Tpps Porphyrin as a Fluorescent Probe for Detection of Aminoglycoside Antibiotics and Their Photocatalytic Applications for the Degradation of Rhodamine B Dye

The meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) porphyrin was successfully synthesized and applied as a selective turn-off sensor for the detection of neomycin and gentamicin antibiotics in aqueous media. The sensing ability of TPPS porphyrin was studied by naked eye detection as well as UV-Vis absorption and fluorescence spectroscopy. The emission intensity of TPPS porphyrin was observed to be decreased dramatically upon addition of neomycin and gentamicin antibiotics. The quantum yield of TPPS porphyrin (56%) also decreases upon addition of neomycin (2%) and gentamycin (9%). The quenching efficiency of neomycin and gentamicin towards the TPPS porphyrin was 99.13% and 96% respectively. The detection limit was calculated to be 7.5×108 M and 1.1×107 M for gentamicin and neomycin respectively, indicating both the antibiotics exhibited efficient quenching abilities. Moreover, the self-assembly of TPPS porphyrin with gentamicin antibiotic have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and FT-IR spectroscopy. Interestingly, TPPS porphyrin with 0-10 equiv. of gentamicin, produces nanorod-like structures. The key driving force for the formation of self-assembled nanostructure of TPPS porphyrin with gentamicin is H-bonding between sulfonate group of TPPS and -NH2 and -OH group of gentamicin. The-self-assembled nanostructure exhibited band gap energy in the range of 2.7 to 3 eV, therefore, for practical application we employed these nanostructures as a photocatalyst for the degradation of RhB dye. Interestingly, nanostructure obtained from 1:2 equiv. of TPPS: gentamicin showed excellent photocatalytic performance, degraded almost 100% of RhB dye in aqueous media upon 240 min. simulated visible light irradiation with rate constant of 2×10-2 min-1. A possible mechanism for the photodegradation of RhB using nanorod like structure is also presented.