High-performance photothermal GA-MoSe2 nanosheet for rapid and sensitive point-of-care detection of C-reactive protein

In the aftermath of the global COVID-19 pandemic, there is a critical need to develop rapid and sensitive diagnostic devices for point-of-care testing (POCT). Despite the numerous benefits of paper-based colorimetric lateral flow immunoassays (LFAs) in rapid onsite diagnosis, their sensitivity and quantitative analysis capability are limited. To overcome the limitations of the current assays, we developed a new rapid diagnostic method that utilizes glycyrrhizic acid-molybdenum diselenide (GA-MoSe₂), a two-dimensional photothermal nanomaterial, for the sensitive detection of C-reactive protein (CRP). GA-MoSe₂ was synthesized via a facile liquid exfoliation method using glycyrrhizic acid as a natural surfactant in distilled water. The GA-MoSe₂ nanosheet presented a notable photothermal effect, exhibiting an excellent photothermal conversion efficiency of 64.6% and high photothermal stability, and was successfully used as a photothermal sensing probe in an LFA. The GA-MoSe₂-based photothermal LFA demonstrated a high analytical performance in CRP detection in the concentration range of 5 to 1000 ng mL^{- 1}, exhibiting a limit of detection of 0.93 ng mL^{- 1} and up to 7-fold signal enhancement relative to those of traditional gold nanoparticle-based colorimetric LFAs. Moreover, the developed sensor showed high selectivity to CRP even in the presence of interfering substances in serum, excellent reproducibility, and long-term stability over 3 weeks of storage. The GA-MoSe₂-based biosensor successfully detected CRP in human serum samples, showing recoveries ranging from 90 to 105% and demonstrating significant capability and feasibility for point-of-care testing.