Photoinduced Disruption of Bisazo Photoswitch-Functionalized Amphiphilic Nanovesicles for High-Efficiency Nanofungicide Delivery.

Photoresponsive nanocarriers are one of the intelligent delivery systems for achieving ordered and controlled drug release. In this study, we developed a fluorescent molecular switch by attaching azo groups to both ends of a nonaethylene glycol (PEG-9) chain. This switch can undergo trans-cis isomerization when exposed to visible light, resulting in observable fluorescence changes. The amphiphilic properties of the switch allow it to self-assemble into nanovesicles, achieving a 60.8% encapsulation efficiency for the fungicide fenopyramid. Visible light illumination of the resulting nanofungicide triggered the trans-cis isomerization of the azo moieties, disrupting the vesicles and releasing the payload. The conformational change of the covalently tethered azo units disrupted the amphiphilic balance of the assemblies, enabling a high drug release efficiency of 92%. The synchronous fluorescence changes of the azo units allowed monitoring of the drug release process via fluorescence imaging. In tests against wheat sharp eyespot, the nanofungicide showed comparable efficacy to the free drug at a 50% reduced dosage, and at a one-third dosage reduction, the effective protection duration was extended by 25%. This azo-functionalized amphiphilic nanocarrier offers a practical approach for developing drug delivery systems that allow for controlled release and monitor.