Polydopamine-Coated Zn-MOF-74 Nanocarriers: Versatile Drug Delivery Systems with Enhanced Biocompatibility and Cancer Therapeutic Efficacy

While MOF-74 drug delivery platforms are known for their high drug loading capacity (DLC) and efficiency (DLE), surface chemistry modifications can further enhance their performance. Two variants of Zn-MOF-74 nanoparticles (particle size < 100 nm, per microscopic analysis) were prepared at room temperature, fully characterized and loaded with doxorubicin (DOX) as a model drug. UV-visible spectrometry revealed a DLE of 96.5% and a DLC of 19.6% for zinc acetate (R_A-MOF-74) nanocarrier, against zinc nitrate (R_N-MOF-74) with 88.8% and 18.3% in the same order. R_A-MOF-74 nanocarriers were coated with polydopamine (PDA) through an in-situ polymerization process to enhance physicochemical properties and compatibility with biological systems. Both the uncoated and PDA-coated R_A-MOF-74 showed accelerated drug release at pH 5.5 due to quicker structural collapse, which experienced an increase of 24.3% for the former and a 6.2% increase for the latter sample. The biological properties of loaded Zn-MOF-74 nanocarriers demonstrated acceptable anti-cancer activity, and possessing low hemolytic activity. Moreover, the cytotoxicity results indicated an inhibition of 85.73% against MDA-MB-231 breast cancer cells for the DOX-loaded MOF-74, notably about 5% higher than that of the pure DOX at a concentration of 400 µg/ml. At the same concentration, loaded MOF-74 showed a hemolytic activity of 9.62%, which was significantly lower than 28.97% assigned to the pure DOX. These results demonstrate the potential of Zn-MOF-74 nanoparticles for diverse medical applications, warranting further investigation of their in vivo performance in both therapeutic and diagnostic roles.