Ciprofloxacin is one of the most prescribed antibiotics in treating bacterial infections, becoming an important pollutant of the wastewaters. Moreover, ciprofloxacin is hard to be destroyed by conventional water treatment processes; therefore, efficient treatments to destroy it are needed in water decontamination. This study offers insights into the performance of 266 nm laser beams on the photodegradation of ciprofloxacin. An Nd:YAG laser was used that emitted 266 nm at an energy of 6.5 mJ (power of 65 mW) and ciprofloxacin water solutions were irradiated up to 240 min. The irradiated solutions were investigated by UV-Vis and FTIR absorption spectroscopy, pH assay, and laser-induced fluorescence. An HPTLC densitometer was used to characterize the laser-induced fluorescence and fluorescence lifetime of photodegradation products. The UV-Vis absorption, FTIR, and laser-induced fluorescence spectra showed the degradation of ciprofloxacin. Moreover, HPTLC densitometry offered the fluorescence and fluorescence lifetime of ciprofloxacin and its three photoproducts as well as their relative quantification. From the FTIR spectra, the molecular structure of two out of three photoproducts was proposed. In conclusion, the laser irradiation method provided the efficient photodegradation of ciprofloxacin, whereas the analytical techniques offered the proper means to monitor the process and detect the obtained photoproducts.

The purpose of this study was to investigate the effectiveness in photodynamic therapy of iron oxide nanoparticles (γ-Fe₂O₃ NPs), synthesized by laser pyrolysis technique, functionalized with 5,10,15,20-(Tetra-4-sulfonatophenyl) porphyrin tetraammonium (TPPS) on human cutaneous melanoma cells, after only 1 min blue light exposure. The efficiency of porphyrin loading on the iron oxide nanocarriers was estimated by using absorption and FTIR spectroscopy. The singlet oxygen yield was determined via transient characteristics of singlet oxygen phosphorescence at 1270 nm both for porphyrin functionalized nanoparticles and rose bengal used as standard. The irradiation was performed with a LED (405 nm, 1 mW/cm²) for 1 min after melanoma cells were treated with TPPS functionalized iron oxide nanoparticles (γ-Fe₂O₃ NPs_TPPS) and incubated for 24 h. Biological tests revealed a high anticancer effect of γ-Fe₂O₃ NPs_TPPS complexes indi-cated by the inhibition of tumor cell proliferation, reduction of cell adhesion, and induction of cell death through ROS generated by TPPS under light exposure. The biological assays were combined with the pharmacokinetic prediction of the porphyrin.

This study presents the spectral characterization of TiO₂ nanoparticles (NPs) functionalized with three porphyrin derivatives: 5,10,15,20-(Tetra-4-aminophenyl) porphyrin (TAPP), 5,10,15,20-(Tetra-4-methoxyphenyl) porphyrin (TMPP), and 5,10,15,20-(Tetra-4-carboxyphenyl) porphyrin (TCPP). UV-Vis absorption and Fourier transform infrared spectroscopy–attenuated total reflection (FTIR-ATR) spectroscopic studies of these porphyrins and their complexes with TiO₂ NPs were performed. In addition, the efficiency of singlet oxygen generation, the key species in photodynamic therapy, was investigated. UV-Vis absorption spectra of the NPs complexes showed the characteristic bands of porphyrins. These allowed us to determine the loaded porphyrins on TiO₂ NPs functionalized with porphyrins. FTIR-ATR revealed the formation of porphyrin-TiO₂ complexes, suggesting that porphyrin adsorption on TiO₂ may involve the pyrroles in the porphyrin ring, or the radicals of the porphyrin derivative. The quantum yield for singlet oxygen generation by the studied porphyrin complexes with TiO₂ was higher compared to bare porphyrins for TAPP and TMPP, while for the TCPP-TiO₂ NPs complex, a decrease was observed, but still maintained a good efficiency. The TiO₂ NPs conjugates can be promising candidates to be tested in photodynamic therapy in vitro assays.

Hydrogels are ideal candidates for the sustained local administration of antimicrobial drugs because they have customizable physicochemical properties that allow drug release kinetics to be controlled and potentially address the issue of systemic side effects. Consequently, the purpose of this study was to use 266 nm-pulsed laser beams to photo-crosslink gelatin methacryloyl hydrogels using Irgacure 2959 as a photo-initiator to reduce the curing time and to have an online method to monitor the process, such as laser-induced fluorescence. Additionally, irradiated chlorpromazine was loaded into the hydrogels to obtain a drug delivery system with antimicrobial activity. These hydrogels were investigated by UV–Vis and FTIR absorption spectroscopy, scanning electron microscopy, and laser-induced fluorescence spectroscopy and their structural and morphological characteristics, swelling behavior, and drug release profile were obtained. As a result the morphology, swelling behavior, and drug release profile were influenced by both the energy of the laser beam and the exposure time. The optimal hydrogel was obtained after 1 min of laser irradiation for Irgacure 2959 at 0.05% w/v concentration and gelatin methacryloyl at 10% w/v concentration. The hydrogels loaded with irradiated chlorpromazine show significant antimicrobial activity against Staphylococcus aureus and MRSA bacteria and a non-cytotoxic effect against L929 fibroblast cell lines.

In this paper, laser beam resonant interaction with pendant microdroplets that are seeded with a laser dye (Rhodamine 6G (Rh6G)) water solution or oily Vitamin A emulsion with Rhodamine 6G solution in water is investigated through fluorescence spectra analysis. The excitation is made with the second harmonic generated beam emitted by a pulsed Nd:YAG laser system at 532 nm. The pendant microdroplets containing emulsion exhibit an enhanced fluorescence signal. This effect can be explained as being due to the scattering of light by the sub-micrometric drops of oily Vitamin A in emulsion and by the spherical geometry of the pendant droplet. The droplet acts as an optical resonator amplifying the fluorescence signal with the possibility of producing lasing effect. Here, we also investigate how Rhodamine 6G concentration, pumping laser beam energies and number of pumping laser pulses influence the fluorescence behavior. The results can be useful in optical imaging, since they can lead to the use of smaller quantities of fluorescent dyes to obtain results with the same quality.

The combination of TiO₂ nanoparticles (NPs) and photosensitizers (PS) may offer significant advantages in photodynamic therapy (PDT) of melanoma, such as improved cell penetration, enhanced ROS production, and cancer selectivity. In this study, we aimed to investigate the photodynamic effect of 5,10,15,20-(Tetra-N-methyl-4-pyridyl)porphyrin tetratosylate (TMPyP4) complexes with TiO₂ NPs on human cutaneous melanoma cells by irradiation with 1 mW/cm² blue light. The porphyrin conjugation with the NPs was analyzed by absorption and FTIR spectroscopy. The morphological characterization of the complexes was performed by Scanning Electron Microscopy and Dynamic Light Scattering. The singlet oxygen generation was analyzed by phosphorescence at 1270 nm. Our predictions indicated that the non-irradiated investigated porphyrin has a low degree of toxicity. The photodynamic activity of the TMPyP4/TiO₂ complex was assessed on the human melanoma Mel-Juso cell line and non-tumor skin CCD-1070Sk cell line treated with various concentrations of the PS and subjected to dark conditions and visible light-irradiation. The tested complexes of TiO₂ NPs with TMPyP4 presented cytotoxicity only after activation by blue light (405 nm) mediated by the intracellular production of ROS in a dose-dependent manner. The photodynamic effect observed in this evaluation was higher in melanoma cells than the effect observed in the non-tumor cell line, demonstrating a promising potential for cancer-selectivity in PDT of melanoma.