Spray-dried mucoadhesive microparticles from pectic polysaccharide of durian fruit-hulls

Abstract

The purpose of this research was to prepare mucoadhesive microparticles of pectic polysaccharide (from durian rinds, Durio Zibethinus) by using spray drying technique for nasal protein delivery compared to commercial pectins. The molecular weight of pectic polysaccharide, commercial high and low methoxylated (HM, LM) citrus pectins 237,595, 246,198 and 309,170, respectively. A mini spray dryer was used to obtain these powder in formulation with mannitol, lactose, maltodextrin, colloidal silica and/or propylene glycol as filler and shaper. Production yields were between 28.87 – 55.60%. Small particle size of 5 - 8 µm was from low pectic polysaccharide concentration. All spray dried powders were bulky and almost spherical with smooth surface but collapsed at high inlet temperature and low feed rate. At 75% RH and room temperature, moisture content increased to about 12% of the powder weight. The swelling index and mucoadhesive force of powders when attached to the cellulose acetate membrane soaked with 10% mucin solution was 13 – 55 and 4 - 14 Newtons, respectively. BSA loading decreased the particle sizes of LM and HM pectin microparticles but had no effect on that of pectic polysaccharide. BSA:pectin ratio slightly affected the surface smoothness which was ranked 1:10 > 1:5 > 1:3. Data FTIR spectra could conclude that pectic polysaccharide was high methoxylated pectin and BSA-pectin complex formation was obtained. The results of CD spectra indicated that the secondary structure of BSA after spray drying process was not different from native BSA. The stability of spray dried protein was confirmed using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The data indicated that BSA was conserved in spite of exposure to high temperature (120 ºC) of spray dryer. Protein loadings of all types of pectin microparticles were between 3.5 – 9.34%. BSA released from spray dried LM pectin microparticle were not more than 60% probably due to high molecular weight. The cytotoxicity using MTT assay of microparticles with the formulation of pectic polysaccharide including Aerosil® was higher than HM and LM pectin. However, the cell viability using trypan blue after permeation experiment of all types of pectin microparticles was not significantly different and not less than 75%. TEER of nasal epithelial cell (RMPI2650) monolayer of 100-110 Ωcm² was not changed along the permeation experiment. These results and the photographs of cell staining FITC phalloidin indicated the pectins did not open the tight junction. Nevertheless, the BSA permeation from all types of pectin through nasal epithelial cell (RMPI2650) monolayer was ranged from 35 to 60% and ranked PP>HM>LM due the high molecular weight of LM pectin.