Paper test cards discriminate between viral and bacterial infections
Testing at the point-of-care (PoC) offers great healthcare benefits to patients and professionals globally with rapid turnaround times and accurate results. These tests often rely on lateral flow immunoassays, where biomarkers are detected on a nitrocellulose membrane. Although the areas covered by paper-based diagnostics are increasing, and the tests are also inexpensive and environmentally friendly, the provided information is usually qualitative.
Electrochemical detection on a paper-based test card
The EU-funded IMPETUS project aims to revolutionise PoC testing through the production of paper-based electrochemical biosensors that provide a quantitative readout. “Our system uses disposable test cards that combine the simplicity of lateral flow tests but offers a quantitative detection of biomarkers in sample liquids,” explains project coordinator Rainer Hainberger. The consortium replaced nitrocellulose, which is commonly found in commercial lateral flow devices, as it’s very brittle and cannot be efficiently processed. Instead, they used a special paper developed in the project, which allows high throughput fabrication as well as the possibility to mount a silicon microchip that facilitates the acquisition of electrochemical signals. This enables the quantitative measurement of biomarkers. IMPETUS established screen, flexo and inkjet printing processes as well as a novel method of chip mounting for roll-to-roll production of the test card on a pilot line facility. A printed paper-based battery using the appropriate anode and cathode materials was also developed. The consortium implemented and tested various prototypes of the printed biosensing card. The measurement readout data is wirelessly transferred through a standardised smartphone interface. This is a significant advancement to other lateral flow devices that employ an optical readout using, for example, mobile phone cameras, an approach that is phone-specific and susceptible to ambient light conditions. Moreover, the IMPETUS paper-based test card uses only sustainable and no plastic materials, making it environmentally friendly. It is also cost-effective as the cards are fabricated using roll-to-roll printing and assembly processes.
Discriminating between bacterial and viral infections
As an application example, IMPETUS will fulfil the consumer need for fast and inexpensive PoC detection of bacterial and viral infections. The consortium developed compatible immunoassays allowing for the quantitative detection of two molecular biomarkers in blood. This use case deviates from the conventional application of lateral flow devices for testing single parameters in a non-quantitative way, for example, for pregnancy tests or Covid-19 antigen tests. Instead, it gives the practitioner the power to distinguish between bacterial and viral infections based on the quantitative detection of the two biomarkers, which often have similar symptoms but require different care. “IMPETUS brings the laboratory into the physician’s office,” emphasises Hainberger. This requires only a few drops of blood to the test card and will avoid the false prescription of antibiotics in cases with viral infection. Moreover, it overcomes the need for expensive analysis equipment and can be used by healthcare professionals in medical practices. It is also suitable for regions where medical care and diagnostics are not sufficiently available. The IMPETUS detection method can be tailored to quantitatively measure other molecular biomarkers for different applications, such as cardiovascular diseases. At the same time, the pilot line is based on a versatile manufacturing concept that is easy to be adapted for various production processes and sensing applications. It can be employed to manufacture sensors and actuators implemented in applications beyond medical diagnostics, for example, for food safety and environmental monitoring.
Keywords
IMPETUS, functional printing, electrochemical detection, paper, biomarker, bacterial infection, viral infection, diagnostics, test cards, point-of-care, POC, lateral flow immunoassay, point-of-care testing
