Efficient colorimetric point-of-care detection and imaging of multiple biomolecules utilizing photonic liquid crystal composite on gold nanoisland thin films for label-free sensing

Accurate and timely identification of infections is crucial for effective treatment and controlling disease spread. While single biomarkers have traditionally served diagnostic purposes, their sensitivity and specificity limitations call for a more comprehensive approach. Simultaneous detection of multiple biomolecules shows promise in improving accuracy, expediting analysis, and enhancing pathology screening. Therefore, there is a pressing need to develop a noninvasive biosensor capable of quantifying various infection-associated biomarkers concurrently, such as albumin proteins and bacterial molecules. In this endeavor, a novel biosensor has been developed, leveraging a color-indicating optical platform that utilizes gold nanoisland films (AuNIFs) enveloped by cholesteric liquid crystals (CLCs). The integration of CLCs and AuNIFs capitalizes on their sensitive interfacial interactions, highlighting the potential for robust biosensing. Changes in biomolecule concentrations induce discernible alterations in the CLCs–AuNIFs interface alignment, profoundly impacting the hybrid plasmonic–photonic behavior of AuNIFs. The resulting CLCs–AuNIFs biosensor demonstrates exceptional sensitivity and precision in detecting E. coli concentrations and albumin levels. Notably, the biosensor achieves a label-free limit of detection, with an impressive sensitivity of 1 × 106 CFU/ml for E. coli and 10 ng/ml for bovine serum albumin (BSA). This innovative biosensor offers rapid detection, visual clarity, label-free operation, and the ability to detect multiple concentrations of both microbial agents and albumin. Changes in biomolecule concentrations induce noticeable shifts in interface alignment, thereby modulating the hybrid plasmonic–photonic dynamics of AuNIFs. The potential applications of this advancement span biomedical, microbial, and industrial sectors. This unified biosensor has the potential to revolutionize infection-related diagnostics and containment measures, serving as an ideal point-of-care solution. This ground-breaking development leads the way in multi-biomarker detection in infection diagnosis, with profound implications for future of infection diagnostics and therapeutic interventions.