Integrated “Sense and Treat” Enzyme Logic Systems for Battlefield Injuries

This research project is conducted in a close collaboration with Prof. Joseph Wang, University of California - San Diego (UCSD)

PI: Joseph Wang (UCSD), Co-PI: Evgeny Katz (Clarkson)

Title: "Integrated Enzyme-Logic Systems for "Sense and Treat" Injured Soldiers"
Co-PI: E. Katz
Office of Naval Research (ONR)
Award No: N00014-08-1202

Time Period: 09/01/08 - 08/31/12

Hospital-on-a-chip targets battlefield

An Office of Naval Research program seeks to embed a field hospital-on-a-chip that could monitor a soldier's injuries and administer medications. If successful, the four-year, $1.6 million program would provide U.S. soldiers with a wearable device to constantly monitor vital signs and help treat wounds. Microfluidic laboratories on-a-chip are being crafted for a variety of special-purpose devices that would allow unskilled personnel to perform specialized tests in the field. Inexpensive lab on-a-chip devices are also being designed to lower the cost and increase the speed of common medical tests. A hospital on-a-chip, however, would be the first multipurpose microfluidic chip capable of making complex diagnoses and administering different drugs. According to the researchers Evgeny Katz of Clarkson University (Potsdam, N.Y.) and Joseph Wang of the University of California-San Diego, treatment within the first 30 minutes after sustaining a battlefield wound is essential to saving soldiers' lives. The hospital-on-a-chip would allow soldier to automatically receive emergency treatment, even if unconscious. The researchers said they already have a blueprint for realizing their "sense-and-treat" system. The chip would monitor fluids like sweat and blood for the "biomarkers" of common battlefield injuries such as shock or fatigue. It would then automatically inject the appropriate drugs. Katz will measure biomarkers in body fluids using custom designed enzymes that enable the chip to make a battlefield diagnosis. Wang will build a prototype hospital-on-a-chip that uses microfluidic channels to process enzymes, deduce a diagnosis and administer the proper drug. Eventually, the researchers plan to make the device implantable so that it can not only increase survival rates on the battlefield but also constantly monitor individual soldiers' health.

Background: Since the majority of battlefield deaths occur within the first 30 minutes after  injury, rapid diagnosis and  treatment are crucial for enhancing the soldier survival rate. Different types battlefield injuries require  different therapeutic  interventions. Integrated autonomous medical feedback systems hold great promise for improving the diagnosis and treatment of injured soldiers. The ‘Sense and Act’ feedback-loop approach is currently being used for the management of diabetes in connection to electrochemical glucose sensors and insulin-delivery pumps.

Objective: The goal of this collaborative activity is to develop next-generation ‘sense and treat’ autonomous devices for enhancing the survival rate of injured soldiers in battlefield settings. Our objective is to carefully design and critically test an enzyme-logic sensing system for providing reliable assessment of the overall physiological condition during an injury and initiating an optimal and timely self treatment through interface with stimuli-responsive drug delivery actuators or a RF-connected drug-delivery patch. 

Basic Concept of Enzyme-Logic Diagnostics

Enzyme logic systems comprised of several concatenated logic gates operating in a concerted manner are capable of processing the biochemical information received in the form of various combinations of chemical signals according to the principles of Boolean logic. Multiple inputs (markers) thus trigger a cascade of enzymatic reactions. Integration of biocomputing elements with sensing processes would allow multi-signal analysis followed by biochemical processing of the data, giving the final answer regarding the physiological conditions of a patient in a digital (“YES” or “NO”) format.

Review papers:
J. Wang, E. Katz, Digital biosensors with built-in logic for biomedical applications. Israel Journal of Chemistry 2011, 51, 141-150
J. Wang, E. Katz, Digital biosensors with built-in logic for biomedical applications – Biosensors based on biocomputing concept. Anal. Bioanal. Chem. 2010, 398, 1591-1603.

Multiplexing of Injury Codes for the Parallel Operation of Enzyme Logic Gates

The development of a highly parallel enzyme logic sensing concept employing a novel encoding scheme for the determination of multiple pathophysiological conditions is reported. The new concept multiplexes a contingent of enzyme-based logic gates to yield a distinct ‘injury code’ corresponding to a unique pathophysiological state as prescribed by a truth table. The new concept is illustrated using an array of NAND and AND gates to assess the biomedical significance of numerous biomarker inputs including creatine kinase, lactate dehydrogenase, norepinephrine, glutamate, alanine transaminase, lactate, glucose, glutathione disulfide, and glutathione reductase to assess soft-tissue injury, traumatic brain injury, liver injury, abdominal trauma, hemorrhagic shock, and oxidative stress. Under the optimal conditions, physiological and pathological levels of these biomarkers were detected through either optical or electrochemical techniques by monitoring the level of the outputs generated by each of the six logic gates.
By establishing a pathologically meaningful threshold for each logic gate, the absorbance and amperometric assays tendered the diagnosis in a digitally-encoded 6-bit word, defined as an ‘injury code’. This binary ‘injury code’ enabled the effective discrimination of 64 unique pathological conditions to offer a comprehensive high-fidelity diagnosis of multiple injury conditions.

Such processing of relevant biomarker inputs and the subsequent multiplexing of the logic gate outputs to yield a comprehensive ‘injury code’ offers significant potential for the rapid and reliable assessment of varied and complex forms of injury in circumstances where access to a clinical laboratory is not viable. While the new concept of parallel and multiplexed enzyme logic gates is illustrated here in connection to multi-injury diagnosis, it could be readily extended to a wide range of practical medical, industrial, security and environmental applications.

J. Halámek, J.R. Windmiller, J. Zhou, M.-C. Chuang, P. Santhosh, G. Strack, M.A. Arugula, S. Chinnapareddy, V. Bocharova, J. Wang, E. Katz, Multiplexing of injury codes for the parallel operation of enzyme logic gates.
Analyst 2010, 135, 2249-2259.

The approach was developed by a research team leaded by Dr. Jan Halámek.

Bio-Logic Analysis of Injury Biomarker Patterns in Human Serum Samples
Digital biosensor systems analyzing biomarkers characteristic of liver injury (LI), soft tissue injury (STI) and abdominal trauma (ABT) were developed and optimized for their performance in serum solutions spiked with injury biomarkers in order to mimic real medical samples. The systems produced ‘Alert’-type optical output signals in the form of “YES-NO” separated by a threshold value. The new approach aims at the reliable detection of injury biomarkers for making autonomous decisions towards timely therapeutic interventions, particularly in conditions when a hospital treatment is not possible. The enzyme-catalyzed reactions performing Boolean AND / NAND logic operations in the presence of different combinations of the injury biomarkers allowed high-fidelity biosensing. Robustness of the systems was confirmed by their operation in serum solutions, representing the first example of chemically performed logic analysis of biological fluids and a step closer towards practical biomedical applications of enzyme-logic bioassays.

J. Zhou, J. Halámek, V. Bocharova, J. Wang, E. Katz, Bio-logic analysis of injury biomarker patterns in human serum samples. Talanta 2011, 83, 955-959.

The experiments in human serum solutions were performed by PhD student Jian Zhou.

Accomplishments / Impact / Transitions:

Increased complexity and processing capability of enzyme logic designs.

Introduced and evaluated new concept of multiplexing enzyme logic outputs into ‘injury code’ through the parallel operation of logic gates.

Developed minimally invasive electronic transducers, signal-responsive materials & actuators.

Impact of work – the ability to multiplex detection of six unique injuries using the parallel operation of enzyme logic-based biochemical networks.

Transitioning towards immobilization of enzymes to form dry reagents suitable for field-use biosensors.

Transitioning towards the development of smart & robust materials for targeted delivery of medication tailored to each injury scenario.

The work is performed in Clarkson (Katz) and UCSD (Wang) in the frame of the collaborative project supported by ONR.

Updated on February 20, 2011