation among individual wells. This technology has the capability to achieve near real-time detection with improved sensitivity and selectivity. This is due to the two factors associated with the technology: (1) event-based electrochemical detection process, where the individual step in the formation of the binding complex results in a specific change to the electrochemical conductance due to the pertubation of the electrical double layer at the base of the each well. (2) The nanoporous membrane is an electrical insulator and is structurally robust throughout hence there is improved signal-to-noise ratio and cross-contamination between is minimized. Another advantage of this technique is the use of electrical signal in protein identification as compared to the use of optical methods; hence, it is a noninvasive and a label-free technique. The signal acquisition is simple and it uses the existing data acquisition and signal analysis methods. We have demonstrated the use of this technology for addressing a specific clinical problem: identification of vulnerable coronary plaque in the perioperative state.

A nanomonitor compared to ELISA for C-reactive protein detection in patient blood

The nanomonitors are multi scale “point-of care” devices comprised of high density nanopores formed from the integration of nanoporous alumina membranes onto metallic microscale platforms. The nanomonitors have approximately 250,000 nanowells per sensing site and use antibody binding reactions for detection of proteins. The antigen explored was C-reactive protein (CRP), an inflammatory biomarker associated with cardiovascular disease. Protein detection on the nanomonitor was achieved through electrical impedance spectroscopy. We performed a prospective cohort study of patients undergoing vascular surgery and compared the nanomonitor results to the industry standard ELISA (enzyme-linked immuno-sorbant assay) for the measurement of CRP in patient blood using Bland-Altman and mixed effects model statistical techniques. No statistical difference was found between the nanomonitor, ELISA, and CRP results, p = 0.994. In addition, the mean inter-assay coefficient of variation (CV) for the nanomonitor was 1.3%, and mean intra-assay CV 1.8%. The mean inter-assay CV for ELISA was 6.1%, and mean intra-assay CV was 5.2%. The nanomonitor time-to-result was 15 minutes and the ELISA was 3 hours, a critical time saving for patient care. In conclusion, we validated the use of the nanomonitor in clinical patient blood samples for the detection of CRP.

Nanomonitors: Nanomaterial Based Devices Towards Clinical Immunoassays

The immobilization of biomolecules on a solid substrate and their localization in “small” regions are major requirements for a variety of biomedical diagnostic applications, where rapid and accurate identification of multiple biomolecules is essential. In this specific application we have fabricated nanomitors for identifying specific protein biomarkers based on the electrical detection of antibody-antigen binding events. The nanomonitor, lab-on-a-chip device technology is based on electrical detection of protein biomarkers. It is based on developing high density, low volume multi-well plate devices. The scientific core of this technology lies in integrating nanomaterial with micro fabricated chip platforms and exploiting the improve surface area to volume to improve the detection. The devices that have been developed utilize electrical detection mechanisms where capacitance and conductance changes due to protein binding are used as “signatures” for biomarker profiling. In comparison to optical methods, the electrical detection technique is non-invasive as well as a label free. The signal acquisition is simple and it uses the existing data acquisition and signal analysis methods