Photopolymerized maleilated chitosan/methacrylated silk fibroin micro/nanocomposite hydrogels as potential scaffolds for cartilage tissue engineering

Hydrogels composed of natural materials exhibit great application potential in artificial scaffolds for cartilage repair as they can resemble the extracellular matrices of cartilage tissues comprised of various glycosaminoglycan and collagen. Herein, the natural polymers with vinyl groups, i.e. maleilated chitosan (MCS) and methacrylated silk fibroin (MSF) micro/nanoparticles, were firstly synthesized. The chemical structures of MCS and MSF micro/nanoparticles were investigated using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then MCS/MSF micro/nanocomposite hydrogels were prepared by the photocrosslinking of MCS and MSF micro/nanoparticles in aqueous solutions in the presence of the photoinitiator Darocur 2959 under UV light irradiation. A series of properties of the MCS/MSF micro/nanocomposite hydrogels including rheological property, equilibrium swelling, sol content, compressive modulus, and morphology were examined. The results showed that these behaviors could be tunable via the control of MSF content. When the MSF content was 0.1%, the hydrogel had the compressive modulus of 0.32±0.07MPa, which was in the range of that of articular cartilage. The in vitro cytotoxic evaluation and cell culture of the micro/nanocomposite hydrogels in combination with mouse articular chondrocytes were also investigated. The results demonstrated that the micro/nanocomposite hydrogels with TGF-β1 was biocompatible to mouse articular chondrocytes and could support cells attachment well, indicating their potential as tissue engineering scaffolds for cartilage repair.This study was supported by National Natural Science Foundation of China (Grant No. 51203123, 51403165, 51503161) and the National Key Research and Development Program of China (No.2016YFA0101102)

Effect of Crystallization on Shape Memory Effect of Poly(lactic Acid)

The opportunity for the preparation of high-performance shape memory materials was brought about by the excellent mechanical properties of poly(lactic acid) (PLA). As the effect of crystallization on shape memory was still unclear, this brings constraints to the high-performance design of PLA. The PLA plates with different aggregation structure were prepared by three kinds of molding methods in this paper. The PLA plates were pre-stretched with a series of different strains above glass transition temperature (i.e., 70 °C). The recovery stress and ratio of the material were measured above stretching temperature (i.e., 80 °C). Prolonging of annealing time resulted in more perfect crystal structure and higher crystallinity. The crystal region acted as network nodes in shape memory PLA, and crystal region structure determined the shape memory performance. Based on the experimental results, the structural evolution of network nodes in shape memory PLA was established

Functional hydrogel dressings for wound management: a comprehensive review

Hydrogels have gained significant attention as wound dressings due to their potential for rapid healing. Researchers have actively explored a range of techniques for antimicrobial applications, including incorporating drug payloads, utilizing inorganic nanometals, and harnessing the properties of natural cationic polymers. In terms of hemostasis and coagulation promotion, techniques such as drug delivery, adhesive physical hemostasis, and adhesive functional groups have been studied. To control inflammation, researchers have investigated the application of natural antioxidants and antioxidant functional groups, which have demonstrated anti-inflammatory effects. Furthermore, the smart responsiveness of hydrogel wound dressings to pH, temperature, and light has been explored. This review presents a summary of the research progress and application prospects in these areas and offers an outlook on the future development direction of hydrogel wound dressings

Poly(lactic acid) toughen by aromatic sulfonamide toward balanced rheology processing and mechanical properties

The inherent brittleness of poly(lactic acid) (PLA) usually limits its application in the high ductile requirements sector. To address the above issue, n-ethyl-p-toluenesulfonamide (N-PTSA) as the toughening agent, was utilized to optimize the rheological and mechanical performance of the PLA matrix. The microstructure, thermal stability, rheological behavior, and mechanical properties of PLA/N-PTSA were systematically investigated. A rheological test showed that N-PTSA can reduce the melt processing viscosity of PLA matrix and the decreasing of processing viscosity strongly depended on the N-PTSA content rather than shear rate. Mechanical properties results confirmed that the 14.7% N-PTSA can improve the toughness of PLA/N-PTSA without deteriorating the tensile strength and Yong’s modulus. This reason was ascribed to the reduction of hydrogen bonds of PLA matrix caused by N-PTSA to accelerate the movement of PLA molecular chain meanwhile forming new hydrogen bond between PLA and N-PTSA. By adding N-PTSA, the thermal stability of PLA was decreased. With the synergistic effect of plasticizing and toughening N-PTSA, the rheology and mechanical properties of PLA had been effectively improved

Nanoscale zero-valent iron/persulfate enhanced upflow anaerobic sludge blanket reactor for dye removal: Insight into microbial metabolism and microbial community

Specifičnost sporta u širem smislu je iz razloga što je moguć za sve osobe, bez obzira na zdravstveni i antropološki status, dob, spol, rasu ili bilo koji drugi kriterij i usmjeren je na uspješnost. Na temelju te specifičnosti može poslužiti kao odlična marketinška platforma za sportaše. Veliku važnost u uspješnosti sportaša ima i sam imidž. Problem ovoga rada može se definirati kao korištenje imidža sportaša za postizanje sportskih i ekonomskih rezultata i različitih vrijednosti uz skriveni i negativan kontekst za sportskog potrošača. Cilj rada je pobliže istaknuti težinu i važnost imidža sportaša, ali sa specifičnim naglaskom na negativne kontekste pojedinih sportaša koji su to iskoristili. Može se reći kako su pojedini vrhunski sportaši koristili svoj teško stečeni imidž, na kojem su zaradili velika priznanja i prihode, kako bi se zaštitili i zavarali sportske potrošače.The specificity of sport in the broader sense is because it is possible for all people, regardless of health and anthropological status, age, gender, race or any other criterion and is aimed at success. Based on that specificity, it can serve as an excellent marketing platform for athletes. The very importance of athletes' success is also the image itself. The problem of this work can be defined as the use of athlete's image to achieve sporting and economic results and different values with a hidden and negative context for a sports consumer. The aim of the paper is to outline the weight and importance of athletes' images, but with a specific focus on the negative contexts of individual athletes who have used it. It can be said that some top athletes used their hard-earned image, earning big prizes and revenue to protect and bother sports consumers

High-Performance Photopolymerized Poly(vinyl alcohol)/Silica Nanocomposite Hydrogels with Enhanced Cell Adhesion

Poly(vinyl alcohol) (PVA) hydrogels have been considered as promising implants for various soft tissue engineering applications because of their tissue-like viscoelasticity and biocompatibility. However, two critical barriers including lack of sufficient mechanical properties and non-tissue-adhesive characterization limit their application as tissue substitutes. Herein, PVA is methacrylated with ultralow degrees of substitution of methacryloyl groups to produce PVA-glycidyl methacrylate (GMA). Subsequently, the PVA-GMA/methacrylate-functionalized silica nanoparticle (MSi)-based nanocomposite hydrogels are developed via the photopolymerization approach. Interestingly, both PVA-GMA-based hydrogels and PVA-GMA/MSi-based nanocomposite hydrogels exhibit outstanding compressive properties, which cannot be damaged through compressive stressstrain tests in the allowable scope of a tensile tester. Moreover, PVA-GMA/MSi-based nanocomposite hydrogels demonstrate excellent tensile properties compared with neat PVA-GMA-based hydrogels, and 15-, 14-, and 24-fold increase in fracture stress, elastic modulus, and toughness, respectively, is achieved for the PVAGMA/MSi-based hydrogels with 10 wt % of MSi. These remarkable enhancements can be ascribed to the amount of long and flexible polymer chains of PVA-GMA and the strong interactions between the MSi and PVA-GMA chains. More interestingly, exciting improvements in the cell adhesion can also be successfully achieved by the incorporation of MSi nanoparticles.This study was supported by the National Key Research and Development Program of China (no. 2016YFA0101102) and Natural Science Foundation of Hubei Province (no. 2018CFB685). P.X. acknowledges funding from the Australian Research Council Future Fellowship (FT170100301)

Confined Crystallization of Pigment Red 146 in Emulsion Droplets and Its Mechanism

In this work, the effect of confined space on crystallization processes of pigments was investigated by using C.I. Pigment Red 146 (PR 146) as a model compound. The colloidal system (i.e., emulsion droplets) was used as a nanoreactor to prepare nanoscale PR 146 for the inkjet printer. The effects of the space confinement were investigated by comparing the products of PR 146 prepared from bulk solution, macroemulsion, and miniemulsion. The results showed that PR 146 crystallized in mini-emulsion had the narrowest particle size distribution and the average particle size can be as small as 172.5 nm, one order of magnitude smaller than the one obtained from the bulk solution. X-ray diffraction (XRD) data revealed that PR 146 crystallized in all three solutions where the crystalline state and had similar crystallite sizes. The process mechanism of crystallization confined in the miniemulsion droplets was proposed and explained. The function mechanism of the co-stabilizer during the crystallization of PR 146 in emulsion was also explained. It was found that sodium chloride could counteract the pressure difference as an osmotic pressure agent and prevent the migrating of water from small droplets into big droplets. The influences of dosages of emulsifiers and co-stabilizers on droplet size and the size of the obtained PR 146 particles were evaluated and the optimal conditions were determined. Furthermore, the disparity of PR 146 products prepared by different methods was investigated by UV–Vis spectra. The aqueous dispersion of PR 146 crystallized in miniemulsion had the highest absorbance and darkest color