Enhanced Stability and Photochemical Activity of Photosystem I from the Green Alga Chlamydomonas reinhardtii Upon Encapsulation in Organic Matrixes

Photosynthesis is a fundamental process that convertslight energy into chemical energy, driven by photosystems. Thesechlorophyll-protein complexes enable a light-dependent electrontransport chain, producing ATP and NADPH, which are essential forcarbon fixation. Photosystem I (PSI), well-known for its greaterphotochemical performance and stability, has been utilized in hybridnanodevices as a light converter and photocatalyst. However,membrane proteins, including PSI, often suffer from stability lossand decreased activity following purification due to their removalfrom the thylakoid membrane environment. To address thesechallenges, isolated PSI from Chlamydomonas reinhardtii wasencapsulated into different biodegradable polymers, including polylactic co-glycolic acid (PLGA), poly lactic acid (PLA), and chitosan(Ch), using double emulsion and ionic gelation methods, and stable PSI nanoparticles (100−500 nm) with tailored surface chargeswere produced. These matrices provide a stabilizing shell mimicking the natural environment, enhancing PSI stability and activityunder different conditions of both temperature and pH. Herein, reported results demonstrate that encapsulated PSI maintains higherphotochemical activity over time compared to detergent-stabilized PSI, with chitosan showing the highest efficiency in preservingPSI activity under strong light and extended periods. Remarkably, the encapsulated PSI retained activity up to 7−8 times greaterover 28 days compared to the same complex stabilized in detergents. Finally, encapsulation offers enhanced stability and activity,leveraging the advantages of the microalgae in sustainable biomass production over land plants. This work paves way forenvironmentally friendly and efficient photocatalytic systems integrating photosynthetic components