Pressure-Induced Fluorescence Enhancement of the BSA-Protected Gold Nanoclusters and the Corresponding Conformational Changes of Protein

Abstract

We investigated the pressure-induced fluorescence enhancement of BSA-protected gold nanoclusters, AuNCs@BSA, and the corresponding conformational changes of ligand protein by in situ fluorescence and IR spectral measurements. It is documented that the fluorescence enhancement of AuNCs@BSA is essentially attributed to the conformational changes of the ligand, which undergoes substantial secondary and tertiary structural changes. Under compression BSA loses more buried α-helical structure, while it changes oppositely in the AuNCs@BSA as the protein adopts a more flexible conformational state at the boundary surface of gold nanoclusters. The present work will be helpful to understand the fundamental mechanism and to reveal the important factors of ligands in nanoclusters, which are hope to improve the luminescence efficiency of gold nanoclusters in final.

Fluorescent Gold Nanoclusters for Selective Detection of Dopamine in Cerebrospinal fluid

“…Several outer sphere gold atoms had Au 1+ oxidation state, because some of the carbonyl functional groups containing amino acids from BSA native protein were coordinated with the outer sphere gold atoms during BSA-Au NCs formation. BSA-Au NCs were also stabilized with a thiol functional group (-SH) of cysteine amino acids, which were present in the BSA native protein when disulfide bonds were broken down into thiol functional groups, following the addition of 1 M NaOH solution to the reaction mixture30.…”

Biomediated Atomic Metal Nanoclusters: Synthesis and Theory

“…BSA-stabilized AuNCs exhibit this predicted pressure-dependent fluorescence increase over a range of 0.1-1,050 MPa (Fig. 11) [83]. Upon comparison to atmospheric pressure, BSA-AuNCs show a 70.1 % increased fluorescence intensity when exposed to maximum pressure of 1,050 MPa [83].…”

“…11) [83]. Upon comparison to atmospheric pressure, BSA-AuNCs show a 70.1 % increased fluorescence intensity when exposed to maximum pressure of 1,050 MPa [83]. It can be hypothesized that other proteins will also exhibit this pressure dependence in nanoclusters fluorescence.…”

“…The tertiary structure of the protein influences the fluorescence profile of the clusters. When proteins are subjected to increased pressure, the intramolecular electrostatic and hydrophobic interactions are disrupted leading to ionization of the amino and carboxylic groups within the protein [83,84]. This ionization will allow for more electron density to be pushed to the metal core and therefore increase fluorescence intensity.…”

Two-dimensional correlation spectroscopy in polymer study

“…The generalized 2DCOS can elucidate information in spectral variations, e.g., IR (Kim et al, 2006b; Cerdà-Costa et al, 2009; Huang et al, 2009; Unger et al, 2009, 2011; Del Río et al, 2010; Huang and Kuo, 2010; Jelèić et al, 2010; Jia et al, 2010; Lee et al, 2010, 2012; Peng et al, 2010; Popescu and Vasile, 2010, 2011; Zheng et al, 2010; Cheng et al, 2011; Jin et al, 2011; Kuo and Liu, 2011; Musto et al, 2011; Quaroni et al, 2011; Wang and Wu, 2011; Zhang et al, 2011; Ando et al, 2012; Qu et al, 2012; Su et al, 2012; Wu et al, 2012; Chai et al, 2013; Lai and Wu, 2013; Park et al, 2013; Shinzawa et al, 2013; Wang et al, 2013, 2014; Galizia et al, 2014; Hou et al, 2014; Noda, 2014c; Seo et al, 2014), Raman (Radice et al, 2010; Tang et al, 2010; Ma et al, 2011; Ji et al, 2012; Pazderka and Kopecký Jr, 2012; Brewster et al, 2013; Grzeszczuk et al, 2013; Noda, 2014d), terahertz (THz) (Hoshina et al, 2012, 2014), X-ray (Guo et al, 2011), UV-Vis (Hong et al, 2005; Jiang and Wu, 2008; Sikirzhytski et al, 2012; Zhong et al, 2012), NMR (Oh et al, 2009; Li et al, 2013), fluorescence (Hur et al, 2011; Zhang et al, 2013), and even chromatography (Izawa et al, 2001), under various external perturbations, such as thermal, electrical, optical, magnetic, and chemical perturbations (Noda, 1986, 1993; Hong et al, 2005; Kim et al, 2006b; Jiang and Wu, 2008; Cerdà-Costa et al, 2009; Huang et al, 2009; Oh et al, 2009; Unger et al, 2009; Del Río et al, 2010; Huang and Kuo, 2010; Jelèić et al, 2010; Jia et al, 2010; Lee et al, …”