Nanomaterials for enhanced photoprotection in photosynthetic microorganisms

Photosynthetic microorganisms, such as microalgae, are key contributors to global carbon fixation and hold great potential for applications in sustainable production of commodities and biotechnology. However, their efficiency is often limited by environmental stressors, particularly high light intensity, which induces photoinhibition, oxidative stress, and a consequent decline in overall performance. Advances in nanotechnology offer promising strategies to mitigate these effects and enhance organismal resilience [1]. This work investigates the use of carbon-based nanomaterials, specifically single-walled carbon nanotubes (CNTs) and nanodiamonds (NDs), as tools to improve photoprotection and maintain photosynthetic stability under stress, focusing on the green microalga Chlamydomonas reinhardtii [2,3]. The results indicate that the potential phytotoxic effects of nanomaterials can be minimized by optimizing their physicochemical properties and dispersion. Low concentrations of well-dispersed, purified, and small-sized CNTs or hydroxylated NDs did not negatively affect growth or pigment accumulation. Under photoinhibitory conditions, samples treated with CNTs showed reduced Photosystem II (PSII) inactivation, lower excitation pressure, higher rates of electron transport, and enhanced non-photochemical quenching compared to untreated controls [2]. In parallel, NDs exhibited effective ROS-scavenging properties and contributed to maintaining redox homeostasis under photooxidative conditions [3]. The precise mechanisms of interaction between carbon nanotubes and photosynthetic structures remain to be fully elucidated. Studies on the energy flow within these biohybrid systems have yielded conflicting results. To explore this further, we examined the electro-optical interactions of CNTs with isolated photosynthetic components of varying complexity. Our results suggest a possible leakage of photosynthetic electrons toward the nanotubes, most likely occurring at the PSII acceptor site, thereby facilitating non-radiative energy dissipation [4]. Overall, integrating nanomaterials with photosynthetic systems presents a promising strategy to enhance light use efficiency, safeguard against photoinhibition, and enhance the biotechnological potential of microalgae. The outcomes of this research highlight the potential of algal nanobiotechnology in developing advanced biohybrid systems aimed at the sustainable generation of bio-based products and environmental resilience.