We report a photofunctional stainless steel (PSS) that has antimicrobial property which is provided by reactive oxygen species (ROS) generated from the photosensitizer (PS). For the fabrication of the photofunctional stainless steel, the photosensitizer of hematoporphyrin (HP) was covalently bonded to the surface of 316L stainless steel (316LSS) through an esterification reaction. The PSS plate was investigated by x-ray photoelectron spectroscopy (XPS), reflectance UV–Vis absorption, and fluorescence spectroscopy. ROS generation from the PSS plate was studied by using the decomposition reaction of 1,3-diphenyl-isobenzofuran (DPBF). The results suggest that the immobilized photosensitizer molecules on the surface of the PSS plate still possess their intrinsic optical and functional properties including the ROS generation. The antimicrobial property of the PSS plate was successfully demonstrated with the decomposition of biofilm and the suppression of the biofilm formation on the surface of the PSS plate.

We report bactericidal effect of photosensitizer (H2TPP: 5,10,15,20-tetraphenyl-21H,23H-porphyrin) through non-uptake pathway and efficacy of the photofunctional silicon polymer to the decomposition of the formed biofilm and the suppression of the biofilm formation. The photoftmctional silicon polymer (PSP), which is the silicon polymer embedded with a photosensitizer, is fabricated by a simple solvent swell-encapsulation-shrink method. Reactive oxygen generation from PSP was confirmed by using the decomposition reaction of 1,3-diphnyl-isobenzofuran (DPBF). Also, singlet oxygen generation which is one of the reactive oxygen species (ROS) from PSP is directly confirmed with time and wavelength resolved singlet oxygen phosphorescence spectroscopy. For the influence study of ROS under the non-uptake condition of photosensitizer (PS to bacteria), photodynamic inactivation (PDI) effect of PSP is evaluated for Gram-positive, Gram-negative bacteria, and fungi. Those microorganisms were inactivated by PSP within 1 h under the given power of laser light (63.7 mW/cm(2)). Among the bacteria, especially, Staphylococcus aureus as the Gram-positive bacteria were completely disinfected under the given experimental condition. Furthermore, PSP successfully demonstrates the decomposition of the formed biofilm and the suppression of the biofilm formation with green light emitting diode (GLED, 3.5 mW/cm(2),lambda(max) = 517 nm, FWHM = 37 nm), which shows the practical application possibility of bactericidal material. (C) 2015 Elsevier B.V. All rights reserved.

The principle of photodynamic treatment (PDT) involves the administration of photosensitizer (PS) at diseased tissues, followed by light irradiation to produce reactive oxygen species (ROS). In cells, a moderate increase in ROS plays an important role as signaling molecule to promote cell proliferation, whereas a severe increase of ROS causes cell damage. Previous studies have shown that low levels of ROS stimulate cell growth through PS drugs-treating PDT and nonthermal plasma treatment. However, these methods have side effects which are associated with low tissue selectivity and remaining of PS residues. To overcome such shortcomings, we designed hematoporphyrin-incorporated polyurethane (PU) film induced generation of extracellular ROS with singlet oxygen and free radicals. The film can easily control ROS production rate by regulating several parameters including light dose, PS dose. Also, its use facilitates targeted delivery of ROS to the specific lesion. Our study demonstrated that extracellular ROS could induce the formation of intracellular ROS. In vascular endothelial cells, a moderated increase in intracellular ROS also stimulated cell proliferation and cell cycle progression by accurate control of optimum levels of ROS with hematoporphyrin-incorporated polymer films. This modulation of cellular growth is expected to be an effective strategy for the design of next-generation PDT.

Pheophorbide-a derivatives have been reported to be potential photosensitizers for photodynamic therapy (PDT). In this study, photophysics of pheophorbide-a derivatives (PaDs) were investigated along with their photodynamic tumoricidal effect in vitro. PaDs were modified by changing the coil length and/or making the hydroxyl group (–OH) substitutions. Their photophysical properties were studied by steady-state and time-resolved spectroscopic methods. The photodynamic tumoricidal effect was evaluated in the mouse breast cancer cell line (EMT6). Lifetime and quantum yield of fluorescence and quantum yields of triplet state and singlet oxygen were studied to determine the dynamic energy flow. The coil length of the substituted alkyl group did not significantly affect the spectroscopic properties. However, the substitution with the hydroxyl group increased the quantum yields of the triplet state and the singlet oxygen due to the enhanced intersystem crossing. In order to check the application possibility as a photodynamic therapy agent, the PaDs with hydroxyl group were studied for the cellular affinity and the photodynamic tumoricidal effect of EMT6. The results showed that the cellular affinity and the photodynamic tumoricidal effect of PaDs with the hydroxyl group depended on the coil-length of the substituted alkyl group.

Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH2 (399.70 eV) was increased significantly and –N=CH (400.80 eV) and –NH3+ (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.

We report the fabrication of photofunctional Co-Cr alloy plate that is prepared by a simple modification process for photodynamic application. Photoinduced functionality is provided by the photosensitizer of hematoporphyrin (Hp) that initially generates reactive oxygen species (ROS) such as superoxide anion radical and singlet oxygen. The photosensitizer with carboxyl group was chemically bonded to the surface of the Co-Cr alloy plate by esterification reaction. Microstructure and elemental composition of the Co-Cr alloy plate were checked with scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS). Fabrication of the photofunctionality of the Co-Cr alloy plate was confirmed with X-ray photoelectron spectroscopy (XPS), reflectance UV-Vis absorption, and emission spectroscopy. Reactive oxygen generation from the photofunctional Co-Cr alloy plate was confirmed by using the decomposition reaction of 1,3-diphenylisobenzofuran (DPBF). The results suggest that the immobilized photosensitizer molecules on the surface of Co-Cr alloy plate still possess their optical and functional properties including reactive oxygen generation. To open the possibility for its application as a photodynamic material to biological system, the fabricated photofunctional Co-Cr alloy is applied to the decomposition of smooth muscle cells.

Fabrication and photophysical study of photofunctional nanoporous alumina membrane (PNAM) were performed, and its application of photodynamic antimicrobial chemotherapy (PACT) was investigated. Nanoporous alumina membrane (NAM) was fabricated by two-step aluminium anodic oxidation process. Surface of the fabricated NAM was modified with organo-silane agent to induce covalent bonding between NAM and a photosensitizer (PtCP: [5,10,15-triphenyl-20-(4-methoxycarbonylphenyl)-porphyrin] platinum). PtCP was covalently bonded to the surface of the modified NAM by nucleophilic acyl substitution reaction process. The morphology and the photophysical properties of the fabricated PNAM were confirmed with field emission scanning electron microscope (FE-SEM), steady-state spectroscopies, and nanosecond laser-induced time-resolved spectroscopy. For the efficacy study of PNAM in PACT, an enveloped animal virus, vesicular stomatitis virus (VSV), was utilized as a target organism. Antiviral effect of the PNAM-PACT was measured by the extent of suppression of plaque-forming units (PFU) after the light irradiation. In the cultures inoculated with PACT-treated VSV, the suppression of PFU was prominent, which demonstrates that PNAM is a potential bio clean-up tool.

Plasma surface modifications of polymer scaffolds using biomolecules such as oxygen, nitrogen, and other active grafting molecules have been studied to enhance biological responses such as cell attachment, spreading, and proliferation. According to the reports, nitrogen grafting requires corrosive or mixture gas environment, or post treatment. This study aimed to evaluate a simple atmospheric pressure plasma surface modification in order to graft nitrogen derivatives and to promote biological responses. In this study, a polycarprolactone (PCL) film was modified within 10 min by argon atmospheric pressure discharge (Ar-APGD). Excited argon atoms, nitrogen atoms, oxygen atoms, and hydroxyl functional groups were observed from the optical emission spectra of the discharge. Decreased carbonyl functional groups and ether functional groups were observed; notably, immobilized nitrogen was observed on the PCL surface after the Ar-APGD treatment. Promoted neonatal Human Dermal Fibroblast (nHDF) growth patterns were observed on the Ar-APGD-treated surface.

Photodynamic Therapy (PDT) is a promising approach for killing microorganism and especially for the inactivation of antibiotic-resistant strains. The photodynamic process rapidly generates reactive oxygen species (ROS) as for instance peroxides, hydroxyl radicals, superoxide ions, and singlet oxygen. Among them, the singlet oxygen is considered to be a major causative agent of cellular damage in photodynamic process. Due to advantage of the cytotoxic effect of PDT on bacteria, the PDT method has been one of the most appropriate tools to prevent the microbes which result in biofilm formation. This work describes a method of singlet oxygen generating nanolayer coating on NiTi alloy which shows a good biocompatibility. The 5,10,15-triphenyl-20-(4-carboxyphenyl)-porphyrin] platinum (PtCP) functional nanolayer coatings were prepared in two steps. In the first step, Al coating was prepared on biomedical NiTi alloy substrate by DC magnetron sputtering, and then this coated substrate alloy was immersed into hot water to form Al2O3 coatings. In the second step, a photosensitizer (PS) with carboxyl group was chemically attached to the hydroxyl-terminated Al2O3 coatings by a direct esterification method. The microstructure and the elemental and phase composition of the coating were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), and X-ray diffraction (XRD). Results from this study show that the PtCP functional nanolayer coating is composed of many perpendicular nanosheet structures. These very thin nanosheet structures with the thickness of a few nanometers mainly show amorphous phase. The singlet oxygen generation efficiency of the PS being chemically bonded on these nanosheets was detected by an indirect chemical method by using the decomposition of 1,3-diphenyl-isobenzofuran (DPBF).

A new photo-catalyst of [5,10,15-triphenyl-20-(4-methoxycarbonylphenyl)-porphyrin] platinum was synthesized and its photophysical study revealed that it had a high quantum yield of singlet oxygen generation. As an application study, a stereo-specific synthesis of (+)-deoxoartemisinin was performed. The induced high triplet quantum yield (0.96±0.03) of [5,10,15-triphenyl-20-(4-methoxycarbonylphenyl)-porphyrin] resulted the high singlet oxygen quantum yield of 0.90±0.04. The photo-catalytic effect was compared with that of methylene blue (MB) which was generally used as a photo-catalyst for these types of stereo-specific syntheses of organic compounds. The yield of synthesized (+)-deoxoartemisinin was correlated with singlet oxygen quantum yield.