Development of ciprofloxacin-conjugated DNA–functionalized Ag NPs: nanoengineering, enhanced drug delivery, and multifunctional biological evaluation

DNA-functionalized metallic nanostructures offer an attractive interface for integrating biomolecular functionality with the physicochemical properties of silver nanoparticles (Ag NPs). This study developed ciprofloxacin-conjugated DNA-functionalized silver nanoparticles (CIP-DN-Ag NPs) for CIP delivery with potential antimicrobial and anticancer biological activity. Drug release and skin permeation evaluated drug availability, while antioxidant assays provided additional characterization. DN-Ag NPs were prepared by coprecipitation, with DNA serving as a surface-functionalizing and stabilizing/capping ligand, followed by CIP association with the Ag nanoparticle surface. The nanoparticles exhibited a hydrodynamic diameter of 156.4 nm and a zeta potential of −18.6 mV. CIP-DN-Ag NPs showed enhanced aqueous solubility (0.85 ± 0.03 μg/mL) compared with DN-Ag NPs (0.60 ± 0.04 μg/mL). FTIR, XRD, DSC, FESEM, and AFM analyses supported nanoparticle formation and CIP association with the DNA-functionalized Ag nanoparticle surface. In vitro CIP release reached 73.0 ± 1.5% within 8 h, compared with 32.5 ± 1.5% for free CIP, while chicken-skin permeation reached 98.0 ± 2.0% at 240 min. Release kinetics followed the Korsmeyer–Peppas model (R2 = 0.9276; n = 0.5908), whereas permeation followed the Higuchi model (R2 = 0.9937). CIP-DN-Ag NPs demonstrated chemical radical-scavenging activity against DPPH, H2O2, hydroxyl radicals, and nitric oxide. Antibacterial activity produced inhibition zones of 22.8 ± 1.3 and 21.7 ± 1.5 mm against S. aureus and E. coli, respectively. Against A375 cells, CIP-DN-Ag NPs showed an apparent IC50 of 32.5 ± 3.0 µM compared with 45.5 ± 3.5 μM for free CIP, indicating greater apparent cytotoxic potency under the investigated conditions.