Novel tools for point-of-care therapeutic drug monitoring

Among all antipsychotic medications, clozapine is not only the most effective but also has a well-established relationship between its blood concentration and its therapeutic effect. However, clozapine can cause serious side effects (such as seizures or neutropenia) when its blood concentration is high. Although there is a commercially available gold nanoparticle-based immunoassay to monitor clozapine concentration in patients’ blood, it suffers from the issues of poor limitation-of-detection, unstable readings and high assay cost.

Here the team is developing new biosensing tools that are more sensitive, reliable and affordable than the colorimetric assay currently in the market. To extend the project's impact, the investigators will work with local K-12 students in several outreach programs, with the goal to train the students to develop novel tools based on the new understanding of aptamers and encourage them into a career path in science, technology, engineering and mathematics.

Through the support of this project, the team of investigators will select aptamers that bind clozapine with high affinity and specificity and use them to establish highly reliable aptamer-based sensing tools for clozapine dose titration and routine clozapine’s blood concentration monitoring. Aptamers are DNA or RNA molecules that can bind specific targets strongly, including small-molecule therapeutics.

Aptamers will be selected and optimized through the innovative SELEX-NGS platform, which effectively identifies sequences that bind rapidly and strongly with specific small-molecule targets, while the affinities against other structurally similar compound are low. Taking advantage of the selected clozapine aptamers, a personal glucose meter can be repurposed to detect clozapine concentration in blood.

In addition, a differential sensor array that discriminates clozapine from its structurally similar compounds can be developed. Moreover, a nanopipette sensing platform for digital quantification of clozapine molecules will also be created. Taking advantage of novel DNA carrier designs, clozapine molecules can be counted one by one as they translocate through a nanopipette device.

The acquired nanopipette readings can also be used to further improve the aptamer sensor designs. The proposed research involves both tool development and fundamental understanding of small molecule-aptamer interactions.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.