Biomacromolecules

Three-dimensional (3D) bioprinting offers a great alternative to traditional techniques in tissue reconstruction, based on seeding cells manually into a scaffold, to better reproduce organs' complexity. When a suitable bioink is engineered with appropriate physicochemical properties, such a process can advantageously provide a spatial control of the patterning that improves tissue reconstruction. The design of an adequate bioink must fulfill a long list of criteria including biocompatibility, printability, and stability. In this context, we have developed a bioink containing a precisely controlled recombinant biopolymer, namely, elastin-like polypeptide (ELP). This material was further chemoselectively modified with cross-linkable moieties to provide a 3D network through photopolymerization. ELP chains were additionally either functionalized with a peptide sequence Gly-Arg-Gly-Asp-Ser (GRGDS) or combined with collagen I to enable cell adhesion. Our ELP-based bioinks were found to be printable, while providing excellent mechanical properties such as stiffness and elasticity in their cross-linked form. Besides, they were demonstrated to be biocompatible, showing viability and adhesion of dermal normal human fibroblasts (NHF). Expressions of specific extracellular matrix (ECM) protein markers as pro-collagen I, elastin, fibrillin, and fibronectin were revealed within the 3D network containing cells after only 18 days of culture, showing the great potential of ELP-based bioinks for tissue engineering

Refining the Design of Diblock Elastin-Like Polypeptides for Self-Assembly into Nanoparticles

Diblock copolymers based-on elastin-like polypeptide (ELP) have the potential to undergo specific phase transitions when thermally stimulated. This ability is especially suitable to form carriers, micellar structures for instance, for delivering active cargo molecules. Here, we report the design and study of an ELP diblock library based on ELP-[M1V3-i]-[I-j]. First, ELP-[M1V3-i]-[I-j] (i = 20, 40, 60; j = 20, 90) that showed a similar self-assembly propensity (unimer-to-aggregate transition) as their related monoblocks ELP-[M1V3-i] and ELP-[I-j]. By selectively oxidizing methionines of ELP-[M1V3-i] within the different diblocks structures, we have been able to access a thermal phase transition with three distinct regimes (unimers, micelles, aggregates) characteristic of well-defined ELP diblocks.Nanomedicine: an integrative approac

Annealing and biasing effects on the structural and optical properties of PECVD-grown TiO2 films from TTIP/O2 plasma

International audienceThis work presents a study of the structural, morphological, and optical properties of titanium dioxide thin films prepared via plasma enhanced chemical vapour deposition at the floating potential (Vf) or substrate bias (Vb) of − 10 and − 50 V, after being submitted to annealing processes varying the temperature from 450 to 850 °C. By tuning the annealing temperature and substrate bias voltage respectively, which could be helpful for the explanation about the thermal effect and the influence of ion bombardment on TiO2 films obtained from low-temperature plasma deposition. The results have shown that the TiO2 thin films grown at Vf and − 10 V persist in the anatase phase even after annealing at 850 °C. The phase transformation from anatase to rutile occurred in the case of − 50 V, and the crystallization enhancement has been identified as the annealing temperature increased. From scanning electron microscopy measurements, the formation of gradient columnar morphology was also perceived in the cases of Vf and − 10 V, with increasing annealing temperature at 850 °C, these structures disappear transforming into homogeneous columns with larger size at Vf and granular structure at − 10 V. In the case of − 50 V, a well-organized columnar morphology has been found in the as-deposited film, and it also can be modified into granular structure with the post-annealing effect at 850 °C but without thickness reduction. Spectroscopic ellipsometry (SE) study was used to determine the effect of annealing temperature on the thickness and on the optical constant of TiO2 thin films. SE shows that the band gap of TiO2 thin films was found to decrease when the annealing temperature increases. Meanwhile, the annealing temperature of 450 °C leads to a decrease of refractive indices of the films grown at Vf and − 10 V, but has no effect on the film of − 50 V. Then further increase of annealing temperature at 850 °C, an improvement of refractive indices can be identified for all the films deposited with various bias voltages

Thermosensitive Hybrid Elastin-like Polypeptide-Based ABC Triblock Hydrogel

We report the synthesis of a well-defined hybrid ABC triblock terpolymer containing a synthetic poly(trimethylene carbonate) (PTMC) block A and a thermosensitive BC diblock of recombinant elastin-like polypeptides (ELPs). The triblock in diluted solution (0.1–0.3% w/v), at low temperatures in ultrapure water, forms micellar structures of 10–60 nm sizes in diameter as characterized by dynamic light scattering (DLS) and liquid atomic force microscopy (AFM). While heated above its transition temperature (Tt), larger particles of 200–300 nm sizes are obtained, consistent with the formation of coacervates. When concentrated, the viscosity of the triblock copolymer solution progressively increases, giving a free-standing gel at 4% w/v formed by a network of micron-sized particles. The formed hydrogels are thermally reversible, and their sol–gel transitions are fast and sharp. The gel formation mechanism appears to interestingly biomimic tropoelastin, the native monomeric form of natural elastin, as demonstrated by optical and cryogenic-scanning electron microscopy (cryo-SEM) imaging

Chromosomal assignment of seven rat homeobox genes to rat chromosomes 3, 4, 7, and 10.

Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.info:eu-repo/semantics/publishe