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Author(s): Albert C. Aragons [1, 2, 3]; Naomi L. Haworth [4]; Nadim Darwish (corresponding author) [1, 2]; Simone Ciampi (corresponding author) [5]; Nathaniel J. Bloomfield [4]; Gordon G. Wallace [5]; [...]

We describe a methodology to perform reliable tunneling spectroscopy in electrochemical media. Sequential in situ tunneling spectra are recorded while the electrochemical potential of the electrode is scanned. Spectroscopic data are presented as conductance maps or conductograms that show the in situ electronic structure of an electrode surface while it undergoes an electrochemical reaction. The conductance map or conductogram represents the redox fingerprint of an electrode/liquid interface in a specific medium and can serve to predict its electrochemical behavior in a quantitative energy scale. The methodology is validated studying the reversible oxidation and passivity of an iron electrode in borate buffer, and we describe the main quantitative information that can be extracted concerning the semiconducting properties of the Fe passive film. This methodology is useful to study heterogeneous catalysis, electrochemical sensing and bioelectronic systems.

We present a new procedure to prepare Pt/Ir probes for electrochemical scanning tunneling microscopy (STM) and spectroscopy applications. We detail the experimental setup and the improvements over previous methods. The probes have been used successfully for measurements of tunneling spectroscopy under electrochemical control, which requires scanning the potential of the tip at high velocity.

Neurotransmitters are stored in synaptic vesicles, where they have been assumed to be in free solution. Here we report that in Torpedo synaptic vesicles, only 5% of the total acetylcholine (ACh) or ATP content is free, and that the rest is adsorbed to an intravesicular proteoglycan matrix. This matrix, which controls ACh and ATP release by an ion-exchange mechanism, behaves like a smart gel. That is, it releases neurotransmitter and changes its volume when challenged with small ionic concentration change. Immunodetection analysis revealed that the synaptic vesicle proteoglycan SV2 is the core of the intravesicular matrix and is responsible for immobilization and release of ACh and ATP. We suggest that in the early steps of vesicle fusion, this internal matrix regulates the availability of free diffusible ACh and ATP, and thus serves to modulate the quantity of transmitter released.

A complex of CstF-64 and the SL2 snRNP has been found to connect mRNA 3' end formation and trans-splicing in Caenorhabditis elegans operons. CstF-64 is the homolog to the RNA-binding subunit of mammalian CstF. Immunoprecipitations were carried out using an antibody to C. elegans CstF-64. SL2 RNA is precipitated with alpha CstF-64 while other snRNAs were not.

The RNA binding characteristics of wild-type and deletion constructs of polypyrimidine tract binding protein that have RNA recognition motifs in both an oligomeric and monomeric context were examined to correlate structural motifs with their roles. Results showed that there is no strong correlation between the RNA binding affinity and specificity upon oligomerization. However, the mode of RNA interaction and dimerization is related.

The scanning tunneling microscope break junction technique is employed to explain the various transport characteristics that are exhibited by the long conjugated molecular wires. The impact of the length and the temperature on the conductance behavior of these wires is also analyzed.

The oxidation and reduction processes of both polycrystalline tin and Sn (100) single crystals are investigated in borate buffer solution of pH 7.5 using cyclic voltammetry and in-situ characterizations such as Raman scattering, potential modulated reflectance spectroscopy (PMRS), and electrochemical scanning tunneling microscopy (EC-STM).