Doxycycline conjugated with polyvinylpyrrolidone-encapsulated silver nanoparticles: a polymer's malevolent touch against Escherichia coli

Abstract

The emergence of multi-resistant pathogens has necessitated the investigation of new strategies to cope with this ever-increasing threat to public health. In this context, we combined silver nanoparticles (AgNPs) with doxycycline (DO), an antibiotic from the class of tetracyclines, to evaluate the potentiality of this hybrid as a bactericidal agent against E. coli. Polyvinylpyrrolidone (PVP) was used as a stabilizer to prevent the excessive growth and agglomeration of AgNPs. Interestingly, DO bound directly to PVP and had its concentration increased around the particle as a consequence of this interaction. As a result, the AgNPs/DO conjugates presented enhanced bactericidal properties compared to the individual components. Stabilizing agents are generally unwanted on the surfaces of nanoparticles because of their potential to block adsorption surface sites. However, we have shown that PVP played a paramount role in concentrating DO around the particle, which culminated in an increased bactericidal activity towards E. coli.