A hybrid of mPEG-b-PCL and G1-PEA dendrimer for enhancing delivery of antibiotics

The development of novel materials is essential for the efficient delivery of drugs. Therefore, the aim of the study was to synthesize a linear polymer dendrimer hybrid star polymer (3-mPEA) comprising of a generation one poly (ester-amine) dendrimer (G1-PEA) and a diblock copolymer of methoxy poly (ethylene glycol)-b-poly(epsilon-caprolactone) (mPEG-b-PCL) for formulation of nanovesicles for efficient drug delivery. The synthesized star polymer was characterized by FTIR, H-1 and C-13 NMR, HRMS, GPC and its biosafety was confirmed by MTT assays. Thereafter it was evaluated as a nanovesicle forming polymer. Vancomycin loaded nanovesicles were characterized using in vitro, molecular dynamics (MD) simulations and in vivo techniques. MTT assays confirmed the nontoxic nature of the synthesized polymer, the cell viability was 77.23 to 118.6%. The nanovesicles were prepared with size, polydispersity index and zeta potential of 52.48 +/- 2.6 nm, 0.103 +/- 0.047, -7.3 +/- 1.3 mV respectively, with the encapsulation efficiency being 76.49 +/- 2.4%. MD simulations showed spontaneous self-aggregation of the dendritic star polymer and the interaction energy between the two monomers was -146.07 +/- 4.92, Van der Waals interactions playing major role for the aggregates stability. Human serum albumin (HSA) binding studies with Microscale Thermophoresis (MST) showed that the 3-mPEA did not have any binding affinity to the HSA, which showed potential for long systemic circulation. The vancomycin (VCM) release from the drug loaded nanovesicles was found to be slower than bare VCM, with an 65.8% release over a period of 48 h. The in vitro antibacterial test revealed that the drug loaded nanovesicles had 8- and 16-fold lower minimum inhibitory concentration (MIC) against methicillin sensitive Staphylococcus aureus and methicillin-resistant S. aureus strains (MRSA) compared to free drug. The flow cytometry study showed 3.9-fold more dead cells of MRSA in the population when samples were treated with the drug loaded nanovesicles than the bare VCM at concentration 0.488 mu g/mL. An in vivo skin infection mice model showed a 20-fold reduction in the MRSA load in the drug loaded nanovesicles treated groups compared to bare VCM. These findings confirmed the potential of 3-mPEA as a promising biocompatible effective nanocarrier for antibiotic delivery.