Hongjun Yang

The effect of natural silk fibroin microparticles on the physical properties and drug release behavior of biomedical polyurethane filament

Abstract In this study, filaments comprising natural silk fibroin microparticles (NSFP) and biomedical polyurethane (BPU) were prepared via wet-spinning as a reusable-controlled drug-delivery system. The rheological properties of the spinning solution were studied to examine the effect of NSFP on the BPU/NSFP filament formation. The influences of NSFP content and spinning conditions on the morphology, molecular interactions, mechanical properties, and swelling performance of BPU/NSFP filaments were also investigated. The morphology and mechanical property studies showed that NSPF and BPU exhibit good compatibility. The capacity of the BPU/NSFP filaments as drug loading carriers and drug release behavior were studied by spectroscopy. The presence of NSFP in the drug controlled system increase the drug loading amount and enhance the drug release time. This paper presents a well-designed manufacturing method for preparing BPU/NSFP filaments with good controlled drug delivery.

Silk-based systems for highly efficient photothermal conversion under one sun: portability, flexibility, and durability

As one of the most promising techniques for harvesting solar energy, solar-powered generation of steam has great potential for application in sterilization, desalination, and other industrial processes. Although various methods of solar-powered steam generation have been reported, it remains a challenge to develop solar steam generators with durability, portability, and high photothermal performance for practical use. In this study, a novel device composed of reduced graphene oxide and silk fabric (RGO–silk-fabric) was demonstrated for highly efficient, solar-driven generation of steam. The unique fabric structure of silk and the broadband absorption by RGO allowed the RGO–silk-fabric to exhibit high light absorption in the wavelength range of 300 to 2500 nm. Benefitting from the capillary effect and superb air permeability, the RGO–silk-fabric system with a thermal insulator (polyethylene foam) exhibited remarkably high photothermal performances (an evaporation rate of 1.48 kg m−2 h−1) under one sun irradiation (1 kW m−2), even with minimal RGO content. Moreover, the RGO–silk-fabric showed great washability, flexibility, and excellent mechanical strength for low-cost, durable, and portable solar-steam applications. The simple fabrication process and scalability of the RGO–silk-fabric are expected to promote widespread application of the approach in water purification and other industrial processes.

The effect of native silk fibroin powder on the physical properties and biocompatibility of biomedical polyurethane membrane.

Naturally derived fibers such as silk fibroin can potentially enhance the biocompatibility of currently used biomaterials. This study investigated the physical properties of native silk fibroin powder and its effect on the biocompatibility of biomedical polyurethane. Native silk fibroin powder with an average diameter of 3u2009µm was prepared on a purpose-built machine. A simple method of phase inversion was used to produce biomedical polyurethane/native silk fibroin powder hybrid membranes at different blend ratios by immersing a biomedical polyurethane/native silk fibroin powder solution in deionized water at room temperature. The physical properties of the membranes including morphology, hydrophilicity, roughness, porosity, and compressive modulus were characterized, and in vitro biocompatibility was evaluated by seeding the human umbilical vein endothelial cells on the top surface. Native silk fibroin powder had a concentration-dependent effect on the number and morphology of human umbilical vein endothelial cells growing on the membranes; cell number increased as native silk fibroin powder content in the biomedical polyurethane/native silk fibroin powder hybrid membrane was increased from 0% to 50%, and cell morphology changed from spindle-shaped to cobblestone-like as the native silk fibroin powder content was increased from 0% to 70%. The latter change was related to the physical characteristics of the membrane, including hydrophilicity, roughness, and mechanical properties. The in vivo biocompatibility of the native silk fibroin powder–modified biomedical polyurethane membrane was evaluated in a rat model; the histological analysis revealed no systemic toxicity. These results indicate that the biomedical polyurethane/native silk fibroin powder hybrid membrane has superior in vitro and in vivo biocompatibility relative to 100% biomedical polyurethane membranes and thus has potential applications in the fabrication of small-diameter vascular grafts and in tissue engineering.

Effect of Silane Coupling Agent on Physical Properties of Polypropylene Membrane Reinforced by Native Superfine down Powder

In order to improve the compatibility between native superfine down powder (NSDP) and polypropylene (PP), NSPD was surface-modified by grafting with a silane coupling agent. After modification of NSDP, Fourier-Transform infrared spectrometry was used to investigate the chemical reaction between NSDP and silane coupling agent, and the spectroscopy indicated that silane coupling agent was successfully grafted onto the particle surface. Modified and unmodified NSDP was used to reinforce PP membrane by hot-press method, and the morphology, thermal properties, melt mass-flow rate and mechanical properties of PP/NSDP hybrid membrane was investigated. The melt mass-flow rate, tensile stress, and break elongation of the hybrid membranes initially increased and then decreased with the increase of silane coupling agent concentration, which significantly correlated with the silane coupling agent amount that adhered on the particle surface. Up to 3% silane coupling agent concentration was sufficient to cover the NSDP surface and improve the compatibility between PP and NSDP. With continuously increasing of silane coupling agent concentration, the melt mass-flow rate and mechanical properties decreased, which ascribed to the decreasing bonding strength of entanglement network between long-chain hydrocarbon segments on NSDP surface and PP matrix. PP/NSDP hybrid membrane with excellent thermal and mechanical properties can be obtained by controlling the silane coupling agent concentration.