Plasmonic Mediated Atomically Thin Aluminum Quasicrystal for Dopamine Sensing

Dopamine levels are linked to neurological illnesses like Parkinson's and Alzheimer's. Thus, reliable and sensitive detection of dopamine is crucial for early diagnosis and surveillance of neurodegenerative diseases. Non-noble-metal-based nanomaterials are ideal for light-mediated sensing of organic molecules. Among these, two-dimensional (2D) quasicrystal (QC) structures consisting of five elements (Al₇₀Co₁₀Fe₅Ni₁₀Cu₅ (2D Al QC)) provide active sites due to their high surface-to-volume ratio, making them excellent for organic chemical sensing. Here, we propose a simple, label-free, spatial self-phase-modulation (SSPM)-based sensing method in liquid form. SSPM-based time evolution of the diffraction pattern for varied mixing levels of a 1100 ppb dopamine solution shows a shift in the SPR-activated 2D Al QC nanostructure solution. The 1100 ppb solution shows a different dN/dI value, indicating a change in sensitivity to the nonlinear refractive index and time constant. SSPM is used to demonstrate dopamine-sensing methods and to perform qualitative and quantitative evaluations. The SSPM-based sensing has been further compared with other optical sensing methods, such as Raman Spectroscopy, UV-vis Spectroscopy, and FTIR Spectroscopy. The experimental observations are also explained using DFTB-based simulations.The current SSPM method can be used for rapid, large-scale medical diagnostics.