Aptamer duo-based portable electrochemical biosensors for early diagnosis of periodontal disease.

Recently, point-of-care tests (POCT) have gained much attention due to their convenient, fast, simple, and easy characteristics. For POCT, portability is an essential feature. In this study, we have successfully fabricated a portable mini-potentiostat. Using chronoamperometry, electrical signals of this portable mini-potentiostat were measured, and the analytical performance of electrochemical aptasensors was compared with a benchtop potentiostat. The electrochemical signals measured by mini-potentiostat can be displayed on the screen of a smartphone. To verify the analytical performance of this portable electrochemical aptasensor platform with a mini-potentiostat, two well-known model protein biomarkers, vaspin, a type 2 diabetes biomarker, and thrombin, a biomarker for pulmonary metastasis and cardiovascular disease, were confirmed to be detected by using corresponding aptamer duo. After solid verification of this portable electrochemical aptasensor platform, we have successfully implemented this portable mini-potentiostat system to develop a portable sandwich-type binding pair of aptamers-based electrochemical biosensor, which can diagnose periodontal disease by measuring ODAM biomarker. The linear range of this ODAM biosensor was 0 to 15 nM with a detection limit of 0.02 nM and 1 nM in buffer and saliva, respectively. The sensitivity of this biosensor has been greatly enhanced, compared to previously developed surface plasmon resonance (SPR) or lateral flow assay (LFA) based aptasensors. This study showed that this new portable aptamer duo-based biosensor is expected to diagnose the early stage of periodontal diseases from real samples, such as saliva or gingival crevicular fluid in a short time as a point-of-care (POC) testing.

A new lateral flow strip assay (LFSA) using a pair of aptamers for the detection of Vaspin.

A new lateral flow strip assay (LFSA) using a pair of aptamers has been designed and successfully developed using a pair of aptamers-functionalized with gold nanoparticles (AuNPs). This new LFSA biosensor system utilizes a cognate aptamer duo binding to vaspin, a target protein, at the two different binding sites, and exhibited a sensitive and highly selective response to vaspin. A sandwich-type format in LFSA was developed based on biotin-labeled primary V1 aptamer immobilized on streptavidin coated membrane as a capturing probe and secondary V49 aptamer conjugated with AuNPs as a signaling probe. Using this LFSA, vaspin could be visibly observed within the detectable concentrations of vaspin up to 5nM in both buffer and serum conditions. The sensitivity of this LFSA developed in this study was ranged from 0.137 to 25nM in buffer and from 0.105 to 25nM in spiked human serum, respectively. The limit of detection (LOD) of this LFSA was found to be 0.137nM and 0.105nM in buffer and spiked human serum condition, respectively. Therefore, this study has shown successful development of a simple yet effective LFSA for vaspin detection, and this development is not only limited to this target, but also other targets with a pair of aptamers available, without any special and laborious instrumentations. This system will be particularly useful as a screening tool for rapid on-site detection of any targets with a pair of aptamers generated.