Polyphosphoester-modified Cellulose Nanocrystals for Stabilizing Pickering Emulsion Polymerization of Styrene

Controlled biointerfaces with biomimetic phosphorus-containing polymers

Phosphorus is a ubiquitous and one of the most common elements found in living organisms. Almost all molecules containing phosphorus in our body exist as analogs of phosphate salts or phosphoesters. Their functions are versatile and important, being responsible for forming the genetic code, cell membrane, and mineral components of hard tissue. Several materials inspired from these phosphorus-containing biomolecules have been recently developed. These materials have shown unique properties at the biointerface, such as nonfouling ability, blood compatibility, lubricity, mineralization induction capability, and bone affinity. Several unfavorable events occur at the interface of materials and living organisms because most of these materials have not been designed while taking host responses into account. These unfavorable events are directly linked to reducing functions and shorten the usable periods of medical devices. Biomimetic phosphorus-containing polymers can improve the reliability of materials in biological systems. In addition, phosphorus-containing biomimetic polymers are useful not only for improving the biocompatibility of material surfaces but also for adding new functions due to the flexibility in molecular design. In this review, we describe the recent advances in the control of biointerfacial phenomena with phosphorus-containing polymers. We especially focus on zwitterioninc phosphorylcholine polymers and polyphosphoesters.

Cellulose nanocrystals: Pretreatments, preparation strategies, and surface functionalization

Cellulose nanocrystals (CNCs) have attracted great interest from researchers from academic and industrial areas because of their interesting structural features and unique physicochemical properties, such as magnificent mechanical strength, high surface area, and many hydroxyl groups for chemical modification, low density, and biodegradability. CNCs are an outstanding contender for applications in assorted fields comprehensive of, e.g., biomedical, electronic gadgets, water purifications, nanocomposites, membranes. Additionally, a persistent progression is going on in the extraction and surface modification of cellulose nanocrystals to fulfill the expanding need of producers to fabricate cellulose nanocrystals-based materials. In this review, the foundation of nanocellulose that emerged from lignocellulosic biomass and recent development in extraction/preparation of cellulose nanocrystals and different types of cellulose nanocrystal surface modification techniques are summed up. The different sorts of cellulose modification reactions that have been discussed are acetylation, oxidations, esterifications, etherifications, ion-pair formation, hydrogen bonding, silanization, nucleophilic substitution reactions, and so forth. The mechanisms of surface functionalization reactions are also introduced and considered concerning the impact on the reactions. Moreover, the primary association of cellulose and different forms of nanocellulose has likewise been examined for beginners in this field.

Particle-stabilized oil-in-water emulsions as a platform for topical lipophilic drug delivery

Low-environmental-impact emulsion systems for transdermal drug delivery in topical treatment have gained increasing interest. However, low stability and adverse systemic side effects severely decrease their efficiency. This study proposed a stable oil-in-water (O/W) emulsion loaded with bifonazole (BFZ) as a lipophilic drug stabilized by poly(2-isopropoxy-2-oxo-1,3,2-dioxaphospholane)-modified cellulose nanocrystals (CNC-g-PIPP) as vehicles for topical delivery of lipophilic drugs. We fully characterized stability, BFZ-loaded particle-stabilized emulsions (PEs) for morphology, droplet size, and its distribution. In addition, we evaluated the in vitro drug-releasing capacity and in vitro skin permeation of BFZ in a porcine skin animal model using a side-bi-side® diffusion cell. An O/W BFZ-loaded emulsion stabilized with CNC-g-PIPP particles (BFZ-loaded CP-PE) with a small mean droplet size of 2.54 ± 1.39 μm was developed and was stable for > = 15 days without a significant change in droplet size. The BFZ-loading efficiency in PEs was 83.1 %. BFZ was slowly released over an extended period, and the releasing ratio from BFZ-loaded CP-PE was only 17 % after 48 h. The BFZ-loaded CP-PE showed a ∼4.4-fold increase in BFZ permeation and penetration compared to a conventional surfactant-stabilized emulsion and BFZ control solution. Fluorescence-labeling studies showed that BFZ-loaded CP-PE could well penetrate skin layers from the stratum corneum (SC) to the dermis. In addition, histopathology studies of porcine skin treated with the PE formulation showed an intact SC with unaltered adjacent structures and no observed signs of inflammation. Therefore, the proposed CP-PE shows great potential as a transdermal drug carrier for enhancing lipophilic drug permeation.