A Novel Rapid Test to Detect Anti-SARS-CoV-2 N Protein IgG Based on Shear Horizontal Surface Acoustic Wave (SH-SAW).

Since the Coronavirus disease 2019 (COVID-19) pandemic outbreak, many methods have been used to detect antigens or antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including viral culture, nucleic acid test, and immunoassay. The shear-horizontal surface acoustic wave (SH-SAW) biosensor is a novel pathogen detection platform with the advantages of high sensitivity and short detection time. The objective of this study is to develop a SH-SAW biosensor to detect the anti-SARS-CoV-2 nucleocapsid antibody. The rabbit sera collected from rabbits on different days after SARS-CoV-2 N protein injection were evaluated by SH-SAW biosensor and enzyme-linked immunosorbent assay (ELISA). The results showed that the SH-SAW biosensor achieved a high correlation coefficient (R = 0.9997) with different concentrations (34.375-1100 ng/mL) of the "spike-in" anti-N protein antibodies. Compared to ELISA, the SH-SAW biosensor has better sensitivity and can detect anti-N protein IgG signals earlier than ELISA on day 6 (p < 0.05). Overall, in this study, we demonstrated that the SH-SAW biosensor is a promising platform for rapid in vitro diagnostic (IVD) testing, especially for antigen or antibody testing.

A Prototype Antibody-based Biosensor for Measurement of Salivary MMP-8 in Periodontitis using Surface Acoustic Wave Technology.

Periodontitis is an economically important disease which is highly prevalent worldwide. Current diagnostic approaches are time-consuming and require interpretation of multiple aspects of clinical and radiographic assessment. Chair-side monitoring of inflammatory mediators of periodontitis could provide immediate information about disease activity, which can inform patient management. We aimed to develop a novel prototype biosensor to measure salivary matrix metalloproteinase-8 (MMP-8) using specific antibodies and surface acoustic wave (SAW) technology. The analytical performance of the prototype biosensor was compared to standard enzyme-linked immunosorbent assay (ELISA) using unstimulated saliva samples obtained from patients with periodontitis before and after non-surgical treatment (N = 58), patients with gingivitis (N = 54) and periodontally healthy volunteers (N = 65). Receiver operator characteristic (ROC) analysis for distinguishing periodontitis from health revealed an almost identical performance between the sensor and ELISA assays (area under curve values (AUC): ELISA 0.93; SAW 0.89). Furthermore, both analytical approaches yielded readouts which distinguished between heath, gingivitis and periodontitis, correlated identically with clinical measures of periodontal disease and recorded similar post-treatment decreases in salivary MMP-8 in periodontitis. The assay time for our prototype device is 20 minutes. The prototype SAW biosensor is a novel and rapid method of monitoring periodontitis which delivers similar analytical performance to conventional laboratory assays.

Rayleigh SAW-Assisted SH-SAW Immunosensor on X-Cut 148-Y LiTaO3.

In this paper, we describe a shear horizontal surface acoustic wave (SH-SAW) immunosensor that utilizes induce agitation by a Rayleigh SAW (R-SAW) on an X-cut 148-Y LiTaO3 substrate. On this substrate, SH-SAWs and R-SAWs with different frequencies can be effectively generated at an interdigital transducer (IDT). First, to consider the power flow angles of SH-SAWs and R-SAWs on this substrate, the 360-MHz delay lines with six different tilt angles were designed and fabricated. From the experiments, an optimal power flow angle of 9° for the SH-SAW on this substrate is obtained. Second, in order to consider the immunoreactions of the SH-SAW immunosensors, a delay line with a tilt angle of 9° was designed and fabricated on this substrate. The delay line, which can generate two SAWs, namely, a 100-MHz SH-SAW and an 88.8-MHz R-SAW, has a propagation area covered with antigens of human serum albumin between transmitting and receiving IDTs. The immunoreactions caused by antigen-antibody binding events on the surface of the delay line were investigated on the basis of the velocity changes of the SH-SAWs for sensing with and without the assistance of an R-SAW. As a result, it was confirmed that the SH-SAW velocity changes due to antigen-antibody reactions can be markedly increased by the assistance of R-SAW agitation.