Noncovalent Coassembly Strategy for Electron Redistribution-Driven Hemoglobin Stabilization

Conventional covalent modification of hemoglobin (Hb) for oxygen delivery platforms often compromises its native functionality and faces a stability-degradability conflict. Here, using a 9-fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF)-derived low-molecular-weight gelator, we propose a noncovalent strategy to achieve ultrafast Hb integration with structural and functional preservation through a solvent-triggered gelation method. The results show that Hb loading completes within 1 min, which achieves great improvement over chemical strategies, representing a technical breakthrough that overcomes the efficiency limit of traditional covalent methods. Experimental analyses combined with density functional theory (DFT) simulations demonstrate that carboxyl groups of Hb form H-bonds with both amide and carboxyl moieties of Fmoc-FF, while π-π stacking occurs between the heme porphyrin ring and aromatic Fmoc groups. DFT calculations and wave function analyses suggest an electron redistribution-driven stabilization mechanism mediated by noncovalent interactions, providing theoretical innovation for Hb stabilization. Through electron redistribution, Hb can passivate reactive terminal regions and preserve the porphyrin core to enhance structural stability and protect the O₂ binding function. Through systematic validation, the Fmoc-FF/Hb complex demonstrates stability in terms of nondestructive encapsulation, rheological robustness, and hydrolytic stability in physiological environments. Furthermore, Hb in the complex state shows significant application potential in terms of biocompatibility, diffusion-erosion-based degradability in a simulated blood environment, and shear-thinning injectability. Therefore, with the triad of minute-level engineering, electron redistribution mechanism, and bioinspired design, this work establishes a promising strategy for Hb stabilization, providing novel insights into viable Hb loading for novel oxygen delivery platform development.