Abstract
Engineering hollow and porous platinum nanostructures using biomolecular templates is currently a significant focus for the enhancement of their facet-dependent optical, electronic, and electrocatalytic properties. However, remains a formidable challenge due to lack of appropriate biomolecules to have a structure-function relationship with nanocrystal facet development. Herein, human hemoglobin found to have facet-binding abilities that can control the morphology and optical properties of the platinum nanoclusters (Pt NCs) by regulation of the growth kinetics in alkaline media. Observations revealed the growth of unusual polyhedra by shape-directed nanocluster attachment along a certain orientation accompanied by Ostwald ripening and, in turn, yield well-dispersed hollow single-crystal nanotetrahedrons, which can easily self-aggregated and crystallized into porous and polycrystalline microspheres. The spontaneous, biobased organization of Pt NCs allow the intrinsic aggregation-induced emission (AIE) features in terms of the platinophilic interactions between Pt(II)-Hb complexes on the Pt(0) cores, thereby controlling the degree of aggregation and the luminescent intensity of Pt(0)@Pt(II)−Hb core−shell NCs. The Hb-Pt NCs exhibited high-performance electrocatalytic oxygen reduction providing a fundamental basis for outstanding catalytic enhancement of Hb-Pt catalysts based on morphology dependent and active site concentration for the four-electron reduction of oxygen. The as-prepared Hb-Pt NCs also exhibited high potential to use in cellular labeling and imaging thanks to the excellent photostability, chemical stability, and low cytotoxicity.
Highlights
Demonstrated that Pt hollow nanocrystals can be used as a suitable catalyst in oxygen reduction reaction (ORR), since they exhibited sustainable enhancement simultaneously in durability and Pt mass activity in acid fuel cells[5]
In spite of significant progress in controlling the size of platinum nanoclusters (Pt NCs) via the gas-phase deposition, a few successes were obtained via chemical reduction methods[7,10]; Besides, to date no report has yet been found for controlled shapes of fluorescent metal nanoclusters, and likewise there are few reports and applications for fluorescent Pt NCs so that the presented protocols for synthesis of fluorescent Pt NCs usually require multiple steps and toxic organic solvents or additive agents[11,12]
We have found the potential application of Hb/Pt NCs in electrocatalytic oxygen reduction owing to the unique hollow porous structure of Pt crystals[24]
Summary
Nanoclusters and their Application to Catalytic Oxygen Reduction and Cancer Imaging. Fatemeh Molaabasi[1,2], Morteza Sarparast[3], Mojtaba Shamsipur[4], Leila Irannejad[2], Ali Akbar Moosavi-Movahedi[5], Abouzar Ravandi[6], Behnam Hajipour Verdom7 & Reza Ghazfar[3]. There is relatively little insight into structure-property relationships for the controlled synthesis of fluorescent nanocrystals using peptides and proteins as biotemplates mediating particular growth directions Bearing these important issues in mind, in this study, the most important discovery is dealing with the shape-controlled synthesis of fluorescent Pt NCs with a strong shell effect of Hb, accompanied by aggregationinduced emission (AIE) effect due to oriented attachment and Ostwald ripening mechanisms; the interesting results which are totally different from the commonly used proteins, i.e., Lys and BSA, as stabilizing agents for the synthesis of Pt NCs13,23. We have found the potential application of Hb/Pt NCs in electrocatalytic oxygen reduction owing to the unique hollow porous structure of Pt crystals[24] Their electrocatalytic criteria such as mass and specific activity, durability, and the number of transferred electrons have been investigated regarding the formation reaction time, morphology, surface structure, surface to volume ratio, and the content of aggregated platinum nanoclusters. Based on the mechanistic information obtained from successful experiments, this study can provide useful insights into a biomimetic material design utilizing engineered proteins or peptides to predict synthesis of shape-controlled NCs exposing selective surfaces which will be applicable to catalysis, optoelectronics, and medical applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
