http://dx.doi.org/10.4314/tjpr.v12i2.1   

Abstract

Purpose: To investigate the effect of lyoprotectants on the physical and storage stability of lyophilised bovine serum albumin-loaded chitosan/dextran sulphate (BSA-loaded CS/DS) nanoparticles.

Methods: BSA-loaded CS/DS nanoparticles were prepared by ionic-gelation technique. The nanoparticles were harvested by ultra-centrifugation and then various lyoprotectants at different concentrations were added to the nanoparticles prior to lyophilisation at – 40 ^oC for 24 h. Particle size and distribution as well as zeta potential of the nanoparticles were measured by dynamic light scattering method. Entrapment efficiency and BSA retained in the nanoparticles matrices were determined spectrophotometrically at λ_max of 595 nm. 

Results: The results indicate that 0.5 %w/v trehalose was the most effective lyoprotectant and it essentially maintained the particle size of lyophilised BSA-loaded CS/DS nanoparticles which changed slightly from 188 ± 11 nm to 174 ± 14 nm during lyophilisation. Mannitol was also as effective as trehalose at 0.1 and 1.0 % w/v in stabilising the nanoparticles.  The particle size of lyophilized nanoparticles increased moderately from 188 ± 11 nm to 234 ± 12 nm and 287 ± 18 nm at 0.1 and 1.0 % w/v, respectively. In contrast, the other lyoprotectants (inulin and histidine) did not show stabilizing effects. Moreover, trehalose also  reduced the degree of particle aggregation from 329 ± 16 to 836 ± 21 nm upon storage for 24 h as compared to CS/DS nanoparticles without trehalose; from 438 ± 14 to 1298 ± 18 (p < 0.05). The rate of BSA leakage from the nanoparticles containing trehalose was reduced from 92 to 42 % over a 11-day storage period compared with 99 to 0 % for CS/DS nanoparticles without trehalose.

Conclusion: Trehalose (0.5 % w/v) is a promising lyoprotectant for storage stabilisation of BSA-loaded CS/DS nanoparticles.