Sol–gel encapsulation of binary Zn(II) compounds in silica nanoparticles. Structure–activity correlations in hybrid materials targeting Zn(II) antibacterial use

• Hybrid Zn(II)-Schiff material and SiO2 nanoparticle synthesis and characterization
• Entrapment and drug release study verify nanomaterial physicochemical properties.
• Bio-activity of zinc-loaded SiO2 nanospheres merits antibacterial nanotechnology.
• Improvement of antibacterial activity toward multiresistance in infectious pathogens
• Molecular protection and nanomedicinal treatment against bacterial infections

In the emerging issue of enhanced multi-resistant properties in infectious pathogens, new nanomaterials with optimally efficient antibacterial activity and lower toxicity than other species attract considerable research interest. In an effort to develop such efficient antibacterials, we a) synthesized acid-catalyzed silica-gel matrices, b) evaluated the suitability of these matrices as potential carrier materials for controlled release of ZnSO4 and a new Zn(II) binary complex with a suitably designed well-defined Schiff base, and c) investigated structural and textural properties of the nanomaterials. Physicochemical characterization of the (empty-loaded) silica-nanoparticles led to an optimized material configuration linked to the delivery of the encapsulated antibacterial zinc load. Entrapment and drug release studies showed the competence of hybrid nanoparticles with respect to the a) zinc loading capacity, b) congruence with zinc physicochemical attributes, and c) release profile of their zinc load. The material antimicrobial properties were demonstrated against Gram-positive (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus) and negative (Escherichia coli, Pseudomonas aeruginosa, Xanthomonas campestris) bacteria using modified agar diffusion methods. ZnSO4 showed less extensive antimicrobial behavior compared to Zn(II)-Schiff, implying that the Zn(II)-bound ligand enhances zinc antimicrobial properties. All zinc-loaded nanoparticles were less antimicrobially active than zinc compounds alone, as encapsulation controls their release, thereby attenuating their antimicrobial activity. To this end, as the amount of loaded zinc increases, the antimicrobial behavior of the nano-agent improves. Collectively, for the first time, sol–gel zinc-loaded silica-nanoparticles were shown to exhibit well-defined antimicrobial activity, justifying due attention to further development of antibacterial nanotechnology.

In confronting the emerging issue of increased multi-resistance in infectious pathogens, novel binary Zn(II)/Zn(II)-Schiff hybrid nanomaterials were developed. Their antimicrobial properties were demonstrated against Gram positive/negative bacteria using agar diffusion methods. For the first time, chemical–biological correlations in zinc-encapsulated silica nanoparticles draw attention and project merit toward antibacterial nanotechnology.Figure optionsDownload as PowerPoint slide