Impact of microalgae culture conditions over the capacity of copper nanoparticle biosynthesis Gerardo Salas-Herrera 1 & Susana González-Morales 1 & Adalberto Benavides-Mendoza 1 & Adali O. Castañeda-Facio 2 & Fabián Fernández-Luqueño 3 & Armando Robledo-Olivo 4 Received: 18 March 2018 /Revised and accepted: 25 January 2019 # Springer Nature B.V. 2019 Abstract The biosynthesis of metallic nanoparticles (NPs) has been previously reported using a variety of organic molecules produced by microalgae. However, the results obtained could vary due to the metabolic responses that microalgae have to different culture conditions which could affect the characteristics of the produced nanoparticles. In the present report, copper nanoparticle formation was evaluated by the microalgae Chlorella kessleri, Dunaliella tertiolecta, and Tetraselmis suecica, developed under combined conditions of low (L-) and high (L+) illumination, with low (S-) and high salinity (S+). The illumination was 12 h:12 h light/dark. NP formation was evaluated 72 h after exposure to copper salt. Cupric oxide (CuO) NPs were detected spectrophotometrically in both the culture media (extracellular NPs) and cells (intracellular NPs) of Ch. kessleri with absorbance in the range of 200 to 235 nm. Metallic copper NPs (Cu n ) were detected with an absorbance between 540 and 560 nm in treatments with cells of C. kessleri and D. tertiolecta which were grown in L+S-, while T. suecica cells showed Cu n NPs formations in L-S-, L-S+, and L+S-. The size difference of the NPs was measured by scanning electron microscopy (SEM), in treatments with cells of C. kessleri , ranging in size from 15 to 25 nm (L-S-) and 55 to 65 nm (L+S-). In treatments with culture media, sizes from 35 to 45 nm (L-S-) of NPs were obtained. Differences in the biosynthesis of Cu-based NPs are possible, depending on the culture conditions and the strain of microalgae to be utilized. Keywords Phyconanotechnology . Chlorella kessleri . Dunaliella tertiolecta . Tetraselmis suecica . Salt stress . Cupric oxide Introduction The production of inorganic NPs through biosynthesis by mi- croorganisms such as bacteria, fungi, and microalgae has been explored by several authors for the development of low-cost and eco-friendly technologies (Li et al. 2011). Microalgae have been highlighted as a potential source of diverse biomol- ecules such as proteins, pigments, carbohydrates, alkaloids, terpenes, peptides, and some aromatic compounds, which may be involved in the reduction of metal ions for the forma- tion and stabilization of metal NPs, without producing toxic by-products (Siddiqi and Husen 2016). Copper-based NPs are of great industrial interest since they have similar prop- erties to other NPs which are based on less abundant metals (Shobha et al. 2014). These NPs’ properties allow their ap- plication in several processes, such as in catalysis (Gawande et al. 2016), gas sensors, solar energy transformation, and semiconductors (Singh et al. 2016). In agriculture, copper NPs have been used to control several pathogens such as fungi and some bacteria (Singh Sekhon 2014), as well as being used as a crop production enhancer (Hafeez et al. 2015). However, Shobha et al. (2014) report that only 5% of the research papers in the area of nanoparticle biosynthe- sis correspond to copper-oxide (CuO) NPs, with the major focus being on the production of silver NPs, accounting for 59% of the publications. * Armando Robledo-Olivo armando.robledo@uaaan.edu.mx; armando.robledo@outlook.com 1 Horticulture Department, Universidad Autónoma Agraria Antonio Narro, Unidad Saltillo, Blvd Antonio Narro 1923, Buenavista, 25315 Saltillo, Coahuila, Mexico 2 Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, Unidad Saltillo, Blvd. Venustiano Carranza e Ing, José Cárdenas s/n, 25280 Saltillo, Coahuila, Mexico 3 Sustainability of Natural Resources and Energy, Avenida Industrial Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, 25900 Ramos Arizpe, Coahuila, Mexico 4 Food Science & Technology Department, Universidad Autónoma Agraria Antonio Narro, Unidad Saltillo, Blvd Antonio Narro 1923, Buenavista, 25315 Saltillo, Coahuila, Mexico Journal of Applied Phycology https://doi.org/10.1007/s10811-019-1747-8