The impact of liposomes and related systems characteristics on the skin penetration process

Liposomi so sferični vezikli, velikosti od 20 nm do 4 µm. Njihova ovojnica je sestavljena iz enega ali več lipidnih dvoslojev, v sredici pa je vodni medij. Vezikli imajo zaradi precejšnje podobnosti med membrano liposoma in celično membrano velik potencial kot dostavni sistemi za dostavo spojin oz. kozmetično aktivnih sestavin v (globlje) plasti kože. V diplomski nalogi smo naredili pregled literature o obstoječih raziskavah, v katerih so raziskovalci proučevali vpliv različnih lastnosti liposomov in liposomom sorodnih sistemov na učinkovitost njihove penetracije v kožo. Dodatno smo izvedli tudi krajši pregled trga kozmetičnih izdelkov na osnovi liposomov in liposomom sorodnih sistemov. S sistematičnim pregledom dveh različnih podatkovnih baz smo našli 34 člankov, ki so proučevali učinkovitost penetracije liposomov, transferosomov in etosomov. Ugotovili smo, da na globino penetracije liposomov in liposomom sorodnih sistemov vplivajo pogoji nanosa (tj. ali je koža pod okluzijo ali ne), sestava veziklov (tj. vsebnost različnih pomožnih snovi) in njihove lastnosti (velikost, naboj, število slojev v membrani) oz. vrsta nosilnega sistema (liposomi vs. transferosomi vs. etosomi). V skoraj vseh raziskavah so prišli do sklepa, da klasični liposomi ne penetrirajo v globlje plasti kože, ampak ostanejo na njeni površini oziroma v zgornjih plasteh rožene plasti povrhnjice. Pri testiranjih in vivo so ugotovili, da lahko transferosomi penetrirajo v globje plasti kože (15-40 µm globoko), kadar so uporabljeni pod neokluzivnimi pogoji. Boljšo penetracijo v kožo v primerjavi s klasičnimi liposomi pripisujejo fleksibilnosti njihove membrane in manjši velikosti vezikla, za dostavo aktivnih spojin pa je pomembna tudi večja učinkovitost inkapsulacije. Penetracijo vezikularnih nosilcev so uspeli izboljšati tudi z dodatkom površinsko aktivnih snovi ali etanola v srednjem koncentracijskem območju. Odkar je Bangham leta 1963 odkril liposome, so se ti v prvi vrsti začeli uveljavljati predvsem v medicini (zdravila, cepiva itd.). Kasneje so prednosti liposomov in liposomom sorodnih sistemov začeli uporabljati tudi v kozmetologiji, kjer so leta 1986 razvili prvo liposomsko kremo proti staranju Capture, znamke Christian Dior. S pregledom trga smo identificirali 90 kozmetičnih izdelkov z vsebnostjo liposomov in liposomom sorodnih sistemov. Analizirali smo jih glede na vrsto nosilnega sistema, tehnološko obliko kozmetičnega izdelka, državo izvora, prodajno mesto in cenovni razpon. Ugotovili smo, da so na trgu v največji meri dostopni kozmetični izdelki, ki vsebujejo klasične liposome, najmanj pa so zastopani etosomi. Zastopanost različnih veziklov v kozmetičnih izdelkih na trgu je v skladu s številom študij, ki so proučevale liposome, transferosome in etosome, in sicer smo zasledili največ objav na temo klasičnih liposomov, najmanj pa s področja etosomov.Liposomes are spherical vesicles ranging in size from 20 nm to 4 µm. Their membrane is composed of one or more lipid bilayers with a hydrophilic core. Because of the similarities between their membrane composition and the cell membrane, they have great potential for delivering substances or cosmetic active ingredients into the deeper layers of skin. The aim of this bachelor’s thesis is to conduct a literature review of already published articles, in which researchers reported on the effectiveness of the penetration of liposomes and their related systems, depending on their characteristics, as well as to further review the market in cosmetic products containing liposomes and their related systems. The literature review of two different databases yielded 34 articles that comply with the purpose of this study. Thus, this thesis reviews the influence of different parameters on the penetration efficiency of liposomes, transferosomes, and ethosomes. It was revealed that liposomes and their related systems penetrate differently depending on the different conditions under which they were used (occlusive or non-occlusive), composition (the use of additives) and characteristics (size, charge, number of layers), or the type of delivery system (liposomes vs. Transferosomes vs. ethosomes). Almost every research reported that liposomes do not penetrate the skin deeply, instead they remain in the upper layers of the stratum corneum. In in vivo testing, transferosomes can penetrate the deeper layers of skin (15–40 µm deep) when used under non-occlusive conditions. In comparison to liposomes, transferosomes penetrate the skin better due to their membrane elasticity, smaller vesicle size, and higher encapsulation efficiency. In almost all studies, the penetration of vesicles improved when they were used together with surfactants or ethanol, in certain concentrations. Ever since Bangham discovered liposomes in 1963, they have begun to gain ground primarily in medicine (medications, vaccines, etc.). Later, the benefits of liposomes and their related systems began to be used in cosmetology, where in 1986 the first liposomal anti-aging cream was developed, Capture by Christian Dior. When reviewing the market, 90 cosmetic products containing liposomes and their related systems were considered and then analysed by vesicle type, technological form, country origin, market availability, and price range. It was found that liposomal cosmetic products are the most widely available ones on the market, while ethosomal cosmetic products are the least available ones. The results of the review of the market correlate to the number of studies found in the literature review, where it was established that most studies concern liposomes, while those concerning ethosomes are minimal