Synthetic Biocatalysis in Erythrocyte Microreactors for Gasotransmitter H₂S Production and Vessel Vasodilation

Designing therapeutic microreactors that emulate natural cells to execute vital metabolic processes and interact with biological systems is a significant challenge in synthetic biology and bioengineering. In this study, erythrocyte microreactors capable of prolonged hydrogen sulfide (H₂S) production for therapeutic vasodilation are developed. The microreactors are fabricated by encapsulating a pyridoxal 5'-phosphate-polylysine (PLP-PLys) complex into erythrocytes using a hypotonic swelling method. The optimized process achieved a loading efficiency of 61.5%, ensuring the uniform distribution of PLP-PLys within the erythrocytes while maintaining structural integrity and cellular viability. Synthetic biocatalysis within these microreactors is initiated through a cascade reaction mediated by PLP-PLys complex and hemoglobin (Hb) upon exposure to L-cysteine (L-Cys). This system demonstrated efficient H₂S production with sustained kinetics, achieving peak concentrations of 6.2 µm after 180 min. The therapeutic potential of the microreactors is validated in vitro using isolated thoracic aortic rings. Upon L-Cys exposure, the microreactors generated localized H₂S, inducing significant vasodilation, with a 39.17% reduction in vascular tension. Fluorescence imaging further confirmed H₂S production within blood vessels, highlighting the specificity and efficacy of the erythrocyte microreactors. This innovative platform offers a controlled, sustained strategy for gasotransmitter delivery, presenting promising applications in cardiovascular therapy and beyond.