In-vitro evaluation of alginate as an encapsulation matrix for pH-dependent delivery of bacteriophage T4L and T7L...

Encapsulation of pH-sensitive biomolecules like endolysins having therapeutic properties in an inert polymeric matrix is one of the exciting approaches for delivery. Alginate has been demonstrated to protect the integrity of encapsulated material. T4L (18.7 kDa) and T7L (17 kDa) endolysins are the peptidoglycan degrading enzymes that are deactivated under acidic conditions. In the current study, the encapsulation of T4L/T7L in calcium-alginate beads and their pH-dependent release has been assessed. Beads displayed encapsulation efficiencies of 57 ± 2 % and 62 ± 2 % for T4L and T7L respectively. Characterization by BET and SEM analyses revealed highly porous and shrunken morphologies of freeze dried beads (FDB) /T4L-FDB and T7L-FDB respectively. Furthermore, a faster release of T4L/T7L (> 95 % in ∼40 h) was observed in FDB, as compared to WB (∼ 80 % in 40 h). Additionally, diffusion exponent (n) values of 0.92 and 0.93 exhibited by T4L/T7L-WB/FDB in HCl-PBS system, thus exhibiting a combination of release mechanisms that followed Korsmeyer-peppas model. However, FDB optimally preserved the lytic activities of T4L/T7L (∼ 98 %) at 25 °C for up to one month. The results established that alginate has an excellent potency for protecting the integrity and functionality of T4L/T7L.