AIE Luminogens for Deep-Tissue Biological Imaging

The patent applies the inversion principle by designing luminogens that exhibit the opposite behavior of conventional dyes: instead of being bright in solution and dark in aggregate, these AIEgens are non-emissive or weakly emissive in solution but become highly emissive when aggregated. This is achieved by introducing twisting units (such as tetraphenylethene groups) that restrict intramolecular motion in the aggregate state, converting non-radiative decay pathways into radiative emission.

The patent employs parameter changes by modifying the molecular structure to include specific twisting units and donor-acceptor combinations that alter the photophysical properties. By changing the molecular conformation and electronic structure, the luminogens achieve aggregation-induced emission enhancement while maintaining solubility and biocompatibility in various physiological environments.

The patent applies composite material principles by combining twisting units (for AIE properties) with extended π-conjugated systems (for red-shifted emission) in a single molecular architecture. The molecule contains both the rigid twisting core that restricts motion and promotes AIE, and the extended conjugated wings that absorb and emit at longer wavelengths, achieving both AIE enhancement and red-shifted emission simultaneously.

The patent uses segmentation by dividing the molecular structure into distinct functional segments: a twisting core unit that provides AIE activity and extended π-conjugated units that determine emission wavelength. This modular design allows independent optimization of AIE properties and emission characteristics, resolving the contradiction between maintaining π-conjugation for red-shift and introducing twisting for AIE.

The patent applies this principle by replacing expensive, toxic, and complex inorganic nanomaterials with simple, biocompatible organic molecules that can be easily synthesized and metabolized. These organic AIEgens serve as temporary imaging agents that fulfill their function and are then naturally eliminated, avoiding the long-term toxicity concerns associated with inorganic nanomaterials.

The patent uses parameter changes by transitioning from inorganic to organic material composition, fundamentally altering the chemical properties to achieve biocompatibility while maintaining optical performance. The organic molecules exhibit appropriate solubility, metabolic stability, and low toxicity profiles that are inherently difficult to achieve with inorganic nanomaterials.

The patent applies inversion by designing fluorogens that reverse the conventional aggregation behavior: instead of suffering from aggregation-caused quenching, these AIE-based nanoparticles exhibit aggregation-caused emission enhancement. The restricted intramolecular motion in the nanoparticle aggregate state converts what would normally be non-radiative decay into radiative emission, providing bright fluorescence for deep-tissue imaging.

The patent uses composite material principles by combining AIEgen molecules with nanoparticle carriers or amphiphilic structures. This creates a composite system where the AIEgen core provides bright emission upon aggregation, while the outer shell or surface modification ensures solubility, stability, and biocompatibility in physiological environments, enabling both deep-tissue penetration and high signal-to-noise ratio.