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Polymers inspired by phospholipids: polyesters with dihydrogen phosphate pendant group

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Giovanni Bortoloni Perin
Total Authors: 1
Document type: Doctoral Thesis
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
Defense date:
Examining board members:
Maria Isabel Felisberti; Edvaldo Sabadini; Camila Alves de Rezende; Cesar Liberato Petzhold; Juliana da Silva Bernardes
Advisor: Maria Isabel Felisberti

Phosphorylated polyesters structurally similar to phospholipids were prepared by the phosphorylation of hydroxylated polyesters, which were synthesized via the polycondensation of glycerol and aliphatic dicarboxylic acids catalyzed by the enzyme Candida antarctica lipase B immobilized on an acrylic resin (CALB). The polycondensation of glycerol and diacids (adipic, suberic, sebacic, and dodecanedioic acids) catalyzed by CALB resulted in hydroxylated and branched polyesters, independently of the temperature, solvent, and diacid. The mechanism of the polymerization, proposed from kinetic data and the polyester structure, is composed by two steps: the enzymatic esterification of primary hydroxyls of glycerol, and acyl migration, which occurs in parallel, and converts primary hydroxyl esters into secondary hydroxyl ester, and results in the polyester branching. The enzymatic esterification is the main reaction up to the carboxylic acid conversion pCOOH ? 0.65 - 0.75, with rate constant around ten times higher than that one of the acyl migration. At pCOOH ? 0.65 - 0.75, the acyl migration is the predominant reaction and determines the structure of the polyesters. In general, hydroxylated polyesters with highest molar mass were formed using sebacic and dodecanedioic acids in reactions performed in bulk at 80 °C under nitrogen flow. The phosphorylation of the hydroxylated polyesters using phosphoryl chloride as phosphorylation agent and triethylamine as catalyst resulted in phosphorylated polyesters with a degree of phosphorylation of 36 ± 11 mol%. The hydroxylated and phosphorylated polyesters present five and ten different repetitive units, respectively, as elucidated by 1D and 2D NMR data. Regarding the properties, the polymers vary from more hydrophilic and amorphous for polyesters based on adipic acid to more hydrophobic and semicrystalline for polyesters based on dodecanedioic acid. The hydroxylated and phosphorylated polyesters are thermally stable up to 250 °C under inert atmosphere. The hydroxylated and phosphorylated polyesters form nanoparticles in aqueous solution, which present hydrodynamic radius and zeta potential in the range from 71 to 250 nm, and from -46 mV to -10 mV, respectively, depending on the nature and concentration of the polyester. The nanoparticles based on the phosphorylated polyesters can be loaded with up to 25 wt% of Oil Red O in aqueous media and acts as a phase transfer agent, releasing it into an organic phase. Nanoparticles based on phosphorylated poly(glycerol sebacate) loaded with a hydrophilic substrate and polymersomes loaded with enzymes were used as synthetic models of proto-organelles and incorporated into micrometric coacervate droplets for the construction of membraneless and multicompartmentalized synthetic protocells at pH = 5.5. At pH = 7.5, the nanoparticles disassemble and release the substrate to the coacervate environment, which diffuses to the polymersomes where is converted by the enzyme into a fluorescent product and it is stored in the coacervate. Therefore, these protocells are capable of producing a given product within the protocells trought the communication between the proto-organelles, mimetizing a metabolic process (AU)

FAPESP's process: 18/01562-6 - Polymers inspired by phospholipids: polyesters with dihydrogen phosphate pendent group
Grantee:Giovanni Bortoloni Perin
Support Opportunities: Scholarships in Brazil - Doctorate (Direct)