Surface microchannel-based unidirectional-flow assay for periodontitis screening via amplification-free and sensitive detection of Porphyromonas gingivalis rRNA.

Periodontitis, a highly prevalent chronic inflammatory disease, necessitates efficient screening methods. Detection of Porphyromonas gingivalis (P. gingivalis), a key periodontal pathogen, in saliva offers a promising non-invasive approach through the traditional methods such as bacterial culture and qRT-PCR for screening periodontitis. However, these traditional methods for detecting P. gingivalis are impractical for on-site and large-scale screening. To address these issues, this study developed a unidirectional-flow assay based on the surface microchannel (SMC) membrane. First, by targeting high-abundance rRNA, this assay eliminates the need for nucleic acid amplification. Second, by replacing commercial nitrocellulose membrane with SMC membrane, this assay effectively prevents the interception of probe/target nucleic acid complex during lateral flowing. This design significantly enhances the capture efficiency at the test line and the detection sensitivity. The experiment results demonstrated that this test strip achieved a limit of detection as low as 1.0 × 103 CFU/mL for P. gingivalis within 6 min and exhibited good specificity. Besides, the clinical experiments suggested that the results obtained by this assay were highly consistent with those from qRT-PCR and clinician diagnosis, further verifying its feasibility and potential for the rapid screening of periodontitis. This assay eliminates the need for nucleic acid amplification while maintaining high sensitivity, offering rapid and user-friendly operation for on-site and large-scale screening of periodontitis.