Synthetic graphene-copper nanocomposites interact with the hACE-2 enzyme and inhibit its biochemical activity

This study demonstrates the copper nanocomposite-induced enzymatic inhibition of human angiotensin I-converting enzyme-2 (hACE-2) by complex stabilization through the formation of the enzyme nanocomposite. The immediate application of this work is related to ACE-2 as a mechanism of SARS-CoV-2 entry into cells. Moreover, ACE-2 enzyme regulation is a potential therapeutic strategy in hypertension and cardiovascular disease, diabetes, lung injury, and fibrotic disorders. Thus, inhibition of ACE-2 with nanocomposite therapy, may have pharmacologic application with regard to infectious and non-infectious diseases. Synthesized copper nanocomposites described here alone with a commercially available compound, were tested for their potential to inhibit hACE-2 activities. Following wet chemical synthesis, Cu/CuO nanoparticles and graphene-copper (GO-Cu) complexes were synthesized and characterized for their chemical integrity. Cu/CuO formed well-dispersed clusters of 390 ± 100 nm, that when complexed with the hACE-2 enzyme exhibited larger clusters of 506 ± 56 nm. The formation of the Cu/CuO and hACE-2 enzyme complex was monitored by analyzing the zeta potential, which reflected the surface charge distribution of the complex. A negatively charged Cu/CuO nanocomposite nearly becomes neutral when complexed with hACE-2 further assuring the complex formation. Formation of this complex and its inactivation of hACE-2 was evaluated using a standardized protocal for enzymatic activity. Similarly, carboxylate-functionalized graphene was complexed with copper, and its inhibitory effect was studied. Each step in the GO-Cu composite formation was monitored by characterizing its surface electrical properties, resulting in a decrease in its zeta potential and conductivity when complexed with copper. The interaction of the nanocomposites with hACE-2 was confirmed by 2D-FDS and gel electrophoresis analysis. GO-Cu was a rapid and efficacious inhibitor compared to Cu-CuO, especially at lower concentrations (2 μg ml^-1). Considering the environmental friendliness of copper and graphene and their use in industries as surface coating materials, we anticipate that use of these composites once proven effective, may have future antimicrobial application. Utility of nanocomposites as antimicrobials, either as a surface antimicrobial or as an in vivo therapeutic, could be invisioned for use against current unknown and/or emergent pathogens.