Bottlebrush Polymers for Articular Joint Lubrication: Influence of Anchoring Group Chemistry on Lubrication Properties.

The role of carboxylic, aldehyde, or epoxide groups incorporated into bottlebrush macromolecules as anchoring blocks (or cartilage-binding blocks) is investigated by measuring their lubricating properties and cartilage-binding effectiveness. Mica modified with amine groups is used to mimic the cartilage surface, while bottlebrush polymers functionalized with carboxylic, aldehyde, or epoxide groups played the role of the lubricant interacting with the cartilage surface. We demonstrate that bottlebrushes with anchoring blocks effectively reduce the friction coefficient on modified surfaces by 75-95% compared to unmodified mica. The most efficient polymer appears to be the one with epoxide groups, which can react spontaneously with amines at room temperature. In this case, the value of the friction coefficient is the lowest and equals 0.009 ± 0.001, representing a 95% reduction compared to measurements on nonmodified mica. These results show that the presence of the functional groups within the anchoring blocks has a significant influence on interactions between the bottlebrush polymer and cartilage surface. All synthesized bottlebrush polymers are also used in the preliminary lubrication tests carried out on animal cartilage surfaces. The developed materials are very promising for future in vivo studies to be used in osteoarthritis treatment.

Chitosan-Grafted-Poly(N-vinylcaprolactam)-Decorated Fe3O4@SiO2 Core-Shell Nanoformulation as an Efficient Drug Delivery System for Poorly Soluble Drugs.

Hydrocortisone, a commonly used anti-inflammatory drug, has limited aqueous solubility and several side effects. To address this challenge, as a proof-of-concept, this article demonstrates the development of a controlled-release drug delivery system (DDS) for hydrocortisone using chitosan-grafted poly(N-vinylcaprolactam) (CS-g-PNVCL)-coated core-shell Fe3O4@SiO2 nanoformulations (NFs). Reported magnetic nanoparticles (NPs) were synthesized and modified with silica, PNVCL, and CS precursors to enhance the biocompatibility of DDS and drug-loading efficiency. The release rate of hydrocortisone from Fe3O4@SiO2@CS-g-PNVCL NFs was observed to be higher at lower pH values, and the smart polymer coating demonstrated temperature responsiveness, facilitating drug release at higher temperatures. Fe3O4@SiO2@CS-g-PNVCL NFs exhibited a cell viability of around 97.2 to 87.3% (5-100 µg/mL) after 24-48 h, while the hydrocortisone-NFs had a cell viability of around 93.2 to 82.3%. Our findings suggest that CS-g-PNVCL-coated Fe3O4@SiO2 NPs effectively enhance the solubility, loading capacity, and targeted delivery of poorly soluble drugs, thereby improving their therapeutic efficacy and bioavailability.

Chitosan-based biomaterials for the treatment of bone disorders.

Bone is an alive and dynamic organ that is well-differentiated and originated from mesenchymal tissues. Bone undergoes continuous remodeling during the lifetime of an individual. Although knowledge regarding bones and their disorders has been constantly growing, much attention has been devoted to effective treatments that can be used, both from materials and medical performance points of view. Polymers derived from natural sources, for example polysaccharides, are generally biocompatible and are therefore considered excellent candidates for various biomedical applications. This review outlines the development of chitosan-based biomaterials for the treatment of bone disorders including bone fracture, osteoporosis, osteoarthritis, arthritis rheumatoid, and osteosarcoma. Different examples of chitosan-based formulations in the form of gels, micro/nanoparticles, and films are discussed herein. The work also reviews recent patents and important developments related to the use of chitosan in the treatment of bone disorders. Although most of the cited research was accomplished before reaching the clinical application level, this manuscript summarizes the latest achievements within chitosan-based biomaterials used for the treatment of bone disorders and provides perspectives for future scientific activities.

Recent developments in natural and synthetic polymeric drug delivery systems used for the treatment of osteoarthritis.

Osteoarthritis (OA), is a common musculoskeletal disorder that will progressively increase in older populations and is expected to be the most dominant cause of disability in the world population by 2030. The progression of OA is controlled by a multi-factorial pathway that has not been completely elucidated and understood yet. However, over the years, research efforts have provided a significant understanding of some of the processes contributing to the progression of OA. Both cartilage and bone degradation processes induce articular cells to produce inflammatory mediators that produce proinflammatory cytokines that block the synthesis of collagen type II and aggrecan, the major components of cartilage. Systemic administration and intraarticular injection of anti-inflammatory agents are the first-line treatments of OA. However, small anti-inflammatory molecules are rapidly cleared from the joint cavity which limits their therapeutic efficacy. To palliate this strong technological drawback, different types of polymeric materials such as microparticles, nanoparticles, and hydrogels, have been examined as drug carriers for the delivery of therapeutic agents to articular joints. The main purpose of this review is to provide a summary of recent developments in natural and synthetic polymeric drug delivery systems for the delivery of anti-inflammatory agents to arthritic joints. Furthermore, this review provides an overview of the design rules that have been proposed so far for the development of drug carriers used in OA therapy. Overall it is difficult to state clearly which polymeric platform is the most efficient one because many advantages and disadvantages could be pointed to both natural and synthetic formulations. That requires further research in the near future.