Multifunctional phenanthroline-sporopollenin conjugates: A robust biopolymer platform for integrated biomedical therapy

The quest for robust, biocompatible, and multifunctional biopolymers remains a cornerstone of advanced drug delivery research. Sporopollenin, a natural exine microcapsule, stands out for its unparalleled chemical resilience and structural integrity. This study reports the strategic synthesis and comprehensive evaluation of five bio-based sporopollenin microcapsules, with a specific focus on two novel phenanthroline-functionalized derivatives (Sp-AC and Sp-GEC). The structural architecture and physicochemical properties of the synthesized platforms were rigorously elucidated using FT-IR), Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX). Beyond their structural stability, Sp-AC and Sp-GEC exhibited exceptional biological multifunctionality. Both derivatives demonstrated potent bactericidal efficacy characterized by low Minimum Bactericidal Concentration/Minimum Inhibitory Concentration (MBC/MIC) ratios and significant radical scavenging potential (Half-maximal inhibitory concentration, IC₅₀: 77.05 µg/mL and 50.98 µg/mL, respectively). Most notably, these microcapsules displayed a highly desirable selective toxicity profile, exerting robust anti-proliferative effects against colorectal (HT-29) and hepatic (Hep-G2) cancer cell lines while maintaining significantly lower toxicity toward healthy liver cells (THLE-2). These findings position phenanthroline-modified sporopollenin as a superior, multifunctional platform that bridges the gap between material durability and targeted biomedical therapy, offering a promising trajectory for next-generation therapeutic delivery systems.