Ultrasensitive Love-SAW Biosensor Based on Self-Assembled DMSN@AuNPs with In Situ Amplification for Detecting Biomarker Procalcitonin in Exhaled Breath Condensate

The COVID-19 pandemic has highlighted the importance of early screening and pathogen identification for the effective treatment of pneumonia. Exhaled breath condensate (EBC) provides a noninvasive and easily accessible method for early diagnosis of respiratory diseases, as it captures biomarkers from the airway lining fluid, offering a timely and reliable reflection of respiratory inflammation. Procalcitonin (PCT) is a biomarker widely used to assess infection type and severity, particularly for distinguishing between bacterial and nonbacterial pneumonia. However, detecting PCT especially in EBC is challenging due to its extremely low concentrations. In this work, we developed an ultrasensitive Love-type surface acoustic wave (Love-SAW) biosensor based on self-assembled gold nanoparticles on dendritic mesoporous silica nanoparticles (DMSN@AuNPs) with in situ amplification for PCT detection in EBC. Dendritic mesoporous silica nanoparticles (DMSNs), an emerging porous material with features of large surface area, high thermal stability, and ease of functionalization were employed to load a large amount of AuNPs that can spontaneously grow in situ to further enhance the sensing performance. An automatic detection system was also developed to integrate with the Love-SAW biosensor for multichannel detection of PCT in EBC for pneumonia screening. The DMSN@AuNPs based Love-SAW biosensor demonstrates remarkable performance with a detection range of 0.01-10 ng/mL and detection limit of 3.7 pg/mL, which is about 350 times higher than conventional AuNPs-based methods. These results validate the potential of DMSN@AuNPs based Love-SAW biosensors for ultrasensitive detection of low-concentration biomarkers, providing a promising platform for in vitro diagnostics.