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Developing a redox-mediated single NP detection for bioconjugate analysis.

Award Number: R21GM155760
ORGANIZATION: NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 09/01/2024
PERIOD OF PERFORMANCE END DATE: 08/31/2026

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Developing a redox-mediated single NP detection for bioconjugate analysis. - Although immunoassays are a critical part of bioanalytical chemistry, the rapid and selective analysis of biomolecules continues to be a complicated aspect of biomedical research. The long-term goal is to develop single-entity electrochemistry to improve the current methods, primarily based on enzyme-linked immunosorbent assay (ELISA) and related techniques. The PI aims to use electrochemical detection for simultaneous qualitative and quantitative analysis down to a single bioconjugate to allow rapid routine detection. The overall objective in this proposal is to use antibody/antigen interactions as proof of concept for single entity amperometry: measure the current vs. time at ultramicroelectrodes (UME, diam < 30 micrometers) that will respond to single antibody/antigen conjugates. The antibodies will be tagged to Au nanoparticles (NPs) and detected using electrochemical reactions. The central hypothesis is that we can measure currents from individual antibody/antigen conjugates by measuring the reaction rate of separate redox mediators. The rationale is that electrochemical detection of antigens should be possible under conditions relevant to biomedical analysis. We will achieve single biomolecule resolution by detecting individual bioconjugates interacting with an electrode surface. By isolating a single bioconjugate, we will demonstrate a detection limit of a single molecular antigen in the direct assay mode. The project will test the central hypothesis by pursuing the following specific aims: (1) developing a redox-mediated approach suitable for antibody-NP detection. (2) Antibody/Antigen detection in biological samples. We will study the selectivity of the technique and leveraging electron transfer (ET) through pinholes as a suitable mechanism to overcome biofouling. This aim also includes the effect of non-specific binding and agglomeration or aggregation. The distance between the electrode and the NP, attached to an antibody, is relatively large for tunneling, and the distance-dependence of ET will translate into a time-dependence of the experimental current that will be used to discriminate specific vs non-specific interactions. To design a redox-mediated scheme, we will use Marcus theory of ET to select the redox pairs. The detection schemes will be validated with assays used for ensemble measurements, and we will pursue the detection of single molecules using the novel redox-mediated single-entity electrochemical scheme. The applicant believes the proposed research is innovative because it focuses on single-entity electrochemistry that is expected to yield single molecule detection through antibody/NP conjugates. The proposed research is significant because it is expected to provide a novel way for the rapid and sensitive detection of antibody/antigen interactions, with the potential of enabling simultaneous qualitative and quantitative information with minimal supplies and electrochemical instrumentation.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2025 ( Subtotal = $181,028 )
2025	2025	BOARD OF REGENTS OF THE NEVADA SYSTEM OF HIGHER ED	1664 N VIRGINIA ST # 285	RENO	NV	89557	WASHOE	USA	Biomedical Research and Research Training	000	2	8/12/2025	NON-COMPETING CONTINUATION	$181,028
														Subtotal = $181,028

Issue Date FY: 2024 ( Subtotal = $206,028 )
2024	2024	BOARD OF REGENTS OF THE NEVADA SYSTEM OF HIGHER ED	1664 N VIRGINIA ST # 285	RENO	NV	89557	WASHOE	USA	Biomedical Research and Research Training	000	1	8/8/2024	NEW	$206,028
														Subtotal = $206,028

Grand Total All Awards = $387,056

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Developing a redox-mediated single NP detection for bioconjugate analysis.

Award Number: R21GM155760

ORGANIZATION: NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 09/01/2024

PERIOD OF PERFORMANCE END DATE: 08/31/2026

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