Macrophage scavenger receptor A mediates the uptake of gold colloids by macrophages in vitro.

Aims: While numerous studies have reported on nanoparticle uptake by phagocytic cells, the mechanisms of this uptake are poorly understood. A metastudy of research focusing on biological particulate matter has postulated that nanoparticles cannot be phagocytosed and therefore must enter cells via pinocytosis. The purpose of this study was to identify the route(s) of uptake of gold nanoparticles in vitro and to determine if these route(s) depend on particle size.

Gold nanoparticle quantitation via fluorescence in solution and cell culture.

This chapter provides a protocol for quantitative analysis of gold in solution as well as gold uptake by macrophages. A 96-well fluorescence assay was developed to be able to determine gold concentrations for a given gold nanoparticle as well as quantify the degree of gold nanoparticle uptake by macrophages. This assay detects a decrease in the fluorescence of a dye upon forming a complex with gold and a ligand.

The tail of KdsC: conformational changes control the activity of a haloacid dehalogenase superfamily phosphatase.

The phosphatase KdsC cleaves 3-deoxy-D-manno-octulosonate 8-phosphate to generate a molecule of inorganic phosphate and Kdo. Kdo is an essential component of the lipopolysaccharide envelope in Gram-negative bacteria. Because lipopolysaccharide is an important determinant of bacterial resistance and toxicity, KdsC is a potential target for novel antibacterial agents.

Nanoparticle interaction with plasma proteins as it relates to particle biodistribution, biocompatibility and therapeutic efficacy.

Proteins bind the surfaces of nanoparticles, and biological materials in general, immediately upon introduction of the materials into a physiological environment. The further biological response of the body is influenced by the nanoparticle-protein complex. The nanoparticle's composition and surface chemistry dictate the extent and specificity of protein binding.

Interaction of colloidal gold nanoparticles with human blood: effects on particle size and analysis of plasma protein binding profiles.

Nanoparticle size and plasma binding profile contribute to a particle's longevity in the bloodstream, which can have important consequences for therapeutic efficacy. In this study an approximate doubling in nanoparticle hydrodynamic size was observed upon in vitro incubation of 30- and 50-nm colloidal gold in human plasma. Plasma proteins that bind the surface of citrate-stabilized gold colloids have been identified.

Preclinical studies to understand nanoparticle interaction with the immune system and its potential effects on nanoparticle biodistribution.

Nanoparticles have unique physicochemical properties which make them promising platforms for drug delivery. However, immune cells in the bloodstream (such as monocytes, platelets, leukocytes, and dendritic cells) and in tissues (such as resident phagocytes) have a propensity to engulf and eliminate certain nanoparticles. A nanoparticle's interaction with plasma proteins (opsonins) and blood components (via hemolysis, thrombogenicity and complement activation) may influence uptake and clearance and hence potentially affect distribution and delivery to the intended target sites.

Single amino acid substitutions in either YhjD or MsbA confer viability to 3-deoxy-d-manno-oct-2-ulosonic acid-depleted Escherichia coli.

The Escherichia coli K-12 strain KPM22, defective in synthesis of 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo), is viable with an outer membrane (OM) composed predominantly of lipid IV(A), a precursor of lipopolysaccharide (LPS) biosynthesis that lacks any glycosylation. To sustain viability, the presence of a second-site suppressor was proposed for transport of lipid IV(A) from the inner membrane (IM), thus relieving toxic side-effects of lipid IV(A) accumulation and providing sufficient amounts of LPS precursors to support OM biogenesis. We now report the identification of an arginine to cysteine substitution at position 134 of the conserved IM protein YhjD in KPM22 that acts as a compensatory suppressor mutation of the lethal DeltaKdo phenotype.

Redefining the requisite lipopolysaccharide structure in Escherichia coli.

Gram-negative bacteria possess an asymmetric lipid bilayer surrounding the cell wall, the outer membrane (OM). The OM inner leaflet is primarily composed of various glycerophospholipids, whereas the outer leaflet predominantly contains the unique amphiphilic macromolecule, lipopolysaccharide (LPS or endotoxin). The majority of all gram-negative bacteria elaborate LPS containing at least one 2-keto 3-deoxy-D-manno-octulosonate (Kdo) molecule.