Introduction:

The emergence of antibiotic resistance has become a public health threat. A major contributor to this global healthcare problem is poor efficiency of drug delivery, necessitating the development of more efficient targeting and stimuli-responsive drug delivery systems. Furthermore, to ensure potential clinical applications, non-cytotoxicity is also warranted. Due to their intrinsic biocompatibility, straightforward synthesis, facile surface functionalization, and photothermal conversion efficiency, polydopamine nanoparticle (PDNP) has recently emerged as a promising candidate for the development of multi-functional drug nanocarriers. This study aims to investigate the impact of the structure of the antibiotics tetracycline (Tet) and chloramphenicol (Chl) on they efficiency of PDNP as antibiotic nanocarriers.

Methods/Results:

The effect of the structure of antibiotics Tet and Chl on drug loading efficiency on PDNP was studied, where the antibiotics were added either during or after nanoparticle synthesis. Additionally, its effect on the efficiency of passive and laser-induced drug release from PDNP was also examined. The synthesized PDNP were imaged using Atomic Force Microscopy, and the amount of antibiotics loaded on and released from PDNP was quantified using UV/Vis Spectrophotometry. Our results show that the drug loading efficiency is higher for the smaller molecule, Chl, when drugs are loaded after nanoparticle synthesis. On the contrary, for Tet, which exhibits higher π-π stacking ability, loading on PDNP was more efficient during synthesis, while the particles are still growing. Our results also suggest that the molecular structure of the drug dictates the amount of drug released from PDNP: release efficiency for Chl is always higher than Tet, regardless of the drug loading method. Furthermore, the effect of photothermal treatment via laser stimulation on the efficiency of drug release from PDNP nanocarriers was evaluated. For both Tet and Chl, release efficiency is consistently higher under laser-induced heating than without laser treatment.

Conclusion:

Overall, our results highlight that both the molecular structure of the drug and the manner of loading and release are important determinants in optimizing the efficiency of PDNP as a drug nano-delivery system.