Mechanical properties of alginate-liposomes-based beads with encapsulated resveratrol

Abstract

In this work mechanical behavior of four different formulations of alginate-based beads was tested. The alginate beads were prepared by means of extrusion technique. As a model encapsulated bioactive substance resveratrol-loaded liposomes were used. The beads were composed as follows: 1.5% alginate beads; 1.5% alginate beads encapsulating liposomes; 1.5% alginate/30% sucrose beads encapsulating liposomes and 1.5% alginate/0.5% chitosan beads encapsulating liposomes. The mechanical properties (e.g. maximal forces required for reaching the default deformation, maximal stresses and the Young’s modulus) of aforementioned beads were determined by testing the single bead submerged in water using the AG-X plus Universal Testing Machine (Shimadzu, Japan). Results showed the decrease in maximal forces (stresses) and increase in elasticity of the examined beads upon encapsulation of resveratrol-loaded liposomes. After addition of sucrose and coating with chitosan, maximal forces respectively remained constant and decreased, while elastic modulus also remained constant and increased, respectively. Tested compression method can be used in the determination of mechanical properties of different alginate-based beads.

U ovom radu su ispitane mehaničke karakteristike četiri različite formulacije čestica na bazi alginata. Čestice su pripremljenje koristeći metodu ekstruzije. Kao model supstanca za inkapsulaciju korišćni su lipozomi sa inkapsuliranim resveratrolom. Formulacije čestica su sledeće: 1,5% alginatne čestice; 1,5% alginatne čestice sa inkapsuliranim lipozomima; 1,5% alginatne čestice sa inkapsuliranim lipozomima sa dodatkom 30% saharoze i 1,5% alginatne čestice sa inkapsuliranim lipozomima sa dodatnim slojem 0,5% hitozana. Mehaničke karakteristike (tj. maksimalne sile potrebne za dostizanje unapred definisane deformacije, maksimalni naponi i Jungovi moduli elastičnosti) gore pomenutih čestica su određene testiranjem pojedinačnih čestica uronjenih u vodu, koristeći AG-X plus Universal Testing Machine (Shimadzu, Japan). Rezultati su pokazali da nakon inkapsulacije lipozoma sa resveratrolom u alginatne čestice dolazi do smanjenja maksimalne sile potrebne za postizanje zadate deformacije, kao i do povećanja elastičnosti ispitivanh čestica. Nakon dodatka saharoze i oblaganja alginatnih čestica slojem hitozana, maksimalna sila ostaje nepromenjana, odnosno dolazi do njenog smanjenja; slicno, vrednosti modula elastičnosti takođe ostaju konstantne, odnosno povećavaju se. Ispitivana metoda kompresije može se koristiti za određivanje mehaničkih karakteristika različitih čestica na bazi alginata.