Entrapment and growth of Chlamydomonas reinhardtii in biocompatible silica hydrogels

• Published in: Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2019-01, Vol.173, p.233-241
• Main Authors: Homburg, Sarah Vanessa, Venkanna, Deepak, Kraushaar, Konstantin, Kruse, Olaf, Kroke, Edwin, Patel, Anant V.
• Format: Article
• Language: English
• Subjects: Alginates - chemistry; Biocompatible Materials - chemistry; Biocompatible Materials - pharmacology; Buffers; Cells, Immobilized - cytology; Cells, Immobilized - drug effects; Chitosan - chemistry; Chlamydomonas reinhardtii - cytology; Chlamydomonas reinhardtii - drug effects; Chlamydomonas reinhardtii - growth & development; Elastic Modulus; Hydrogels - chemistry; Hydrogels - pharmacology; Mechanical stability; Microalgae; Phosphates - chemistry; Photosynthesis - drug effects; Photosynthetic activity; Potassium Compounds - chemistry; Silica hydrogels; Silicon Dioxide - chemistry; Transparency; Tromethamine - chemistry
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2018.09.075

[Display omitted] •Replacement of KOH by Tris buffer to adjust the pH of the sol resulted in a short gelation and in transparent hydrogels.•Increased precursor concentrations reduced gelation times, i.e. reduced time until nutrients can be supplied.•Investigated hydrogels exhibit a 10 times lower stiffness than those in previous reports.•Addition of chitosan to the sol improved abrasion resistance. At the same time, a low absorption was maintained.•Entrapped microalga C. reinhardtii remained photosynthetically active and grew in this artificial environment. In this work, we aimed at improved viability and growth of the microalga Chlamydomonas reinhardtii in transparent silica hydrogels based on low-ethanol, low-sodium and low-propylamine synthesis. Investigation into replacement of conventional base KOH by buffers dipotassium phosphate and tris(hydroxymethyl)aminomethane along with increased precursor concentrations yielded an aqueous synthesis route which provided a gelation within 10 min, absorptions below 0.1 and elastic moduli of 0.04–4.23 kPa. The abrasion resistance enhanced by 41% compared to calcium alginate hydrogels and increased to 70–85% residual material on addition of chitosan. Entrapment of microalgae in low-sodium and low-propylamine silica hydrogels maintained the PSII quantum yield above 0.3 and growth rates of 0.23 ± 0.01 d−1, similarly to cells entrapped in calcium alginate. These promising results pave the way for the entrapment of sensitive, photosynthetically active and growing cells for in robust biotechnological applications.