Among different materials investigated as drug carriers (liposomes, micelles, polymeric nanoparticles and metal oxides) interesting are silica particles. The properties of silica particles (chemical and mechanical stability, hydrophilicity, biocompatybility) give an opportunity to use this material as a new universal drug delivery system [1]. Silica has an interesting capability due to possibility for tailoring their surface reactivity and realising desirable electrical surface potential (zeta potential) that can be obtained by the surface modification. The separated silica particles possess a negative charge what is demanded. Negatively charged particles are repelled by the negatively charged cell membrane so these particles should be slowly detected and rejected. This effect helps the particles avoid elimination from the body. SiO₂ degrades in the body by hydrolysis of siloxane bonds into Si(OH)₄, which is eliminated through the kidneys [2].

As a model drugs we used substances such as methylene blue, diclofenac sodium and famotidine. Drugs were loaded onto silica spherical particles (diameter size 150 nm) by soaking and filtration, and after centrifugation solution was analyzed by a spectrophotometer. In order to analyze adsorption data in aqueous media, Langmiur and Freundlich models were used.

We have found that the chemical structure of the drugs influence the drug-loading amount. Simple structure of diclofenac sodium causes low level of the adsorption (0.42%). The best adsorption results we have obtain for the methylene blue (36%) which have more difficult structure and better possibility to connect with silica.

References:

[1] H. Jaganathan, B. Godin “Biocompatibility assessment of Si-based nano- and micro-particles” Adv. Drug Deliv. Rev. 2012, doi:10.1016/j.addr.2012.05.008

[2] Kortesuo P, Ahola M, Karlsson S, Kangasniemi I, Yli-Urpo A, Kiesvaara J: Silica xerogels as an implantable carrier for controlled drug delivery - evaluation of drug distribution and tissue effects after implantation. Biomaterials 2000, 21, 193-198.

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