Biofilm formed from a tri-ureasil organic−inorganic hybrid gel for use as a cubebin release system

In this work, we report the effects of catalyst amount on a tri-ureasil hybrid gel prepared by the sol−gel route, with the aim of controlling the film-forming time. Investigation of the key properties of biofilms produced from the hybrid gels revealed that varying the amount of acid catalyst could tune the film-forming time, without changing the structural features of the thin and transparent films. Independent of catalyst amount, springthe films presented low toxicity towards cells, indicating their suitability for use as new transdermal drug delivery systems. Due to the hydrophobic nature of the polyoxypropylene (PPO polyether chains) present in the hybrid films, very low water uptake was observed. This characteristic could be advantageous, since materials that show high swelling behavior can cause inflammatory responses in cells. The hybrid film with incorporation of a bioactive agent (cubebin, isolated from Piper cubeba seeds) was evaluated as a drug delivery system. Release of the drug from the matrix displayed a two-step pattern, kinetically controlled by (i) slow diffusion of cubebin molecules, and (ii) fast diffusive mass transport created by the solute−solvent interaction. The release of cubebin from the tri-ureasil hybrid film could be employed for radical scavenging and for the treatment of diseases such as cancer, leishmaniasis, and trypanosomiasis.