Multiplexed Ultrafast Photothermal Digital Polymerase Chain Reaction Based on Oligo(Phenylene-Ethynylene)

Periodontal disease results from an imbalance between bacterial complexes and the immune system. However, periodontal disease diagnosis is limited by its time-consuming nature, long processing time, and high costs. In this study, we suggest an ultrafast, highly sensitive, and multitargeted plasmonic photothermal-based digital polymerase chain reaction (dPCR) method using a novel plasmonic photothermal-based dPCR chip combined with photothermal materials and organic interfacial chemicals for periodontal disease diagnosis. This platform can detect biofilm-forming bacteria (Streptococcus mutans), red complex bacteria (Porphyromonas gingivalis), and orange complex bacteria (Campylobacter rectus and Prevotella nigrescens). The ultrafast plasmonic photothermal-based dPCR technique amplified multiple target genes over 45 cycles within 14 min, and a fluorescence scanning system measured the fluorescence intensity within 9 min. The sensitivity of detection of standard bacteria and artificial saliva containing bacteria showed a sensitivity of 10¹ copies/μL. Furthermore, multiplex PCR was performed with a plasmonic photothermal-based dPCR device to confirm the possibility of multiplex PCR of bacterial mixtures containing four species. This plasmonic photothermal-based dPCR platform can be utilized as a point-of-care molecular diagnostic device for the ultrafast diagnosis of diseases in real-time in various fields.