Protein release from dihydroxyacetone-based poly(carbonate ester) matrices

A universal powder-laden crosslinked chitosan microneedle patch for high-dose controllable drug delivery

In this study, we constructed a novel powder-laden core-shell crosslinked chitosan microneedle patch for high-dose and controllable delivery of various drugs, including both macromolecular biological drugs and small-molecule chemical drugs. Direct loading of drug powders greatly improved drug loading capacity and minimized degradation. The results of the in vitro drug release study suggested that the release behaviors of the most tested drugs (both macromolecular drugs and small-molecule drugs) can be tuned by adjusting the crosslink density of the microneedle shell to achieve either rapid or sustained release of the loaded drug. The in vivo hypoglycemic efficacy test in streptozotocin-induced diabetic mice further proved that the onset and duration of the insulin-laden patch can be customized by adjusting the crosslink density. Furthermore, a combination of microneedle patches with different crosslink densities not only rapidly reduced blood glucose levels to normoglycemic levels (within 1 h) but also maintained normoglycemia for up to 36 h. The insulin loaded in the patch also showed good stability during storage at 40 °C for 6 months. Our results suggest that this powder-laden patch represents a strong candidate for addressing the multiple challenges in the preparation and application of polymeric microneedles and shows promise in clinical applications.

Dihydroxyacetone: A User Guide for a Challenging Bio-Based Synthon

1,3-dihydroxyacetone (DHA) is an underrated bio-based synthon, with a broad range of reactivities. It is produced for the revalorization of glycerol, a major side-product of the growing biodiesel industry. The overwhelming majority of DHA produced worldwide is intended for application as a self-tanning agent in cosmetic formulations. This review provides an overview of the discovery, physical and chemical properties of DHA, and of its industrial production routes from glycerol. Microbial fermentation is the only industrial-scaled route but advances in electrooxidation and aerobic oxidation are also reported. This review focuses on the plurality of reactivities of DHA to help chemists interested in bio-based building blocks see the potential of DHA for this application. The handling of DHA is delicate as it can undergo dimerization as well as isomerization reactions in aqueous solutions at room temperature. DHA can also be involved in further side-reactions, yielding original side-products, as well as compounds of interest. If this peculiar reactivity was harnessed, DHA could help address current sustainability challenges encountered in the synthesis of speciality polymers, ranging from biocompatible polymers to innovative polymers with cutting-edge properties and improved biodegradability.

Silica Hydrogels as Platform for Delivery of Hyaluronic Acid

Hyaluronic acid (HA) is chondroprotective and anti-inflammatory drug used clinically for treatment of inflammatory disorders (arthritis, skin diseases, bowel diseases, etc.). In addition, HA is a crucial ingredient in the cosmetic products used to eliminate the unpleasant consequences of inflammatory skin diseases. The main disadvantages that limit its use are its low mechanical properties and its rapid biodegradation. In this paper, silica hydrogels are considered as a promising matrix for HA to improve its properties. The hybrid HA-silica hydrogels were synthesized by the sol-gel method. Morphology of the hydrogels was investigated by optical microscopy and scanning electron microscopy methods. Taking into account their potential applications for topical and injectable delivery, much attention was paid to investigation of deformation properties of the hydrogels under shear, compression, and tension. Their resistance to enzymatic degradation in vitro was estimated. Kinetics and mechanisms of HA release from the hybrid hydrogels in vitro were also studied. It was found that the indicated properties can be controlled by synthesis conditions, HA molecular weight, and its loading in the hydrogels. Silica hydrogels are a prospective platform for the development of new soft formulations and cosmetic compositions of HA with improved pharmacological and consumer properties.

Development of Novel Oral Formulations of Disulfide Antioxidants Based on Porous Silica for Controlled Release of the Drugs

Powerful antioxidant α-lipoic acid (LA) exhibits limited therapeutic efficiency due to its pharmacokinetic properties. Therefore, the purpose of this work was to evaluate the ability of silica-based composites of LA as well as its amide (lipoamide, LM), as new oral drug formulations, to control their release and maintain their therapeutic concentration and antioxidant activity in the body over a long time. The composites synthesized at different sol–gel synthesis pH and based on silica matrixes with various surface chemistry were investigated. The release behavior of the composites in media mimicking pH of digestive fluids (pH 1.6, 6.8, and 7.4) was revealed. The effects of chemical structure of the antioxidants, synthesis pH, surface chemistry of the silica matrixes in the composites as well as the pH of release medium on kinetic parameters of the drug release and mechanisms of the process were discussed. The comparative analysis of the obtained data allowed the determination of the most promising composites. Using these composites, modeling of the release process of the antioxidants in accordance with transit conditions of the drugs in stomach, proximal, and distal parts of small intestine and colon was carried out. The composites exhibited the release close to the zero order kinetics and maintained the therapeutic concentration of the drugs and antioxidant effect in all parts of the intestine for up to 24 h. The obtained results showed that encapsulation of LA and LM in the silica matrixes is a promising way to improve their bioavailability and antioxidant activity.

Degradable high Tg sugar-derived polycarbonates from isosorbide and dihydroxyacetone

Step-growth polymerization and degradation behavior of fully sugar-derived high T_g alternating and random polycarbonates from isosorbide and dihydroxyacetone.

Biodegradable Kojic Acid-Based Polymers: Controlled Delivery of Bioactives for Melanogenesis Inhibition

Kojic acid (KA) is a naturally occurring fungal metabolite that is utilized as a skin-lightener and antibrowning agent owing to its potent tyrosinase inhibition activity. While efficacious, KA's inclination to undergo pH-mediated, thermal-, and photodegradation reduces its efficacy, necessitating stabilizing vehicles. To minimize degradation, poly(carbonate-esters) and polyesters comprised of KA and natural diacids were prepared via solution polymerization methods. In vitro hydrolytic degradation analyses revealed KA release was drastically influenced by polymer backbone composition (e.g., poly(carbonate-ester) vs polyester), linker molecule (aliphatic vs heteroatom-containing), and release conditions (physiological vs skin). Tyrosinase inhibition assays demonstrated that aliphatic KA dienols, the major degradation product under skin conditions, were more potent then KA itself. All dienols were found to be less toxic than KA at all tested concentrations. Additionally, the most lipophilic dienols were statistically more effective than KA at inhibiting melanin biosynthesis in cells. These KA-based polymer systems deliver KA analogues with improved efficacy and cytocompatible profiles, making them ideal candidates for sustained topical treatments in both medical and personal care products.

Polymers from sugars: cyclic monomer synthesis, ring-opening polymerisation, material properties and applications

This feature article gives an overview of sugar-based polymers that can be made by ring-opening-polymerisation and their applications.

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.

Prolonged Release of Bioactive Model Proteins from Anionic Microgels Fabricated with a New Microemulsion Approach

PURPOSE

Therapeutic proteins have become an integral part of health care. However, their controlled delivery remains a challenge. Protein function depends on a delicate three dimensional structure, which can be damaged during the fabrication of controlled release systems. This study presents a microgel-based controlled release system capable of high loading efficiencies, prolonged release and retention of protein function.

METHODS

A new DMSO/Pluronic microemulsion served as a reaction template for the crosslinking of poly(acrylic acid) and oligo (ethylene glycol) to form microgels. Poly(acylic acid) molecular weights and microgel crosslinking densities were altered to make a series of microgels. Microgel capacity to capture and retain proteins of different sizes and isoelectric points, to control their release rate (over ~30 days) and to maintain the biofunctionality of the released proteins were evaluated.

RESULTS

Microgels of different sizes and morphologies were synthesized. Loading efficiencies of 100% were achieved with lysozyme in all formulations. The loading efficiency of all other proteins was formulation dependent. Release of lysozyme was achieved for up to 30 days and the released lysozyme retained over 90% of its activity.

CONCLUSIONS

High loading efficiencies and prolonged release of different proteins was achieved. Furthermore, lysozyme's functionality remained uncompromised after encapsulation and release. This work begins to lay the foundation for a broad platform for the delivery of therapeutic proteins.