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Microfiber (MF) has a similar structure to natural leather. Four rare earth (RE) elements, La, Ce, Gd, and Er, were loaded onto the surface of microfibers through plant tannins to prepare a wearable microfiber-based X-ray shielding material (RE-MF), and the X-ray shielding performance was tested. The analysis results of ultraviolet absorption spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) indicate that the rare earth elements can be uniformly loaded onto the surface of ultrafine fibers using plant tannins. The test results of X-ray shielding performance show that within the photon energy of 100 keV, the microfiber materials loaded with four rare earth elements have good X-ray shielding performance, and the shielding efficiency is increased with the increase of the loading amount of rare earth element and the thickness of microfiber. In the 20-80 keV energy range, the shielding efficiency of 2.6 mm Gd4-MF is up to 60% against X-rays, nearly equal to that of 0.25 mm lead plate but with non-toxicity, softness and wearability features. The test results of mechanical properties show that the microfiber-based X-ray protective material maintains the original good mechanical properties of microfibers, and is expected to be widely used in the field of X-ray protection.

Fe (III) modified collagen fibers were used to immobilize catalase through the cross-linking of glutaraldehyde. The loading amount of catalase on the supporting matrix was 16.7 mg/g, and 35% enzymatic activity was remained. A series of experiments were conducted on free and immobilized catalase in order to investigate their optimal pH and temperature, and the thermal, storage and operation stability. Results suggest that the free and immobilized catalase prefer similar pH and temperature condition, which were pH 7.0 and 25 degrees C. It should be noted that the thermal stability of catalase was considerably improved after immobilization owing to the fact that the enzyme kept 30% of relative activity after incubation at 75 degrees C for 5 h. On the contrary, the free catalase was completely inactive. As for the storage stability, the immobilized catalase kept 88% of relative activity after stored at room temperature for 12 days while the free one was completely inactive under the same conditions. Moreover, the immobilized catalase preserved 57% of relative activity after being reused 26 times, exhibiting excellent operation stability. Consequently, this investigation suggests that collagen fiber can be used as excellent supporting matrix for the immobilization of catalase, and it is potential to be used for the immobilization of similar enzymes.

Objective: To investigate the selective removal of tannins from Polygonum cuspidatum extracts by using collagen fiber adsorbent, and to evaluate the adsorption and desorption performances of collagen fiber adsorbent to tannins., Method: The adsorbent was prepared from bovine skin collagen fiber through crosslinking reaction of glutaraldehyde, and then used for the selective removal of tannins from P. cuspidatum extracts. Gelatin-turbidity method, gelatin-ultraviolet spectrometry method and HPLC were used for detection of tannins in the solutions. Ethanol-water solutions with varying concentration were used to test their desorption ability of tannins in order to choose proper desorption solution. On the basis of batch experimental results, the column adsorption and desorption tests were carried out, by using gelatin-turbidity method for detection of tannins., Result: The collagen fiber adsorbent exhibited excellent adsorption selectivity to tannins. It was found that tannins of P. cuspidatum were completely removed, while nearly no adsorption of active components (resveratrol as representative) was found. Moreover, the collagen fiber adsorbent could be regenerated by using 30% ethanol-water solution and then reused., Conclusion: The collagen fiber adsorbent can be considered as a promising material for selective removal of tannins from P. cuspidatum extracts.