# Breakthrough Blocking-Layer Stability for Broader Clinical Utility of Continuous Aptamer Biosensors

> **NIH NIH R21** · UNIVERSITY OF CINCINNATI · 2024 · $232,290

## Abstract

PROJECT SUMMARY
The use of 10-14 day continuous glucose monitors for diabetes management is a historical achievement in
modern diagnostics, but unfortunately it remains an isolated success despite acute needs for the real-time
monitoring of many other molecules across the broader field of human disease management (cardiac, drug
dosing, fertility, etc.). The limitation is that glucose sensors are enzymatic, limiting their generalizability to other
analytes (i.e., enzymes oxidize/reduce the target molecule). Unlike enzymatic sensors, electrochemical
aptamer-based (EAB) sensors are broadly generalizable, demonstrated by several examples of real-time, in-
vivo molecular monitoring at nanomolar to micromolar concentrations. Unfortunately, in-vivo device longevity
remains a significant challenge for the clinical adoption of EAB sensors.
EAB sensors conventionally use a monolayer of redox-tagged aptamers and alkylthiol blocking molecules on a
gold working electrode. These self-assembled monolayers (SAMs) rapidly degrade on gold electrodes in real
biofluids at body temperature of 37 °C. The mechanisms of degradation of EAB SAMs have not been well-
understood in complex biofluids, which then limits the ability to pursue techniques to improve longevity. Our
preliminary data now provides major insights into the true mechanisms of SAM degradation. With this improved
understanding of degradation, its is now feasible to pursue stable operation for at least 5 days. Multi-day
operation would then allow EABs to be credibly pursued for applications beyond glucose, and for the first time,
proper research could begin on resolving the next expected longevity bottlenecks that would likely prevent 1-2
week operation (e.g. fouling, nuclease attack, etc.).
The central hypothesis is that at minimum 5 day EAB sensor operation can be achieved through a blocking layer
with superior stability achieved by either (1) electrochemically stabilizing an alkylthiol blocking layer during sensor
fabrication, or (2) replacing an alkylthiol blocking layer with a inorganic dielectric film that has a similar density of
defects supporting efficient electron transfer. 5 day operation would provide a leap forward in clinical relevance,
and is 10-20X greater the typical limit of 6-12 hours. 5 day operation would then position the PI Heikenfeld to
pursue clinical research, and would ignite critically-needed partnerships with industry leaders in glucose sensors.
The PI Heikenfeld is a new NIH investigator, but is well-prepared to pursue this longevity breakthrough given his
deep expertise in biosensors, and his co-PI’s White and Porter’s expertise in EAB sensors and electrochemical
blocking layers.

## Key facts

- **NIH application ID:** 10888235
- **Project number:** 5R21EB033874-03
- **Recipient organization:** UNIVERSITY OF CINCINNATI
- **Principal Investigator:** Jason Heikenfeld
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $232,290
- **Award type:** 5
- **Project period:** 2022-09-19 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10888235

## Citation

> US National Institutes of Health, RePORTER application 10888235, Breakthrough Blocking-Layer Stability for Broader Clinical Utility of Continuous Aptamer Biosensors (5R21EB033874-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10888235. Licensed CC0.

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