Nanovesicle-Based Delivery of Magnesium Chlorophyllin for Photodynamic Inactivation in Agriculture

Photodynamic inactivation offers a broad-spectrum anti-pathogen strategy for agriculture but requires effective delivery of the photodynamic activators to enable efficacy. Herein, we demonstrate that nanovesicles based on sodium dodecylbenzenesulfonate (SDBS) and cetyltrimethylammonium bromide (CTAB), prepared with modifiers to either enhance or reduce the stability of the bilayer membrane, can encapsulate and improve the functionality of magnesium chlorophyllin (Mg-chl). SDBS/CTAB nanovesicles with sizes as small as ∼90 nm can be fabricated with encapsulation efficiencies of >60% for Mg-chl. The incorporation of unsaturated modifiers into nanovesicle membranes enables triggered Mg-chl release upon re-wetting, whereas the introduction of hydrophobic moieties substantially slows Mg-chl release via a more diffusion-governed mechanism. Nanovesicles enabled substantially higher light-activated killing of the plant pathogen P. syringae in simulated field conditions, with rapid binding and/or bacterial uptake observed within five mins of nanovesicle exposure. In addition, nanovesicles facilitated improved Mg-chl penetration into plant roots. This combination of enhanced anti-bacterial activity and tunable photosensitizer uptake offers promise to deliver photosensitizing agents or other functional hydrophilic bioactives for improved crop protection.