Thermally responsive membrane-based microbiological sensing component for early detection of membrane biofouling

Early detection of bacteria in water treatment is desired to mitigate system biofouling and potential human health impacts. This research involved the development of an antibody-based sensor, which was attached to a hydroxypropyl cellulose (HPC) modified cellulose acetate ultrafiltration membrane surface, to target bacteria. HPC was chosen because it collapses above and expands below a lower critical solution temperature (43 °C), thus allowing temperature modulation. The membrane had a high target recovery efficiency (10–18%) in both single bacterium and complex samples (simulated by adding organics and competitive organisms). Sensor recovery was decreased (to 5–7%) following temperature activation (above 50 °C) due to adverse impacts of temperature on the antibody. The membrane was able to be regenerated (with 0.1 M NaOH) and reused three consecutive times. The thermally responsive sensing membrane developed from this work was specifically developed to detect biofoulants in membrane-based water treatment processes. However, it could be adapted to address a range of environmental detection concerns, such as pathogen detection.

Research Highlights
► The membrane-based microbiological sensor provided rapid results (20 min) and demonstrated a recovery efficiency (up to 20%) of targeted bacteria, which is comparable to similar findings.
► The membrane was thermally responsive, demonstrating surface roughness changes above and below the activation temperature, and could still detect targeted bacteria. However, target detection was significantly reduced at temperatures above the polymer film LCST (43 °C).
► In order to determine if temperature activation results in increased sensor recovery in complex samples, future studies must include either alternative bio-recognition molecules (aptamers) that are unaffected by thermal changes above 43 °C or polymer films that have lower LCSTs, preferably below 40 °C, to preserve antibody function.
► The membrane-based sensor was able to be regenerated by using the elution reagent 0.1 M NaOH up to 3 times, which can greatly reduce the cost of the sensor.