Cosmeceuticals are cosmetic-hybrids intended to enhance health and beauty of the skin. Topical delivery of antioxidants from natural bioresources has gained attention in line with the increasing demand for harmless cosmetics. Tetraselmis tetrathele is a microalgae species, which has high antioxidant contents. In this work, ternary phase analysis with different compositions of oil, surfactant, and water was conducted to evaluate homogeneity and stability of nanoemulsion lotion containing 1% T. tetrathele extract. The three formulations T1, T2, and T3 containing various percentages of the surfactant Tween 80, T1 (20 wt% of Tween 80), T2 (15 wt% of Tween 80), and T3 (10 wt% of Tween 80), were analyzed for size and zeta potential to evaluate stability of the nanoemulsion. All particles were nanosized ranging from 102.3 to 249.5 nm. Zeta potential analysis for all emulsions showed negative values from − 33.2 to − 71.7 mV, which indicates high stability of the nanoemulsion. In order to evaluate the storage stability, a stability test was conducted at different temperature levels (4, 25, and 45 °C) for 10 weeks. At all temperature conditions, T1, T2, and T3 were stable with exception of T3 that precipitated and sedimented after 8 weeks. This study illustrated that T. tetrathele extract can be used as bioactive compound for nanocosmeceutical products, which has high homogeneity and stability.

Microalgae can use either ammonium or nitrate for its growth and vitality. However, at a certain level of concentration, ammonium nitrogen exhibits toxicity which consequently can inhibit microalgae productivity. Therefore, this study is aimed to investigate the tolerance of Tetraselmis tetrathele to high ammonium nitrogen concentrations and its effects on growth rate, photosynthetic efficiency (Fv/Fm), pigment contents (chlorophyll a, lutein, neoxanthin, and β-carotene), and fatty acids production. Experiments were performed at different ammonium nitrogen concentrations (0.31–0.87 gL−1) for 6 days under a light source with an intensity of 300 μmol photons m−2 s−1 and nitrate-nitrogen source as the experimental control. The findings indicated no apparent enhancement of photosynthetic efficiency (Fv/Fm) at high levels of ammonium nitrogen (NH4+-N) for T. tetrathele within 24 h. However, after 24 h, the photosynthetic efficiency of T. tetrathele increased significantly (p < 0.05) in high concentration of NH4+-N. Chlorophyll a content in T. tetrathele grown in all of the different NH4+-N levels increased significantly compared to nitrate-nitrogen (NO3-N) treatment (p < 0.05); which supported that this microalgal could grow even in high level of NH4+-N concentrations. The findings also indicated that T. tetrathele is highly resistant to high ammonium nitrogen which suggests T. tetrathele to be used in the aquaculture industry for bioremediation purpose to remove ammonium nitrogen, thus reducing the production cost while improving the water quality.

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