John Morseman - Academia.edu (original) (raw)

Papers by John Morseman

Journal of Fluorescence, 1999

PBXL™ dyes are a group of phycobilisome-based fluors that provide high sensitivity in direct fluo... more PBXL™ dyes are a group of phycobilisome-based fluors that provide high sensitivity in direct fluorescent detection formats. Phycobilisomes are proteinaceous, supramolecular complexes that are photosynthetic antennae complexes in red algae and cyanobacteria. For the PBXL dyes, the phycobilisome has been chemically cross-linked in such a way that it remains water soluble and stable. Stabilized phycobilisomes (PBXL dyes) have high complex weights (between 10 and 15 million daltons) and Stokes shifts (up to 121 nm). They contain many hundreds of chromophores coordinated to transfer green and yellow light efficiently down an energy gradient to emit red light at wavelengths around 666 nm. Each PBXL dye can deliver up to 1400 chromophores per binding event without additional signal generation steps, signal amplification, or enzyme substrates. PBXL dyes provide a physical amplification of signal, enabling ultrasensitive, direct fluorescent detection of specific binding events. A number of studies done in our laboratory and in collaborating laboratories are summarized in this article. These studies demonstrated the utility of PBXL dyes in select high-sensitivity applications, such as a thyroid stimulating hormone (TSH) microplate immunoassay, detection of the low-density cell surface marker CD56 using flow cytometry, BSA–biotin, and actin detection in a western blot format and paternity testing using a DNA array on glass slides. PBXL dyes have the potential for providing a highly sensitive, simple, and direct fluorescent detection method to a wide range of targets and assay formats that could reduce costs associated with reagents and labor as well as decreasing the time to the first result.

PBXL™ dyes are a group of phycobilisome-based fluors that provide high sensitivity in direct fluo... more PBXL™ dyes are a group of phycobilisome-based fluors that provide high sensitivity in direct fluorescent detection formats. Phycobilisomes are proteinaceous, supramolecular complexes that are photosynthetic antennae complexes in red algae and cyanobacteria. For the PBXL dyes, the phycobilisome has been chemically cross-linked in such a way that it remains water soluble and stable. Stabilized phycobilisomes (PBXL dyes) have high complex weights (between 10 and 15 million daltons) and Stokes shifts (up to 121 nm).They contain many hundreds of chromophores coordinated to transfer green and yellow light efficiently down an energy gradient to emit red light at wavelengths around 666 nm. Each PBXL dye can deliver up to 1400 chromophores per binding event without additional signal generation steps, signal amplification, or enzyme substrates. PBXL dyes provide a physical amplification of signal, enabling ultrasensitive, direct fluorescent detection of specific binding events. A number of studies done in our laboratory and in collaborating laboratories are summarized in this article. These studies demonstrated the utility of PBXL dyes in select high-sensitivity applications, such as a thyroid stimulating hormone (TSH) microplate immunoassay, detection of the low-density cell surface marker CD56 using flow cytometry, BSA-biotin, and actin detection in a western blot format and paternity testing using a DNA array on glass slides. PBXL dyes have the potential for providing a highly sensitive, simple, and direct fluorescent detection method to a wide range of targets and assay formats that could reduce costs associated with reagents and labor as well as decreasing the time to the first result.

Luminescent solar concentrators (LSCs) harvest sunlight by absorption in a luminescent centre and... more Luminescent solar concentrators (LSCs) harvest sunlight by absorption in a luminescent centre and re-emission in a red-shifted and narrow-band spectrum within a waveguide. Fluorescence resonance energy transfer (FRET) can allow for more efficient LSCs. Our research goal is to produce an LSC technology based on the biological properties of phycobilisomes which are antennae proteins from algae that naturally exhibit FRET, absorbing blue-green light and emitting red. In this paper, we present our initial results of incorporating phycobilisomes into waveguides and coupling these waveguides to solar cells to form a proof of concept for a phycobilisome-based LSC (phyco-LSC). We present initial experimental data and modeling results that establish the feasibility of the concept and make projections of ultimate system performance. Our modeling suggests that with optimized phycobilisomes, photon concentration ratios close to ten could be achieved for practically sized LSCs. This is an international collaboration bringing together the PV expertise of NRL and Imperial College London with the bioscience expertise of Columbia Biosciences and the waveguide fabrication expertise of the Fraunhofer lAP.

Phycobiliproteins play an important role in fluorescent labeling, particularly for flow cytometry... more Phycobiliproteins play an important role in fluorescent labeling, particularly for flow cytometry. The spectral properties of R-phycoerythrin (R-PE) and allophycocyanin (APC) have made them the dominant reagents in this class of fluorochromes. In this study, we evaluate a lesser-known but potentially important series of low-molecular weight cryptomonad-derived phycobiliproteins (commercially termed the CryptoFluor™ dyes) for their applicability to flow cytometry, both in extracellular and intracellular labeling applications. Methods: Several cell lines were labeled with biotinconjugated antibodies against expressed extracellular surface proteins, followed by streptavidin conjugates of three cryptomonad phycobiliproteins (CryptoFluor-2, Crypto-Fluor-4, and CryptoFluor-5). Cells were then analyzed by flow cytometry using a variety of laser lines and emission filters to establish the optimal excitation/emission characteristics for each fluorochrome. Some cells were permeabilized and labeled for intracellular antigens, also using the cryptomonad fluorochromes. Where appropriate, parallel samples were labeled with other fluorochromes (including R-PE, APC, the cyanin dyes Cy3 and Cy5, and others) to gauge the performance of the cryptomonad fluorochromes against fluorescent labels previously evaluated for flow cytometry. Results: CryptoFluor-2 possessed excitation/emission maxima similar to those of APC and Cy5, with good Published 2001 Wiley-Liss, Inc. † Phycobiliproteins are photosynthetic energy transfer proteins that possess distinctively strong pigmentation and unique fluorescent properties (1). Phycobiliproteins have been widely utilized as protein-conjugatable markers in fluorescence-based detection systems, particularly in flow cytometric immunophenotyping (2-4). They are water soluble, possess high-fluorescence quantum yields, have large Stokes shifts, and a resistance to photobleaching. These characteristics make them ideal candidates for fluorescence detection (1). In many cases, their excitation and emission maxima correspond to the laser emission †

2010 35th IEEE Photovoltaic Specialists Conference, 2010

2012 38th IEEE Photovoltaic Specialists Conference, 2012

ABSTRACT In this work we aim to investigate flexible luminescent solar concentrators (LSCs) for t... more ABSTRACT In this work we aim to investigate flexible luminescent solar concentrators (LSCs) for the purpose of portable power generation. We will focus on Surelight® PE-610, which is a tandem fluorophore consisting of R-Phycoerythrin and Rhodamine, as well as PbSe nanorods, as the luminescent species. The luminescent quantum yield, LQY, of PE-610 was measured as 53% in buffer solution, and 75% when deposited in a thin-film. Computational simulations show that a 25cm by 25cm LSC with a 0.1mm thick thin-film containing PbSe nanorods, a LQY of 70% and a substrate thickness of 3mm has an optical efficiency of 4.5±0.1%. An identical LSC with a 0.5mm thick substrate had an optical efficiency of 1.7±0.1% meaning substrate thickness is a key factor for flexible LSCs. A primary advantage of PE-610 as a LSC material is that it is bio-derived, and therefore cheap and abundant. The PbSe nanorods have the advantage of a broad absorption spectrum, though the LQY used is still speculative at this time.

Journal of Fluorescence, 1999

Journal of Biomolecular Screening, 2001

Advanced Materials, 2009

Solar concentrators can significantly reduce the use of expensive semiconductor materials in phot... more Solar concentrators can significantly reduce the use of expensive semiconductor materials in photovoltaic (PV) energy conversion. Luminescent solar concentrators (LSCs) are especially promising because they do not need to track the sun to obtain high optical concentration factors. [3] In this work, we demonstrate LSCs employing phycobilisomes, which are photosynthetic antenna complexes that concentrate excited states in red algae and cyanobacteria. The phycobilisomes are cast in a solid-state matrix that preserves their internal Förster energy-transfer pathways and large wavelength shift between absorption and emission. Casting is a simple fabrication technique that also eliminates any need for expensive high-index glass or plastic. By comparing the performance of intact and partly decoupled complexes, we establish that energy transfer within intact phycobilisomes reduces LSC self-absorption losses by approximately (48 AE 5)%. These results suggest that phycobilisomes are a model for a new generation of cast LSCs with improved efficiency at high optical concentrations.

Journal of Immunological Methods, 2001

Phycobilisomes are cyanobacterial photosynthetic energy transfer complexes partly composed of phy... more Phycobilisomes are cyanobacterial photosynthetic energy transfer complexes partly composed of phycobiliproteins, proteins that are widely used as conjugable fluorochromes for flow cytometry. The brightness and photostability of phycobiliproteins suggest that intact phycobilisomes could constitute even brighter probes for fluorescence-based detection systems. Stabilized phycobilisomes have been isolated and the red-excited, far red-emitting Spirulina platensis-derived complex PBXL-3 was accessed as a fluorochrome for flow cytometric immunodetection of surface antigens on immune cells. Although the large size of intact phycobilisomes initially precluded efficient cell surface labeling, the addition of a Ž . PEG spacer arm between PBXL-3 and its conjugated avidin molecule designated PBXL-3L reduced the steric hindrance associated with the high molecular weight PBXL complex. PBXL-3L increased the surface labeling surface-to-noise ratio and subsequent sensitivity by several-fold over commonly used red-excited fluorochromes such as APC. Interestingly, low Ž . power laser sources including helium-neon and red diode were particularly efficient at exciting PBXL-3. PBXL-3 was also compatible in with other fluorochromes for multicolor flow cytometry applications. In summary, PBXL-3 was found to possess superior sensitivity and efficiency for flow cytometric immunodetection, particularly with low power laser sources. q

Journal of Fluorescence, 1999

PBXL™ dyes are a group of phycobilisome-based fluors that provide high sensitivity in direct fluo... more PBXL™ dyes are a group of phycobilisome-based fluors that provide high sensitivity in direct fluorescent detection formats. Phycobilisomes are proteinaceous, supramolecular complexes that are photosynthetic antennae complexes in red algae and cyanobacteria. For the PBXL dyes, the phycobilisome has been chemically cross-linked in such a way that it remains water soluble and stable. Stabilized phycobilisomes (PBXL dyes) have high complex weights (between 10 and 15 million daltons) and Stokes shifts (up to 121 nm).They contain many hundreds of chromophores coordinated to transfer green and yellow light efficiently down an energy gradient to emit red light at wavelengths around 666 nm. Each PBXL dye can deliver up to 1400 chromophores per binding event without additional signal generation steps, signal amplification, or enzyme substrates. PBXL dyes provide a physical amplification of signal, enabling ultrasensitive, direct fluorescent detection of specific binding events. A number of studies done in our laboratory and in collaborating laboratories are summarized in this article. These studies demonstrated the utility of PBXL dyes in select high-sensitivity applications, such as a thyroid stimulating hormone (TSH) microplate immunoassay, detection of the low-density cell surface marker CD56 using flow cytometry, BSA-biotin, and actin detection in a western blot format and paternity testing using a DNA array on glass slides. PBXL dyes have the potential for providing a highly sensitive, simple, and direct fluorescent detection method to a wide range of targets and assay formats that could reduce costs associated with reagents and labor as well as decreasing the time to the first result.

2010 35th IEEE Photovoltaic Specialists Conference, 2010

2012 38th IEEE Photovoltaic Specialists Conference, 2012

Journal of Fluorescence, 1999

Journal of Biomolecular Screening, 2001

Advanced Materials, 2009

Journal of Immunological Methods, 2001