As discussed earlier, freezing destroys peptide structures
Cabrera, O
Effective concentration 0.251 % w/w (optimal ~0.5% w/w) Clinical evidence Studies indicate that ethosomal encapsulation of retinol using TPGS modification substantially reduces degradation rates at room temperature while maintaining particle size stability
References Balderas-Vazquez CL, et al
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PLoS ONE 10:1371 Acknowledgments This work was supported by the Hungarian National Scientific Research Foundation [grant number OTKA K 105956]