An Interferometric Point-Of-Care Device for Fast and Sensitive Bacteria Quantification

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ICN2 researchers published in ACS Sensors an affordable method for bacteria detection useful for hospital on-site testing and as a clinical point-of-care (PoC) device. Real patient samples were analysed in a hospital setting using a simple one-step process with sample-to-data turnaround time of 40 min. The work was developed within the H2020 European project RAIS.

Conditions such as sepsis, where the survival chances might decrease by 7–8% for every hour that the infection remains untreated, require fast and accurate diagnosis. Outpatients or post-operative patients suspected of bacterial infections also need rapid diagnosis and categorization. Unfortunately, available diagnostic technologies offer slow turnaround times and low sensitivity making an optimal personalized therapy difficult to design. There is a clinical demand for a rapid, sensitive, direct, and affordable method for bacteria detection useful for hospital on-site testing and as a clinical point-of-care (PoC) device.

The Nanobiosensors and Bioanalytical Applications Group, led by Prof. Laura M. Lechuga from the ICN2 (a center of BIST and CSIC) and CIBER-BBN, has recently published a work in ACS Sensors tackling this need in collaboration with ICFO, EPFL (Switzerland) and Hospital Universitari Vall d’Hebrón. Within the framework of the H2020 European project RAIS the researchers have developed an integrated portable and stand-alone instrument based on optical interferometry which, when employed with specialized nanoplasmonics, can directly detect bacterial cells from patient blood plasma.

The researchers evaluated the clinical utility of the biosensor platform using patient blood plasma samples from the Sepsis Bank located at Hospital Universitari Vall d’Hebron. Real patient samples were analysed in the hospitals setting using a simple one-step process with sample-to-data turnaround time of 40 min. The combination of customized microarrays bioprinted onto high performance gold nanohole substrates, combined with an in-house built sophisticated and portable Lens-free Interferometric Microscopy (LIM) device, proved to be a fast and sensitive E. coli quantification method requiring minimal blood plasma volume.

A high sensitivity of 1 bacterial cell has been achieved both in buffer and diluted plasma conditions. The assay involved a direct label-free quantification of E. Coli without sample preprocessing and/or use of secondary antibodies or labels, providing quantification in a simple one-step process. The test could thus be carried out by nonexpert personnel at the bedside of patients and have a strong impact in guiding quick medical decisions across various clinical scenarios. The approach presented in this work paves the way for modern implementable Point of Care diagnostics in the clinical settings for pathogen detection.