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Developing rapid diagnostics for antibiotics with Optimer reagents

Antibiotic resistance is increasing globally and represents one of the biggest public health challenges of our time. In the US alone, there are more than 2.8 million cases of antibiotic-resistant infections each year, leading to over 35,000 deaths. But researchers are working to tackle this problem, and Optimers are offering one potential solution.

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Need for new point-of-care tests

Our partners, QSM Diagnostics, are developing a rapid biosensor platform that will enable fast, cost-effective, point-of-care testing to improve patient treatment and preserve antibiotics as viable treatments for future generations.

Busy clinicians often don’t have the time or facilities to tailor antibiotic doses to each patient. Consequently, all patients receive one selected dose: for some patients this will be the required dose, for some patients this will be too high, resulting in side effects, and for some patients it will be too low, pushing them outside the treatment window. Maintaining the dose of antibiotics within the treatment window offers the best use of this treatment, allowing treatment without side effects and minimizing the overuse of antibiotics.

Antibiotic-selective Aptamers

Small molecule targets, such as antibiotics, have proven challenging with the use of traditional affinity reagents. At Aptamer Group, our specialized platform for the development of small molecule specific Optimer reagents enables the discovery of high affinity, high selectivity reagents for this target class.

We developed Optimers for the fluoroquinolone, moxifloxacin. Selectivity analysis of the parent aptamer and Optimers showed that they detect the moxifloxacin target in a concentration-dependent manner but show no interaction with homologous levofloxacin or ciprofloxacin. This high level of target selectivity enables the specific detection and quantification of the antibiotic to ensure the signal achieved in the resulting diagnostic assay is indicative of the target moxifloxacin.

Aptamer or Optimer? Optimizing the biosensor

The performance of both the longer parent aptamer and Optimer reagents was analyzed on the biosensor. Both aptamer-based and Optimer-based biosensors showed concentration-dependent responses to the moxifloxacin target in buffer over the full concentration range 0-500 µM. Considering the manufacturing benefits of the Optimer over the aptamer, the company progressed the Optimer molecule for further analysis.

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Antibiotic detection in human serum

To assess the Optimer-based biosensor in a clinically relevant sample matrix, QSM Diagnostic worked with antibiotic spiked into 50% human serum and pure human serum samples. Within the 50% serum matrix samples, the detection signal was maintained for the Optimer biosensors for concentrations above 100 μM, while this limit of detection increased to 250 μM in pure serum.

This data demonstrates the ability of Optimers to act as biorecognition elements for the development of novel diagnostic assays.

Continuing our partnership

Following this initial proof-of-concept work for the Optimer-based biosensors, we will continue to work in partnership with QSM Diagnostics as the platform parameters are optimized. Optimization of the Optimer reagents’ surface concentration on the electrode, the addition of blocking reagents to minimize serum interference, and different sample incubation times are all planned at QSM Diagnostics to ensure the best performance from the rapid diagnostic assay.

This diagnostic platform can be applied to a diverse range of targets by simply switching the Optimer biorecognition element on the biosensor surface. We are happy to work with QSM Diagnostics to support the development of novel rapid diagnostic tests for alternative targets of interest on this platform.

To find out more download the application note.

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