Nanocomposites and nanomaterials

Effects of nanostructured calcium silicate hydrate (C-S-H) seeds on model microorganisms 
Sikora P.1,2, Augustyniak A.1,3, John E.1, Stephan D.1
1 Building Materials and Construction Chemistry, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
E-mail: pawel.sikora@zut.edu.pl
3 Faculty of Civil Engineering and Architecture, West Pomeranian University of Technology, Szczecin. Al. Piastow 50, 70-311 Szczecin, Poland
2 Department of Immunology, Microbiology and Physiological Chemistry, Faculty of Biotechnology and Animal Husbandry, West Pomeranian University of Technology, Szczecin. Al. Piastow 45, 70-311 Szczecin, Poland
The sustainability of building materials can be measured in different directions. Safety is by far one of the most important factors taken into account in the modern construction industry. For the aspect of environmental safety, new building materials and their components should be studied in terms of their influence on living organisms. Recently, nanostructured calcium silicate hydrate (C-S-H) seeds were introduced as a promising accelerator for cement hydration.
In our study, C-S-H seeds were used and tested on reference strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans. Materials were used in a manner corresponding to standard procedures in the preparation of cementitious composites. Morphology and viability of cells were tested with microscopy, spectrophotometry, and culture methods.
In most cases, C-S-H seeds inhibited the growth of model microorganisms. Nevertheless, this effect depends on the type and concentration of the used material. Furthermore, C-S-H seeds had an effect on the population development which resulted in shifts observed in the kinetic curves. The interaction of C-S-H seeds with bacterial biofilms led to variable results, depending on whether Gram positive or Gram negative bacteria were used. Overall, the highest resistance to C-S-H seeds was expressed by P. aeruginosa. C-S-H seeds caused several effects on model microorganisms depending on the genera, used concentration and the type of applied material. Microorganisms can resist or even be stimulated to grow with certain types of C-S-H seeds. On the other hand, the detected toxicity shows that C-S-H seeds may limit the growth of opportunistic pathogens. 
Acknowledgement: This research was supported by the National Science Centre within the project No. 2016/21/N/ST8/00095 (PRELUDIUM 11).