Upconverting phosphor technology-based lateral flow assay for the rapid and sensitive detection of anti-Trichinella spiralis IgG antibodies in pig serum

A smartphone-based enhanced colorimetric immunoassay for the detection of Trichinella spiralis infection

Trichinellosis is a serious foodborne and zoonotic parasitic disease caused by Trichinella family. At present, the main on-site detection method for Trichinella spiralis (T. spiralis) infection is the lateral flow assay (LFA). Other diagnostic techniques for this parasite cannot be applied to on-site testing due to their reliance on special instruments. Here, we established an ELISA smartphone-based method for detecting anti-T. spiralis antibodies in pig serum. The use of horseradish peroxidase-labeled goat anti-pig IgG-modified gold nanoparticle (AuNPs@HRP-IgG) effectively increased the sensitivity of the method. The entire reaction was carried out at room temperature without the need for special instruments. A low-cost and portable device for imaging and processing experimental data was also developed. Validation analysis revealed that the specificity of the test was 98.89 %, while its sensitivity was 100.00 %. T. spiralis antibodies could be detected in pig serum beginning at 25 dpi after infection with the muscle larvae. This visual immunosensor facilitates on-site detection of T. spiralis, especially in regions lacking specialized laboratory equipment.

Simultaneous detection of circulating tumor DNAs using a SERS-based lateral flow assay biosensor for point-of-care diagnostics of head and neck cancer

Circulating tumor DNA (ctDNA) has recently emerged as an ideal target for biomarker analytes. Thus, the development of rapid and ultrasensitive ctDNA detection methods is essential. In this study, a high-throughput surface-enhanced Raman scattering (SERS)-based lateral flow assay (LFA) strip is proposed. The aim of this method is to achieve accurate quantification of TP53 and PIK3CA E545K, two types of ctDNAs associated with head and neck squamous cell carcinoma (HNSCC), particularly for point-of-care testing (POCT). Raman reporters and hairpin DNAs are used to functionalize the Pd-Au core-shell nanorods (Pd-AuNRs), which serve as the SERS probes. During the detection process, the existence of targets could open the hairpins on the surface of Pd-AuNRs and trigger the first step of catalytic hairpin assembly (CHA) amplification. The next stage of CHA amplification is initiated by the hairpins prefixed on the test lines, generating numerous "hot spots" to enhance the SERS signal significantly. By the combination of high-performing SERS probes and a target-specific signal amplification strategy, TP53 and PIK3CA E545K are directly quantified in the range of 100 aM-1 nM, with the respective limits of detection (LOD) calculated as 33.1 aM and 20.0 aM in the PBS buffer and 37.8 aM and 23.1 aM in human serum, which are significantly lower than for traditional colorimetric LFA methods. The entire detection process is completed within 45 min, and the multichannel design realizes the parallel detection of multiple groups of samples. Moreover, the analytical performance is validated, including reproducibility, uniformity, and specificity. Finally, the SERS-LFA biosensor is employed to analyze the expression levels of TP53 and PIK3CA E545K in the serum of patients with HNSCC. The results are verified as consistent with those of qRT-PCR. Thus, the SERS-LFA biosensor can be considered as a noninvasive liquid biopsy assay for clinical cancer diagnosis.