Tomoki Maeda

A nanocomposite approach to develop biodegradable thermogels exhibiting excellent cell-compatibility for injectable cell delivery

A new class of injectable nanocomposite thermogels having excellent cell-compatibility were developed through cooperative self-assembly of biodegradable poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) copolymer micelles and clay nanosheets for effective cell delivery. This study will be valuable for the establishment of injectable cell delivery technology.

Effects of salt concentrations of the aqueous peptide-amphiphile solutions on the sol-gel transitions, the gelation speed, and the gel characteristics

Hydrogels made of peptide amphiphiles (PA) have attracted a lot of interest in biomedical fields. Considering the applications of PA hydrogels, the control of the gelation speed and the gel characteristics is essential to predominantly determine the usefulness and practicability of the hydrogels. In this work, the effects of the salt concentrations using sodium dihydrogenorthophosphate (NaH2PO4) on the sol-gel transition behaviors, especially the gelation speed and the gel characteristics of the designed PA (C16-W3K) hydrogels in aqueous solution were discussed. It was found that the original solution state before rheological testing was independent of the salt concentration, which was confirmed by observing the self-assembly structures and the peptide secondary structures of PA through transmission electron microscopy (TEM) and circular dichroism spectroscopy (CD). The PA solutions with different salt concentrations, however, presented a profound difference in the gelation speed and the gel characteristics: the solution exhibited higher gelation speeds and higher mechanical properties at higher salt concentrations. Concurrently, the density, the length of wormlike micelles, and the conformational ratio of β-sheets to α-helices in the equilibrium PA solutions all increased with the increase in the salt concentrations.

Highly Functionalized Polyethylene Terephthalate for Food Packaging

Abstract Polyethylene terephthalate (PET) is a remarkably balanced material for beverage containers and food packaging with required mechanical and barrier properties. However, to contain tasteful beverages such as beer, fresh juice, and wine, the original barrier property of PET is not yet sufficient. Additionally, for the eco-friendly use of PET by reducing the thickness of PET bottles or PET films, which would lead to a decrease in the consumption of PET resins, the mechanical properties of PET should be enhanced. In this chapter, the backgrounds of PET-based packaging and its requirements will be summarized and discussed regarding the industrial applications of PET. In consequence, two different approaches to improve the mechanical and the barrier properties of PET for food packaging were introduced: thin-film coating for the effective improvement of the barrier properties, and nanofiller blending for the enhancement of the barrier and the mechanical properties of PET.

Electrospinning and surface modification methods for functionalized cell scaffolds

Abstract For tissue engineering scaffolds, fibrous structures are effective due to morphology similar to that of extracellular matrix. Cell attachment and its proliferation could be enhanced by the structural optimization and the surface modification of the scaffolds. In this chapter, effective techniques for making optimal scaffolds, including electrospinning and surface modification methods, will be discussed. Electrospinning is a process whereby polymer nanofibers can be formed in an electrostatic field. The nanoscale diameter and the high porosity of the electrospun scaffolds—that actually resemble the structure of the extracellular matrices—can provide favorable environment for cells. Moreover, the addition of desirable functionalities to the scaffolds by surface modification techniques, such as plasma treatment and surface graft copolymerization, offers considerable advantages, eventually enhancing cell attachment and cell proliferation. We will discuss several successful cases made via well-controlled structures and surfaces that will lead to form new highly functionalized scaffolds.

In vitro basic fibroblast growth factor (bFGF) delivery using an antithrombogenic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer coated with a micropatterned diamond-like carbon (DLC) film

In this study, a newly designed drug-release platform composed of an antithrombogenic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer was introduced, which was impregnated with basic fibroblast growth factor (bFGF) (bFGF/MPC polymer) to enhance the endothelial cell activation. The platform was also coated with an ultrathin micropatterned diamond-like carbon (DLC) film (DLC/bFGF/MPC polymer) to precisely control the drug release rate and the cell compatibility. The resulting DLC/bFGF/MPC polymer could effectively prolong the bFGF release rate by depositing the micropatterned DLC. The number of adherent platelets on the DLC/bFGF/MPC polymer was significantly lower (about 1/14) than that on a currently used stent made of stainless steel (SUS316L), indicating the enhanced antithrombogenicity in the DLC/bFGF/MPC polymer. The proliferation of endothelial cells on the DLC/bFGF/MPC polymer and the DLC/MPC polymer (without bFGF) were also examined. It was found that the optical density of HUVEC on the DLC/bFGF/MPC polymer determined by WST-8 assay was higher by 25%than that on the DLC/MPC polymer (without bFGF) measured after 72 h of incubation. Our results suggest that the released bFGF that contributes to the expression of other growth factors results in the early proliferation of the HUVEC on the DLC/bFGF/MPC polymer.

Polymer Surface Modifications by Coating

Fine printing on polymers can be realized by controlling the wettability of the polymeric surface, which can be efficiently conducted by coating through the modification of the surface with another material. Synthesizing a material on polymers is often very challenging highly due to the low thermal durability of the polymers. Therefore, selecting good coating methods and considering coating materials and polymers are indispensable. The coating methods are normally categorized as organic, inorganic, and metallurgical coatings. In more detail, the photo-grafting polymerization, the initiated chemical vapor deposition, and the UV-curable coatings are utilized for organic coatings on polymers. The plasma-enhanced chemical vapor deposition and the magnetron sputtering are used as inorganic coatings, while the electroless plating and the vapor deposition are employed in metallurgical coatings. Each method for the coatings on polymers are discussed and overviewed.