Photo-irradiation effects on poly(vinylpyridines)

Nishiyama, Satoko; Tajima, Masahiro; Yoshida, Yasuhiko

doi:10.1016/j.colsurfa.2007.04.179

Cited by 4 publications

(9 citation statements)

References 17 publications

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“…In our previous experiments on the UV irradiation of PVPy, a long emission band in the visible wavelength range, excited at a visible wavelength, was observed after UV irradiation, [4][5][6][7][8][9] and it was absent from those of acidtreated PVPy without UV irradiation. 6,8) To control the chemical states of PVPy surfaces, we needed to elucidate the changes occurring with UV irradiation.…”

Section: Introductionmentioning

confidence: 81%

“…In our previous studies, [2][3][4][5][6][7][8][9][10] for ease of handling, UV irradiation at 254 nm was performed using a small Hg lamp equipped with a color filter to reduce long-wavelength light under air, and for orthosubstituted PVPy, a longer irradiation time was used according to their photoreactivity to confirm their photoreactions. UV-irradiated PVPy films are abbreviated as PVPy+UV, hereafter.…”

Section: Uv Irradiation Proceduresmentioning

confidence: 99%

“…1), and its derivatives. [2][3][4][5][6][7][8][9][10] Today, PVPy is often used for nanostructured materials. The first observation of pyridine (Py) fluorescence was reported in the 1970s, 11) because Py has very low fluorescence quantum yield.…”

Section: Introductionmentioning

confidence: 99%

“…[22][23][24][25][26][27][28] It has been thought that the binding energy (BE) is closely related to their electronic states, and correlations between XPS results and their properties, such as charge density 29) and gas phase basicity, 30) have been investigated. In recent years, we have observed the surface morphologies of PVPy films 2,3,9) and characterized the generated alkylpyridiniums (Py þ R; R: alkyl) and cogenerated bromide (Br À ) by XPS. 2,3) In this study, we observed the decreases in the concentrations of those surface-generated ions to determine the depth ablated by Ar þ beam etching, because it is difficult to determine the etched depth for PVPy (pure substance).…”

Section: Introductionmentioning

confidence: 99%

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Ultraviolet Irradiation Effects on and Depth Profiles in X-ray Photoelectron Spectra of Poly(vinylpyridine) Thin Films

Nishiyama

Tajima

Nakajima

et al. 2008

jjap

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The N 1s core binding energies of spin-coated poly(vinylpyridine) (PVPy), quaternized PVPy, and UV-irradiated PVPy were determined using X-ray photoelectron spectroscopy, and the depth profiles were determined using Ar þ beam etching. In typical N 1s spectra, cationic nitrogen atoms appeared at a binding energy 2 -3 eV higher than that of neutral pyridine (Py). Changes in alkylpyridiniums in N 1s and bromide in Br 3p were determined according to etching cycles. In our PVPy cases, two types of nitrogen appeared at a region of high energy compared with that of neutral Py, and the differences in the binding energies between those states and neutral Py were all less than 2 eV. These nitrogens can be assigned to hydrogen-bonded Py and a complex formed among Py rings. Neutral Py, the complex Py, and hydrogen-bonded Py are very close together, and they were located at 399.0, 399.7, and 400.6 eV, respectively. Traces of ionic species were observed only in IR spectra.

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Section: Introductionmentioning

confidence: 81%

Section: Uv Irradiation Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultraviolet Irradiation Effects on and Depth Profiles in X-ray Photoelectron Spectra of Poly(vinylpyridine) Thin Films

Nishiyama

Tajima

Nakajima

et al. 2008

jjap

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“…Pyridine is well known to undergo photo cleavage in the pyridine-water solution. 12,13 The origin of the light sensitive system lies with the self-protonated side-chain unit on the backbone of poly P 4 VP. 14 Irradiation of the system P 4 VP with 250 nm wavelength is leading to the protonation of the polymeric pyridine (Py* in the excited state).…”

Section: Photo-cleavable Polymersmentioning

confidence: 99%

Cell sheet patterning using photo-cleavable polymers

Apostol

Mironava

Yang

et al. 2011

Polym J

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We have found that poly (4-vinylpyridine) (P 4 VP) and poly (methylmethacrylate) thin films can be etched with ultraviolet A (UVA) radiation. Furthermore, we also found that dermal fibroblasts could be cultured successfully on the P 4 VP polymer, with a doubling time comparable to tissue culture Petri dish standards. Consequently, we were able to grow tissue on P 4 VP substrates, this could easily be lifted using UVA radiation. The cell sheets that were removed were then re-plated at a lower density and a series of assays was performed at 3 and 6 days. Although only a small amount of damage was discernable at day 3 nearly complete recovery was observed at day 6. The technique was used to pattern areas within the tissue, where other types of cells could be inserted. To demonstrate the technique, a hybrid tissue layer was produced, in which the dermal fibroblasts in a circular area at the center of the sample were removed by exposure through a mask. A keratinocyte layer was inserted, which adhere to the fibroblast layer forming a tissue with integrated layers of two distinct cell types. Polymer Journal (2011) 43, 723-732; doi:10.1038/pj.2011; published online 8 June 2011Keywords: biopolymers; cells INTRODUCTION A significant shortcoming of conventional tissue engineering methods is the loss of differentiated cell functions during cell collecting. Typical cell collecting techniques use proteolytic enzymes such as trypsin or dispase, which irreversibly damage cell surface proteins, such as growth factor receptors, ion channels and cell-to-cell junction proteins. 1 This result in an inability to assemble constructs from multiple cell types, which is an important requirement in tissue engineering.To address these shortcomings, cell sheet engineering has been proposed as a new methodology to facilitate the non-invasive collect of cultured cells as intact cell sheets. 2 As the cell sheets collected through this technique are recovered with intact cell-to-cell junctions and deposited extracellular matrix whole-cell sheets can be transferred to other tissue surfaces to produce versatile two-dimensional or threedimensional tissues. 3 Cell sheet engineering advanced rapidly with the development of culture dishes covalently grafted with temperatureresponsive polymers. These culture surfaces allowed whole, contiguous cell sheets to spontaneously detach from the surface simply by briefly decreasing the temperature. 4,5 This technique was also used to culture four layers of cardiomyocytes, which successfully formed pulsatile myocardial tissue in vitro and in vivo. 6 Other studies using epidermal keratinocytes have shown that it was possible to maintain the differentiated functions after the cell sheets were collected. 7 However, although thermoresponsive culture surfaces have shown success in producing whole sheets of hard, cell-dense tissues such as myocardium, the technique is not suitable for tissue patterning and for soft tissue. For example, biological soft tissue like brain and adipose are difficult to manipulate (for the...

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