In the present study, multifunctional core-shell fibre mats were designed by co-electrospinning. These core-shell fibre mats have three different functionalities: 1) they are magnetic, 2) they change their optical properties with the pH of the media, and 3) they are sensitive to O2. The shell is formed by a fluorescent pH-sensitive co-polymer which was previously synthesised and characterized by our research group. The core is a suspension formed by magnetic nanoparticles in a solution made up by a lipophilic indicator dye (oxygen indicator; PtOEP) and, poly-methyl methacrylate, in THF. The magnetic nanoparticles were prepared by encapsulation of magnetite within a cross-linked polymeric matrix (MMA-co-EDMA). To our knowledge, this is the first time that three functionalities (magnetic properties, sensitivity to pH, and response to O2 concentration) were successful conjugated on the same micro- or nano-material via a facile one-step process with high yield and cost effectiveness.
The morphology of the well-organized core-shell fibres were characterized by high resolution scanning electron microcopy (HRSEM), transmission electron microcopy (TEM), and confocal laser microscopy. The luminescent properties of core-shell fibre mats were analysed and successfully used for simultaneously monitoring pH (from 6 to 8) and O2, showing complete reversibility, high sensitivity (i.e., Ksv = 7.07 bar−1 for determining O2 in aqueous media), high magnetic susceptibility, and short response times.