The Preparation And Application Of Fluorescent Keratin Nanofibers Mats

The regeneration and recycling of wastes have been highly valued in recent years, abandoned human hair in barber shop was collected and dissolved with L-cystein/urea system to get the regenerated human hair keratin powder in this paper, which could be applied in environment engineering. Three parts in this paper were implemented as followed:?1? The optimal conditions in L-cystein/urea system were designed into single factor experiments, including dissolution time, temperature, pH value, L-cystein and urea concentrations. It has been proved that the dissolution ratio of human hair is increased and the extraction ratio of regenerated human hair keratin has the maximum value with the higher of reaction conditions, while the variation tendency is contrary in experiment of urea concentration. The optimal condition is 5 g broken human hair is put into 100 ml solution with 0.248 M L-cystein and 2 M urea for 10 hours in 85?, and the pH value of solution is 12. The dissolution ratio and extraction ratio in this condition is 91.46% and 54.14%, respectively. And the human hair keratin contains 17 kinds of amino acids and the average molecular weight is 36 kDa, In addition, FTIR-ATR?XRD?Raman and C spectra tests of human hair and the regenerated kerain were implemented, and the analysis above illustrated that the ?-helix structure was turned into ?-sheet structure partly during the extraction.?2? The regenerated human hair powder was used to prepare nanofibers mats with polycaprolactone. With the increasing of keratin content from 0 to 60%, the conductivity of polymer solutions was changed from 0.098 ms·cm-1 to 2.38 ms·cm-1, the viscosity of polymer solutions was decreased from 1665.6 mPa·s to 230.32 mPa·s, the resulting diameter of nanofibers was decreased from 365nm to 85nm. In addition, the application properties, including tensile and contact angle, were tested, the obtained data proved that the adding of keratin could decrease the breaking strength from 12.91 MPa to 2.31 MPa and the broken elongation from 99.4% to 23%, while the hydrophilicity of mats were improved greatly about 39.25°at the initial state and infiltrated totally after 20 s. What's more, the thermal stability of nanofibers was increased with the higher keratin content, the fastest degradation temperature was from 410? turned to 396? and the speed also decreased about 8.33%/min. To get more knowledge of this change, XRD and FTIR-ATR analysis were applied here to compare the hydrogen bonds and degree of crystallinity, it was obvious that increased hydrogen bonds and decreased degree of crystallinity have crucial effect to the decreased tensile. Finally, the regeneraed human hair keratin content in the nanofiber was selected to 40%.?3? The fluorescent ZnO QDs ?10 nm? was synthesized by sol-gel method, and the emission was at 540 nm excited by 350 nm. The fluorescent keratin nanofibers mats were prepared by supersonic adsorption of 0.05 M ZnO QDs on the nanofibers surface for 5 min. After adsorption of ZnO QDs, the morphology and crystallinity of nanofibers was stayed well and the contact angle was much better with rough surface. By EDS testing, the proportion of Zn is 11.65%. To study the optical properties of fluorescent nanofibers mats, UV-Vis was applied and the curves showed two absorption peaks, which are located at 360 nm attributed to ZnO NPs and 280 nm attributed to C=O of PCL. In addition, the fluorescent mats were immersed in different concentrations of Pb²⁺ and Sb²⁺ solutions to observing the variation of fluorescence. The results showed that fluorescence was disappeared at 10 ppm (Pb²⁺ pH=3.01) and 100 ppb (Sb²⁺, pH=2.69), which means that the prepared fluorescent keratin nanofibers mats have potential in metal ions detection.