|Prof. Abraham Badu-Tawiah
||Ohio State University
Kumasi South Hospital and Agona Government Hospital
The proposed research will use rationally designed and synthesized ionic probes (Aim 1) to facilitate ultrasensi-tive mass spectrometric detection of malaria biomarkers captured on paper-based microfluidic analytical plat-form (Aim 2). The 3D paper device supports both immunoassays (i.e., antibody reactions) and on-chip MS de-tection. In Aim 3, we will establish the correlation between biomarker (HRP-2 and Aldolase) concentration and parasite density using blood spiked with parasitized erythrocytes and clinical blood samples via analysis on ex-isting bench-top ion trap mass spectrometer, capable of MS/MS.
To evaluate our on-demand diagnostic approach (in terms of stability, specificity and sensitivity), clinical sam-ples will be collected directly on the paper device in both low-risk (peri-urban community) and high-risk (remote field) settings in Ghana. In this surveillance on-demand testing, de-identified samples collected from both peri-urban and rural settings will comprise of sick hospitalized (symptomatic) population and community-based (asymptomatic) population. To address biological variability due to sex, we will use known malaria prevalence for male and female to determine sample size. The three Aims are integrated, but differ in many respects includ-ing the specific experimental design. Thus, this section is divided into rationale, experimental design and prelimi-nary data, expected results, and potential pitfalls.
Malaria surveillance and Diagnostics
We expect to achieve the following milestones at the end of Aim 1: (1) to reach an optimized probe de-sign/structure that is stable after immunoassay enabling easy storage and transport for centralized test analy-sis; (2) to have established an amplification strategy that (i) has minimal effect on antibody binding capacity and (ii) provides PCR-level sensitivity through MS; and (3) to have developed probe stimulation chemistry that is fast or can be terminated (after initiation) to allow effective control of the MS signal amplification process. With-out signal amplification, our current detection limit (2.8 ng/mL) is comparable to that of ELISA (1 ng/mL) for HRP 2 antigen.24 Therefore, we believe the proposed amplification strategy will afford sensitivities close to that of PRC using only finger prick blood (~20 μL). We expect to develop a self-sustained paper device that requires no special storage conditions. The devices are expected to be reliable for at least 30 days after the time of use. Patients are expected to perform only two tasks when using the device: (1) application of sample and (2) the addition of a wash buffer to remove unbound species.
Malaria management through an on-demand diagnostic approach using novel ionic probes