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The delivery of drugs is a great challenge, since most of active pharmaceutical ingredients developed today are hydrophobic and poorly water soluble. From this perspective, drug encapsulation on biodegradable and biocompatible polymers can surpass this problem. Poly(γ-glutamic acid) (PGGA), a bioedible and biocompatible polymer has been chosen for this purpose. Carboxylic side groups of PGGA have been partially esterified with 4-phenyl-butyl bromide, producing a series of aliphatic–aromatic ester derivatives with different hydrophilic–lipophilic balances. Using nanoprecipitation or emulsion/evaporation methods, these copolymers were self-assembled in a water solution, forming nanoparticles with average diameters between 89 and 374 nm and zeta potential values between −13.1 and −49.5 mV. The hydrophobic core containing 4-phenyl-butyl side groups was used for the encapsulation of an anticancer drug, such as Doxorubicin (DOX). The highest encapsulation efficiency was reached for a copolymer derived from PGGA, with a 46 mol% degree of esterification. Drug release studies carried out for 5 days at different pHs (4.2 and 7.4) indicated that DOX was released faster at pH 4.2, revealing the potential of these nanoparticles as chemotherapy agents.

One of the treatments for cancer is chemotherapy but most anticancer drugs have a low therapeutic index, which causes toxicity complications in the healthy tissues [1]. To minimize these complications and improve the effect of the existing drugs, drug delivery by nanoparticles have drawn more attention as they are easy to produce and can also be prepared through biocompatible polymers [2]. Here, we report the preparation of polymer nanoparticles derived from esters of poly(¿-glutamic acid) which could be able to encapsulate hydrophobic drugs that can be used as drug delivery systems (DDS) for the treatment of different tumours. In this work, PGGA has been modified in order to improve its solubility in organic solvents and its processing capacity of this water-soluble polymer. Due to the fact that most of the anticancer drugs are lipophilic, the hydrophobic modification of PGGA will enhance the drug encapsulation.

We report a novel approach for the modular and convergent construction of biocompatible graft copolymers starting from bacterial poly(¿-glutamic acid)(¿-PGA) and incorporating poly(lactic acid) (PLA). This synthesis strategy is controlled at different levels: (a) the choice of a suitable initiator for the ring-opening polymerization of lactide; (b) the chemical elaboration of the polylactic fragments; and (c) their convergent “grafting to” functionalization of bacterial ¿-PGA propargyl ester using copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) click chemistry. The graft copolymers are characterized in terms of their thermal and macromolecular properties, their conformational preferences through molecular modelling, and their cytotoxicity. Peer Reviewed Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles

Poly(gamma-glutamic acid) (gamma-PGA) is one of the few bacterial polymers in nature; as such, it possesses the added value of a “green birth” (fermentation) and “green death” (biodegradability), which is ideal for sustainable macromolecular platforms. Efficient functionalization strategies are required in order to transform the native bacterial biopolymer into a material with tailored properties for bulk scale or biomedical applications. We report on a novel approach to the facile functionalization of bacterial gamma-PGA, realized with several levels of control: (a) the modulation of the molecular weight through sonication, and the solubilization in organic solvents through counterion exchange with suitable quaternary ammonium salts, (b) the introduction of reactive functionalities through reactions in homogeneous conditions in organic solvents, to afford homo- or copolymers; (c) a second tier functionalization using copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) click chemistry.

Comb-like ionic complexes were prepared from polyuronic acids (pectinic and alginic acids) and alkyltrimethylammonium surfactants bearing linear alkyl chains with 18, 20 and 22 carbon atoms. In the condensed state, these complexes were able to self-assemble in ordered structures which were thermally stable up to ~200ºC. The complexes were analysed by DSC and WAXS/SAXS and compared to their analogous made from poly(γ-glutamic acid). They all adopt a biphasic layered structure in which the main chain and the alkyl side chain alternate with a nanometric periodicity. Alkyl side chains were partially crystallized in these complexes and they show reversible melting at temperatures within the 60-80ºC range depending on the length of the polymethylene segment.