Unveiling the interplay between homogeneous and heterogeneous catalytic mechanisms in copper–iron nanoparticles working under chemically relevant tumour conditions

Abstract

The present work sheds light on a generally overlooked issue in the emerging field of bio-orthogonal catalysis within tumour microenvironments (TMEs): the interplay between homogeneous and heterogeneous catalytic processes. In...

Heterogeneous-Driven Glutathione Oxidation: Defining the Catalytic Role of Chalcopyrite Nanoparticles

“…We investigated the reactivity of the CuFeS 2 /GSH system by using MS and 1 H NMR to monitor both GSH and GSSG. The initial concentration of GSH was set to 5 mM in order to mimic the intracellular environment. ,, We detected the product GSSG after 3 and 24 h of reaction by MS (detected ions: [M + H] + = 613 and [M + Na] + = 635) (Figure a). 1 H NMR analysis also confirmed both the generation of GSSG and the consumption of GSH.…”

“…We then probed the byproduct generated in the reaction with GSH using 1,3-diphenylisobenzofuran (DPBF). Prior to studying the CuFeS 2 –GSH reaction, we evaluated whether DPBF was capable of reacting with H 2 O 2 or with • O 2 – , two potential byproducts of the GSH oxidation reaction. , Our results suggested that DPBF could not react with added H 2 O 2 either in the absence or presence of GSH (Figure S10a,b), but did with KO 2 , a source of superoxide anions (Figure S10c,d). Therefore, a decrease in DPBF absorbance present in a mixture of CuFeS 2 with GSH can be related to the generation of • O 2 – (Figure S11).…”

“…Specifically, the combination of Cu and Fe in a single nanoplatform has been demonstrated to be an efficient strategy in cancer therapy. ,− The origin of this synergy relies on the role of Cu as a cocatalyst in Fe-driven Fenton reactions. , Cu + can react with Fe 3+ in a thermodynamically favorable process (Δ E = 0.6 V) to regenerate active Fe 2+ species, thus avoiding the highly energetic H 2 O 2 reaction with Fe 3+ to yield the desired Fe 2+ reactive species in the absence of Cu + . However, Cu present in Cu–Fe oxides can suffer from lixiviation phenomena under TME conditions in a similar way as reported for CuO nanoparticles (Figure ). Once released into its ionic form in solution, Cu can catalyze GSH oxidation following a homogeneous pathway .…”

“…Schematic display of the GSH oxidation steps occurring in the presence of a copper–iron nanocatalyst containing either a spinel-like oxide configuration (top) or a chalcopyrite composition (bottom). For oxide-based catalysts, GSH promotes the Cu release from the crystalline structure through complex formation, and once in solution, GSH is oxidized by the Cu­(II)/O 2 system . In this work, we present a CuFeS 2 catalyst that maintains the catalytic activity while preventing the rapid release of Cu ions.…”

“…To explore other catalytic pathways that do not entail a huge metal release, we have developed a new synthesis route to chalcopyrite CuFeS 2 nanoparticles (NPs) and evaluated their catalytic response toward GSH oxidation and H 2 O 2 conversion into ROS. In our previous research, we identified the in situ formation of Cu–SG complexes when CuFe-oxide NPs reacted with GSH . Inspired by the chemical strength of the Cu–S bonding in the complex, we have designed these chalcopyrite NPs where Cu occupies tetrahedral sites surrounded by S anions.…”