Molecular Photovoltaics and the Photoactivation of Mammalian Cells

Kuritz, Tanya; Lee, I.; Owens, Elizabeth; Humayun, Mark S.; Greenbaum, Elias

doi:10.1109/tnb.2005.850480

Cited by 27 publications

(14 citation statements)

References 26 publications

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“…Studies performed with retinoblastoma cells treated with PSI proteoliposomes have shown that the cells increased the intracellular level of calcium in response to light. 18 However, there was no direct evidence of membrane incorporation of PSI in the treated cells and the mechanism behind the observed response remains uncertain.…”

Section: Introductionmentioning

confidence: 98%

“…This method does not require a modification of the genetic material of the cell 13,18 and thus poses a smaller risk for mutagenesis or carcinogenesis, opening a perspective for future clinical applications. The method proposed by Greenbaum et al uses the Photosystem I (PSI) reaction center, a pigment-protein complex from the photosynthetic membranes of bacteria, algae and plants.…”

Section: Introductionmentioning

confidence: 99%

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Incorporation of Photosynthetic Reaction Centers in the Membrane of Human Cells: Toward a New Tool for Optical Control of Cell Activity

et al. 2008

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The Photosystem I (PSI) reaction center is a photosynthetic membrane complex in which light-induced charge separation is accompanied by the generation of an electric potential. It has been recently proposed as a means to confer light sensitivity to cells possessing voltage-activated ion channels, but the feasibility of heterologous incorporation has not been demonstrated. In this work, methods of delivery and detection of PSI in the membrane of human cells are presented. Purified fractions of PSI were reconstituted in proteoliposomes that were used as vehicles for the membrane incorporation. A fluorescent impermeable dye was entrapped in the vesicles to qualitatively analyze the nature of the vesicle-cell interaction. After incorporation, the localization and orientation of the complexes in the membrane was studied using immuno-fluorescence microscopy. The results showed complexes oriented as in native membranes, which were randomly distributed in clusters over the entire surface of the cell. Additionally, analysis of cell viability showed that the incorporation process does not damage the cell membrane. Taken together, the results of this work suggest that the mammalian cellular membrane is a reasonable environment for the incorporation of PSI complexes, which opens the possibility of using these molecular photovoltaic structures for optical control of cell activity.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Incorporation of Photosynthetic Reaction Centers in the Membrane of Human Cells: Toward a New Tool for Optical Control of Cell Activity

et al. 2008

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“…. Isolated PSI has been employed in a wide range of applications from using proteoliposomes in order to photosensitize mammalian cells to suspending PSI particles in a Nafion film in solid-state photovoltaics (Baker et al 2014b;Kuritz et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Enhanced photocurrent from Photosystem I upon in vitro truncation of the antennae chlorophyll

et al. 2015

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Current effects on climate change and dwindling fossil fuel reserves require new materials and methods to convert solar energy into a viable clean energy source. Recent progress in the direct conversion of light into photocurrent has been well documented using Photosystem I. In plants, PSI consists of a core complex and multiple light-harvesting complexes, denoted LHCI and LHCII. Most of the methods for isolating PSI from plants involve a selective, detergent solubilization from thylakoids followed by sucrose gradient density centrifugation. These processes isolate one variant of PSI with a specific ratio of Chl:P700. In this study, we have developed a simple and potentially scalable method for isolating multiple PSI variants using Hydroxyapatite chromatography, which has been well documented in other Photosystem I isolation protocols. By varying the wash conditions, we show that it is possible to change the Chl:P700 ratios. These different PSI complexes were cast into a PSI-Nafion-osmium polymer film that enabled their photoactivity to be measured. Photocurrent increases nearly 400% between highly washed and untreated solutions based on equal chlorophyll content. Importantly, the mild washing conditions remove peripheral Chl and some LHCI without inhibiting the photochemical activity of PSI as suggested by SDS-PAGE analysis. This result could indicate that more P700 could be loaded per surface area for biohybrid devices. Compared with other PSI isolations, this protocol also allows isolation of multiple PSI variants without loss of photochemical activity.

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“…SSPM, also known as Kelvin probe force microscopy (KPFM), has been previously used to map the surface morphology and the corresponding local electrostatic potential of Photosystem I reaction centers [1], air-liquid interface [2], proteoliposomes [3], and bacteriorhodopsin [4] in nanometer resolution.…”

mentioning

confidence: 99%

Scanning Surface Potential Microscopy of Spores on Planar Surfaces

et al. 2009

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We have investigated the electrostatic potential of Bacillus thuringiensis (BT) spores on various substrates by using our combined atomic force microscopy (AFM) and scanning surface potential microscopy (SSPM) technique. SSPM, also known as Kelvin probe force microscopy (KPFM), has been previously used to map the surface morphology and the corresponding local electrostatic potential of Photosystem I reaction centers The adhesion of Bacillus anthracis-the cause of anthrax and a likely biological threat-to solid surfaces is important for cleanup after an accidental or deliberate release. However, directly studying B. anthracis spores with advanced instrumentation is problematic due to safety concerns. As a first step, we are examining adhesion of BT, which is a closely related species and is often used as a simulant to study B anthracis. Bacterial spore adhesion to inert surfaces is generally believed to involve surface hydrophobicity [5-6], surface polarity [7], surface electrical charge [8][9], and van der Waals force.The BT spores were imaged with the side-by-side AFM and SSPM, as illustrated in Fig. 1A and 1B. Both the size and surface potential were measured by section analysis. The SSPM surface potential section analysis is shown in Fig. 2. At a relative humidity RH = 64%, the surface potential between BT and substrate is -1.50 V, and the substrate potential is -0.57 V. Table 1 shows the BT and substrate potentials at a RH ranging from 9% to 64%. The shape and dimension of the spore were confirmed by scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM). We did not locate any spores on mica surface. This is because the surface potential of mica is extremely high, -4.8 V at RH 15%, leading to a strong electrostatic repulsion between the mica surface and the spore. For the same reason, the adhesion force measurement between the spore and mica by AFM is zero. Our SSPM results are thus consistent with adhesion force measurements.

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Molecular Photovoltaics and the Photoactivation of Mammalian Cells

Cited by 27 publications

References 26 publications

Incorporation of Photosynthetic Reaction Centers in the Membrane of Human Cells: Toward a New Tool for Optical Control of Cell Activity

Incorporation of Photosynthetic Reaction Centers in the Membrane of Human Cells: Toward a New Tool for Optical Control of Cell Activity

Enhanced photocurrent from Photosystem I upon in vitro truncation of the antennae chlorophyll

Scanning Surface Potential Microscopy of Spores on Planar Surfaces

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