Gold nanoparticle conjugated PLGA–PEG–SA–PEG–PLGA multiblock copolymer nanoparticles: synthesis, characterization, in vivo release of rifampicin

A series of succinate linearly linked PLGA–PEG–SA–PEG–PLGA multiblock copolymers were synthesized using direct melt polycondensation and characterized using inherent viscosity, gel permeation chromatography (GPC), FTIR and 1H-NMR spectroscopy techniques. Gold nanoparticles (AuNPs) were synthesized using an as-synthesized citrate–PEG (CPEG) hybrid dendron, which acts as a reducing agent as well as a stabilizing agent. The CPEG capped AuNPs were characterized using UV–visible spectroscopy and TEM analysis. The Au-conjugated PLGA–PEG–SA–PEG–PLGA multiblock copolymer NPs were loaded with the tuberculosis drug rifampicin (RIF) using ultrasonication followed by solvent evaporation and were characterized by TEM, powder XRD and XPS analyses. The RIF loading efficiency and percentage drug content of RIF loaded Au-conjugated multiblock copolymer NPs were evaluated using UV–visible spectroscopy. The RIF loading efficiency and RIF content of the AuNP conjugated multiblock copolymer NPs were 41.8–75.7% and 11.5–17.7% respectively. The in vivo drug release studies in male Wistar rats show that AuNP conjugated multiblock copolymer NPs exhibit drug release up to 240 h. The nanoconjugates exhibit 18.13–29.41 μg mL−1 of Cmax with a delayed Tmax of 72 h and the relative bioavailability is increased to 107–190.