No abstract

Similarly to enzymes,f unctionalized gold nanoparticles efficiently catalyze chemical reactions,hence the term nanozymes.H erein, we present our results showing how surface-passivated gold nanoparticles behave as synthetic nanonucleases,a ble to cleave pBR322 plasmid DNAwith the highest efficiency reported so far for catalysts based on asingle metal ion mechanism. Experimental and computational data indicate that we have been successful in creating acatalytic site precisely mimicking that suggested for natural metallonucleases relying on as ingle metal ion for their activity.I tc omprises one Zn(II) ion to which ap hosphate diester of DNAi s coordinated. Importantly,a si nn ucleic acids-processing enzymes,apositively charged arginine playsakey role by assisting with transition state stabilization and by reducing the pK a of the nucleophilic alcohol of as erine.O ur results also show howd esigning ac atalyst for am odel substrate (bis-pnitrophenylphosphate) may provide wrong indications as for its efficiency when it is tested against the real target (plasmid DNA).

A series of 2-nm gold nanoparticles passivated with different thiols all featuring at least one triazacyclonanone-Zn(II) complex and different flanking units (a second Zn(II) complex, a triethyleneoxymethyl derivative or a guanidinium of arginine of a peptide) were prepared and studied for their efficiency in the cleavage of the RNA-model substrate 2-hydroxypropyl-p-nitrophenyl phosphate. The source of catalysis for each of them was elucidated from the kinetic analysis (Michaelis–Menten profiles, pH dependence and kinetic isotope effect). The data indicated that two different mechanisms were operative: One involving two Zn(II) complexes and the other one involving a single Zn(II) complex and a flanking guanidinium cation. The mechanism based on a dinuclear catalytic site appeared more efficient than the one based on the cooperativity between a metal complex and a guanidinium.

There is currently a lack of efficient reagents to transfect cells with large plasmid DNA, which would be enabling tools for gene editing using CRISPR/Cas9 technology. Herein we report the...

Transfecting nucleic acids into various cells is a key procedure in biological research also envisioned for therapeutic applications. In our effort to obtain simple reagents that would be readily accessible from commercial building blocks, we recently reported peptide dendrimers as single component siRNA transfection reagents accessible in pure form by solid-phase peptide synthesis. Here, we extend our studies of these dendrimers by identifying analogs bearing a coumarin or BODIPY fluorescent label in their core and displaying comparable siRNA transfection efficiencies, pH dependent aggregation, siRNA binding, and secondary structures. Fluorescence resonance energy transfer (FRET) studies show that the dendrimers are tightly associated with siRNA within the formed nanoparticles at pH 7.4 but are released into solution at pH 5.0 and can participate in endosome escape by destabilizing the membrane at this pH value. Colocalization studies furthermore suggest that peptide dendrimers and siRNA remain tightly associated throughout the transfection process.