Sol–gel coating-derived liquid marbles as highly efficient micro-photobioreactors for cyanobacterial cultivation

Monolayer nanoparticle-covered liquid marbles (mNPc LMs), fabricated using a sol–gel SiO₂ coating as the particle source, were developed as micro-photobioreactors (PBRs) for high-efficiency cyanobacterial cultivation at the laboratory scale. Compared to solid PBRs and powder-coated LMs, the mNPc LM system combines the dual advantages of a higher specific surface area (compared to the former) and greater optical transparency (compared to the latter), leading to significantly improved cyanobacterial growth efficiency. Notably, the mNPc LM exhibits high transparency comparable to a bare droplet while offering superior manipulation controllability. This is evidenced by its consistent coalescence under vertical impact (avoiding the rebound typical of bare droplets) and the switchable coalescence behavior achieved through interfacial jamming in horizontal contact experiments. Acoustic field vibration technology was demonstrated to effectively prevent cell sedimentation, thereby further enhancing cyanobacterial growth efficiency within the mNPc LM. This work presents a promising mNPc LM-based technical platform for highly efficient cyanobacterial cultivation, with significant potential for applications in algal biotechnology.