Single-Step Biofriendly Synthesis of Surface Modifiable, Near-Spherical Gold Nanoparticles for Applications in Biological Detection and Catalysis

There is an increased interest in understanding the toxicity and rational design of gold nanoparticles (GNPs) for biomedical applications in recent years. Such efforts warrant reliable, viable, and biofriendly synthetic methodology for GNPs with homogeneous sizes and shapes, particularly sizes above 30 nm, which is currently challenging. In the present study, an environmentally benign, biofriendly, singlestep/ single-phase synthetic method using dextrose as a reducing and capping agent in a buffered aqueous solution at moderate temperature is introduced. The resulting GNPs are near-spherical, stable, catalytically active, place exchangeable, and water-soluble within the size range of 10-120 nm. The added advantage of the biologically friendly reaction medium employed in this new synthetic approach provides a method for the direct embedment/integration of GNPs into biological systems such as the E. coli bacterium without additional capping ligand or surface modification processes

One-Step Synthesis of Highly Monodispersed, Spherical Gold Nanoparticles of 10-120 nm and Applications in Chemistry and Biology

In recent years there are significant studies going on understanding the toxicity and rational design of gold nanoparticles (GNPs) for biomedical applications. Such efforts warrant reliable and viable green synthetic methodology for GNPs with homogenous sizes and shapes, particularly sizes above 30 nm which is currently challenging. In the present study, an environmentally benign green, one-step, one-phase and efficient synthetic approach was introduced for the synthesis of catalytically effective and surface modifiable GNPs. In this approach GNPs were synthesized by using dextrose as a reducing agent and also a stabilizing agent in aqueous medium, by maintaining the nucleation and growth without the additional need of seeding process. The resulting GNPs were highly monodispersed with spherical shape in the size range of 10-120 nm. Due to the added advantages of the biologically friendly reaction medium employed in this new synthetic scheme, GNPs in the size range of 5-50 nm were simultaneously synthesized and integrated into the bacteria

Organocatalytic Synthesis and Evaluation of Polycarbonate Pendant Polymer:β-Cyclodextrin-Based Nucleic Acid Delivery Vectors

A family of mPEG-<i>b</i>-polycarbonate (mPEG-PC) diblock pendant polymers were synthesized from trimethylene carbonate and other cyclic carbonate monomers bearing hydrophobic guest ligands via organocatalytic ring-opening polymerization using 1,4,5-triazabicyclo[4.4.0]­dec-5-ene catalyst or 1,8-diazabicyclo[5.4.0]­undec-7-ene/thiourea cocatalyst. Diblock copolymers composed of a methoxy­poly­(ethylene oxide) (mPEG) block and a polycarbonate block containing either homopolymer or mixed polycarbonates (PC) were prepared by homopolymerization or copolymerization of the cyclic carbonate monomers in the presence of mPEG2000 or mPEG5000 initiator to give materials having a tunable pendant group density along the polycarbonate backbone. Polycarbonate blocks targeting the 2.4–10 kDa range were prepared with good molecular weight control and modest polydispersities (averaging ∼1.3). Complexation of plasmid DNA with β-cyclodextrin–polyethylenimine2.5 kDa produced nanoparticle cores that were then coated with the mPEG–PC diblock copolymers to produce transfection complexes in the 100–250 nm size range. Stable transfection complexes prepared at N/P ratios >10 had slightly positive ζ potentials and showed comparable or modestly better transfection efficiencies in HeLa cells than the commercial transfection agent, Lipofectamine2000. Transfection efficiencies were not dependent on polycarbonate block molecular weights. The mPEG-PC constructs displayed similar efficacy for adamantyl and cholesteryl pendants that strongly bind to β-cyclodextrin; however, slightly better performance was observed for the weakly bound pendant, benzyl. These findings suggest that pDNA release is largely mediated by hydrolysis of the ester-bound pendant ligand within the endolysosomal compartment of the cell, with desorption of the mPEG–PC layer also contributing to plasmid release and activation in the case of weak binding pendant groups. We infer from these results that mPEG-PC may be an effective degradable transfection agent for <i>in vivo</i> applications