Feasibility of a point-of-care test based on quantum dots with a mobile phone reader for detection of antibody responses

Abstract

We developed a novel and portable fluorescent sensor that integrates a lateral flow assay with a quantum dot (Qdots) label and a mobile phone reader for detection of specific antibodies in human serum. We evaluated the utility of this assay to test for antibodies to the Taenia solium rT24H antigen. It was a retrospective study by examining 112 positive human sera from patients with neurocysticercosis (NCC) including samples from patients with single viable cyst (n = 18), two or more viable cysts (n = 71), and subarachnoid (racemose) cysts (n = 23). These samples were collected from previous study subjects in Lima, Peru under an approved study protocol in Peru. The sera were made anonymous under a protocol approved by the CDC Institutional Review Board. Definitive diagnosis of the subject was established by computed-tomography and/or magnetic resonance imaging. To test the specificity of the assay, we evaluated a panel of serum samples obtained from patients with other infections (n = 24), and serum samples from persons in the United States and Egypt who had not traveled outside their country, and therefore are presumed negative for cysticercosis (n = 128). The assay specificity in the negative panel was 99% (95–100%) while assay sensitivity was 89% (79–95%) in NCC patients with two or more viable cysts. Our assay has performance characteristics similar to those of traditional platforms for the detection of NCC and shows promise as a mobile phone reader-based point-of-care test for antibody detection.

Author summary

Point-of-care (POC) assays are important tools in control and elimination of parasitic diseases such as lymphatic filariasis, malaria, and leishmaniasis. Most POC assays use immunochromatographic and lateral flow assay principles with gold nanoparticles as a reporter. Assays based on gold nanoparticles usually provide qualitative or semi-quantitative results and have relatively low sensitivity. However, other reporter alternatives are available, including quantum dots (Qdots), up-converting phosphor nanoparticles, and superparamagnetic particles. We developed a Qdots-based test in a lateral flow assay format with a mobile phone reader to detect antibody responses, using neurocysticercosis (NCC) as a disease model, and found that the performance is similar to the traditional platform for detecting antibody responses in subjects with NCC. The incorporation of the mobile phone reader offers the advantage of portability and adaptability for use in areas where laboratories are not immediately accessible. This novel POC assay with mobile phone reader is a feasible option for antibody response s detection.