ABSTRACT Confocal fluorescence microscopy is fundamentally constrained by the trade‐off between signal quality and phototoxicity, as achieving high resolution typically necessitates intense excitation or high fluorophore concentrations. This work introduces a hierarchical plasmonic energy‐funneling architecture to overcome this limitation. The strategy is implemented via a partially‐etched curved gold grating (PECG) substrate, functioning as a macroscopic coupler to focus surface plasmon polaritons (SPPs). These SPPs subsequently drive superimposed nanocones acting as plasmonic nano‐antennas to excite localized surface plasmons (LSPs), facilitating cascade field confinement via synergistic SPP‐LSP coupling. This two‐stage mechanism produces an 821‐fold fluorescence enhancement, yielding a signal‐to‐noise ratio (SNR) improvement of 42 dB at ultra‐low 1 n m dye concentrations. Such high SNR preserves a stable photon budget during live‐cell imaging, enabling continuous observation of fine cytoskeletal dynamics for over 60 min under a significantly reduced laser intensity of 0.2 mW. Furthermore, by applying sparse deconvolution and AI‐based denoising to this high‐fidelity data, a lateral resolution of 120 nm is achieved. This work establishes a rational design strategy for plasmonics, demonstrating an effective solution to the core challenge of low SNR in fluorescence microscopy and paving the way for non‐destructive interrogation of sensitive cellular processes.
Zhou et al. (Mon,) studied this question.