One-Pot Heterointerfacial Metamorphosis for Synthesis and Control of Widely Varying Heterostructured Nanoparticles

Proteolysis-regulated excited state electron transfer of Ag2S/In(OH)3@BSA nanocomposites for fluorescence-photoelectrochemistry dual-mode biosensing of heparin

Sharing the same photoexcitation process, fluorescence (FL) and photoelectrochemistry (PEC) accomplish optical-optical and optical-electrochemical switches respectively, and are both widely used in diverse fields. However, since FL and PEC are mutually exclusive in principle, it is difficult to obtain intense FL and PEC responses in a system, limiting FL-PEC dual-mode applications. In this study, Ag2S quantum dots (QDs) and In(OH)3 nanoblocks (NBs) are simultaneously synthesized by BSA-templated bio-mineralization, and the excited state electrons of Ag2S/In(OH)3@BSA nanocomposites (NCs) are further regulated by a proteolysis process. Owing to the coating of BSA, excited state electrons primarily return to ground state via radiation transition, resulting in a robust FL signal. When BSA is hydrolyzed by trypsin, the excited state electrons preferentially transfer to the electron acceptors, and the exposed Ag2S/In(OH)3@BSA NCs generate a strong PEC signal. Consequently, heparin, acting as an inhibitor of trypsin, can regulate the FL-PEC switch, allowing for the quantification of heparin by both the decrease in FL signals and the increase in PEC signals. Therefore, a dual-mode biosensor is established to detect heparin using FL and PEC signals, with linear ranges of 0.75-750 U mL-1 and 3.75 × 10-3 to 37.5 U mL-1, and limits of detection of 0.68 U mL-1 and 4.97 × 10-4 U mL-1, respectively. Additionally, the biosensor is used to monitor the rapid metabolism of heparin within 20 h in rats. Overall, this work demonstrates that manipulating excited state electrons of nanomaterials through a biological process offers an alternative perspective for designing FL-PEC dual-mode sensing systems.

Regioselective epitaxial growth of metallic heterostructures

Constructing regioselective architectures in heterostructures is important for many applications; however, the targeted design of regioselective architectures is challenging due to the sophisticated processes, impurity pollution and an unclear growth mechanism. Here we successfully realized a one-pot kinetically controlled synthetic framework for constructing regioselective architectures in metallic heterostructures. The key objective was to simultaneously consider the reduction rates of metal precursors and the lattice matching relationship at heterogeneous interfaces. More importantly, this synthetic method also provided phase- and morphology-independent behaviours as foundations for choosing substrate materials, including phase regulation from Pd20Sb7 hexagonal nanoplates (HPs) to Pd8Sb3 HPs, and morphology regulation from Pd20Sb7 HPs to Pd20Sb7 rhombohedra and Pd20Sb7 nanoparticles. Consequently, the activity of regioselective epitaxially grown Pt on Pd20Sb7 HPs was greatly enhanced towards the ethanol oxidation reaction; its activity was 57 times greater than that of commercial Pt/C, and the catalyst showed increased stability (decreasing by 16.3% after 2,000 cycles) and selectivity (72.4%) compared with those of commercial Pt/C (56.0%, 18.2%). This work paves the way for the design of unconventional well-defined heterostructures for use in various applications.

Synthesis of silver-palladium Janus nanoparticles using co-sputtering of independent sources: experimental and theorical study

Janus-type nanoparticles are important because of their ability to combine distinct properties and functionalities in a single particle, making them extremely versatile and valuable in various scientific, technological, and industrial applications. In this work, bimetallic silver-palladium Janus nanoparticles were obtained for the first time using the inert gas condensation technique. In order to achieve this, an original synthesis equipment built by Mantis Ltd. was modified by the inclusion of an additional magnetron in a second chamber, which allowed us to use two monometallic targets to sputter the two metals independently. With this arrangement, we could find appropriate settings at room temperature to promote the synthesis of bimetallic Janus nanoparticles. The structural properties of the resulting nanoparticles were investigated by transmission electron microscopy (TEM), and the chemical composition was analyzed by TEM energy dispersive spectroscopy (TEM-EDS), which, together with structural analysis, confirmed the presence of Janus-type nanostructures. Results of molecular dynamics and TEM simulations show that the differences between the crystalline structures of the Pd and Ag regions observed in the TEM micrographs can be explained by small mismatches in the orientations of the two regions of the particle. A density functional theory structural aims to understand the atomic arrangement at the interface of the Janus particle.

Steering DNA Condensation on Engineered Nanointerfaces

DNA has received increasing attention in nanotechnology due to its ability to fold into prescribed structures. Different from the commonly adopted base-pairing strategy, an emerging class of amorphous DNA materials are formed by DNA's abiological interactions. Despite the great successes, a lack of nanoscale nucleation/growth control disables more advanced considerations. This work aims at harnessing the heterogeneous nucleation of metal-ion-glued DNA condensates on nanointerfaces. Upon unveiling key orthogonal factors including solution pH, ionic cross-linkers, and surface functionalities, chemically programmable DNA condensation on nanoparticle seeds is achieved, resembling a famous Stöber process for silica coating. The nucleation rules discovered on individual nanoseeds can be passed on to their dimeric assemblies, where broken spherical symmetry and the existence of interparticle gaps help a regiospecific DNA gelation. The steerable DNA condensation, and the multifunctions from DNA, metal ions, and nanocores, hold a great promise in noncanonical DNA nanotechnology toward novel applications.