Silicification‐Induced Cell Aggregation for the Sustainable Production of H₂ under Aerobic Conditions

Abstract

Photobiological hydrogen production is of great importance because of its promise for generating clean renewable energy. In nature, green algae cannot produce hydrogen as a result of the extreme sensitivity of hydrogenase to oxygen. However, we find that silicification-induced green algae aggregates can achieve sustainable photobiological hydrogen production even under natural aerobic conditions. The core-shell structure of the green algae aggregates creates a balance between photosynthetic electron generation and hydrogenase activity, thus allowing the production of hydrogen. This finding provides a viable pathway for the solar-driven splitting of water into hydrogen and oxygen to develop green energy alternatives by using rationally designed cell-material complexes.

Improvement in the Photobiological Hydrogen Production of Aggregated Chlorella by Dimethyl Sulfoxide

“…The aggregates produced approximately 22.3 μmol H 2 within 48 h at a rate of 0.38 μmol H 2 (mg chlorophyll) −1 h −1 if they were cultured with Tris/acetate/phosphate (TAP) medium in 60 mL serum bottles (30 mL head space and 30 mL medium) under 100 μE m −2 s −1 illumination. This phenomenon is consistent with previous results . To improve photobiological H 2 production, DMSO was added into the TAP medium at concentrations of 0.1, 0.5, 1.0, and 2.0 vol %.…”

“…According to the method suggested by Xiong and colleagues, we prepared aggregated Chlorella by using poly(diallyldimethylammonium chloride) (PDADMAC)‐induced silicification . The resulting algae–SiO 2 aggregates had a typical diameter of 100 μm (Figure A, C), and silica nanoparticles, which played a vital role in cellular aggregation, could be found on the cellular surface (Figure B).…”

Therapeutic Potential of Biomineralization‐Based Engineering

“…[52] LBL engineering has been extensively used to increase the biomineralization ability of cells. [72,73] LBL-based engineering is a flexible platform for on-demand mineralization, by which the density and thickness of mineral shells can be controlled by adjusting the molecular weight of the polymer and repeated cycles of deposition. [24] Regarding cell silicification, a positively charged polymer with polyamines can assemble onto the cell surface via the LBL technique or electrostatic absorption, [71] leading to in situ silicification.…”

Microalgal Hydrogen Production

“…In the natural normoxic environments, green algae lose the capacity to produce hydrogen due to the sensitivity of hydrogenase to oxygen. However, the salinized Chlorella pyrenoidosa aggregates induced by polydiallyldimethylammonium chloride (PDADMAC) can achieve sustainable photobiohydrogen production even under natural aerobic conditions . The resulting algae silicified aggregates typically have a diameter of 100 µm, and silica nanoparticles can be found on the cell surface.…”

“…The clustered Chlorella pyrenoidosa system establishes a balance between photosynthesis electron production and hydrogenase activity in the core‐shell structure of green algae aggregates, that is, the dynamic balance between oxygen consumption and oxygen production. Thus, under normal aerobic conditions, the interior of the agglomerates is relatively free of oxygen …”