Incorporation of Acrylate Based Spiropyran Monoliths in Micro-Fluidic Devices for Photo-Controlled Electroosmotic Flow

Spiropyran photochromic compounds can be switched using light exposure between a non-polar spiro form (SP) and a zwitterionic merocyanine form (MC) that is subject to protonation (MC-H+). It has recently been demonstrated by Walsh et al. that, under acidic conditions, electroosmotic flow (EOF) generated in vinyl based spiropyran monoliths can be modulated using light irradiation [1]. In this paper, we report a spiropyran-modified acrylate based monolith which is particularly sensitive to protonation in the MC form, producing a positively charged surface that converts to the unpolar SP form by exposure to white light. When the MC-H+ form is dominant, it produces a charged surface which enables a relatively high flow rate (up to 1.6 μl/min) to be generated under electroosmotic conditions. Upon exposure to white light, the concentration of MC-H+ decreases due to the photo-conversion to the uncharged SP form, with up to 20% reduction of the EOF. The process is reversible, and removal of the light source results in a flow increase back to the original rate. The ability to alter flow rates in micro-fluidic channels using light has very significant implications, as it could dramatically simplify the manner in which micro-flow systems are controlled.

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Positively Charged Surface Induces Discontinuous Transition for the High Order Structure in Duplex DNA

Biochemical and Biophysical Research Communications ◽

10.1006/bbrc.1995.2390 ◽

1995 ◽

Vol 214 (3) ◽

pp. 1040-1044 ◽

Cited By ~ 2

Author(s):

Y.S. Melnikova ◽

N. Kumazawa ◽

K. Yoshikawa

Keyword(s):

High Order ◽

Order Structure ◽

Duplex Dna ◽

Charged Surface ◽

High Order Structure ◽

Discontinuous Transition ◽

Positively Charged

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Pineal response types in the frog's brain under white light exposure

Experimental Brain Research ◽

10.1007/bf00238466 ◽

1979 ◽

Vol 36 (1) ◽

Cited By ~ 5

Author(s):

J. Cadusseau ◽

F. Gaillard ◽

G. Galand

Keyword(s):

White Light ◽

Light Exposure

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The solution structure of ribosomal protein S4 Delta 41 reveals two subdomains and a positively charged surface that may interact with RNA

The EMBO Journal ◽

10.1093/emboj/17.16.4559 ◽

1998 ◽

Vol 17 (16) ◽

pp. 4559-4571 ◽

Cited By ~ 30

Author(s):

M. A. Markus

Keyword(s):

Ribosomal Protein ◽

Solution Structure ◽

Charged Surface ◽

Ribosomal Protein S4 ◽

Positively Charged

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Light, Alertness, and Alerting Effects of White Light: A Literature Overview

Journal of Biological Rhythms ◽

10.1177/0748730418796443 ◽

2018 ◽

Vol 33 (6) ◽

pp. 589-601 ◽

Cited By ~ 23

Author(s):

Renske Lok ◽

Karin C. H. J. Smolders ◽

Domien G. M. Beersma ◽

Yvonne A. W. de Kort

Keyword(s):

White Light ◽

Light Exposure ◽

Neural Mechanisms ◽

Dependent Manner ◽

Experimental Paradigm ◽

Research Paradigms ◽

Lighting Conditions ◽

Literature Overview ◽

Dose Dependent ◽

As Effects

Light is known to elicit non–image-forming responses, such as effects on alertness. This has been reported especially during light exposure at night. Nighttime results might not be translatable to the day. This article aims to provide an overview of (1) neural mechanisms regulating alertness, (2) ways of measuring and quantifying alertness, and (3) the current literature specifically regarding effects of different intensities of white light on various measures and correlates of alertness during the daytime. In general, the present literature provides inconclusive results on alerting effects of the intensity of white light during daytime, particularly for objective measures and correlates of alertness. However, the various research paradigms employed in earlier studies differed substantially, and most studies tested only a limited set of lighting conditions. Therefore, the alerting potential of exposure to more intense white light should be investigated in a systematic, dose-dependent manner with multiple correlates of alertness and within one experimental paradigm over the course of day.

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Photoradiation models for the clinical ex vivo treatment of autologous bone marrow grafts

Blood ◽

10.1182/blood.v70.2.484.bloodjournal702484 ◽

1987 ◽

Vol 70 (2) ◽

pp. 484-489

Author(s):

J Atzpodien ◽

SC Gulati ◽

A Strife ◽

BD Clarkson

Keyword(s):

Bone Marrow ◽

Tumor Cells ◽

White Light ◽

Ex Vivo ◽

Light Exposure ◽

B Cell Lymphoma ◽

Autologous Bone Marrow ◽

Neoplastic Cells ◽

Drug Concentrations ◽

Autologous Bone

To assess the potential of photoradiation therapy for the in vitro purging of residual tumor cells from autologous bone marrow (BM) transplants, we studied normal marrow and tumor cell clonogenicity in response to different light-activated compounds by using the fluorescent dyes dihematoporphyrin ether (DHE) and merocyanine-540 (MC- 540). After photoradiation of cells with white light, both DHE and MC- 540 showed high cytocidal activity toward lymphoid and myeloid neoplastic cells but had a significantly lesser effect on normal granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and mixed colony- forming (CFU-GEMM) progenitor cells. Acute promyelocytic leukemia (HL- 60), non-B, non-T, CALLA-positive acute lymphoblastic leukemia (Reh), and diffuse histocytic B cell lymphoma (SK-DHL-2) cell lines were exposed to different drug concentrations in combination with white light at a constant illumination rate of 50,000 lux. With DHE doses varying from 2.0 to 2.5 micrograms/mL and MC-540 concentrations of 15 to 20 micrograms/mL, clonogenic tumor cells could be reduced by more than 4 logs when treated alone or in mixtures with normal irradiated human marrow cells. However, preferential cytotoxicity towards neoplastic cells was highly dependent on the mode of light activation. MC-540 had no substantial effect on malignant lymphoid (SK-DHL-2) and myeloid (HL-60) cells and on normal marrow myeloid (CFU-GM) precursors when drug incubation was performed in the dark and followed by light exposure of washed cells. Equal doses of MC-540 (15 to 20 micrograms/mL) could preferentially eliminate tumor cells under conditions of simultaneous light and drug treatment (30 minutes at 37 degrees C). When using DHE (2.5 micrograms/mL), 29.3%, 46.8%, and 27.5% of normal marrow CFU-GM, BFU-E, and CFU-GEMM, respectively, were spared after sequential drug and light exposure of cells, whereas simultaneous treatment reduced both normal (CFU-GM) and neoplastic cells below the limits of detection. In summary, our results indicate the usefulness of various photoradiation models for the ex vivo treatment of leukemic and lymphomatous bone marrow autografts.

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Myenteric Denervation of the Gut with Benzalkonium Chloride: A Review of Forty Years of an Experimental Model

Canadian Journal of Gastroenterology and Hepatology ◽

10.1155/2019/3562492 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7 ◽

Cited By ~ 2

Author(s):

Sérgio Britto Garcia ◽

Stefânia Bovo Minto ◽

Isabela de Souza Marques ◽

Vinicius Kannen

Keyword(s):

Experimental Model ◽

Benzalkonium Chloride ◽

Charged Surface ◽

Therapeutic Tool ◽

Initial Report ◽

Functional Aspects ◽

Surface Active ◽

Rat Gut ◽

Shed Light ◽

Positively Charged

Experimental denervation of organs plays a key role in understanding the functional aspects of the normal innervation as well as the diseases related to them. In 1978 the experimental model of myenteric denervation of the rat gut by serosal application of benzalkonium chloride (BAC) was proposed. BAC is a positively charged surface-active alkylamine and is a powerful cationic detergent, which destroys bacteria after ionic attraction and for this reason is largely used as a surgical antiseptic. Since its initial report, the BAC-induced myenteric denervation model has been used to study many functional and pathological aspects of the enteric nervous system. So far this is the only pure method of myenteric denervation available for research in this area. Promising reports in the literature have shed light on the possibilities for the development of new uses of the BAC-denervation experimental model as a therapeutic tool in some pathological situations. This review aims to shed light on the main historical and recent findings provided by this experimental model.

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Characterization of distinct molecular interactions responsible for IRF3 and IRF7 phosphorylation and subsequent dimerization

Nucleic Acids Research ◽

10.1093/nar/gkaa873 ◽

2020 ◽

Vol 48 (20) ◽

pp. 11421-11433

Author(s):

Louise Dalskov ◽

Ryo Narita ◽

Line L Andersen ◽

Nanna Jensen ◽

Sonia Assil ◽

...

Keyword(s):

Immune Response ◽

Transcription Factors ◽

Molecular Interactions ◽

Adaptor Proteins ◽

Innate Immune ◽

Charged Surface ◽

Regulatory Domain ◽

Phosphorylation Event ◽

Positively Charged

Abstract IRF3 and IRF7 are critical transcription factors in the innate immune response. Their activation is controlled by phosphorylation events, leading to the formation of homodimers that are transcriptionally active. Phosphorylation occurs when IRF3 is recruited to adaptor proteins via a positively charged surface within the regulatory domain of IRF3. This positively charged surface also plays a crucial role in forming the active homodimer by interacting with the phosphorylated sites stabilizing the homodimer. Here, we describe a distinct molecular interaction that is responsible for adaptor docking and hence phosphorylation as well as a separate interaction responsible for the formation of active homodimer. We then demonstrate that IRF7 can be activated by both MAVS and STING in a manner highly similar to that of IRF3 but with one key difference. Regulation of IRF7 appears more tightly controlled; while a single phosphorylation event is sufficient to activate IRF3, at least two phosphorylation events are required for IRF7 activation.

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Circadian Potency Spectrum with Extended Exposure to Polychromatic White LED Light under Workplace Conditions

Journal of Biological Rhythms ◽

10.1177/0748730420923164 ◽

2020 ◽

Vol 35 (4) ◽

pp. 405-415 ◽

Cited By ~ 1

Author(s):

Martin Moore-Ede ◽

Anneke Heitmann ◽

Rainer Guttkuhn

Keyword(s):

Spectral Sensitivity ◽

White Light ◽

Light Exposure ◽

Human Subjects ◽

Light Sources ◽

Led Light ◽

Light Spectra ◽

Timing System ◽

Circadian Timing System ◽

Spectral Sensitivity Curve

Electric light has enabled humans to conquer the night, but light exposure at night can disrupt the circadian timing system and is associated with a diverse range of health disorders. To provide adequate lighting for visual tasks without disrupting the human circadian timing system, a precise definition of circadian spectral sensitivity is required. Prior attempts to define the circadian spectral sensitivity curve have used short (≤90-min) monochromatic light exposures in dark-adapted human subjects or in vitro dark-adapted isolated retina or melanopsin. Several lines of evidence suggest that these dark-adapted circadian spectral sensitivity curves, in addition to 430- to 499-nm (blue) wavelength sensitivity, may include transient 400- to 429-nm (violet) and 500- to 560-nm (green) components mediated by cone- and rod-originated extrinsic inputs to intrinsically photosensitive retinal ganglion cells (ipRGCs), which decay over the first 2 h of extended light exposure. To test the hypothesis that the human circadian spectral sensitivity in light-adapted conditions may have a narrower, predominantly blue, sensitivity, we used 12-h continuous exposures of light-adapted healthy human subjects to 6 polychromatic white light-emitting diode (LED) light sources with diverse spectral power distributions at recommended workplace levels of illumination (540 lux) to determine their effect on the area under curve of the overnight (2000–0800 h) salivary melatonin. We derived a narrow steady-state human Circadian Potency spectral sensitivity curve with a peak at 477 nm and a full-width half-maximum of 438 to 493 nm. This light-adapted Circadian Potency spectral sensitivity permits the development of spectrally engineered LED light sources to minimize circadian disruption and address the health risks of light exposure at night in our 24/7 society, by alternating between daytime circadian stimulatory white light spectra and nocturnal circadian protective white light spectra.

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The Effect of Ionic Charge on the Adsorption of Organic Dyes onto Titanate Nanotubes

Australian Journal of Chemistry ◽

10.1071/ch09326 ◽

2010 ◽

Vol 63 (2) ◽

pp. 270 ◽

Cited By ~ 51

Author(s):

Dmitry V. Bavykin ◽

Katherine E. Redmond ◽

Benjamin P. Nias ◽

Alexander N. Kulak ◽

Frank C. Walsh

Keyword(s):

Aqueous Solution ◽

Organic Dyes ◽

Dye Adsorption ◽

Titanate Nanotubes ◽

Charged Surface ◽

Dye Molecules ◽

Ionic Charge ◽

Eriochrome Black T ◽

Opposite Trend ◽

Positively Charged

The adsorption of dye molecules from aqueous solution onto the surface of titanate nanotubes (which have been synthesized via an alkaline hydrothermal treatment) has been studied. The ionic charge on the dye molecules was found to affect their ability to adsorb onto the titanate nanotube surface. In the case of (cationic) methylene blue, the adsorption was preferable on the negatively charged surface of titanate nanotubes rather than on positively charged P25 TiO2 nanoparticles. In the case of (anionic) Eriochrome Black T dye, the opposite trend was found. Herein, the dynamics of dye adsorption and the effect of pH on the adsorption capacity are considered.

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