Thermodynamics of adsorption of lysozyme on gold nanoparticles from second harmonic light scattering

Mishra, Kamini; Das, Puspendu K.

doi:10.1039/c8cp07299j

Cited by 20 publications

(15 citation statements)

References 60 publications

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“…FTIR spectroscopy has been chosen to assess the nature of different kinds of groups and their interactions on the surface of AuNPs. Recently, experimental data related to the adsorption of Lyz on AuNPs has been reported by Mishra et al 65 However, information about the specific attachment and stability of Lyz in the presence of IL-modified AuNPs is still inadequate. Therefore, the appearance and displacement of some specific bands have been focused earnestly to showcase various groups present on AuNPs to harness specificity of Lyz bonding sites.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Ionic Liquid-Modified Gold Nanoparticles for Enhancing Antimicrobial Activity and Thermal Stability of Enzymes

Kumar

Sindhu

Venkatesu

2021

ACS Appl. Nano Mater.

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The synthesis of nanoparticles using ionic liquids (ILs) has attracted intensive research; however, synthesis and surface tailoring of gold nanoparticles (AuNPs) using ILs for enzyme immobilization have not yet been reported. Herein, we synthesized the various IL-modified AuNPs using different ILs, which are having common cation 1-ethyl-3-methyl-imidazolium (EMIM) and variable anions [BF 4−1 (AuNP-IL1), (CH 3 OSO 3 ) −1 (AuNP-IL2), (CH 3 CH 2 OSO 3 ) −1 (AuNP-IL3), and Cl −1 (AuNP-IL4)] by reduction of gold salt. The formation of IL modified AuNPs has been confirmed using UV−vis, zeta-potential, FTIR, and transmission electron microscopy (TEM). Thereafter, the centrifuged IL-modified AuNPs are being immobilized with a lysozyme (Lyz) enzyme to evaluate the effect of different AuNP covering groups (capping agent and IL's anions) for Lyz microbial activity, thermal and structural stabilities through interaction studies, spectroscopic techniques, and morphology investigation by TEM. AuNP-IL1 has increased the microbial activity of Lyz up to 2.6 fold at the concentration of 4 nM, and AuNP-IL2 is highly efficient to dextrously preserve enzyme activity against packaging for 4 weeks. The higher Michaelis−Menten constant (K M ) has been observed for Lyz immobilized in the AuNP-IL2 due to higher binding with the AuNP-IL2. Apparently, the higher specific constant (K cat /K M ) of immobilized Lyz has been observed in the case of AuNP-IL3 and shows more specific binding of Lyz with this particular IL-mediated AuNPs. The significant thermal stability enhancement about 8.11 °C is observed for transition temperature (T m ) of Lyz in the presence of sulfur group-containing IL-modified AuNPs like AuNP-IL2 and AuNP-IL3, which depends on the specific interacting ability of these AuNPs with Lyz. Therefore, the study reveals the variant character of sulfur-containing IL-modified AuNPs for higher activity and thermal and structural stability of Lyz. Surprisingly, this has created a way to monitor sulfur and hydrophobic interactions on AuNPs for enzyme immobilization through means of controlling surface modifications and interactions.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Ionic Liquid-Modified Gold Nanoparticles for Enhancing Antimicrobial Activity and Thermal Stability of Enzymes

Kumar

Sindhu

Venkatesu

2021

ACS Appl. Nano Mater.

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“…To corroborate the IRRAS results, we conducted SHG experiments to probe binding. SHG has been used to report on binding of proteins to lipid bilayers and lysozyme to gold nanoparticles . Here, the IRRAS signal is specific to the phosphate binding event, while the SHG signal captures changes in the interfacial electric dipole moment that includes water, ions, as well as the monolayer/phosphate complex.…”

Section: Resultsmentioning

confidence: 99%

“…SHG has been used to report on binding of proteins to lipid bilayers 45 and lysozyme to gold nanoparticles. 46 Here, the IRRAS signal is specific to the phosphate binding event, while the SHG signal captures changes in the interfacial electric dipole moment that includes water, ions, as well as the monolayer/phosphate complex. We do not expect changes in the signal intensity to occur in one direction (i.e., increase as phosphate concentration increases); rather, we observe that the SHG gives a signal response as a function of phosphate concentration and is consistent with the IRRAS data for both U-Guan + and U-Ammo + showing phosphate sequestering at the interface.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Thermodynamic Signatures of the Origin of Anti-Hofmeister Selectivity for Phosphate at Aqueous Interfaces

Grooms

Neal

et al. 2020

J. Phys. Chem. A

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The selectivities and driving forces governing phosphate recognition by charged receptors at prevalent aqueous interfaces is unexplored relative to the many studies in homogeneous solutions. Here we report on electrostatic binding versus hydrogen-bond-assisted electrostatic binding of phosphate (H2PO4 –) for two important receptor classes in the unique microenvironment of the air–water interface. We find that the methylated ammonium receptor (U-Ammo + ) is dominated by electrostatic binding to phosphate anions and fails to be selective for phosphate binding over chloride, whereas the highly phosphate-selective guanidinium receptor (U-Guan + ) provides synergistic hydrogen-bonding and electrostatic interactions. Apparent binding constants were evaluated in situ for U-Ammo + and U-Guan + using temperature-controlled infrared reflection–absorption spectroscopy with Langmuir-type fitting. Thermodynamic quantities showed enthalpically driven binding affinities of U-Guan + and U-Ammo + receptors (ΔH°b = −71 (±9) kJ/mol and ΔH°b = −155 (±13) kJ/mol, respectively). U-Guan + revealed a nearly fourfold smaller entropic barrier to binding (ΔS°b = −132 (±34) J/mol K) than the U-Ammo + receptor (ΔS°b = −440 (±45) J/mol K), attributed to hydration differences. The larger entropic penalty for the U-Ammo + receptor is correlated with a molecular expansion shown in surface pressure–area isotherms, whereas the smaller entropic penalty of the U-Guan + receptor conversely correlated with no expansion. The U-Guan + receptor also revealed anti-Hofmeister selectivity for phosphate over chloride, while the non-hydrogen-bonding U-Ammo + receptor followed Hofmeister selectivity. Our results indicate that hydrogen bonding is an integral chemical design element for achieving anti-Hofmeister selectivity for phosphate.

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“…More specifically, SHS has been used in resonant and nonresonant conditions to characterize nanoparticle dispersions and the adsorption of molecular species. Resonant SHS relies either on resonances of the nanoparticles, such as, for example, the localized surface plasmon of metallic nanoparticles, − or on (electronic) resonances of the adsorbate. − Therefore, resonant SHS is necessarily limited in the types of nanoparticles and adsorbates that can be studied, given by the constraints of conventional laser wavelengths and can, in principle, suffer from photochemistry and two-photon fluorescence. On the other hand, nonresonant SHS, while lower in signal intensity as it is not enhanced by resonances, is not expected to influence the sample and provides a wider variety of potential applications.…”

Section: Introductionmentioning

confidence: 99%

In Situ Label-Free Study of Protein Adsorption on Nanoparticles

et al. 2021

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Improving the design of nanoparticles for use as drug carriers or biosensors requires a better understanding of the protein–nanoparticle interaction. Here, we present a new tool to investigate this interaction in situ and without additional labeling of the proteins and/or nanoparticles. By combining nonresonant second-harmonic light scattering with a modified Langmuir model, we show that it is possible to gain insight into the adsorption behavior of blood proteins, namely fibrinogen, human serum albumin, and transferrin, onto negatively charged polystyrene nanoparticles. The modified Langmuir model gives us access to the maximum amount of adsorbed protein, the apparent binding constant, and Gibbs free energy. Furthermore, we employ the method to investigate the influence of the nanoparticle size on the adsorption of human serum albumin and find that the amount of adsorbed protein increases more than the surface area per nanoparticle for larger diameters.

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Thermodynamics of adsorption of lysozyme on gold nanoparticles from second harmonic light scattering

Abstract: Lysozyme adsorption on gold nanoparticles is an enthalpically driven process while the entropy contribution is favourable but insignificant.

Cited by 20 publications

References 60 publications

Ionic Liquid-Modified Gold Nanoparticles for Enhancing Antimicrobial Activity and Thermal Stability of Enzymes

Ionic Liquid-Modified Gold Nanoparticles for Enhancing Antimicrobial Activity and Thermal Stability of Enzymes

Thermodynamic Signatures of the Origin of Anti-Hofmeister Selectivity for Phosphate at Aqueous Interfaces

In Situ Label-Free Study of Protein Adsorption on Nanoparticles

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