Yuying Feng

Spectroscopic studies on the interaction of hypocrellin A and hemoglobin

The spectrophotometric and spectrofluorimetric studies revealed that hemoglobin (Hb) could interact with hypocrellin A, a photosensitizing drug used in photodynamic therapy. It was found that this kind of interaction can induce the conformational changes in Hb. In addition, based on fluorescence quenching titration and electron paramagnetic resonance spectroscopy results, the binding parameters, thermodynamic parameters are obtained. The quenching mechanism is also proposed.

A new sol-gel silica nanovehicle preparation for photodynamic therapy in vitro

We report a facile silica nanovehicle preparation procedure for hydrophobic drug delivery, which is carried out in water without adding any surfactant and additional catalyst. This strategy includes hydrophobic drug nanopaticle preparation by reprecipitation method and in situ hydrolyzation and polymerization to encapsulate this naoparticle using only N-(beta-amimoethyl)-gamma-aminopropyltriethoxysilane (AETPS). To demonstrate this technique hypocrellin A (HA), a hydrophobic photosensitizing anticancer drug, is embedded into silica nanovehicle using this simple method. The resulting HA encapsulated nanovehicles (HANV) are monodisperse and stable in aqueous solution. Comparative studies with free HA and entrapped HA have demonstrated that the encapsulation effect on the embedded photosensitizer nanoparticle significantly enhances the efficacy of singlet oxygen generation and, thereby, the in vitro photodynamic efficacy.

Mitochondria-targeting photosensitizer-encapsulated amorphous nanocage as a bimodal reagent for drug delivery and biodiagnose in vitro

The use of ceramic nano-carriers containing anti-cancer drugs for targeted delivery that span both fundamental and applied research has attracted the interest of the scientific community. In this paper, a hydrophobic photodynamic therapy drug, hypocrellin A (HA), was successfully encapsulated in water-soluble amorphous silica nanocage (HANC) by an improved sol-gel method. These nanocages are of ultrasmall size, highly monodispersed, stable in aqueous suspension, and retain the optical properties of HA. Moreover, these nanocages can be effectively delivered, subsequently taken up by cancer cells and finally targeted to mitochondria. In addition, incubation time dependent photodynamic efficacy difference between HANC and HA was investigated for the first time. Especially, the nanocages, owning extremely high stable fluorescence comparing with free HA, also have potentials as efficient probes for optical biodiagnose in vitro. All these properties of HANC could possibly make it especially promising to be used as a bimodal reagent for photodynamic therapy and biodiagnose.

Delivering a hydrophobic anticancer drug for photodynamic therapy by amorphous formulation

An amorphous formulation of hypocrellin A for photodynamic therapy is reported which can provide stable aqueous dispersion of such hydrophobic photosensitizers. In vitro studies have demonstrated the active uptake of amorphous formulation of hypocrellin A into the mitochondria of tumor cells. Compared with Tween-80 micelle embedded hypocrellin A, low dark-toxicity but similar light-toxicity of the amorphous one to drug impregnated tumor cells was observed. Thus, the potential of using amorphous formulation of hypocrellin A as drug delivery system for photodynamic therapy has been demonstrated.

Spectroscopic studies on the interaction of hypocrellin A with myoglobin

Experimental results of UV-visible absorption spectroscopy and fluorescence spectroscopy indicate that hypocrellin A, which has been studied in photodynamic therapy, can interact with the surface of myoglobin through hydrophobic forces, and form a complex. Based on the Stern–Volmer equation, the quenching constants of the process can be calculated to be 4.81×1012 L mol−1 s−1 (t=25°C) and 4.54×1012 L mol−1 s−1 (t=42°C) respectively, and the binding constant is 5.53×104 M−1 (t=25°C), while the binding sites is 0.94 (t=25°C). In addition, Electron paramagnetic resonance and fluorescence spectroscopic analysis suggests that that the quenching mechanism of the interaction process occurs through the electron transfer between hypocrellin A and myoglobin.

Raman spectroscopic study of photosensitive damage to lysozyme structure sensitized by hypocrellin A

Laser Raman spectroscopy was used to detect the nature of the structural change in lysozyme sensitized by hypocre- llin A (HA) at the molecular level. The results indicated that the orderly structure of lysozyme has been damaged by the active oxygen ( 1 O2 ,O −· and ·OH, etc.) generated by HA, and cause the changes in H-bonds system of the main chain and the side

Affinity studies of hypocrellin B and mono-cysteine substituted hypocrellin B with CT-DNA using spectroscopic methods

The interaction of anticancer drug hypocrellin B (HB) and mono-cysteine substituted hypocrellin B (MCHB) with calf thymus deoxyribonucleic acid (CT-DNA) has been investigated using spectral methods. The results of UV-visible spectra showed that the HB and MCHB can intercalate into the base-stacking domain of the CT-DNA double helix. Further stud- ies based on fluorescence spectroscopy and circular dichroism (CD) spectroscopy also supported the intercalation mecha- nism.

DNA binding and photo-induced DNA cleavage activity of Elsinochrome A in visible light

The interaction of Elsinochrome A (EA) with calf thymus DNA (CT-DNA) has been investigated by UV-vis spectra and fluorescence spectra. The results show that EA can bind with CT-DNA and binding sites are destroyed after irradiation by visible light, which indicates that EA is a promising candidate for photodynamic therapy. In addition, the binding mechanism is studied using fluorescence quenching test and ethidium bromide (EB) replace assay experiments. The results suggest that EA and CT-DNA are binding with a strong force and the major binding mode of EA with DNA could be the electrostatic binding.

Investigation of Photoinduced Electron Transfer Between ZnPcLTs and Guanine: The Role of Type I Mechanism in Photodamage of Calf Thymus DNA

Abstract The photoinduced electron transfer between ZnPcLTs and guanine was studied by steady‐state emission and electron spin resonance as well as time‐resolved absorption and emission, indicating the key role of type I (electron transfer) mechanism in photodynamic damage of calf thymus DNA by ZnPcLTs.