Optimizing the conditions of PGSu synthesiswith simplex method

Poly(glycerol succinate) – PGSu – is one of glycerol polyesters which has focused nowadays the interestof scientists developing new biomaterials. Probably the polyester could be used as a drug carrier or asa cell scaffold in tissue engineering. Due to its potential use in medicine, it is extremely important todevelop a synthesis and then optimize it to obtain a material with desired properties. In this work oneflask two-step polycondensation of glycerol and succinic anhydride to PGSu is presented. Synthesiswas optimized with the simplex method and also described using a second-degree equation with twovariables (temperature and time) to better find the optimum conditions. PGSu was characterized byFTIR spectroscopy, NMR spectroscopy, degree of esterification was determined, and also molecularweight was calculated for each experiment using Carothers equation. A new synthesis route wasdeveloped and optimized. Temperature and time influence on molecular weight and esterificationdegree of obtained polyester are presented. Based on experiments conducted in this work, it waspossible to obtain poly(glycerol succinate) with molecular weight of 6.7 kDa

The catalyst-free polytransesterification for obtaining linear PGS optimized with use of 22 factorial design

Poly(glycerol sebacate) (PGS) is a polyester that is particularly useful for tissue engineering appli- cations. Many researchers have focused on the application and characterization of materials made from PGS. Synthesis is often superficially described, and the prepolymer is not characterized before crosslinking. Considering the different functionality of each monomer (glycerine – 3, sebacic acid – 2), materials with a branched structure can be obtained before the crosslinking process. Branched struc- tures are not desirable for elastomers. In this work, method to obtain linear PGS resins is presented. Moreover, synthesis was optimized with the use of the Design of Experiments method for minimizing the degree of branching and maximizing the molecular weight. The process was described via mathe- matical models, which allows to the association of process parameters with product properties. In this work ca. 1kDa and less than 10% branched PGS resin was produced. This resin could be used to make very flexible elastomers because branching is minimized

Stress-Induced Intensification of Deoxyshikonin Production in <i>Rindera graeca</i> Hairy Root Cultures with Ester-Based Scaffolds

In vitro plant cell and tissue culture systems allow for controlling a wide range of culture environmental factors selectively influencing biomass growth and the yield of secondary metabolites. Among the most efficient methods, complex supplementation of the culture medium with elicitors, precursors, and other functional substances may significantly enhance valuable metabolite productivity through a stress induction mechanism. In the search for novel techniques in plant experimental biotechnology, the goal of the study was to evaluate stress-inducing properties of novel biodegradable ester-based scaffolds made of poly(glycerol sebacate) (PGS) and poly(lactic acid) (PLA) influencing on the growth and deoxyshikonin productivity of Rindera graeca hairy roots immobilized on the experimental constructs. Rindera graeca hairy roots were maintained under the dark condition for 28 days in three independent systems, i.e., (i) non-immobilized biomass (a reference system), (ii) biomass immobilized on PGS scaffolds, and (iii) biomass immobilized on PLA scaffolds. The stress-inducing properties of the applied polymerized esters selectively impacted R. graeca hairy roots. The PGS scaffolds caused the production of deoxyshikonin, which does not occur in other culture systems, and PLA promoted biomass proliferation by doubling its increase compared to the reference system