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Drugs with low water solubility are predisposed to poor and variable oral bioavailability and, therefore, to variability in clinical response, that might be overcome through an appropriate formulation of the drug. Polymorphs (anhydrous and solvate/hydrate forms) may resolve these bioavailability problems, but they can be a challenge to ensure physicochemical stability for the entire shelf life of the drug product. Since clinical failures of polymorph drugs have not been uncommon, and some of them have been entirely unexpected, the Food and Drug Administration (FDA) and the International Conference on Harmonization (ICH) has required preliminary and exhaustive screening studies to identify and characterize all the polymorph crystal forms for each drug. In the past, the polymorphism of many drugs was detected fortuitously or through manual time consuming methods; today, drug crystal engineering, in particular, combinatorial chemistry and high-throughput screening, makes it possible to easily and exhaustively identify stable polymorphic and/or hydrate/dehydrate forms of poorly soluble drugs, in order to overcome bioavailability related problems or clinical failures. This review describes the concepts involved, provides examples of drugs characterized by poor solubility for which polymorphism has proven important, outlines the state-of-the-art technologies and discusses the pertinent regulations.

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Bioprinting is a new technology in regenerative medicine that allows the engineering of tissues by specific placement of cells in biomaterials. Importantly, the porosity and the relatively small dimensions of the fibers allow rapid diffusion of nutrients and metabolites. This technology requires the availability of hydrogels that ensure viability of encapsulated cells and have adequate mechanical properties for the preparation of structurally stable and well-defined three-dimensional constructs. The aim of this study is to evaluate the suitability of a biodegradable, photopolymerizable and thermosensitive A–B–A triblock copolymer hydrogel as a synthetic extracellular matrix for engineering tissues by means of three dimensional fiber deposition. The polymer is composed of poly(N-(2-hydroxypropyl)methacrylamide lactate) A-blocks, partly derivatized with methacrylate groups, and hydrophilic poly(ethylene glycol) B-blocks of a molecular weight of 10 kDa. Gels are obtained by thermal gelation and stabilized with additional chemical cross-links by photopolymerization of the methacrylate groups coupled to the polymer. A power law dependence of the storage plateau modulus of the studied hydrogels on polymer concentration is observed for both thermally and chemically cross-linked hydrogels. The hydrogels demonstrated mechanical characteristics similar to natural semi-flexible polymers, including collagen. Moreover, the hydrogel shows suitable mechanical properties for bioprinting, allowing subsequent layer-by-layer deposition of gel fibers to form stable constructs up to at least 0.6 cm (height) with different patterns and strand spacing. The resulting constructs have reproducible vertical porosity and the ability to maintain separate localization of encapsulated fluorescent microspheres. Moreover, the constructs show an elastic modulus of 119 kPa (25 wt% polymer content) and a degradation time of approximately 190 days. Furthermore, high viability is observed for encapsulated chondrocytes after 1 and 3 days of culture. In summary, we conclude that the evaluated hydrogel is an interesting candidate for bioprinting applications

Huge amounts of chitin and chitosans can be found in the biosphere as important constituents of the exoskeleton of many organisms and as waste by worldwide seafood companies. Presently, politicians, environmentalists, and industrialists encourage the use of these marine polysaccharides as a renewable source developed by alternative eco-friendly processes, especially in the production of regular cosmetics. The aim of this review is to outline the physicochemical and biological properties and the different bioextraction methods of chitin and chitosan sources, focusing on enzymatic deproteinization, bacteria fermentation, and enzymatic deacetylation methods. Thanks to their biodegradability, non-toxicity, biocompatibility, and bioactivity, the applications of these marine polymers are widely used in the contemporary manufacturing of biomedical and pharmaceutical products. In the end, advanced cosmetics based on chitin and chitosans are presented, analyzing different therapeutic aspects regarding skin, hair, nail, and oral care. The innovative formulations described can be considered excellent candidates for the prevention and treatment of several diseases associated with different body anatomical sectors.

Polymer-based nanocapsules have been widely studied as a potential drug delivery system in recent years. Nanocapsules—as one of kind nanoparticle—provide a unique nanostructure, consisting of a liquid/solid core with a polymeric shell. This is of increasing interest in drug delivery applications. In this review, nanocapsules delivery systems studied in last decade are reviewed, along with nanocapsule formulation, characterizations of physical/chemical/biologic properties and applications. Furthermore, the challenges and opportunities of nanocapsules applications are also proposed.

This study reports on the synthesis, characterization and peptide release behavior of an in situ physically and chemically cross-linking hydrogel. (Meth)acrylate bearing ABA-triblock copolymers consisting of a poly(ethylene glycol) (PEG) middle block, flanked by thermosensitive blocks of random N-isopropylacrylamide (pNIPAm)/N-(2-hydroxypropyl) methacrylamide dilactate (pHPMAmlac2) and exhibiting lower critical solution temperature behavior in aqueous solution were synthesized. Upon body temperature induced physical gelation, these polymers were cured by Michael type addition reaction with thiolated hyaluronic acid (HA-SH) to yield injectable in situ gelling, biodegradable but structurally stable and biocompatible hydrogels. These stable and elastic networks were prepared by mixing (meth)acrylated ABA-triblock copolymers and thiolated hyaluronic acid at a ratio thiol/(meth)acrylate groups of 1/1. The simultaneous physical and chemical gelation kinetics, investigated by rheological measurements, demonstrated that the physical networks were progressively stabilized as the Michael addition reaction between (meth)acrylate and thiol groups proceeded and that acrylated thermosensitive polymers had a higher reactivity with thiol groups, as compared to methacrylate analogues, resulting in a faster gel formation. The networks, characterized by a remarkable initial structural stability, degraded in time at physiological conditions. The degradability is ensured by the presence of hydrolytically sensitive ester bonds in the cross-links, as well as in the lactate side chains and between PEG and thermosensitive blocks. Methacrylated polymer gels loaded with a model peptide (bradykinin), showed a diffusion controlled release of this peptide, tailorable by the polymer concentration. This tandem system, displaying in situ physical and chemical gelation has a high potential for biomedical applications, such as delivery of peptide and protein biopharmaceuticals.