Impact of Collagen Crosslinking on Dislocated Human Shoulder Capsules-Effect on Structural and Mechanical Properties.

Classical treatments of shoulder instability are associated with recurrence. To determine whether the modification of the capsule properties may be an alternative procedure, the effect of crosslinking treatment on the structure and mechanical properties of diseased human shoulder capsules was investigated. Joint capsules harvested from patients during shoulder surgery (n = 5) were treated or not with UV and/or riboflavin (0.1%, 1.0% and 2.5%). The structure and the mechanical properties of the capsules were determined by atomic force microscopy. The effect of treatments on cell death was investigated. Collagen fibrils were well-aligned and adjacent to each other with a D-periodicity of 66.9 ± 3.2 nm and a diameter of 71.8 ± 15.4 nm in control untreated capsules. No effect of treatments was observed on the organization of the collagen fibrils nor on their intrinsic characteristics, including D-periodicity or their mean diameter. The treatments also did not induce cell death. In contrast, UV + 2.5% riboflavin induced capsule stiffness, as revealed by the increased Young's modulus values (p < 0.0001 for each patient). Our results showed that the crosslinking procedure changed the biomechanics of diseased capsules, while keeping their structural organisation unchanged at the single fibril level. The UV/riboflavin crosslinking procedure may be a promising way to preserve the functions of collagen-based tissues and tune their elasticity for clinically relevant treatments.

Gold, Silver, and Iron Oxide Nanoparticle Incorporation into Silk Hydrogels for Biomedical Applications: Elaboration, Structure, and Properties.

Silk fibroin (SF) is a versatile material with biodegradable and biocompatible properties, which make it fit for broad biomedical applications. In this context, the incorporation of nanosized objects into SF allows the development of a variety of bionanocomposites with tailored properties and functions. Herein, we report a thorough investigation on the design, characterization, and biological evaluation of SF hydrogels incorporating gold, silver, or iron oxide nanoparticles. The latter are synthesized in aqueous media using a biocompatible ligand allowing their utilization in various biomedical applications. This ligand seems to play a pivotal role in nanoparticle dispersion within the hydrogel. Results show that the incorporation of nanoparticles does not greatly influence the mechanism of SF gelation and has a minor impact on the mechanical properties of the so-obtained bionanocomposites. By contrast, significant changes are observed in the swelling behavior of these materials, depending on the nanoparticle used. Interestingly, the main characteristics of these bionanocomposites, related to their potential use for biomedical purposes, show the successful input of nanoparticles, including antibacterial properties for gold and silver nanoparticles and magnetic properties for iron oxide ones.

Development of a novel multiphysical approach for the characterization of mechanical properties of musculotendinous tissues.

At present, there is a lack of well-validated protocols that allow for the analysis of the mechanical properties of muscle and tendon tissues. Further, there are no reports regarding characterization of mouse skeletal muscle and tendon mechanical properties in vivo using elastography thereby limiting the ability to monitor changes in these tissues during disease progression or response to therapy. Therefore, we sought to develop novel protocols for the characterization of mechanical properties in musculotendinous tissues using atomic force microscopy (AFM) and ultrasound elastography. Given that TIEG1 knockout (KO) mice exhibit well characterized defects in the mechanical properties of skeletal muscle and tendon tissue, we have chosen to use this model system in the present study. Using TIEG1 knockout and wild-type mice, we have devised an AFM protocol that does not rely on the use of glue or chemical agents for muscle and tendon fiber immobilization during acquisition of transversal cartographies of elasticity and topography. Additionally, since AFM cannot be employed on live animals, we have also developed an ultrasound elastography protocol using a new linear transducer, SLH20-6 (resolution: 38 µm, footprint: 2.38 cm), to characterize the musculotendinous system in vivo. This protocol allows for the identification of changes in muscle and tendon elasticities. Such innovative technological approaches have no equivalent to date, promise to accelerate our understanding of musculotendinous mechanical properties and have numerous research and clinical applications.

Development of novel anti-Kv 11.1 antibody-conjugated PEG-TiO2 nanoparticles for targeting pancreatic ductal adenocarcinoma cells.

Titanium dioxide (TiO2) has been widely used in many nanotechnology areas including nanomedicine, where it could be proposed for the photodynamic and sonodynamic cancer therapies. However, TiO2 nanoformulations have been shown to be toxic for living cells. In this article, we report the development of a new delivery system, based on nontoxic TiO2 nanoparticles, further conjugated with a monoclonal antibody against a novel and easily accessible tumor marker, e.g., the Kv 11.1 potassium channel. We synthesized, by simple solvothermal method, dicarboxylic acid-terminated PEG TiO2 nanocrystals (PEG-TiO2 NPs). Anti-Kv 11.1 monoclonal antibodies (Kv 11.1-Mab) were further linked to the terminal carboxylic acid groups. Proper conjugation was confirmed by X-ray photoelectron spectroscopy analysis. Kv 11.1-Mab-PEG-TiO2 NPs efficiently recognized the specific Kv 11.1 antigen, both in vitro and in pancreatic ductal adenocarcinoma (PDAC) cells, which express the Kv 11.1 channel onto the plasma membrane. Both PEG TiO2 and Kv 11.1-Mab-PEG-TiO2 NPs were not cytotoxic, but only Kv 11.1-Mab-PEG-TiO2 NPs were efficiently internalized into PDAC cells. Data gathered from this study may have further applications for the chemical design of nanostructures to be applied for therapeutic purposes in pancreatic cancer.

Ordered nanostructures on a hydroxylated aluminum surface through the self-assembly of fatty acids.

We investigate the mechanism of self-assembly of fatty acids (FA) and methyl oleate on an Al oxy-hydroxide surface with a view to deciphering the role and nature of interfacial processes (adsorption, chemical binding, molecular organization, etc.). For this purpose, we focus on parameters related to intrinsic properties of molecules, namely the level of unsaturation and the nature of the head group (carboxylic acid or ester). After the FA adsorption, the presence of coordinative bonded carboxylate species on the Al oxy-hydroxide surface is demonstrated by means of PM-IRRAS analysis. We observe that contact of methyl oleate with the surface leads to its chemical transformation through a saponification reaction. As a consequence, it binds to the surface in a manner similar to that for fatty acids. Through an innovative mode of atomic force microscopy (AFM), the organization of the adsorbed molecules is demonstrated. Our results reveal the existence of highly ordered nanostructures guided by the FA self-assembly. The size of these nanostructures was determined with accuracy, suggesting that it exceeds one FA monolayer. By contrast, no organization was observed with methyl oleate.