Fibrin-Binding Peptide-Functionalized H₂O₂-Responsive Retinoic Acid Micelles for Attenuating Thrombosis-Associated...

Background/Objectives: Thrombotic cardiovascular diseases remain a major cause of morbidity and mortality worldwide. Current antithrombotic therapies are limited by insufficient thrombus targeting. This study aimed to develop a fibrin-binding peptide-functionalized, hydrogen peroxide (H₂O₂)-responsive polymeric micelle and to evaluate its physicochemical properties and biological effects under H₂O₂-induced endothelial oxidative stress and preliminary FeCl₃-induced thrombosis conditions. Methods: A fibrin-binding peptide, P2 (VTFIKC), was screened using computer-aided drug design and evaluated through microscale thermophoresis and in vitro thrombus adhesion assays. An all-trans retinoic acid (atRA)-based boronate ester prodrug, BORA, was synthesized to enable H₂O₂-triggered degradation and drug release. BORA was co-assembled with P2-modified Mal-PEG-b-PAsp to prepare P2-Mal-PEG-b-PAsp/BORA micelles. Their physicochemical properties, H₂O₂ responsiveness, H₂O₂-scavenging activity, cytocompatibility, cytoprotective effects, anti-inflammatory activity, and preliminary in vivo efficacy were evaluated. Results: The resulting micelles exhibited a suitable nanoscale size, acceptable cytocompatibility, H₂O₂-responsive changes in particle size distribution, and concentration-dependent H₂O₂-scavenging activity. In H₂O₂-stimulated human umbilical vein endothelial cells, micelle treatment was associated with improved cell viability, lower intracellular ROS-associated fluorescence, and reduced TNF-α and IL-1β concentrations. In a FeCl₃-induced rat carotid artery thrombosis model, P2-Mal-PEG-b-PAsp/BORA micelles altered platelet- and leukocyte-related hematological indices and exhibited preferential accumulation in the thrombotic carotid artery. Conclusions: P2-Mal-PEG-b-PAsp/BORA micelles combine P2-mediated fibrin-binding potential, H₂O₂-responsive release behavior, and H₂O₂-scavenging activity. The findings provide preliminary support for further investigation of this peptide-functionalized nanoplatform.