Entrapment and growth of Chlamydomonas reinhardtii in biocompatible silica hydrogels.

•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.