Background

The rapid spread of drug resistance in infectious diseases and oncology has developed into a significant threat to the global public health. Cellular resistance mechanisms in both bacteria and cancer cells include cell membrane protein modifications, intracellular drug target alterations, and the over expression of efflux pumps. The overexpression of efflux pump proteins enable cells to expel drugs rapidly from the cell interior, before these compounds can take effective action.

In recent years, the innovation of electrochemical sensors has attracted immense attention, due to their high sensitivity, rapid analysis and ability to analyze complex samples, such as urine and blood. Although no sensor for the point‐of‐care detection of antibiotic resistance has been proposed so far, electrochemical sensors have become a powerful tool in various fields, such as environmental monitoring, biotechnology, and industrial process control. Electrochemical sensors are fast, sensitive, cost effective, and allow for direct in vitro analysis of analytes in biological samples with limited preparation required.

Technology Overview

The technology consists of an electroanalytical method and sensors for the electro‐analytical measurement of membrane permeability (influx and/or efflux) of a cell to antibiotics and anti‐cancer drugs. This quantitative in vitro electrochemical method could be used to rapidly and reliably predict drug susceptibility/drug resistance in target cells. Our method for detecting drug susceptibility is based on 2 electrochemical techniques, voltammetry and impact chemistry. Both techniques provide information about the ability of cells (i.e. bacteria and cancer cells) to take up and retain therapeutic compounds.

Example: A large number of bacterial infections have become resistant to antibiotics due to the presence of drug efflux pumps on the bacterial cell membranes. These efflux pumps expel antibiotics rapidly from the cell interior, before cell viability is compromised.

Using linear sweep voltammetry, it is possible with our method to distinguish between drug susceptible (Figure 1A, blue line) and drug resistance (Figure 1A, red line). Bacteria are captured by a specific antibody at the electrode, exposed to an antibiotic of choice and drug retention in the bacterial cells can be detected within minutes. A higher electrochemical current signal is related to drug efflux from the bacteria, which increases the concentration of analyte at the electrode surface. Under this design, the signal will be compared to that obtained from a drug susceptible bacteria strain.

Similarly, pharmaceutical efflux can be detected from cancer cells. Furthermore, our recent peer-reviewed manuscript on drug uptake in cancer demonstrates the ability of electrochemistry to quantify pharmaceutical uptake in ovarian cancer. In this approach, cells are exposed to a pharmaceutical solution. Within 20 minutes drug susceptible bacteria remove the analyte from solution, resulting in a reduced electrochemical signal. Drug resistant cancer cells often exhibit cell membrane mechanisms to inhibit pharmaceutical uptake in cells. In this case, the measured electrochemical current signal will remain unaltered.

Alternatively, impact chemistry may also be used for our electroanalytical detection method. Under this design, free floating bacteria can be directly detected in a urine or blood sample via collisions with a metal wire that functions as electrode. When an antibiotic is added to a biological sample, bacteria that are drug resistant will result in current spikes greater than those seen in drug susceptible bacteria. This method offers the monitoring of drug susceptibility within seconds.

Both of these methods can provide critical information as to drug resistance in cells, with the technique chosen dependent on the type of cells examined (bacterial vs cancer cells) and their clinical presentation (i.e. within tissues vs body fluids). However, both detection techniques can be incorporated into a portable potentiostatic device, employing disposable screen printed electrodes which can be applied to biological samples.

**Publication:**Kuss, Sabine & Luu, Huy & Nachtigal, Mark. (2020). Electrochemical characterization of carboplatin at unmodified platinum electrodes and its application to drug consumption studies in ovarian cancer cells. Journal of Electroanalytical Chemistry. 872. 114253.

Benefits

A point-of-care biosensor to identify drug susceptibility in patient samples will reduce health care costs and accelerate the treatment of bacterial infections as well as cancer. Based on a urine or blood sample, doctors will be able to assess which antibiotic or chemotherapeutic will be most effective before being prescribed the drug to a patient. With the push of a button, an LED light will indicate which therapeutic compounds bacteria and cancer cells are most susceptible to. Such technology would advance clinical treatment from the current trial-and-error approach to the prescription of evidence-based personalized drug regimens.

Applications

Human and Veterinary Medicine: This method can be used to detect antibiotic and anti‐cancer drug resistance in patients. It could also be used as a platform for the design and development of novel pharmaceutical drug candidates that overcome drug resistance in bacteria and cancer.

Opportunity

Current proof‑of‑concept studies have been done. UM is seeking a partner to assist in further development and validation of the technology for various classes of antibiotics and chemotherapeutics.

Detection of Drug Resistance

Patents

IP Status

Seeking