David Roll - Academia.edu (original) (raw)

Papers by David Roll

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Jul 1, 2004

Roughened silver electrodes are widely used for surface-enhanced Raman scattering (SERS). We test... more Roughened silver electrodes are widely used for surface-enhanced Raman scattering (SERS). We tested roughened silver electrodes for metal-enhanced fluorescence. Constant current between two silver electrodes in pure water resulted in the growth of fractal-like structures on the cathode. This electrode was coated with a monolayer of human serum albumin (HSA) protein that had been labeled with a fluorescent dye, indocyanine green (ICG). The fluorescence intensity of ICG-HSA on the roughened electrode increased by ≈50-fold relative to the unroughened electrode, which was essentially non-fluorescent and increased typically twofold as compared to the silver anode. No fractal-like structures were observed on the anode. Lifetime measurements showed that at least part of the increased intensity was due to an increased radiative decay rate of ICG. In our opinion, the use of in situ generated roughened silver electrodes will find multifarious applications in analytical chemistry, such as in fluorescence based assays, in an analogous manner to the now widespread use of SERS. To the best of our knowledge this is the first report of roughened silver electrodes for metal-enhanced fluorescence.

PubMed, Mar 1, 2003

A new technique called radiative decay engineering can be used to modify fluorescence emissions b... more A new technique called radiative decay engineering can be used to modify fluorescence emissions by changing the free space conditions around the fluorophores.

Analytical Chemistry, Jun 10, 2003

Gold and silver colloids display strong colors as a result of electron oscillations induced by in... more Gold and silver colloids display strong colors as a result of electron oscillations induced by incident light, which are referred to as the plasmon absorption. This absorption is dependent on colloid-colloid proximity, which has been the basis of absorption assays using colloids. We now describe a new approach to optical sensing using the light scattering properties of colloids. Colloid aggregation was induced by avidin-biotin interactions, which shifted the plasmon absorption to longer wavelengths. We found the spectral shift results in changes in the scattering at different incident wavelengths. By measuring the ratio of scattered intensities at two incident wavelengths, this measurement was made independent of the total colloid concentration. The high scattering efficiency of the colloids resulted in intensities equivalent to fluorescence when normalized by the optical density of the fluorophore and colloid. This approach can be used in a wide variety of assay formats, including those commonly used with fluorescence detection.

Langmuir, Jun 21, 2003

We describe two reagentless methods of silver deposition for metal-enhanced fluorescence. Silver ... more We describe two reagentless methods of silver deposition for metal-enhanced fluorescence. Silver was deposited on glass positioned between two silver electrodes with a constant current in pure water. Illumination of the glass between the electrodes resulted in localized silver deposition. Alternatively, silver was deposited on an Indium Tin Oxide cathode, with a silver electrode as the anode. Both types of deposited silver produced a 5-18-fold increase in the fluorescence intensity of a nearby fluorophore, indocyanine green (ICG). Additionally, the photostability of ICG was dramatically increased by proximity to the deposited silver. These results suggest the use of silver deposited from pure water for surface-enhanced fluorescence, with potential applications in surface assays and lab-on-a-chip-based technologies, which ideally require highly fluorescent photostable systems.

Journal of Biological Chemistry, Aug 1, 1981

From 330 ml of rat serum, 222 mg of alpha-1-antitrypsin have been isolated and purified with an o... more From 330 ml of rat serum, 222 mg of alpha-1-antitrypsin have been isolated and purified with an overall yield of approximately 20%. The preparation was homogeneous by the criteria of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, sedimentation equilibrium centrifugation, and immunoelectrophoresis. Rat alpha-1-antitrypsin exhibited Mr = 47,000 +/- 1,500 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 45,000 +/- 1,000 by equilibrium ultracentrifugation; the sedimentation coefficient (s20,w) was 3.29. Rat alpha-1-antitrypsin exhibited a trypsin-combining ratio (moles of trypsin inhibited/mol of alpha-1-antitrypsin) of 0.88. Rat alpha-1-antitrypsin showed significant differences in amino acid composition when compared to human alpha-1-antitrypsin, particularly in lysine, glutamic acid, arginine, methionine, and tyrosine content. Rat alpha-1-antitrypsin contains 14.3 residues/mol of N-acetylglucosamine, 5.0 residues/mol of mannose, 4.2 residues/mol of galactose, and 5.8 residues/mol of sialic acid. Monospecific antibody produced in a rabbit against our purest preparation of rat alpha-1-antitrypsin does not cross-react immunologically against human, calf, fetal calf, mouse, or chicken sera. The availability of a pure preparation of rat alpha-1-antitrypsin as well as the specific alpha-1-antitrypsin antibody will facilitate studies on the biosynthesis and secretion of this important protease inhibitor in an appropriate animal model.

164 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1976.U of I OnlyRestricted to t... more 164 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1976.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

PubMed, 1978

We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the gro... more We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the growth medium, and inside the cell and the net turnover of these polymers during the process of malignant transformation of chick embryo fibroblasts by Rous sarcoma virus. The distribution of label and the turnover kinetics for hyaluronic acid, total glycoproteins, and chondroitins were found to be identical in both normal and transforming cultures. We conclude that nonspecific degradative processes are probably not involved in causing transformation-related alterations in cell surface carbohydrates, althougn degradation of specific macromolecules is not excluded.

Analytical Biochemistry, Feb 1, 1977

Procedures are described for selective quantitation of the monosaccharide content of glycogen, ch... more Procedures are described for selective quantitation of the monosaccharide content of glycogen, chondroitin sulfates, hyaluronic acid, glycoproteins, glycolipids, N-acetylneuraminic acid, and the phosphorylated carbohydrate pools in cultured animal cells. Monosaccharides are released from each type of carbohydrate by selective hydrolysis with enzymes and/or acid and are analyzed by radiochromatographic procedures which give reliable quantitative data with only a few nanomoles of each monosaccharide. Analyses of the entire spectrum of carbohydrates can be carried out using 7-8 mg of animal cell protein.

Journal of Biological Chemistry, Oct 1, 1978

Journal of Fluorescence, Nov 1, 2003

The interactions of fluorophores with noble metal particles can modify their emission spectral pr... more The interactions of fluorophores with noble metal particles can modify their emission spectral properties, a relatively new phenomenon in fluorescence. We subsequently examined indocyanine green (ICG), which is widely used in medical testing and imaging, in close proximity to an electrically roughened platinum electrode. The emission intensity and lifetimes were decreased about 2-fold on the roughened surface as compared to a smooth Pt surface, and the photostability about the same. Platinum does not appear promising for metal enhanced fluorescence, at least for long wavelength fluorophores.

Journal of Fluorescence - J FLUORESC, 2003

The basic nonhistone phosphoprotein 110/8.4 (M.W. x 10~3/pl) was found in 0.35 M NaCI nuclear ext... more The basic nonhistone phosphoprotein 110/8.4 (M.W. x 10~3/pl) was found in 0.35 M NaCI nuclear extracts of four tumor tissues, i.e., fast-growing Novikoff hepatoma, Morris hepatoma 3924A, HeLa cells, and Namalwa cells; it was also found in fetal rat liver. This protein was not detected in normal or regenerating liver and thus may represent an "oncofetal" protein of potential interest as a cancer "marker." Protein 110/8.4 was purified approximately 4000-to 5000-fold under nondenaturing condition from 0.35 M NaCI nuclear extracts of Novikoff hepatoma cells or Namalwa cells by ammonium sulfate fractionation, calcium phosphate gel treatment, and phosphocellulose chromatography. Sodium dodecyl sulfate:polyacrylamide gel electrophoresis of the purified native protein revealed a single polypeptide chain with a molecular weight of approxi mately 110,000. The pi of the protein was estimated to be 8.4 by nonequilibrium pH gradient electrophoresis in 9 M urea; accordingly, this protein was designated 110/8.4. Amino acid analysis showed that Protein 110/8.4 had an acidic:basic amino acid ratio of 1.25 and a high lysine and serine content; approximately 20% of the serine residues were found to be phosphorylated. Hydrazinolysis indicated that the carboxyl-terminal amino acid was serine; the amino terminus appeared to be blocked. Binding of Protein 110/8.4 to DNA was studied by the nitrocellulose filter assay. High-affinity binding occurred at ionic strength equal to or below 0.15 M.

Analytical Chemistry, 2003

Cancer Research, 1978

We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the gro... more We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the growth medium, and inside the cell and the net turnover of these polymers during the process of malignant transformation of chick embryo fibroblasts by Rous sarcoma virus. The distribu tion of label and the turnover kinetics for hyaluronic acid, total glycoproteins, and chondroitins were found to be identical in both normal and transforming cultures. We conclude that nonspecific degradative processes are probably not involved in causing transformation-related alterations in cell surface carbohydrates, although deg radation of specific macromolecules is not excluded.

Cancer Research, Feb 1, 1981

The basic nonhistone phosphoprotein 110/8.4 (M.W. X 10(-3)/pI) was found in 0.35 M NaCl nuclear e... more The basic nonhistone phosphoprotein 110/8.4 (M.W. X 10(-3)/pI) was found in 0.35 M NaCl nuclear extracts of four tumor tissues, i.e., fast-growing Novikoff hepatoma, Morris hepatoma 3924A, HeLa cells, and Namalwa cells; it was also found in fetal rat liver. This protein was not detected in normal or regenerating liver and thus may represent an "oncofetal" protein of potential interest as a cancer "marker." Protein 110/8.4 was purified approximately 4000- to 5000-fold under nondenaturing condition from 0.35 M NaCl nuclear extracts of Novikoff hepatoma cells or Namalwa cells by ammonium sulfate fractionation, calcium phosphate gel treatment, and phosphocellulose chromatography. Sodium dodecyl sulfate:polyacrylamide gel electrophoresis of the purified native protein revealed a single polypeptide chain with a molecular weight of approximately 110,000. The pI of the protein was estimated to be 8.4 by nonequilibrium pH gradient electrophoresis in 9 M urea; accordingly, this protein was designated 110/8.4. Amino acid analysis showed that Protein 110/8.4 had an acidic:basic amino acid ratio of 1.25 and a high lysine and serine content; approximately 20% of the serine residues were found to be phosphorylated. Hydrazinolysis indicated that the carboxyl-terminal amino acid was serine; the amino terminus appeared to be blocked. Binding of Protein 110/8.4 to DNA was studied by the nitrocellulose filter assay. High-affinity binding occurred at ionic strength equal to or below 0.15 M.

The basic nonhistone phosphoprotein 110/8.4 (M.W. x 10~3/pl) was found in 0.35 M NaCI nuclear ext... more The basic nonhistone phosphoprotein 110/8.4 (M.W. x 10~3/pl) was found in 0.35 M NaCI nuclear extracts of four tumor tissues, i.e., fast-growing Novikoff hepatoma, Morris hepatoma 3924A, HeLa cells, and Namalwa cells; it was also found in fetal rat liver. This protein was not detected in normal or regenerating liver and thus may represent an "oncofetal" protein of potential interest

Journal of fluorescence, 2003

Substantial increases in fluorescence emission from fluorophore-protein-coated fractal-like silve... more Substantial increases in fluorescence emission from fluorophore-protein-coated fractal-like silver structures have been observed. We review two methods for silver fractal structure preparation, which have been employed and studied. The first, a roughened silver electrode, typically yielded a 100-fold increase in fluorophore emission, and the second, silver fractal-like structures grown on glass between two silver electrodes, produced a ≈500-fold increase. In addition, significant increases in probe photostability were observed for probes coated on the silver fractal like structures. These results further serve to compliment our recent work on the effects of nobel metal particles with fluorophores, a relatively new phenomenon in fluorescence we have termed both "metal-enhanced fluorescence" [1] and "radiative decay engineering" [2,3]. These results are explained by the metallic surfaces modifying the radiative decay rate (Γ) of the fluorescent labels. We believe t...

Pharmagenomics, Mar 1, 2003

A new technique called radiative decay engineering can be used to modify fluorescence emissions b... more A new technique called radiative decay engineering can be used to modify fluorescence emissions by changing the free space conditions around the fluorophores.

The Journal of Physical Chemistry B, 2004

Tiopronin-protected silver nanoparticles (aVerage diameter ) 5 nm) were partially displaced by (2... more Tiopronin-protected silver nanoparticles (aVerage diameter ) 5 nm) were partially displaced by (2-mercaptopropionylamino) acetic acid 2,5-dioxo-pyrrolidin-1-ylesters via ligand exchange, and the succinimide-terminated silver particles were bound to amine-labeled Dextran 3000 (1 amine/per chain) or Dextran 10 000 (2.5 amine/ per chain), respectively. The particle-Dextran 10 000 adducts were self-aggregated by interactions of multiple amines on Dextran and multi-functionalized ligands on the particle. The transverse plasmon band was blue shifted while the longitudinal plasmon at 575 nm increased, corresponding to the compact aggregation of particles. The particle-Dextran 3000 adducts, which were not aggregated, were coupled to Concanavalin A (Con A) to facilitate the aggregation of particles. The aggregated particles displayed an absorbance spectral change depending on the mole ratio of Con A/particle-Dextran 3000. The particle-Dextran 3000 adduct was released by a competitive complexation of glucose. This process was monitored by both the change in plasmon absorbance and wavelength, with the glucose concentration. The aggregation and dissociation of Con A/particle-Dextran complexes were also verified by TEM images.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2004

Roughened silver electrodes are widely used for surface-enhanced Raman scattering (SERS). We test... more Roughened silver electrodes are widely used for surface-enhanced Raman scattering (SERS). We tested roughened silver electrodes for metal-enhanced fluorescence. Constant current between two silver electrodes in pure water resulted in the growth of fractal-like structures on the cathode. This electrode was coated with a monolayer of human serum albumin (HSA) protein that had been labeled with a fluorescent dye, indocyanine green (ICG). The fluorescence intensity of ICG-HSA on the roughened electrode increased by approximately 50-fold relative to the unroughened electrode, which was essentially non-fluorescent and increased typically two-fold as compared to the silver anode. No fractal-like structures were observed on the anode. Lifetime measurements showed that at least part of the increased intensity was due to an increased radiative decay rate of ICG. In our opinion, the use of in situ generated roughened silver electrodes will find multifarious applications in analytical chemistry, such as in fluorescence based assays, in an analogous manner to the now widespread use of SERS. To the best of our knowledge this is the first report of roughened silver electrodes for metal-enhanced fluorescence.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Jul 1, 2004

Roughened silver electrodes are widely used for surface-enhanced Raman scattering (SERS). We test... more Roughened silver electrodes are widely used for surface-enhanced Raman scattering (SERS). We tested roughened silver electrodes for metal-enhanced fluorescence. Constant current between two silver electrodes in pure water resulted in the growth of fractal-like structures on the cathode. This electrode was coated with a monolayer of human serum albumin (HSA) protein that had been labeled with a fluorescent dye, indocyanine green (ICG). The fluorescence intensity of ICG-HSA on the roughened electrode increased by ≈50-fold relative to the unroughened electrode, which was essentially non-fluorescent and increased typically twofold as compared to the silver anode. No fractal-like structures were observed on the anode. Lifetime measurements showed that at least part of the increased intensity was due to an increased radiative decay rate of ICG. In our opinion, the use of in situ generated roughened silver electrodes will find multifarious applications in analytical chemistry, such as in fluorescence based assays, in an analogous manner to the now widespread use of SERS. To the best of our knowledge this is the first report of roughened silver electrodes for metal-enhanced fluorescence.

PubMed, Mar 1, 2003

A new technique called radiative decay engineering can be used to modify fluorescence emissions b... more A new technique called radiative decay engineering can be used to modify fluorescence emissions by changing the free space conditions around the fluorophores.

Analytical Chemistry, Jun 10, 2003

Gold and silver colloids display strong colors as a result of electron oscillations induced by in... more Gold and silver colloids display strong colors as a result of electron oscillations induced by incident light, which are referred to as the plasmon absorption. This absorption is dependent on colloid-colloid proximity, which has been the basis of absorption assays using colloids. We now describe a new approach to optical sensing using the light scattering properties of colloids. Colloid aggregation was induced by avidin-biotin interactions, which shifted the plasmon absorption to longer wavelengths. We found the spectral shift results in changes in the scattering at different incident wavelengths. By measuring the ratio of scattered intensities at two incident wavelengths, this measurement was made independent of the total colloid concentration. The high scattering efficiency of the colloids resulted in intensities equivalent to fluorescence when normalized by the optical density of the fluorophore and colloid. This approach can be used in a wide variety of assay formats, including those commonly used with fluorescence detection.

Langmuir, Jun 21, 2003

We describe two reagentless methods of silver deposition for metal-enhanced fluorescence. Silver ... more We describe two reagentless methods of silver deposition for metal-enhanced fluorescence. Silver was deposited on glass positioned between two silver electrodes with a constant current in pure water. Illumination of the glass between the electrodes resulted in localized silver deposition. Alternatively, silver was deposited on an Indium Tin Oxide cathode, with a silver electrode as the anode. Both types of deposited silver produced a 5-18-fold increase in the fluorescence intensity of a nearby fluorophore, indocyanine green (ICG). Additionally, the photostability of ICG was dramatically increased by proximity to the deposited silver. These results suggest the use of silver deposited from pure water for surface-enhanced fluorescence, with potential applications in surface assays and lab-on-a-chip-based technologies, which ideally require highly fluorescent photostable systems.

Journal of Biological Chemistry, Aug 1, 1981

From 330 ml of rat serum, 222 mg of alpha-1-antitrypsin have been isolated and purified with an o... more From 330 ml of rat serum, 222 mg of alpha-1-antitrypsin have been isolated and purified with an overall yield of approximately 20%. The preparation was homogeneous by the criteria of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, sedimentation equilibrium centrifugation, and immunoelectrophoresis. Rat alpha-1-antitrypsin exhibited Mr = 47,000 +/- 1,500 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 45,000 +/- 1,000 by equilibrium ultracentrifugation; the sedimentation coefficient (s20,w) was 3.29. Rat alpha-1-antitrypsin exhibited a trypsin-combining ratio (moles of trypsin inhibited/mol of alpha-1-antitrypsin) of 0.88. Rat alpha-1-antitrypsin showed significant differences in amino acid composition when compared to human alpha-1-antitrypsin, particularly in lysine, glutamic acid, arginine, methionine, and tyrosine content. Rat alpha-1-antitrypsin contains 14.3 residues/mol of N-acetylglucosamine, 5.0 residues/mol of mannose, 4.2 residues/mol of galactose, and 5.8 residues/mol of sialic acid. Monospecific antibody produced in a rabbit against our purest preparation of rat alpha-1-antitrypsin does not cross-react immunologically against human, calf, fetal calf, mouse, or chicken sera. The availability of a pure preparation of rat alpha-1-antitrypsin as well as the specific alpha-1-antitrypsin antibody will facilitate studies on the biosynthesis and secretion of this important protease inhibitor in an appropriate animal model.

164 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1976.U of I OnlyRestricted to t... more 164 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1976.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

PubMed, 1978

We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the gro... more We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the growth medium, and inside the cell and the net turnover of these polymers during the process of malignant transformation of chick embryo fibroblasts by Rous sarcoma virus. The distribution of label and the turnover kinetics for hyaluronic acid, total glycoproteins, and chondroitins were found to be identical in both normal and transforming cultures. We conclude that nonspecific degradative processes are probably not involved in causing transformation-related alterations in cell surface carbohydrates, althougn degradation of specific macromolecules is not excluded.

Analytical Biochemistry, Feb 1, 1977

Procedures are described for selective quantitation of the monosaccharide content of glycogen, ch... more Procedures are described for selective quantitation of the monosaccharide content of glycogen, chondroitin sulfates, hyaluronic acid, glycoproteins, glycolipids, N-acetylneuraminic acid, and the phosphorylated carbohydrate pools in cultured animal cells. Monosaccharides are released from each type of carbohydrate by selective hydrolysis with enzymes and/or acid and are analyzed by radiochromatographic procedures which give reliable quantitative data with only a few nanomoles of each monosaccharide. Analyses of the entire spectrum of carbohydrates can be carried out using 7-8 mg of animal cell protein.

Journal of Biological Chemistry, Oct 1, 1978

Journal of Fluorescence, Nov 1, 2003

The interactions of fluorophores with noble metal particles can modify their emission spectral pr... more The interactions of fluorophores with noble metal particles can modify their emission spectral properties, a relatively new phenomenon in fluorescence. We subsequently examined indocyanine green (ICG), which is widely used in medical testing and imaging, in close proximity to an electrically roughened platinum electrode. The emission intensity and lifetimes were decreased about 2-fold on the roughened surface as compared to a smooth Pt surface, and the photostability about the same. Platinum does not appear promising for metal enhanced fluorescence, at least for long wavelength fluorophores.

Journal of Fluorescence - J FLUORESC, 2003

The basic nonhistone phosphoprotein 110/8.4 (M.W. x 10~3/pl) was found in 0.35 M NaCI nuclear ext... more The basic nonhistone phosphoprotein 110/8.4 (M.W. x 10~3/pl) was found in 0.35 M NaCI nuclear extracts of four tumor tissues, i.e., fast-growing Novikoff hepatoma, Morris hepatoma 3924A, HeLa cells, and Namalwa cells; it was also found in fetal rat liver. This protein was not detected in normal or regenerating liver and thus may represent an "oncofetal" protein of potential interest as a cancer "marker." Protein 110/8.4 was purified approximately 4000-to 5000-fold under nondenaturing condition from 0.35 M NaCI nuclear extracts of Novikoff hepatoma cells or Namalwa cells by ammonium sulfate fractionation, calcium phosphate gel treatment, and phosphocellulose chromatography. Sodium dodecyl sulfate:polyacrylamide gel electrophoresis of the purified native protein revealed a single polypeptide chain with a molecular weight of approxi mately 110,000. The pi of the protein was estimated to be 8.4 by nonequilibrium pH gradient electrophoresis in 9 M urea; accordingly, this protein was designated 110/8.4. Amino acid analysis showed that Protein 110/8.4 had an acidic:basic amino acid ratio of 1.25 and a high lysine and serine content; approximately 20% of the serine residues were found to be phosphorylated. Hydrazinolysis indicated that the carboxyl-terminal amino acid was serine; the amino terminus appeared to be blocked. Binding of Protein 110/8.4 to DNA was studied by the nitrocellulose filter assay. High-affinity binding occurred at ionic strength equal to or below 0.15 M.

Analytical Chemistry, 2003

Cancer Research, 1978

We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the gro... more We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the growth medium, and inside the cell and the net turnover of these polymers during the process of malignant transformation of chick embryo fibroblasts by Rous sarcoma virus. The distribu tion of label and the turnover kinetics for hyaluronic acid, total glycoproteins, and chondroitins were found to be identical in both normal and transforming cultures. We conclude that nonspecific degradative processes are probably not involved in causing transformation-related alterations in cell surface carbohydrates, although deg radation of specific macromolecules is not excluded.

Cancer Research, Feb 1, 1981

The basic nonhistone phosphoprotein 110/8.4 (M.W. X 10(-3)/pI) was found in 0.35 M NaCl nuclear e... more The basic nonhistone phosphoprotein 110/8.4 (M.W. X 10(-3)/pI) was found in 0.35 M NaCl nuclear extracts of four tumor tissues, i.e., fast-growing Novikoff hepatoma, Morris hepatoma 3924A, HeLa cells, and Namalwa cells; it was also found in fetal rat liver. This protein was not detected in normal or regenerating liver and thus may represent an "oncofetal" protein of potential interest as a cancer "marker." Protein 110/8.4 was purified approximately 4000- to 5000-fold under nondenaturing condition from 0.35 M NaCl nuclear extracts of Novikoff hepatoma cells or Namalwa cells by ammonium sulfate fractionation, calcium phosphate gel treatment, and phosphocellulose chromatography. Sodium dodecyl sulfate:polyacrylamide gel electrophoresis of the purified native protein revealed a single polypeptide chain with a molecular weight of approximately 110,000. The pI of the protein was estimated to be 8.4 by nonequilibrium pH gradient electrophoresis in 9 M urea; accordingly, this protein was designated 110/8.4. Amino acid analysis showed that Protein 110/8.4 had an acidic:basic amino acid ratio of 1.25 and a high lysine and serine content; approximately 20% of the serine residues were found to be phosphorylated. Hydrazinolysis indicated that the carboxyl-terminal amino acid was serine; the amino terminus appeared to be blocked. Binding of Protein 110/8.4 to DNA was studied by the nitrocellulose filter assay. High-affinity binding occurred at ionic strength equal to or below 0.15 M.

The basic nonhistone phosphoprotein 110/8.4 (M.W. x 10~3/pl) was found in 0.35 M NaCI nuclear ext... more The basic nonhistone phosphoprotein 110/8.4 (M.W. x 10~3/pl) was found in 0.35 M NaCI nuclear extracts of four tumor tissues, i.e., fast-growing Novikoff hepatoma, Morris hepatoma 3924A, HeLa cells, and Namalwa cells; it was also found in fetal rat liver. This protein was not detected in normal or regenerating liver and thus may represent an "oncofetal" protein of potential interest

Journal of fluorescence, 2003

Substantial increases in fluorescence emission from fluorophore-protein-coated fractal-like silve... more Substantial increases in fluorescence emission from fluorophore-protein-coated fractal-like silver structures have been observed. We review two methods for silver fractal structure preparation, which have been employed and studied. The first, a roughened silver electrode, typically yielded a 100-fold increase in fluorophore emission, and the second, silver fractal-like structures grown on glass between two silver electrodes, produced a ≈500-fold increase. In addition, significant increases in probe photostability were observed for probes coated on the silver fractal like structures. These results further serve to compliment our recent work on the effects of nobel metal particles with fluorophores, a relatively new phenomenon in fluorescence we have termed both "metal-enhanced fluorescence" [1] and "radiative decay engineering" [2,3]. These results are explained by the metallic surfaces modifying the radiative decay rate (Γ) of the fluorescent labels. We believe t...

Pharmagenomics, Mar 1, 2003

A new technique called radiative decay engineering can be used to modify fluorescence emissions b... more A new technique called radiative decay engineering can be used to modify fluorescence emissions by changing the free space conditions around the fluorophores.

The Journal of Physical Chemistry B, 2004

Tiopronin-protected silver nanoparticles (aVerage diameter ) 5 nm) were partially displaced by (2... more Tiopronin-protected silver nanoparticles (aVerage diameter ) 5 nm) were partially displaced by (2-mercaptopropionylamino) acetic acid 2,5-dioxo-pyrrolidin-1-ylesters via ligand exchange, and the succinimide-terminated silver particles were bound to amine-labeled Dextran 3000 (1 amine/per chain) or Dextran 10 000 (2.5 amine/ per chain), respectively. The particle-Dextran 10 000 adducts were self-aggregated by interactions of multiple amines on Dextran and multi-functionalized ligands on the particle. The transverse plasmon band was blue shifted while the longitudinal plasmon at 575 nm increased, corresponding to the compact aggregation of particles. The particle-Dextran 3000 adducts, which were not aggregated, were coupled to Concanavalin A (Con A) to facilitate the aggregation of particles. The aggregated particles displayed an absorbance spectral change depending on the mole ratio of Con A/particle-Dextran 3000. The particle-Dextran 3000 adduct was released by a competitive complexation of glucose. This process was monitored by both the change in plasmon absorbance and wavelength, with the glucose concentration. The aggregation and dissociation of Con A/particle-Dextran complexes were also verified by TEM images.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2004

Roughened silver electrodes are widely used for surface-enhanced Raman scattering (SERS). We test... more Roughened silver electrodes are widely used for surface-enhanced Raman scattering (SERS). We tested roughened silver electrodes for metal-enhanced fluorescence. Constant current between two silver electrodes in pure water resulted in the growth of fractal-like structures on the cathode. This electrode was coated with a monolayer of human serum albumin (HSA) protein that had been labeled with a fluorescent dye, indocyanine green (ICG). The fluorescence intensity of ICG-HSA on the roughened electrode increased by approximately 50-fold relative to the unroughened electrode, which was essentially non-fluorescent and increased typically two-fold as compared to the silver anode. No fractal-like structures were observed on the anode. Lifetime measurements showed that at least part of the increased intensity was due to an increased radiative decay rate of ICG. In our opinion, the use of in situ generated roughened silver electrodes will find multifarious applications in analytical chemistry, such as in fluorescence based assays, in an analogous manner to the now widespread use of SERS. To the best of our knowledge this is the first report of roughened silver electrodes for metal-enhanced fluorescence.