Hybrid MoSe2/P3HT Transistor for Real-Time Ammonia Sensing in Biofluids.

Organic and inorganic hybrid field-effect transistors (FETs), utilizing layered molybdenum diselenide (MoSe2) and an organic semiconductor poly(3-hexylthiophene) (P3HT), are presented for biosensing applications. A new hybrid device structure that combines organic (P3HT) and inorganic (MoSe2) components is showcased for accurate and selective bioanalyte detection in human bodily fluids to overcome 2D-transition metal dichalcogenides (TMDs) nonspecific interactions. This hybrid structure utilizes organic and inorganic semiconductors' high surface-to-volume ratio, carrier transport, and conductivity for biosensing. Ammonia concentrations in saliva and plasma are closely linked to physiological and pathological conditions of the human body. A highly sensitive hybrid FET biosensor detects total ammonia (NH4+ and NH3) from 0.5 µM to 1 mM concentrations, with a detection limit of 0.65 µM in human bodily fluids. The sensor's ammonia specificity in artificial saliva against interfering species is showcased. Furthermore, the fabricated hybrid FET device exhibits a stable and repeatable response to ammonia in both saliva and plasma, achieving a remarkable response level of 2300 at a 1 mM concentration of ammonia, surpassing existing literature by 10-fold. This hybrid FET biosensing platform holds significant promise for developing a precise tool for the real-time monitoring of ammonia concentrations in human biological fluids, offering potential applications in point-of-care diagnostics.

Guided mode resonance immunosensor for label-free detection of pathogenic bacteria Pseudomonas aeruginosa.

Photonic biosensors are promising platforms for the rapid detection of pathogens with the potential to replace conventional diagnostics based on microbiological culturing methods. Intricately designed sensing elements with robust architectures can offer highly sensitive detection at minimal development cost enabling rapid adoption in low-resource settings. In this work, an optical detection scheme is developed by structuring guided mode resonance (GMR) on a highly stable, transparent silicon nitride (SiN) substrate and further biofunctionalized to identify a specific bacteria Pseudomonas aeruginosa. The resonance condition of the GMR chip is optimized to have relatively high bulk sensitivity with a good quality factor. The biofunctionalization aims at oriented immobilization of specific antibodies to allow maximum bacteria attachment and improved specificity. The sensitivity of the assays is evaluated for clinically relevant concentrations ranging from 102 to 108 CFU/mL. From the calibration curves, the sensitivity of the chip is extracted as 0.134nm/Log10 [concentration], and the detection modality possesses a favorably good limit of detection (LOD) 89 CFU/mL. The use of antibodies as a biorecognition element complemented with a good figure of merit of GMR sensing element allows selective bacteria identification compared to other non-specific pathogenic bacteria that are relevant for testing physiological samples. Our developed GMR biosensor is low-cost, easy to handle, and readily transformable into a portable handheld detection modality for remote usage.