A Highly Selective Turn-On Biosensor for Measuring Spermine/Spermidine in Human Urine and Blood.

Spermine and spermidine serve as the key biomarkers for early-stage cancer diagnosis. This work reports a rapid, highly selective, and noninvasive sensing platform for spermine/spermidine. The hybrid material, developed in this work, has been characterized by UV-vis, IR, powder XRD, SEM, EDX, and rheological studies. Storage modulus ( G ') and loss modulus ( G ″) measurements infer that embedding boronic acid integrated coumarin softens the agarose gel fibers at room temperature. Stress resistance measurement and subsequent imaging further confirms the softness of the hybrid hydrogel over pure agarose gel and homogeneous distribution of the dye in the hybrid matrix as well. The soft hydrogel with a limit-of-detection (LOD) value of 6 μM showed a nearly 27-fold fluorescence enhancement for spermine. The hybrid hydrogel matrix can be useful within a wide concentration window (6 μM-2.5 mM spermine). Response time (≤7 s) confirms rapid detection ability of the material. Noninterference from various metal ions, common anions, monosaccharides, nucleobases, and amino acids, particularly, histidine, arginine, lysine, ornithine, glutamine, etc.,  makes the hybrid hydrogel suitable for the real-time measurement of spermine in human urinary and blood samples. Furthermore, noninterference from other biogenic amines supports the highly selective nature of the hybrid gel. The ability to measure spermine in urinary samples by the probe offers a noninvasive nature of the sensing platform. Overall, we envisioned that the hybrid material formulation would be useful for diagnosing early-stage tumors and assessing the recovery of patients undergoing chemotherapeutic treatment.