Determination of the Influence of Various Factors on the Character of Surface Functionalization of Copper(I) and Copper(II) Oxide Nanosensors with Phenylboronic Acid Derivatives

Abstract

In this work, we attempt to determine the influence of the oxidation state of copper [Cu(I) vs Cu(II)], the nature of the interface (solid/aqueous vs solid/air), the incubation time, and the structure of N-substituted phenylboronic acids (PBAs) functionalizing the surface of copper oxide nanostructures (NSs) on the mode of adsorption. For this purpose, 4-[(N-anilino)-(phosphono)-S-methyl]phenylboronic acid (1-PBA) and its two analogues (2-PBA and bis{1-PBA}) and the copper oxide NSs were synthesized in a surfactant-/ion-free solution via a synthetic route that allows controlling the size and morphology of NSs. The NSs were characterized by scanning electron microscopy, ultraviolet−visible spectroscopy, Raman spectroscopy, and X-ray diffraction, which confirmed the formation of spherical Cu 2 O nanoparticles (Cu 2 ONPs) with a size of 1.5 μm to 600 nm crystallized in a cubic cuprite structure and leaf-like CuO nanostructures (CuONSs) with dimensions of 80−180 nm in width and 400−700 nm in length and crystallized in a monoclinic structure. PBA analogues were deposited on the surface of the copper oxide NSs, and adsorption was investigated using surface-enhanced Raman spectroscopy (SERS). The changes in the orientation of the molecule relative to the substrate surface caused by the abovementioned factors were described, and the signal enhancement on the copper oxide NSs was determined. This is the first study using vibrational spectroscopy for these compounds.

SERS/TERS Characterization of New Potential Therapeutics: The Influence of Positional Isomerism, Interface Type, Oxidation State of Copper, and Incubation Time on Adsorption on the Surface of Copper(I) and (II) Oxide Nanoparticles

“…This size of the Cu 2 ONPs is confirmed by the UV–vis spectrum, which shows two weak plasma resonances at 590 and 330 nm (Figure C, gray trace). The absorption at 590 nm is due to the band-gap transition of the CuO layer at the surface of the Cu 2 O nanocrystals . The absorption at 330 nm is due to the band-to-band transition in the nanocrystalline Cu 2 O (O 2– :Cu 1+ charge transfer (CT) band (O 2p → Cu 3d)) …”

“…The absorption at 590 nm is due to the band-gap transition of the CuO layer at the surface of the Cu 2 O nanocrystals. 65 The absorption at 330 nm is due to the band-to-band transition in the nanocrystalline Cu 2 O (O 2– :Cu 1+ charge transfer (CT) band (O 2p → Cu 3d)). 66 …”

“…The absorption at 590 nm is due to the band-gap transition of the CuO layer at the surface of the Cu 2 O nanocrystals. 65 The absorption at 330 nm is due to the band-to-band transition in the nanocrystalline Cu 2 O (O 2− :Cu 1+ charge transfer (CT) band (O 2p → Cu 3d)). 66 Cu 2 ONPs show characteristic Raman bands at 630 cm −1 (T 1u ), 486, 420, 219 (strongest E u ), 182, and 148 (T 1u symmetry) cm −1 (Figure 2D) consistent with data from the literature.…”

Homogeneous Pt nanostructures surface functionalized with phenylboronic acid phosphonic acid derivatives as potential biochemical nanosensors and drugs: SERS and TERS studies

“…Previously, we had immobilized these compounds on the surface of Cu(I) and Cu(II) oxides and described (based on the results of SERS) how they interact with these surfaces. 25 Since the nature of the metal is believed to determine the nature of adsorption, these compounds were used in this work to functionalize the PtNP surface and to describe the nature of their interaction with the PtNP surface under different environmental conditions (H 2 O vs. air). This is of great analytical importance, since the determination of adsorption on different metallic substrates allows general conclusions to be drawn about the behavior of these molecules in the presence of metals, which play an important role in living organisms and medicine.…”

“…(Ph) or boronophenyl (Ph B(OH)2 )), the enhancement of the modes by the other molecular fragments should be analyzed.The modes of the boronic acid group, such as ρ r (BO 2 ) at 425 cm À1 , γ(HOBC) + γ(HOBO) + ν 16b at 521 cm À1 are very intense for 1-PBA-PA and absent in the spectra of 2-PBA-PA and bis{1-PBA-PA}, while the δ oop (CBO 2 ) + ν(C-B) mode at 746 cm À1 has intermediate intensity for 1-PBA-PA and low intensity in the spectra of 2-PBA-PA and bis{1-PBA-PA} 46. The modes of the C(P)N fragment appear as SERS signals at495 [δ(CPO)], 640 [ρ w (CPO) + δ(CC(P)N)], 813 [ν(PO) + δ oop (CN[H]C)], 838 [δ(C α N[H]C)], 878 cm À1 [ν(P-O/C) + ρ b (POH) + δ(CPN)] 25,46. The495-cm À1 band has an average intensity for 2-PBA-PA and decreases in intensity in this order: 2PBA-PA >1-PBA-PA > bis{1-PBA-PA}.…”