Recent advances in glycerol polymers: chemistry and biomedical applications

Plasticizers Derived from Biomass Resources: A Short Review

With rising environmental concerns and depletion of petrochemical resources, biomass-based chemicals have been paid more attention. Polyvinyl chloride (PVC) plasticizers derived from biomass resources (vegetable oil, cardanol, vegetable fatty acid, glycerol and citric acid) have been widely studied to replace petroleum-based o-phthalate plasticizers. These bio-based plasticizers mainly include epoxidized plasticizer, polyester plasticizer, macromolecular plasticizer, flame retardant plasticizer, citric acid ester plasticizer, glyceryl ester plasticizer and internal plasticizer. Bio-based plasticizers with the advantages of renewability, degradability, hypotoxicity, excellent solvent resistant extraction and plasticizing performances make them potential to replace o-phthalate plasticizers partially or totally. In this review, we classify different types of bio-based plasticizers according to their chemical structure and function, and highlight recent advances in multifunctional applications of bio-based plasticizers in PVC products. This study will increase the interest of researchers in bio-based plasticizers and the development of new ideas in this field.

Synthesis of poly(1,2-glycerol carbonate)-paclitaxel conjugates and their utility as a single high-dose replacement for multi-dose treatment regimens in peritoneal cancer

A high drug-density, biodegradable polymeric nanocarrier replaces multi-dose paclitaxel treatment regimens.

Current chemotherapeutic dosing strategies are limited by the toxicity of anticancer agents and therefore rely on multiple low-dose administrations. As an alternative, we describe a novel sustained-release, biodegradable polymeric nanocarrier as a single administration replacement of multi-dose paclitaxel (PTX) treatment regimens. The first synthesis of poly(1,2-glycerol carbonate)-graft-succinic acid-paclitaxel (PGC–PTX) is described, and its use enables high, controlled PTX loadings of up to 74 wt%. Moreover, the polymer backbone is composed of biocompatible building blocks—glycerol and carbon dioxide. When formulated as nanoparticles (NPs), PGC–PTX NPs exhibit PTX concentrations >15 mg mL^–1, sub-100 nm diameters, narrow dispersity, storage stability for up to 6 months, and sustained and controlled PTX release kinetics over an extended period of 70 days. A safely administered single dose of PGC–PTX NPs contains more PTX than the median lethal dose of standard PTX. In murine models of peritoneal carcinomatosis, in which the clinical implementation of multi-dose intraperitoneal (IP) treatment regimens is limited by catheter-related complications, PGC–PTX NPs exhibit improved safety at high doses, tumor localization, and efficacy even after a single IP injection, with comparable curative effect to PTX administered as a multi-dose IP treatment regimen.

Catalyst-controlled polycondensation of glycerol with diacyl chlorides: linear polyesters from a trifunctional monomer

Selective activation of diol groups by a borinic acid catalyst enables the synthesis of strictly linear polyesters from glycerol, a trifunctional monomer.

Diarylborinic acids catalyze the formation of linear polyesters from glycerol, a trifunctional, carbohydrate-based monomer. The selective activation of 1,2-diols over isolated alcohols by the organoboron catalyst results in polymers that are essentially free of branching or cross-linking and possess a high fraction of 1,3-enchained glycerol units, as assessed by ¹H and ¹³C NMR spectroscopy. The ability to generate well-defined polyester architectures from glycerol is significant in light of the numerous applications of such macromolecules, particularly in the biomedical area. Isomerization, post-polymerization functionalization and controlled cross-linking reactions of the obtained linear poly(glycerol esters) are demonstrated.

Development and characterization of bioresorbable polyglycerol esters and drug-loaded microparticles

Linear-hyperbranched co(polylactides) containing hyperbranched polyglycerol (PG) block were synthesized and characterized. An estimate of critical micelle concentration as well as aggregative stability and droplet sizes in the emulsion stabilized by the obtained polymers was made. It was shown that an architecture of linear-branched co(polylactides) defines its surface-active properties and characteristics of dispersion systems obtained from it. With an increase in PG block content in copolymers, critical micelle concentration and aggregative stability of emulsions increase. Polylactide microparticles were obtained by organic solvent evaporation technique using acetylsalicylic acid as a drug model. Some properties of microparticles, such as size, incorporation efficiency and in vitro release of immobilized substance, were examined. It was noticed that branching architecture of co(polylactides) has a significant influence on the properties of microparticles. On the one hand, the presence of large PG blocks in linear-branched macromolecules results in the formation of colloidal systems with higher aggregative stability of emulsions and smaller particle size; on the other hand, microparticles formed from such copolymers have lower incorporation efficiency towards water-soluble low-molecular-weight compounds and nonlinear release profile for these substances with a segment of accelerated primary release.

Bio-derived polymers for coating applications: comparing poly(limonene carbonate) and poly(cyclohexadiene carbonate)

Two fully bio-based polycarbonates, poly(limonene carbonate) and poly(cylcohexadiene carbonate), were post-functionalized via thiol–ene reactions and tested as future coating materials.

Enzymatic Synthesis of Biobased Polyesters and Polyamides

Nowadays, "green" is a hot topic almost everywhere, from retailers to universities to industries; and achieving a green status has become a universal aim. However, polymers are commonly considered not to be "green", being associated with massive energy consumption and severe pollution problems (for example, the "Plastic Soup") as a public stereotype. To achieve green polymers, three elements should be entailed: (1) green raw materials, catalysts and solvents; (2) eco-friendly synthesis processes; and (3) sustainable polymers with a low carbon footprint, for example, (bio)degradable polymers or polymers which can be recycled or disposed with a gentle environmental impact. By utilizing biobased monomers in enzymatic polymerizations, many advantageous green aspects can be fulfilled. For example, biobased monomers and enzyme catalysts are renewable materials that are derived from biomass feedstocks; enzymatic polymerizations are clean and energy saving processes; and no toxic residuals contaminate the final products. Therefore, synthesis of renewable polymers via enzymatic polymerizations of biobased monomers provides an opportunity for achieving green polymers and a future sustainable polymer industry, which will eventually play an essential role for realizing and maintaining a biobased and sustainable society.

Recent Advances in Dendritic Macromonomers for Hydrogel Formation and Their Medical Applications

Hydrogels represent one of the most important classes of biomaterials and are of interest for various medical applications including wound repair, tissue engineering, and drug release. Hydrogels possess tunable mechanical properties, biocompatibility, nontoxicity, and similarity to natural soft tissues. The need for hydrogels with specific properties, based on the design requirements of the in vitro, in vivo, or clinical application, motivates researchers to develop new synthetic approaches and cross-linking methodologies to form novel hydrogels with unique properties. The use of dendritic macromonomers represents one elegant strategy for the formation of hydrogels with specific properties. Specifically, the uniformity of dendrimers combined with the control of their size, architecture, density, and surface groups make them promising cross-linkers for hydrogel formation. Over the last two decades, a large variety of dendritic-based hydrogels are reported for their potential use in the clinic. This review describes the state of the art with these different dendritic hydrogel formulations including their design requirements, the synthetic routes, the measurement and determination of their properties, the evaluation of their in vitro and in vivo performances, and future perspectives.

Microfluidic enrichment for the single cell analysis of circulating tumor cells

Resistance to drug therapy is a major concern in cancer treatment. To probe clones resistant to chemotherapy, the current approach is to conduct pooled cell analysis. However, this can yield false negative outcomes, especially when we are analyzing a rare number of circulating tumor cells (CTCs) among an abundance of other cell types. Here, we develop a microfluidic device that is able to perform high throughput, selective picking and isolation of single CTC to 100% purity from a larger population of other cells. This microfluidic device can effectively separate the very rare CTCs from blood samples from as few as 1 in 20,000 white blood cells. We first demonstrate isolation of pure tumor cells from a mixed population and track variations of acquired T790M mutations before and after drug treatment using a model PC9 cell line. With clinical CTC samples, we then show that the isolated single CTCs are representative of dominant EGFR mutations such as T790M and L858R found in the primary tumor. With this single cell recovery device, we can potentially implement personalized treatment not only through detecting genetic aberrations at the single cell level, but also through tracking such changes during an anticancer therapy.

Synthetic Biomaterials from Metabolically Derived Synthons

The utility of metabolic synthons as the building blocks for new biomaterials is based on the early application and success of hydroxy acid based polyesters as degradable sutures and controlled drug delivery matrices. The sheer number of potential monomers derived from the metabolome (e.g., lactic acid, dihydroxyacetone, glycerol, fumarate) gives rise to almost limitless biomaterial structural possibilities, functionality, and performance characteristics, as well as opportunities for the synthesis of new polymers. This review describes recent advances in new chemistries, as well as the inventive use of traditional chemistries, toward the design and synthesis of new polymers. Specific polymeric biomaterials can be prepared for use in varied medical applications (e.g., drug delivery, tissue engineering, wound repair, etc.) through judicious selection of the monomer and backbone linkage.

Aliphatic Polyethers: Classical Polymers for the 21st Century

Polyethers-polymers with the structural element (R'-O-R)n in their backbone--are an old class of polymers which were already used at the time of the ancient Egyptians. However, still today these materials are highly important with applications in all areas of our life, reaching from the automotive and paper industry to cosmetics and biomedical applications. In this Review, different aliphatic polyethers like poly(epoxide)s, poly(oxetane)s, and poly(tetrahydrofuran) are discussed. Special emphasis is placed on the history, the polymerization techniques (industrially and in academia), the properties, the applications as well as recent developments of these materials.

Engineering thermoresponsive polyether-based nanogels for temperature dependent skin penetration

Improved skin penetration of thermoresponsive nanogels into human skin at temperatures above the phase-transition temperature.