Recent Advances in Catalytic Conversion of Biomass to 2,5-Furandicarboxylic Acid

Converting biomass into high value-added compounds has attracted great attention for solving fossil fuel consumption and global warming. 5-Hydroxymethylfurfural (HMF) has been considered as a versatile biomass-derived building block that can be used to synthesize a variety of sustainable fuels and chemicals. Among these derivatives, 2,5-furandicarboxylic acid (FDCA) is a desirable alternative to petroleum-derived terephthalic acid for the synthesis of biodegradable polyesters. Herein, to fully understand the current development of the catalytic conversion of biomass to FDCA, a comprehensive review of the catalytic conversion of cellulose biomass to HMF and the oxidation of HMF to FDCA is presented. Moreover, future research directions and general trends of using biomass for FDCA production are also proposed.

Poliésteres como Biomateriales. Una Revisión

Los materiales biodegradables se utilizan en envases, agricultura, medicina y otras áreas. Para proporcionar resultados eficientes, cada una de estas aplicaciones demanda materiales con propiedades físicas, químicas, biológicas, biomecánicas y de degradación específicas. Dado que, durante el proceso de síntesis de los poliésteres todas estas propiedades pueden ser ajustadas, estos polímeros representan excelentes candidatos como materiales sintéticos biodegradables y bioabsorbibles para todas estas aplicaciones. La siguiente revisión presenta una visión general de los diferentes poliésteres biodegradables que se están utilizando actualmente y sus propiedades, así como nuevos desarrollos en su síntesis y aplicaciones. Palabra clave: biomateriales, polímeros biodegradables, poliésteres, policarbonatos, biopolímeros. Abstract Biodegradable materials are used in packaging, agriculture, medicine, and many other areas. These applications demand materials with specific physical, chemical, biological, biomechanical, and degradation properties to provide efficient results. Since all these properties can be adjusted during the polyesters synthesis process, these polymers represent excellent candidates as biodegradable and bio-absorbable synthetic materials for all these applications. Here, in this review is presented an overview of the different biodegradable polyesters currently used, their properties, and new developments in their synthesis and applications. Keywords: biomaterials, biodegradable polymers, polyesters, polycarbonates, biopolymers.

Antibacterial Poly(ε-CL)/Hydroxyapatite Electrospun Fibers Reinforced by Poly(ε-CL)-b-Poly(Ethylene Phosphoric Acid)

In bone surgery and orthopedics, bioresorbable materials can be helpful in bone repair and countering post-op infections. Explicit antibacterial activity, osteoinductive and osteoconductive effects are essential to achieving this objective. Nonwoven electrospun (ES) fibers are receiving the close attention of physicians as promising materials for wound dressing and tissue engineering; potentially, in high contrast with dense materials, ES mats hamper regeneration of the bone extracellular matrix to a lesser extent. The use of the compositions of inherently biodegradable polyesters (poly(ε-caprolactone) PCL, poly(lactoglycolide), etc.), calcium phosphates and antibiotics is highly prospective, but the task of forming ES fibers from such compositions is complicated by the incompatibility of the main organic and inorganic ingredients, polyesters and calcium phosphates. In the present research we report the synthesis of hydroxyapatite (HAp) nanoparticles with uniform morphology, and demonstrate high efficiency of the block copolymer of PCL and poly(ethylene phosphoric acid) (PEPA) as an efficient compatibilizer for PCL/HAp mixtures that are able to form ES fibers with improved mechanical characteristics. The materials obtained in the presence of vancomycin exhibited incremental drug release against Staphylococcus aureus (St. aureus).

Biobased and Eco-Compatible Beauty Films Coated with Chitin Nanofibrils, Nanolignin and Vitamin E

A stable water-based suspension containing chitin nanofibrils (CN), chitin nanofibrils complexed with nanolignin and the latter containing Vitamin E was prepared starting from CN nanosuspension and nanostructured powders. The water-based coating was deposited by a spray technique on three different renewable and biodegradable films consisting of biodegradable polyesters and starch to prepare possible beauty mask prototypes. After drying, the films were extracted with water to control their potential release on the wet skin and different amounts of released materials were obtained. The results were discussed considering the composition and morphology of the adopted substrates and their interactions with the coating. The eco-compatibility of these films is related to the absence of preservatives and their easy biodegradability in several environmental conditions, decreasing their burden on solid waste management with respect to fossil-based versions.

Leflunomide Sustained Skin Delivery Based on Sulfobetaine-Modified Chitosan Nanoparticles Embedded in Biodegradable Polyesters Films

The aim of the present study was to prepare a leflunomide (LFD) sustained release transdermal delivery system for the treatment of psoriasis. In this context, LFD-loaded nanoparticles (NPs) based on either neat chitosan (CS) or CS modified with [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SDAEM, a sulfobetaine zwitterionic compound) were initially prepared via ionotropic gelation and characterized in terms of in vitro dissolution, physicochemical, and antibacterial properties. Results showed that the use of the SDAEM-modified CS resulted in the formation of LFD-loaded NPs with improved wetting and solubilization properties, better in vitro dissolution profile characteristics (i.e., higher dissolution rate and extent), and improved (enhanced) antibacterial properties. The resultant LFD-loaded NPs were then embedded in suitable thin-film skin patches, prepared via spin-coating, utilizing two different biodegradable polyesters, namely methoxy polyethylene glycol-b-poly(L-lactide) (mPEG-b-PLA, at a ratio of 25/75 mPEG to PLA) and poly(lactic-co-glycolic acid) (PLGA at a ratio of 75/25 DL-lactide/glycolide copolymer). Results showed the formation of polymeric thin-films with no agglomeration (or trapped air) and uniform structure in all cases, while the LFD-loaded NPs were successfully embedded in the polymeric matrix. Analysis of the obtained in vitro dissolution profiles revealed a sustained release profile of the drug for up to approximately twelve days, while between the two proposed systems, the use of CS-SDAEM NPs (independently of the polyester type) was the most promising formulation approach.

Controlling polymer stereochemistry in ring-opening polymerization: a decade of advances shaping the future of biodegradable polyesters

In this review, we describe recent developments in biodegradable polymer synthesis with a focus on the use of discrete complexes and organocatalysts as active initiators for the stereocontrolled ring-opening polymerization of cyclic esters.