Novel analytical methods to assess the chemical and physical properties of liposomes.

Liposomes are used in commercial pharmaceutical formulations (PFs) and dietary supplements (DSs) as a carrier vehicle to protect the active ingredient from degradation and to increase the half-life of the injectable. Even as the commercialization of liposomal products has rapidly increased, characterization methodologies to evaluate physical and chemical properties of the liposomal products have not been well-established. Herein we develop rapid methodologies to evaluate chemical and selected physical properties of liposomal formulations.

Single Molecule Nanopore Spectrometry for Peptide Detection.

Sensing and characterization of water-soluble peptides is of critical importance in a wide variety of bioapplications. Single molecule nanopore spectrometry (SMNS) is based on the idea that one can use biological protein nanopores to resolve different sized molecules down to limits set by the blockade duration and noise. Previous work has shown that this enables discrimination between polyethylene glycol (PEG) molecules that differ by a single monomer unit.

Voltage and blockade state optimization of cluster-enhanced nanopore spectrometry.

Recent work described the use of thiolate-capped gold clusters (Au25(SG)18) with nanopore sensing to increase the residence time of polyethylene glycol (PEG) in an alpha hemolysin pore [Anal. Chem., 2014, 86, 11077].

Neat and complete: thiolate-ligand exchange on a silver molecular nanoparticle.

Atomically precise thiolate-protected noble metal molecular nanoparticles are a promising class of model nanomaterials for catalysis, optoelectronics, and the bottom-up assembly of true molecular crystals. However, these applications have not fully materialized due to a lack of ligand exchange strategies that add functionality, but preserve the properties of these remarkable particles. Here we present a method for the rapid (<30 s) and complete thiolate-for-thiolate exchange of the highly sought after silver molecular nanoparticle [Ag44(SR)30](-4).

Enhanced single molecule mass spectrometry via charged metallic clusters.

Nanopore sensing is a label-free method for characterizing water-soluble molecules. The ability to accurately identify and characterize an analyte depends on the residence time of the molecule within the pore. It is shown here that when a Au25(SG)18 metallic cluster is bound to an α-hemolysin (αHL) nanopore, the mean residence time of polyethylene glycol (PEG) within the pore is increased by over 1 order of magnitude.

An analysis of the sponge microbiome yields an actinomycete that produces the natural product manzamine A.

Sponges have generated significant interest as a source of bioactive and elaborate secondary metabolites that hold promise for the development of novel therapeutics for the control of an array of human diseases. However, research and development of marine natural products can often be hampered by the difficulty associated with obtaining a stable and sustainable production source. Herein we report the first successful characterization and utilization of the microbiome of a marine invertebrate to identify a sustainable production source for an important natural product scaffold.

Au₁₃₇(SR)₅₆ nanomolecules: composition, optical spectroscopy, electrochemistry and electrocatalytic reduction of CO₂.

Au137(SR)56, a nanomolecule with a precise number of metal atoms and ligands, was synthesized. The composition was confirmed by MALDI and ESI mass spectrometry using three unique ligands (-SCH2CH2Ph, -SC6H13, and -SC4H9) and nano-alloys with Ag and Pd. The electrocatalytic properties were tested for CO2 reduction.

Size-dependent molecule-like to plasmonic transition in water-soluble glutathione stabilized gold nanomolecules.

A size-dependent transition from molecule-like to plasmonic behaviour is demonstrated in the case of water soluble Au:SG nanomolecules. This was achieved using PAGE separation of smaller and larger nanomolecules, resulting in an unprecedented 26 bands, in a wide-range from 10's to 1000's of Au-atoms. PAGE separation of larger plasmonic nanomolecules is demonstrated for the first time.

Au103(SR)45, Au104(SR)45, Au104(SR)46 and Au105(SR)46 nanoclusters.

High resolution ESI mass spectrometry of the "22 kDa" nanocluster reveals the presence of a mixture containing Au103(SR)45, Au104(SR)45, Au104(SR)46, and Au105(SR)46 nanoclusters, where R = -CH2CH2Ph. MALDI TOF MS data confirm the purity of the sample and a UV-vis spectrum shows minor features. Au102(SC6H5COOH)44, whose XRD crystal structure was recently reported, is not observed.

Au(144-x)Pd(x)(SR)60 nanomolecules.

Au144-xPdx(SR)60 alloy nanomolecules were synthesized and characterized by ESI mass spectrometry to atomic precision. The number of Pd atoms can be varied by changing the incoming metal ratio and plateaus at 7 Pd atoms. Based on the proposed 3-shell structure of Au144(SR)60, we hypothesize that the Pd atoms are selectively incorporated into the central Au12 icosahedral core.

Post-synthesis surface-modified silicas as adsorbents for heavy metal ion contaminants Cd(II), Cu(II), Cr(III), and Sr(II) in aqueous solutions.

To analyze the influence of silica surface modification and confined space effects on specific interactions of divalent and trivalent metal cations with surface functionalities, three different high surface area silicas with different pore size distributions were modified with the following organosilanes: 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-(trimethoxysilylpropyl)diethylenetriamine, N-(triethoxysilylpropyl)ethylenediaminetriacetic acid (EDTrA), and 3-(2,4-dinitrophenylamino)propyltriethoxysilane. The silicas were characterized by N(2) adsorption and reflectance FTIR spectroscopy before and after surface modification. N(2) adsorption and pore size distributions showed an increase in the pore width for all EDTrA-modified silicas, opposite to what occurred with the other organosilanes.

Ag44(SR)30(4-): a silver-thiolate superatom complex.

Intensely and broadly absorbing nanoparticles (IBANs) of silver protected by arylthiolates were recently synthesized and showed unique optical properties, yet question of their dispersity and their molecular formulas remained. Here IBANs are identified as a superatom complex with a molecular formula of Ag(44)(SR)(30)(4-) and an electron count of 18. This molecular character is shared by IBANs protected by 4-fluorothiophenol or 2-naphthalenethiol.

Ligand dependence of the synthetic approach and chiroptical properties of a magic cluster protected with a bicyclic chiral thiolate.

Chiral gold clusters stabilised by enantiopure thiolates were prepared, size-selected and characterised by circular dichroism and mass spectrometry. The product distribution is found to be ligand dependent. Au(25) clusters protected with camphorthiol show clear resemblance of their chiroptical properties with their glutathionate analogue.