meso-2,6-Dichlorophenyltripyrrinone (TPN-Cl2), a probe molecule for zinc II ions, is dispersed in a polymer host. The red fluorescence peak at 620 nm appears when the molecule forms a complex with zinc at its center. TPN-Cl2 has a high selectivity for zinc II and tolerates many common metal ions present in the human body. The probe molecules are blended with a hydrogel polymer, poly(2-hydroxyethyl methacrylate) (poly HEMA), with 30 wt% dimethylformamide (DMF). The fiber structure with 1 μm diameter is made by electrospinning in DMF solution of the probe and poly HEMA mixture. The fibrous film detects zinc ions with concentrations as low as 10−6 M in real-time both in water and in the commonly used cell culture liquid media Dulbecco's modified Eagle medium (DMEM) and fetal bovine serum (FBS), which contain many metal ions and proteins. The time-resolution is 5 min for 10−6 M and 1 min for 10−5 M. This sensitivity and response speed satisfy the requirements for non-invasive biomedical studies.