A nanoparticle, under biological milieu, is inclined to be combined with various biomolecules, particularly protein, generating an interfacial corona which provides a new biological identity. Herein, the binding interaction between silver nanoparticles (AgNPs) and human serum albumin (HSA) was studied with transmission electron microscopy (TEM), circular dichroism (CD), and multiple spectroscopic techniques. Due to the ground state complex formed mainly through hydrophobic interactions, the fluorescence titration method proved that intrinsic fluorescence for HSA was probably statically quenched by AgNPs. The complete thermodynamic parameters were derived, indicating that the interaction between HSA and AgNPs is an entropy-driven process. Additionally, synchronous fluorescence and CD spectrum results suggested the conformational variation it has upon binding to AgNPs and the α-helix content has HSA visibly decreased. The kinetic experiments proved the double hysteresis effect has in HSA’s binding to the AgNPs surface. Moreover, the binding has between HSA and AgNPs follows the pseudo-second-order kinetic characteristic and fits the Freundlich model for multilayer adsorption. These results facilitate the comprehension about NPs’ underlying biological effects under a physiological environment and promote the secure applications of NPs biologically and medically.

Palladium (Pd), copper (Cu) bimetallic alloy nanoparticles immobilized onto a PDA-coated graphene support (PdÀ Cu/ PDA/RGO) hybrid was synthesized through co-reduction of K 2 PdCl 4 and Cu(NO 3 ) 2 . The Pd to Cu ratio was rationally controlled to obtain the optimum PdÀ Cu/PDA/RGO catalyst. The as-prepared catalyst demonstrated good catalytic activity for hydrogen production by hydrolysis of ammonia borane, high turnover frequency (TOF) of 37.41 mol H 2 per mol Pd À 1 min À 1 at 298 K and a low activation energy (E a ) of 47.97 kJ mol À 1 were accomplished, these metrics were superior to that of PdÀ Cu/RGO nanocatalysts. The comparative results indicate that the PDA-coated graphene (PDA/RGO) support is pivotal for the catalytic activity of PdÀ Cu/PDA/RGO for hydrolysis of ammonia borane. The PDA modified onto GO surface effectively disperse the alloy particles, therefore ensure more catalytic active sites responsible for ammonia borane hydrolysis. The tight anchoring of alloy nanoparticles also enabled excellent cyclic stability, 67.7 % of its initial catalytic activity could be maintained after ten cycles. The current work demonstrates the potential of PdÀ Cu/PDA/RGO in active and durable ammonia borane hydrolysis for hydrogen production.

No abstract