# Spatiotemporal control of concentration gradients with electrochemistry in extracelluar space

> **NIH NIH R35** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2020 · $371,084

## Abstract

Project Summary
 The natural environment is intrinsically spatiotemporally heterogenous at both macroscopic and
microscopic levels. What shapes such a heterogeneity includes the concentration gradients of biologically
relevant chemical species in the extracellular medium including dioxygen (O2), reactive oxygen species (ROS),
as well as essential redox-active transition metals. While a significant amount of effort has been devoted to
spectroscopically image these chemical moieties, our capability to spatiotemporally control their concentration
distributions in the extracellular medium remains limited. This is especially the case for biofilms and microbiota,
in which the microorganisms’ small length scales pose significant challenges for concentration modulation.
The inadequate control of concentration heterogeneity limits our capability of mimicking the natural
environments in vitro and investigating how local concentration gradients affect microbial functionality.
Therefore, there is a need for an advanced method of controlling chemical concentrations at microscopic level.
 Our proposed research aims to use electrochemical nano-/micro-electrodes to spatiotemporally
control the concentration gradients in the extracellular medium. When an electrochemical reaction occurs on
an electrode’s surface, a concentration gradient is established near the electrode. Taking advantages of this
phenomena with the assistance of numerical simulation, we will employ an array of nano-/micro-electrodes
with individually addressable electrochemical potentials to program any arbitrary spatiotemporal
concentration profiles. We will fine-tune the surface chemistry and the electrochemical properties of these
electrodes to ensure biocompatibility and reaction specificity. The developed system will be applied to biofilms
and we aim to investigate how the microbial social behavior will be affected by a perturbation of local O2
concentration. Moreover, we will use this device to mimic the heterogenous environment in the gut and culture
gut microbiota in vitro. An algorithm based on machine learning will be employed to actively adjust electrode
potentials, maintaining a stable concentration profile despite the accumulation of gut microorganisms.
 Ultimately, our work will expand our capability of controlling the concentration heterogeneity in nature.
The developed electrochemical system will serve an in vitro platform to culture microorganisms in their native
environment, or as a tool to perturb the concentration profiles. Combining electrochemistry, inorganic
chemistry, and nanomaterials the research will enable a deeper understanding of the spatial distribution and
temporal response of microbial systems.

## Key facts

- **NIH application ID:** 10029526
- **Project number:** 1R35GM138241-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** Chong Liu
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $371,084
- **Award type:** 1
- **Project period:** 2020-09-15 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10029526

## Citation

> US National Institutes of Health, RePORTER application 10029526, Spatiotemporal control of concentration gradients with electrochemistry in extracelluar space (1R35GM138241-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10029526. Licensed CC0.

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