Ammonia borane hydrolysis is considered as a potential means of safe and fast method of H production if it is efficiently catalyzed. Here a series of nearly monodispersed alloyed bimetallic nanoparticle catalysts are introduced, optimized among transition metals, and found to be extremely efficient and highly selective with sharp positive synergy between 2/3 Ni and 1/3 Pt embedded inside a zeolitic imidazolate framework (ZIF-8) support. These catalysts are much more efficient for H release than either Ni or Pt analogues alone on this support, and for instance the best catalyst NiPt@ZiF-8 achieves a TOF of 600 mol·mol·min and 2222 mol·mol·min under ambient conditions, which overtakes performances of previous Pt-base catalysts. The presence of NaOH boosts H evolution that becomes 87 times faster than in its absence with NiPt@ZiF-8, whereas NaOH decreases H evolution on the related Pt@ZiF-8 catalyst. The ZIF-8 support appears outstanding and much more efficient than other supports including graphene oxide, active carbon and SBA-15 with these nanoparticles. Mechanistic studies especially involving kinetic isotope effects using DO show that cleavage by oxidative addition of an O-H bond of water onto the catalyst surface is the rate-determining step of this reaction. The remarkable catalyst activity of NiPt@ZiF-8 has been exploited for successful tandem catalytic hydrogenation reactions using ammonia borane as H source. In conclusion the selective and remarkable synergy disclosed here together with the mechanistic results should allow significant progress in catalyst design toward convenient H generation from hydrogen-rich substrates in the close future.

Silencing RNA (siRNA) technologies emerge as a promising therapeutic tool for the treatment of multiple diseases. An ideal nanocarrier (NC) for siRNAs should be stable at physiological pH and release siRNAs in acidic endosomal pH, fulfilling siRNA delivery only inside cells. Here, we show a novel application of polyamine phosphate NCs (PANs) based on their capacity to load negatively charged nucleic acids and their pH stability. PANs are fabricated by complexation of phosphate anions from phosphate buffer solution (PB) with the amine groups of poly(allylamine) hydrochloride as carriers for siRNAs. PANs are stable in a narrow pH interval, from 7 to 9, and disassemble at pH's higher than 9 and lower than 6. siRNAs are encapsulated by complexation with poly(allylamine) hydrochloride before or after PAN formation. PANs with encapsulated siRNAs are stable in cell media. Once internalized in cells following endocytic pathways, PANs disassemble at the low endosomal pH and release the siRNAs into the cytoplasm. Confocal laser scanning microscopy (CLSM) images of Rhodamine Green labeled PANs (RG-PANs) with encapsulated Cy3-labeled siRNA in A549 cells show that siRNAs are released from the PANs. Colocalization experiments with labeled endosomes and either labeled siRNAs prove the translocation of siRNAs into the cytosol. As a proof of concept, it is shown that PANs with encapsulated green fluorescence protein (GFP) siRNAs silence GFP in A549 cells expressing this protein. Silencing efficacy was evaluated by flow cytometry, CLSM, and Western blot assays. These results open the way for the use of poly(allylamine) phosphate nanocarriers for the intracellular delivery of genetic materials.

The widespread occurrence of nosocomial infections and the emergence of new bacterial strands calls for the development of antibacterial coatings with localized antibacterial action that are capable of facing the challenges posed by increasing bacterial resistance to antibiotics. The Layer-by-Layer (LbL) technique, based on the alternating assembly of oppositely charged polyelectrolytes, can be applied for the non-covalent modification of multiple substrates, including medical implants. Polyelectrolyte multilayers fabricated by the LbL technique have been extensively researched for the development of antibacterial coatings as they can be loaded with antibiotics, antibacterial peptides, nanoparticles with bactericide action, in addition to being capable of restricting adhesion of bacteria to surfaces. In this review, the different approaches that apply LbL for antibacterial coatings, emphasizing those that can be applied for implant modification are presented.

Ammonia‐borane is one of the most convenient sources of H2 upon hydrolysis under ambient conditions, but the reaction requires a good catalyst to become efficient. Here, H2 production upon hydrolysis of ammonia‐borane is catalyzed by late transition‐metal nanoparticles (NPs). These NPs are stabilized by a first‐ or second‐generation “click” dendrimer containing, respectively 27 and 81 terminal triethylene glycol termini and 9 resp. 27 1,2,3‐triazole intradendritic ligands. No significant dendritic effects were observed, however. The noble‐metal NPs are as expected much more efficient catalysts than the first‐raw transition‐metal NPs, and Rh and PtNPs are the most catalytically active NPs. In the presence of NaOH, however, the reactivity is boosted for all these “click” dendrimer‐stabilized transition‐metal NP catalysts except for the PtNPs. The optimized NaOH concentration is 0.3 M NaOH per mol NH3BH3 for RhNPs. A TOF of up to 611 molnormalH2  molcatalyst−1 min−1 for RhNPs at 20 °C is obtained, which is one of the best results among the literature. Interestingly, the reaction with D2O provides a kinetic isotope effect of kD/kH=2.8 suggesting that O−H bond cleavage of water occurs in the rate‐limiting step. These experiments lead to a proposed mechanism for H2 evolution using the ammonia‐borane hydrolysis reaction.

The modes of generation of nanoparticles (NPs) are of great interest for multiple applications in catalysis, optics, sensing, and nanomedicine. Here, fast reduction of CuSO4·5H2O and Ag salts by commercial cobaltocene yields small, stable, water-soluble Cu and Ag NPs with a narrow size distribution without any other ligand or support. The variation of the Ag salt counteranion (NO3 –, F–, BF4 –) strongly influences both the plasmonic absorption of the AgNPs synthesized in this way and the high apparent rate constant of the AgNP-catalyzed reduction of 4-nitrophenol by NaBH4, showing that the precursor counteranion binds to the AgNP surface. The CuNPs synthesized from CuSO4 and cobaltocene are a recyclable catalyst for the Cu-catalyzed alkyne–azide cycloaddition reaction in water extended to various azides and alkynes, including functionalization of compounds of biomedical interest. Both CuNP and AgNP catalytic activities are also very promising signs for further extension to a variety of other truly efficient metal-NP-catalyzed reactions.

There is an urgent need for the development of effective antibacterial coatings to cope with more and more resistant bacterial strains in medical environments, and particularly to prevent nosocomial infections following bone implant surgery. Polyelectrolyte multilayers (PEMs) based on poly‐l‐lysine (PLL) and complexes of poly(acrylic acid) (PAA) and gentamicin have been fabricated here applying the layer‐by‐layer (LbL) technique. Complexes are prepared by mixing PAA and gentamicin solutions in 500 × 10−3 m NaCl at pH 4.5. The assembly of PLL and the complexes follows an exponential growth allowing a high loading of gentamicin in a four bilayer PEM. Although PEMs are stable and do not degrade at physiological pH, there is a continuous release of gentamicin at pH 7.4. PEMs show an initial burst release of gentamicin in the first 6 h, which liberates 58% of the total gentamicin released during the experiment, followed by a sustainable release lasting over weeks. This release profile makes the coating appealing for the surface modification of bone implants as a high concentration of antibiotics is necessary during implant surgery while a lower antibiotic concentration is needed until tissue is regenerated. PEMs are effective in preventing the proliferation of the Staphylococcus aureus strain.

New PEG-stabilized CuNP catalysts are designed upon Cu(ii) reduction with sodium naphthalenide in MeCN followed by simple purification using the salting-out effect. Their catalytic activity in CuAAC is boosted upon 30 min exposure to air, producing CuO NPs. These NPs are also supported on SBA-15, providing excellent recyclable heterogeneous catalysts that are applied in low amounts for efficient "click" functionalization.

Stimulating brain tissue regeneration is a major challenge after central nervous system (CNS) injury, such as those observed from trauma or cerebrovascular accidents. Full regeneration is difficult even when a neurogenesis-associated repair response may occur. Currently, there are no effective treatments to stimulate brain tissue regeneration. However, biomaterial scaffolds are showing promising results, where hydrogels are the materials of choice to develop these supportive scaffolds for cell carriers. Their combination with growth factors, such as brain-derived neurotrophic factor (BDNF), basic fibroblast growth factor (bFGF), or vascular endothelial growth factor (VEGF), together with other cell therapy strategies allows the prevention of further neuronal death and can potentially lead to the direct stimulation of neurogenesis and vascularisation at the injured site. Imaging of the injured site is particularly critical to study the reestablishment of neural cell functionality after brain tissue injury. This review outlines the latest key advances associated with different strategies aiming to promote the neuroregeneration, imaging, and functional recovery of brain tissue. Graphical abstract