Collagen plays an important role in the formation of extracellular matrix (ECM) and development/migration of cells and tissues. Here we report the preparation of collagen and collagen hydrogel from the skin of tilapia and an evaluation of their potential as a wound dressing for the treatment of refractory wounds. The acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) were extracted and characterized using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), differential scanning calorimetry (DSC), circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR) analysis. Both ASC and PSC belong to type I collagen and have a complete triple helix structure, but PSC shows lower molecular weight and thermal stability, and has the inherent low antigenicity. Therefore, PSC was selected to prepare biomedical hydrogels using its self-aggregating properties. Rheological characterization showed that the mechanical strength of the hydrogels increased as the PSC content increased. Scanning electron microscope (SEM) analysis indicated that hydrogels could form a regular network structure at a suitable PSC content. Cytotoxicity experiments confirmed that hydrogels with different PSC content showed no significant toxicity to fibroblasts. Skin repair experiments and pathological analysis showed that the collagen hydrogels wound dressing could significantly accelerate the healing of deep second-degree burn wounds and the generation of new skin appendages, which can be used for treatment of various refractory wounds.

The pyrolysis characteristics of land biomass (corn stalks (Cs), pine sawdust (Ps)) and coastal zone biomass (Jerusalem artichoke stalks (JAs) and reed (Re)) were investigated based on thermogravimetric analysis (TGA) and products’ analysis. The kinetic parameters were obtained by three isoconversional methods (Friedman, KAS, and FWO) and one model-fitting method (DAEM). The simultaneous effect of high temperature (700–900 °C) and high heating rate (1000 °C/s) on the pyrolysis product simulating the typical conditions of a fluidized bed gasifier was studied. TGA showed that high heating rates deepen the thermal cracking process of biomass. Compared with the land biomass, the initial decomposition temperature (T_i) of the coastal biomass is reduced significantly owing to its higher proportion of hemicellulose. These methods agree with the trends shown by the activation energy (E_a) distribution calculated, with fluctuations between 160 and 350 kJ/mol. The mean value activation energies of Re and JAs were higher than those of Cs and Ps between 10% and 90% conversion. The DAEM model showed that Cs and JAs have a good linear relationship between ln A and E_α during the main pyrolysis stage, while Ps and Re are relatively weaker. The kinetic compensation effect was evident for Cs and JAs during the main thermal cracking stage. Py-GC-MS results confirmed that phenols, hydrocarbons, PAHs, and oxygen heterocycle compounds were strongly present in the released volatile products. High-temperature fast pyrolysis of JAs produced a larger amount of PAH compounds than from Cs, Ps, and Re. A larger amount of hydrocarbons and phenols was generated from high-temperature fast pyrolysis of Ps. Some oxygen-containing volatiles are easily converted into aromatic products with higher stability under high temperature.