Chirality of poly(γ-glutamic acid) directs calcium nanoparticle assembly and adjuvant-like immune activation.

Abstract

Chirality, describing the asymmetry between an object and its mirror image, plays a crucial role in biological recognition and functional material design. Translating this concept to nanoscale systems, chiral polymers can influence nanoparticle self-assembly and cellular interactions. Here, we synthesized three calcium carbonate nanoparticles using poly (γ-glutamic acid) (PGA) with defined l-, d-, and LD-chiral configurations (L-CaNPs, d-CaNPs, and LD-CaNPs). The resulting nanoparticles exhibited comparable surface properties but distinct morphologies and optical activities, with chirality-dependent differences in their interactions with dendritic cells (DCs). Among them, l-CaNPs most effectively promoted DC activation, as evidenced by elevated expression of costimulatory markers (CD80, CD86, and MHC-II) and enhanced calcium signaling, without inducing cytotoxicity. Furthermore, when loaded with the SARS-CoV-2 S1 protein, l-CaNPs significantly enhanced antigen-specific antibody production in mice, demonstrating adjuvant-like immunostimulatory activity without detectable cytotoxicity. These findings demonstrate that PGA chirality dictates nanoparticle morphology and immune modulation, and that l-configured CaNPs provide a promising platform for the development of safe and effective vaccine adjuvants. STATEMENT OF SIGNIFICANCE: Chirality plays a crucial role in biological recognition and functional material design. Translating this concept to nanoscale systems, chiral polymers can influence nanoparticle self-assembly and cellular interactions. In this study, we report a chirality-engineered calcium nanoparticle platform assembled from poly (γ-glutamic acid) with defined L/D-/LD-configurations. By systematically comparing their physicochemical and biological behaviors, we demonstrate that polymer chirality governs nanoparticle assembly, resulting in distinct morphologies that differentially regulate intracellular calcium distribution and APC activation. Among them, l-CaNPs most effectively promoted DC activation, as evidenced by elevated expression of costimulatory markersand enhanced calcium signaling. when loaded with the SARS-CoV-2 S1 protein, l-CaNPs significantly enhanced antigen-specific antibody production. This work focuses on structure-bioactivity relationships and immune modulation driven by material chirality.