Advancement of Fluorescent and Structural Properties of Bovine Serum Albumin-Gold Bioconjugates in Normal and Heavy Water with pH Conditioning and Ageing

TY - JOUR

T1 - Advancement of Fluorescent and Structural Properties of Bovine Serum Albumin-Gold Bioconjugates in Normal and Heavy Water with pH Conditioning and Ageing

AU - Fehér, Bence

AU - Mihály, Judith

AU - Demeter, Attila

AU - Almásy, László

AU - Wacha, András

AU - Varga, Zoltán

AU - Varga, Imre

AU - Pedersen, Jan Skov

AU - Bóta, Attila

N1 - Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2022/1/25

Y1 - 2022/1/25

N2 - The red-emitting fluorescent properties of bovine serum albumin (BSA)–gold conjugates are commonly attributed to gold nanoclusters formed by metallic and ionized gold atoms, stabilized by the protein. Others argue that red fluorescence originates from gold cation–protein complexes instead, not gold nanoclusters. Our fluorescence and infrared spectroscopy, neutron, and X-ray small-angle scattering measurements show that the fluorescence and structural behavior of BSA–Au conjugates are different in normal and heavy water, strengthening the argument for the existence of loose ionic gold–protein complexes. The quantum yield for red-emitting luminescence is higher in heavy water (3.5%) than normal water (2.4%), emphasizing the impact of hydration effects. Changes in red luminescence are associated with the perturbations of BSA conformations and alterations to interatomic gold–sulfur and gold–oxygen interactions. The relative alignment of domains I and II, II and III, III and IV of BSA, determined from small-angle scattering measurements, indicate a loose (“expanded-like”) structure at pH 12 (pD ~12); by contrast, at pH 7 (pD ~7), a more regular formation appears with an increased distance between the I and II domains, suggesting the localization of gold atoms in these regions.

AB - The red-emitting fluorescent properties of bovine serum albumin (BSA)–gold conjugates are commonly attributed to gold nanoclusters formed by metallic and ionized gold atoms, stabilized by the protein. Others argue that red fluorescence originates from gold cation–protein complexes instead, not gold nanoclusters. Our fluorescence and infrared spectroscopy, neutron, and X-ray small-angle scattering measurements show that the fluorescence and structural behavior of BSA–Au conjugates are different in normal and heavy water, strengthening the argument for the existence of loose ionic gold–protein complexes. The quantum yield for red-emitting luminescence is higher in heavy water (3.5%) than normal water (2.4%), emphasizing the impact of hydration effects. Changes in red luminescence are associated with the perturbations of BSA conformations and alterations to interatomic gold–sulfur and gold–oxygen interactions. The relative alignment of domains I and II, II and III, III and IV of BSA, determined from small-angle scattering measurements, indicate a loose (“expanded-like”) structure at pH 12 (pD ~12); by contrast, at pH 7 (pD ~7), a more regular formation appears with an increased distance between the I and II domains, suggesting the localization of gold atoms in these regions.

KW - Change in protein conformation

KW - Fluorescence

KW - Protein–gold conjugates

KW - Red-fluorescence

KW - Small angle neutron scattering

KW - Small angle X-ray scattering

KW - protein-gold conjugates

KW - red-fluorescence

KW - INFRARED-SPECTROSCOPY

KW - INSTRUMENT

KW - change in protein conformation

KW - ANGLE X-RAY

KW - fluorescence

KW - small angle X-ray scattering

KW - small angle neutron scattering

UR - http://www.scopus.com/inward/record.url?scp=85123380375&partnerID=8YFLogxK

U2 - 10.3390/nano12030390

DO - 10.3390/nano12030390

M3 - Journal article

C2 - 35159734

AN - SCOPUS:85123380375

SN - 2079-4991

VL - 12

JO - Nanomaterials

JF - Nanomaterials

IS - 3

M1 - 390

ER -