Binding and Encapsulation of Doxorubicin on Smart Pectin Hydrogels for Oral Delivery

Abstract

Pectins (Pec) of 33 to 74 % esterification degree (DE) were tested with doxorubicin (Dox), a very high toxic drug widely used in cancer therapies. Pec with 35 and 55 % DE were selected because of the Dox binding higher than. Pec microspheres of 35 and 55 % obtained by ionotropic gelation with Ca+2 have 88 and 66 % Dox loading capacity. Kinetic Dox release showed 80.0 and 15.0 % free drug from 35 and 55 % Pec formulations at pH 7.4, 25 ºC for 180 min respectively. Besides, Dox release decrease to 11 % in 55 % Pec microsphere formulation after one year storage at 4 ºC. FTIR analysis of Pec-Dox complex showed hipsochromic shifts for the C=O, N-H and C-C vibrational modes compared to Dox spectrum suggesting strong interaction between the drug cargo and the matrix. Rheological studies of Pec and Pec-dox samples flow behavior exhibited a shear-thinning nature. 55 % Pec showed higher viscosity than the viscosity for 35 % Pec in all range of temperatures analyzed, and decreased when the temperature is raised. Besides, Pec-Dox complexes have higher viscosity values than those of the corresponding Pec samples, and viscosity curves as function of shear rate for 35 % Pec- Dox are above the curves of 55 % Pec-Dox. In both cases, the results are confirming significant interaction between the cargo and the matrix, which also was established in viscoelastic dynamic analysis.