Aggregated gold nanoparticles as photoactivators for the photopolymerization of proteins.

Photopolymerization of bovine serum albumin was carried out using reactive oxygen species (ROS) generated by the irradiation of citrate-stabilized gold nanoparticles by a pulsed Nd:YAG laser. The ROS in this case, singlet oxygen (O), targets aromatic amino acids within the protein to induce photopolymerization or crosslinking. Other ROS, like the hydroxyl radical, can also form in solution and under high-energy irradiation.

Neurotransmitters and neural hormone-based probes for quadruplex DNA sequences associated with neurodegenerative diseases.

The potential of neurotransmitters and neural hormones as possible G-quadruplex DNA binders was analyzed using fluorescence spectroscopy, surface-enhanced Raman spectroscopy (SERS), DNA melting analysis, and molecular docking. G-quadruplex sequences, (GGC) and GC, with roles in Fragile X syndrome and amyotrophic lateral sclerosis (ALS), respectively, were selected, and their interactions with melatonin, serotonin, and gamma-aminobutyric acid (GABA), were studied. Both melatonin and serotonin demonstrated strong interactions with the DNA sequences with hydrogen bonding being the primary mode of interaction, with some non-intercalative interactions involving the π systems.

The binding of a c-MYC promoter G-quadruplex to neurotransmitters: An analysis of G-quadruplex stabilization using DNA melting, fluorescence spectroscopy, surface-enhanced Raman scattering and molecular docking.

The interactions of several neurotransmitter and neural hormone molecules with the c-MYC G-quadruplex DNA sequence were analyzed using a combination of spectroscopic and computational techniques. The interactions between indole, catecholamine, and amino acid neurotransmitters and DNA sequences could potentially add to the understanding of the role of G-quadruplex structures play in various diseases. Also, the interaction of the DNA sequence derived from the nuclear hypersensitivity element (NHE) III region of c-MYC oncogene (Pu22), 5'-TGAGGGTGGGTAGGGTGGGTAA-3', has added significance in that these molecules may promote or inhibit the formation of G-quadruplex DNA which could lead to the development of promising drugs for anticancer therapy.

Honey gold nanoparticles attenuate the secretion of IL-6 by LPS-activated macrophages.

Interleukin-6 (IL-6) is a pleiotropic cytokine that coordinates host immune responses to infection. Though essential to the acute phase response, prolonged IL-6-mediated recruitment of mononuclear cells has been implicated in chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, and Crohn's disease. Accordingly, identifying novel therapeutics that diminish circulating IL-6 levels could benefit individuals suffering from chronic inflammation.

Fluorescence quenching of various indoles by nickel complexes.

The interactions between two nickel complexes with the ligand N,N'-bis (2-pyridylmethylene)-1,3-diaminopropyl and the indoles melatonin, serotonin, tryptamine, and tryptophol were characterized using UV-vis and fluorescence spectroscopy. The fluorescence of all the indoles were quenched in the presence of the complex with a hydroxyl group, indicating that hydrogen-bonding is a necessary interaction for quenching to occur. Various quenching parameters were determined using Stern-Volmer analysis and the quenching was determined to be of a mixed nature with high static quenching values (10-10 M).

Detection of quadruplex DNA by gold nanoparticles.

Gold nanoparticles have been used as a probe to detect low (<10 ppb) concentrations of quadruplex DNA. These nanoparticles display a tendency to form aggregates in the presence of certain quadruplex forms, as observed via enhanced plasmon resonance light scattering (PRLS) signals. These nanoparticles showed differing degrees of interactions with different types of quadruplex and mixed sequences but no interaction with duplex DNA.

Quenching of tryptophan fluorescence in various proteins by a series of small nickel complexes.

A series of twelve anionic, cationic, and neutral nickel(II) complexes have been synthesized and characterized. The interaction of these complexes with bovine serum albumin (BSA), human serum albumin (HSA), lysozyme (Lyso), and tryptophan (Trp) has been studied using steady-state fluorescence spectroscopy. Dynamic and static quenching constants have been calculated, and the role played in quenching by the ligand and complex charge investigated.

Competition between solvent quenching and indole quenching of 9-fluorenone: a spectroscopic and computational study.

The interaction between 9-fluorenone, various indoles and solvents has been studied using steady-state fluorescence spectroscopy and quantum chemical calculations. It was determined that polar protic solvents such as methanol and ethanol significantly quenched the fluorescence of 9-fluorenone but various indoles reversed the solvent quenching. The effect of various solvents on the 9-fluorenone carbonyl vibration was investigated using infrared spectroscopy.

Detection of quadruplex DNA by luminescence enhancement of lanthanide ions and energy transfer from lanthanide chelates.

Small amounts of quadruplex DNA have been detected using luminescence enhancement of aqueous lanthanide ions and energy transfer from lanthanide chelates. The 22mer human telomeric DNA, AGGG(TTAGGG)(3), was detected using europium ions at concentrations as low as 20 ppb DNA. Detection with terbium ions was not possible due to the inherent weak luminescence intensities of lanthanides.

Tryptophol cation conformations studied with ZEKE spectroscopy.

The relative energies of several conformations of the tryptophol cation are determined by zero kinetic energy (ZEKE) photoelectron spectroscopy and photoionization efficiency measurements. Recently published high-resolution electronic spectroscopy on the neutral species determined the absolute configuration of the different conformers in the S1 spectrum. These assignments are utilized in the photoelectron experiments by pumping through conformer specific S1 resonances yielding ZEKE spectra of the specific, assigned conformations.

Multiphoton excited fabrication of collagen matrixes cross-linked by a modified benzophenone dimer: bioactivity and enzymatic degradation.

Multiphoton excited (MPE) photochemistry is used to fabricate model tissue engineering scaffolds directly from types I, II, and IV collagen. A modified benzophenone dimer (BPD) provides the photoactivation and becomes incorporated into the resulting collagen matrixes. Unlike xanthene photochemistries, the benzophenone dimer can be used in acidic environments, where most forms of collagen have the greatest solubility.

Multiphoton-excited microfabrication in live cells via Rose Bengal cross-linking of cytoplasmic proteins.

We demonstrate the use of multiphoton-excited photochemistry to cross-link three-dimensional matrices directly from cytoplasmic proteins in a live cell (starfish oocyte). Fluorescence recovery after photobleaching measurements were used to determine diffusion coefficients inside intracellular cross-linked structures, and it was found that the diffusion was approximately 3 to 4 orders of magnitude slower than in free solution and 2-3 orders of magnitude slower than in cytoplasm and that the value can be tuned by controlling the laser exposure. Complex structures can be fabricated to construct channels and compartments that could be used to isolate cellular processes, and the method should thus be applicable to a broad range of problems in cell biology.

Measurement of normal and anomalous diffusion of dyes within protein structures fabricated via multiphoton excited cross-linking.

We demonstrate microscale spatial and chemical control of diffusion within protein matrixes created through the use of nonlinear multiphoton excited photochemistry. The mobility of fluorescent dyes of different mass and composition within controlled cross-linked environments has been measured using two-photon excited fluorescence recovery after photobleaching (FRAP). The diffusion times for several rhodamine and sulforhodamine dyes within these fabricated structures were found to be approximately 3-4 orders of magnitude slower than in free solution.

Properties of crosslinked protein matrices for tissue engineering applications synthesized by multiphoton excitation.

We demonstrate the fabrication of model scaffolds and extracellular matrices using multiphoton excited photochemistry. This method is three-dimensional in nature and has excellent biocompatibility. Crosslinked matrices were fabricated from the proteins fibrinogen, fibronectin, and concanavalin A using two-photon rose bengal photoactivation and the relatives rates were determined.

Vibrational dynamics of 9-fluorenemethanol using infrared-ultraviolet double-resonance spectroscopy.

Vibrational spectroscopy of jet-cooled 9-fluorenemethanol and its clusters 9-fluorenemethanol-H2O, 9-fluorenemethanol-CH3OH, 9-fluorenemethanol-C2H5OH, and 9-fluorenemethanol-C3H7OH has been carried out using an IR-UV double-resonance method. The spectrum of the OH stretching vibration, v(OH), has been measured for the 9-fluorenemethanol monomer and for each of the clusters. Two conformers of 9-fluorenemethanol, symmetric (sym) and unsymmetric (unsym), have been identified using a combination of spectroscopy and quantum chemical calculations with B3LYP and HF methods using the 6-31G(d) basis set.

Enzymatic activity of alkaline phosphatase inside protein and polymer structures fabricated via multiphoton excitation.

We demonstrate micron scale control of bioactivity through the use of multiphoton excited photochemistry, where this technique has been used to cross-link three-dimensional matrixes of alkaline phosphatase, bovine serum albumin, and polyacrylamide and combinations therein. Using a fluorescence-based assay (ELF-97), the enzymatic activity has been studied using a Michaelis-Menten analysis, and we have measured the specificity constants kcat/KM for alkaline phosphatase in both the protein and polymer matrixes to be on the order of 10(5)-10(6) M(-1) s(-1)and are comparable to known literature values in other environments. It is found that the enzyme is simply entrapped in the polymer matrix, whereas it is completely covalently bound in the protein structures.