Neopterin interactions with magic atom number coinage metal nanoclusters: A theoretical study

Abstract Metal nanoclusters (NCs) are novel materials with low cytotoxicity, high chemical stability, intense luminescence, etc. These characteristics are in great demand during biomarker detection and bioimaging. These properties of metal NCs are exploited by colorimetric, luminescent, and Raman tiny sensors. Neopterin (Nep) is used in medicine as a biomarker of inflammation and immune system activation, cancer, COVID-19, etc. The clusters of Au, Ag, and Cu with magic atom numbers m * equal to 2 and 10 were studied. Gibbs energy of complexation ( E b ) has been established using density functional theory (DFT). The highest E b was determined for the complexes of <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:msubsup> <m:mrow> <m:mtext>Au</m:mtext> </m:mrow> <m:mrow> <m:mn>2</m:mn> </m:mrow> <m:mrow> <m:mtext>+</m:mtext> </m:mrow> </m:msubsup> </m:math> {\text{Au}}_{2}^{\text{+}} and <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:msubsup> <m:mrow> <m:mtext>Cu</m:mtext> </m:mrow> <m:mrow> <m:mn>2</m:mn> </m:mrow> <m:mrow> <m:mtext>+</m:mtext> </m:mrow> </m:msubsup> </m:math> {\text{Cu}}_{2}^{\text{+}} in an alkaline aqueous solution. As a rule, clusters change their symmetry upon the interaction with Nep; their physicochemical properties are also changed. The detection of Nep with Au and Cu NCs seems to be prospective using Raman detection. In particular, Raman detection of Nep should be done using Cu 9 NC, which interacts with all three Nep functional groups (pyrazine, pyrimidine, and side substituent) and causes significant chemical enhancement and shift of the Raman signal. The usage of coinage metal clusters and nanoparticles is expected for precise Nep detection in the near future.