Titanium Dioxide Nanoparticle-Driven Metabolic and Molecular Reprogramming in Cyanobacteria.

Cyanobacteria are promising platforms for bioenergy, carbon sequestration, and bioproduct synthesis, but their photosynthetic efficiency is limited by suboptimal light utilization, electron transport constraints, and environmental stress. Titanium dioxide nanoparticles (n-TiO2) have emerged as powerful photocatalytic materials that can enhance light absorption, modulate electron transport, and influence the redox balance in biological systems. This review advances the concept of photocatalytic-biological coupling, in which n-TiO2 functions as artificial light amplifiers that augment cyanobacterial photosynthesis. Current evidence on the physicochemical properties of n-TiO2, their interactions with cyanobacterial cells, and their effects on photosystems, electron transport chains, and downstream metabolic processes is examined. Particular emphasis is placed on the integration of photophysical and biological mechanisms, including reactive oxygen species (ROS)-mediated signaling, proton motive force (PMF) enhancement, and adenosine triphosphate (ATP) synthesis. Emerging approaches, including nano-bio interface engineering, environmental biotechnology applications, and artificial intelligence-guided optimization, are highlighted. By bridging photophysics, cellular bioenergetics, and computational design within a unified mechanistic framework, this review establishes the scientific foundation needed to translate photocatalytic-biological coupling into scalable and biotechnologically deployable nano-enabled photosynthetic systems.