ABSTRACT
Pectins (Pec) of 33 to 74 % esterification degree 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⺲ have 88 and 66 % Dox loading capacity. Kinetic Dox release showed more than 80.0 and about 30.0 % free drug from 35 % and 55 % Pec formulations at pH 7.4, and 37 °C after 1-h incubation, respectively. Besides, Dox release decrease to 12 % in 55 % Pec microsphere formulation after 1-year storage at 4 °C. FTIR analysis of Pec-Dox complex showed hipsochromic shifts for the σ(C=O), δ(N-H) and σ(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. Fifty-five percent of 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.
Subject(s)
Antineoplastic Agents/chemistry , Doxorubicin/chemistry , Drug Carriers/chemistry , Hydrogels/chemistry , Pectins/chemistry , Administration, Oral , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/metabolism , Capsules , Doxorubicin/administration & dosage , Doxorubicin/metabolism , Kinetics , Microspheres , RheologyABSTRACT
Screening of ciprofloxacin (Cip) with selected biopolymers brings about 90% antibiotic interactions with a coacervate composed of alginate/high metoxylated pectin in 2:1 ratio. Fourier transform infrared spectroscopy analysis provides information about the nature of this interaction, revealing ionic and hydrophobic patterns among the molecules. Alginate/high methoxylated pectin gel microspheres developed by ionic gelation encapsulates 46.8 ± 5.0% Cip. The gel matrix can release Cip in a sustained manner, releasing 42.7 ± 0.2% in 2 h under simulated stomach pH conditions, and 83.3 ± 1.1% Cip release in 80 mM phosphate at pH = 7.40 (intestinal). The increase of sodium chloride from 50 to 200 mM implies a Cip release from 69.0 ± 1.5% to 95.1 ± 3.6% respectively in 2 h. Scanning electron microscopy revealed the cohesive effect of HM pectin over alginate molecules on the microsphere surface. Those results guarantee all Cip contained in the alginate/HM pectin microspheres could be released in an established kinetic profile along the gastrointestinal tract, avoiding the Cip undesirable side effects during absorption.
Subject(s)
Alginates/chemistry , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/metabolism , Ciprofloxacin/chemistry , Ciprofloxacin/metabolism , Drug Carriers/chemistry , Pectins/chemistry , Administration, Oral , Anti-Bacterial Agents/administration & dosage , Biomimetics , Capsules , Ciprofloxacin/administration & dosage , Glucuronic Acid/chemistry , Hexuronic Acids/chemistry , Hydrogen-Ion Concentration , Intestinal Mucosa/metabolism , KineticsABSTRACT
Electron microscopy techniques are used to visualize the spatial distribution of iron nanoparticles inside a mesoporous MCM-41 molecular sieve. Direct observation of the iron oxide nanoparticles by STEM-HAADF imaging reveals a highly non-uniform spatial distribution inside the mesopores. These particles are retained in the pores after a reduction treatment unlike the behavior found in other similar systems. It is found that thermal treatments induce changes in its morphology, creating nanowires from particle strings.
