Encapsulation of A, B/C, and P Riboflavin in Calcium Alginate Particles for the Controlled Release and Antibacterial Application

Objective—to investigate the possibility Aim was to study a possibility of encapsulation of hydrophilic B/C and P forms of riboflavin into calcium alginate particles, to study riboflavin release from the particles and its antibacterial properties. Materials and methods. Alginate particles were obtained by cross-linking of sodium alginate with calcium ions and loaded in situ with B/C and P types of riboflavin. The strains of Pseudomonas aeruginosa bacteria were used to evaluate antibacterial activity. Results. Two polymorphic modifications and salt form of riboflavin (types A, B/C, and P) were successfully encapsulated into calcium alginate particles of about 600 μm in size. Using the methods of optical and electron microscopy, it was demonstrated that types A and B/C retain the shape of crystals and crystalline intergrowths, while type P riboflavin is uniformly distributed in the gel matrix. X-ray phase analysis confirmed the preservation of the crystalline form of type A riboflavin, but revealed that the crystalline aggregates of type B/C become amorphous during encapsulation. It was demonstrated that alginate particles containing type B/C riboflavin are characterized by a prolonged release of the active substance into deionized water, and the equilibrium concentration for type P is already reached within 30 min. It was established that the particles loaded with types B/C and P exhibit a pronounced antibacterial activity against Gram-negative bacteria. Conclusions. The encapsulation of types B/C and P riboflavin into alginate particles allows us to preserve the antibacterial activity of the substance and provide its controlled release.