Amyloid-Inspired Synergistic Short Peptide Scaffold against Mitochondrial Dyshomeostasis in Traumatic Brain Injury

Traumatic Brain Injury (TBI) initiates Ca²⁺ dysregulation, which intensifies mitochondrial oxidative stress, thereby promoting the advancement of secondary neurotoxicity. Studies suggest that, unlike previous understanding of global intracellular Ca²⁺ overload, localized Ca²⁺ microdomains in connection with mitochondrial dysfunction cause the primary toxicity in TBI. This highlights the need for strategies that modulate Ca²⁺ signaling with spatial precision. In this study, we report a supramolecular binary peptide system, comprising coassembled RDI and NDI sequences, designed to disrupt pathological Ca²⁺-reactive oxygen species (ROS) coupling. This coassembled scaffold (1:1 molar stoichiometric ratio) integrates arginine-mediated electrostatic localization with low-affinity, aspartate-based Ca²⁺ coordination, enabling transient interaction with Ca²⁺ microdomains near mitochondrial interfaces. In in vitro conditions of TBI-mimetic injury, the peptide mix selectively reduces mitochondrial Ca²⁺ uptake, leading to a marked suppression of mitochondrial ROS generation. This modulation of Ca²⁺ microdomains stabilizes mitochondrial membrane potential, limits oxidative damage, and improves neuronal viability under excitotoxic stress. MitoSOX assessment showed that the peptide mix evidently suppresses mitochondrial superoxide generation under TBI-mimetic excitotoxic conditions. Peptide treatment stabilizes mitochondrial membrane potential and maintains homeostatic mitochondrial networks, preventing injury-induced fragmentation. In a rodent model of brain injury, administration of the peptide mix reduces peri-lesional cortex and promotes tissue recovery that could directly be associated with improved neuronal survival. Importantly, the peptides function through transient modulation of Ca²⁺ microdomains rather than Ca²⁺ chelation or direct antioxidant activity. These findings establish a new design paradigm for peptide materials targeting Ca²⁺ driven mitochondrial pathology and suggest a promising strategy for mitigating secondary injury mechanisms in neurotrauma.