No abstract

Bacterial nanocellulose (BNC) is a promising material for small-caliber artificial blood vessels, although promoting its anticoagulant properties with more rapid endothelialization would improve long-term patency. Silk fibroin nanoparticles (SFNP) were introduced into the luminal wall surface of BNC conduits both with and without heparin (Hep) through pressurization followed by fixation. Hep was introduced in two ways: (1) embedded within SF nanoparticles to form SF-HepNPs for construction of the BNC-SF-HepNP conduit and (2) chemically grafted onto BNC and BNC-SFNP to form BNC-Hep and BNC-SFNP-Hep conduits. Fourier transform infrared spectroscopy confirmed the formation of SF-HepNPs, although they did not incorporate into the fibrillar network due to their large size. Hep was successfully grafted onto BNC and BNC-SFNP, verified by toluidine blue staining. The hemocompatibility and cytocompatibility of the five samples (BNC, BNC-SFNP, BNC-SF-HepNP, BNC-Hep, and BNC-SFNP-Hep conduits) were compared in vitro. The heparinized BNC-Hep and BNC-SFNP-Hep conduits improved the anticoagulant properties, and BNC-SFNP-Hep promoted human umbilical vein endothelial cell proliferation but also controlled excessive human arterial smooth muscle cell proliferation, assisting rapid endothelialization and improving lumen patency. No significant inflammatory reaction or material degradation was observed after subcutaneous implantation for 4 weeks. Autogenous tissues were observed around the conduits, and cells infiltrated into the edges of all samples, the BNC-SFNP conduit causing the deepest infiltration, providing an appropriate microenvironment for angiogenesis when used in small-caliber blood vessel applications. Few inflammatory cells were found around the BNC-Hep and BNC-SFNP-Hep conduits. Thus, the anticoagulant properties of the BNC-SFNP-Hep conduit and its stimulation of endothelialization suggest that it has great potential in clinical applications as a small-caliber artificial blood vessel.

No abstract

The treatment for corneal damage requires donor corneal transplantation, but there is a serious scarcity of donor corneas worldwide. In this study, we aimed to design a new artificial cornea with good cytocompatibility, excellent optical properties and suture resistance, and great moisturizing properties. A new bacterial nanocellulose (BNC) membrane with anisotropic mechanical properties and high light transmission was produced in a horizontal rotary drum reactor. However, as a potential material for artificial keratoplasty, the transparency and mechanical properties of the new BNC membrane were not satisfactory. Thus, hyaluronic acid (HA) was introduced in the BNC to synthesize the BNC/HA composite membrane by using 1,4-butanediol diglycidyl ether (BDDE) as the chemical cross-linking agent. The micro-morphology, light transmittance, mechanical properties, water content, moisture retention ability, and cytocompatibility of the composite membranes were further evaluated. HA was fixed in the BNC network by the ether bond, and the composite membrane was found to have excellent light transmittance (up to 95.96%). The composite membrane showed excellent mechanical properties, for instance, its tensile strength exceeded the human normal intraocular pressure (IOP) (1.33–2.80 kPa), the maximum burst pressure was about 130 kPa, 46–97 times that of the normal IOP, and its suture force was close to that of the human amniotic membrane (0.1 N). Based on the three-dimensional network scaffold of BNC and the high water absorption characteristics of HA, the artificial cornea had high water content and high moisture retention ability. The rabbit corneal stromal cells cultured in vitro showed that the artificial cornea substitute had excellent cytocompatibility. BDDE is the most frequently used cross-linker in most HA products in the current cosmetic medicine industry owing to its long-term safety records for over 15 years. Therefore, the BNC/HA composite hydrogel cross-linked with BDDE has great potential in artificial keratoplasty or ocular surface repair.

Polycarboxylate ether (PCE) with different main chain structures was prepared by aqueous solution free radical polymerization using unsaturated acids containing sulfonic acid groups, acrylamide groups, and carboxyl groups and isoprenyl polyoxyethylene ether (IPEG). The molecular structure was characterized by infrared spectroscopy and gel chromatography, while adsorption, dispersion, and hydration properties were studied using a total organic carbon analyzer, rheometer, and isothermal microcalorimeter, respectively. The results show that the adsorption process of PCE on cement particles is spontaneous physical adsorption. The adsorption forces are mainly electrostatic interaction, and hydrogen bonding. The introduction of sulfonic acid groups and polycarboxylic acid groups reduces the initial adsorption amount of PCE but can accelerate the adsorption rate of PCE on cement and increase the adsorption amount at the adsorption equilibrium. The introduction of acrylamide groups in the PCE main chain is beneficial to the initial dispersion of PCE and can reduce the plastic viscosity of cement slurry. PCE can delay the hydration of cement. The introduction of acrylamide groups and dicarboxylic acid groups in the PCE main chain helps prolong the induction period of cement hydration, while the introduction of sulfonic acid groups is not conducive to its retarding effect.