Preparation of Polyvinyl Alcohol Fluorescent Nanofiber Mats Modified by Hyperbranched Poly (Phenylalanine-Lysine) via Electrospinning for Metal Ions Detection

Hyperbranched poly (phenylalanine-lysine) (HBPL) is obtained by phenylalanine and lysine and then mixed with Polyvinyl Alcohol (PVA) polymer to electrospin PVA/HBPL fluorescent nanofiber mats (FNM), which is an excellent sensing material for Cu2+ ions in aqueous solutions. In this work, the relationship between mechanical properties, fluorescent properties and the sensing for Cu2+ ions of PVA/HBPL FNM are investigated. PVA/HBPL FNM with different mass ratio of PVA and HBPL are characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), fluorescence spectrum and tensile tester. To further improve the water solubility of PVA/HBPL FNM, thermally cross-linking (TCL)-PVA/HBPL FNM is fabricated. The results indicate that the neat PVA FNM couldn't emit fluorescence under any excitation wavelength, whereas the PVA/HBPL FNM emit blue fluorescence green fluorescence when the irradiation of the excitation wavelength is at 330-385 nm and 450-480 nm, respectively. The tensile strength and Young's modulus of PVA/HBPL FNM are 8.67 MPa and 342.92 MPa, respectively, which suggested 43.1% and 242.7% than that of neat PVA NM. Furthermore, the solubility rate of TCL-PVA/HBPL FNM is significantly decreased in comparison of FNM in absent of cross-linking. It's worth noting that TCL-PVA/HBPL FNM possessed higher recognition than other mental ions and could be used as metal ion detection sensor to combine with Cu2+. Moreover, it represented a linear relationship between the fluorescence intensity and the concentration of Cu2+ in the range of 5 mu M to 100 mu M. The fabricated TCL-PVA/HBPL FNM exhibit high mechanical and fluorescence properties, which make it be potentially envisaged for heavy metal ions detection sensor.

Automated summary

In this study, PVA/HBPL fluorescent nanofiber mats (FNM) were fabricated by synthesizing Hyperbranched poly (phenylalanine-lysine) (HBPL) and mixing it with Polyvinyl Alcohol (PVA). The mechanical and fluorescent properties of PVA/HBPL FNM were investigated, as well as its sensing ability for Cu2+ ions. Different mass ratios of PVA and HBPL were characterized, and PVA/HBPL FNM showed higher tensile strength and Young's modulus compared to neat PVA NM. Furthermore, thermally cross-linked (TCL)-PVA/HBPL FNM with improved water solubility was fabricated. The results demonstrated that TCL-PVA/HBPL FNM exhibited excellent recognition for Cu2+ ions and a linear relationship between fluorescence intensity and Cu2+ concentration in a certain range. Therefore, this study has significant potential for applications in heavy metal ion detection sensors.