TY - JOUR
T1 - Nuclease Hydrolysis Does Not Drive the Rapid Signaling Decay of DNA Aptamer-Based Electrochemical Sensors in Biological Fluids
AU - Shaver, Alexander
AU - Kundu, Nandini
AU - Young, Brian E.
AU - Vieira, Philip A.
AU - Sczepanski, Jonathan T.
AU - Arroyo-Currás, Netzahualcóyotl
N1 - Funding Information:
A.S. and N.A.-C. thank the Johns Hopkins University School of Medicine for providing the funds used to perform the research reported in this work. N.K., B.E.Y., and J.T.S. were supported by the National Institute of General Medical Sciences (R35GM124974) and the Welch Foundation (A1909). P.A.V. was also supported by the National Institute of General Medical Sciences (SC2GM127268). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Publisher Copyright:
©
PY - 2021/5/4
Y1 - 2021/5/4
N2 - Electrochemical aptamer-based (E-AB) sensors are a technology capable of real-time monitoring of drug concentrations directly in the body. These sensors achieve their selectivity from surface-attached aptamers, which alter their conformation upon target binding, thereby causing a change in electron transfer kinetics between aptamer-bound redox reporters and the electrode surface. Because, in theory, aptamers can be selected for nearly any target of interest, E-AB sensors have far-reaching potential for diagnostic and biomedical applications. However, a remaining critical weakness in the platform lies in the time-dependent, spontaneous degradation of the bioelectronic interface. This progressive degradation - seen in part as a continuous drop in faradaic current from aptamer-attached redox reporters - limits the in vivo operational life of E-AB sensors to less than 12 h, prohibiting their long-term application for continuous molecular monitoring in humans. In this work, we study the effects of nuclease action on the signaling lifetime of E-AB sensors, to determine whether the progressive signal loss is caused by hydrolysis of DNA aptamers and thus the loss of signaling moieties from the sensor surface. We continuously interrogate sensors deployed in several undiluted biological fluids at 37 °C and inject nuclease to reach physiologically relevant concentrations. By employing both naturally occurring d-DNA and the nuclease-resistant enantiomer l-DNA, we determine that within the current lifespan of state-of-the-art E-AB sensors, nuclease hydrolysis is not the dominant cause of sensor signal loss under the conditions we tested. Instead, signal loss is driven primarily by the loss of monolayer elements - both blocking alkanethiol and aptamer monolayers - from the electrode surface. While use of l-DNA aptamers may extend the E-AB operational life in the long term, the critical issue of passive monolayer loss must be addressed before those effects can be seen.
AB - Electrochemical aptamer-based (E-AB) sensors are a technology capable of real-time monitoring of drug concentrations directly in the body. These sensors achieve their selectivity from surface-attached aptamers, which alter their conformation upon target binding, thereby causing a change in electron transfer kinetics between aptamer-bound redox reporters and the electrode surface. Because, in theory, aptamers can be selected for nearly any target of interest, E-AB sensors have far-reaching potential for diagnostic and biomedical applications. However, a remaining critical weakness in the platform lies in the time-dependent, spontaneous degradation of the bioelectronic interface. This progressive degradation - seen in part as a continuous drop in faradaic current from aptamer-attached redox reporters - limits the in vivo operational life of E-AB sensors to less than 12 h, prohibiting their long-term application for continuous molecular monitoring in humans. In this work, we study the effects of nuclease action on the signaling lifetime of E-AB sensors, to determine whether the progressive signal loss is caused by hydrolysis of DNA aptamers and thus the loss of signaling moieties from the sensor surface. We continuously interrogate sensors deployed in several undiluted biological fluids at 37 °C and inject nuclease to reach physiologically relevant concentrations. By employing both naturally occurring d-DNA and the nuclease-resistant enantiomer l-DNA, we determine that within the current lifespan of state-of-the-art E-AB sensors, nuclease hydrolysis is not the dominant cause of sensor signal loss under the conditions we tested. Instead, signal loss is driven primarily by the loss of monolayer elements - both blocking alkanethiol and aptamer monolayers - from the electrode surface. While use of l-DNA aptamers may extend the E-AB operational life in the long term, the critical issue of passive monolayer loss must be addressed before those effects can be seen.
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U2 - 10.1021/acs.langmuir.1c00166
DO - 10.1021/acs.langmuir.1c00166
M3 - Article
C2 - 33876937
AN - SCOPUS:85106068570
VL - 37
SP - 5213
EP - 5221
JO - Langmuir
JF - Langmuir
SN - 0743-7463
IS - 17
ER -