Application of guanidine-containing polymers for preparation of pH responsive silica-based particles for drug delivery systems

• Hybrid materials based on silica particles and guanidine containing polymers were synthesized via sol–gel method.
• Polymer grafting influences pH-response and surface properties of final products substantially.
• Anionic (sulfasalazine) and cationic (doxorubicin) drugs were effectively loaded into polymer coated silicas.
• The drug loading and drug release were pH dependent and affected by the nature of grafted polymer and its content.

Guanidine containing polymers were applied to prepare polymer coated silica particles via a sol–gel method as potential candidates for drug encapsulation. Here, we used four types of grafted polymers for surface modification. The grafting amount was evaluated by thermogravimetric and elemental analysis and was in 18–34% range. Also polymer coated silica particles were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry and high resolution electron microscopy. The effect of grafted polymers on particle properties and pH-response has been reported. Anionic (sulfasalazine) and cationic (doxorubicin) drugs were effectively loaded into polymer coated silicas. The drug loading and drug release were pH dependent and affected by the nature of grafted polymer and its content. The properties revealed for investigated system have shown promising results for drug delivery with pH controllable drug release.

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