Purification and functionalization of nanodiamond to serve as a platform for amoxicillin delivery

• Nanodiamond particles (NDPs) were purified by acid and heat treatment method.
• Acid treated NDPs show higher diamond yield (97.5%–99.68%) than heat treated ones.
• NDPs were functionalized with polyethylenimine.
• Experimental protocols for successful loading of amoxicillin on NDPs were developed.

Urinary tract infections (UTIs) cost $0.4–0.5 billion a year in the US and is the second most common disease affecting millions of people. As resistance to antibiotics becomes more common, a greater need for alternative treatments is needed. Nanodiamond particles (NDPs) are actively researched as drug delivery platforms due to their biocompatibility, particle size, and stable inert core. This research is aimed at developing NDPs as antibiotic drug delivery platforms for treating UTIs. To this end, 100 nm, 75 nm, 25 nm and 6 nm size NDPs are purified with acid and heat treatment techniques. Raman spectra of the NDPs showed that the acid treatment method resulted in higher diamond yield. Fourier transform infrared spectroscopy (FTIR) studies showed that both purification techniques result in oxygen terminated surface groups. Efficiency of loading amoxicillin on 25 nm NDPs based on electrostatic interaction of NDPs, functionalizing surfaces of NDPs with hydrogen, and polyethylenimine (PEI) are investigated. It is found that the electrostatic and surface hydrogenation approaches are not efficient in loading amoxicillin on the NDPs. On the other hand, PEI functionalized NDPs produced successful loading with amoxicillin as indicated by the presence of the β-lactam peak at 1770 cm− 1, amide peak at 1680 cm− 1, and bond between PEI NH stretching and amoxicillin –COOH group at 3650 cm− 1 by the FTIR spectra. These results are expected to lay the foundation for developing NDP based targeted drug delivery treatment techniques for treating UTIs and other infectious diseases.

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