Synthesis of Palladium Nanodendrites Using a Mixture of Cationic and Anionic Surfactants

Multi-functional imidazolium dendrimers based on thiacalix[4]arenes: self-assembly, catalysis and DNA binding

For the first time, dendrimers based on thiacalix[4]arenes bearing imidazolium dendrons on one side and alkyl fragments on another side of the macrocyclic platform and symmetrical dendrimers with four dendrons on both sides were synthesized. Dendrons consist of gallic acid-based branches functionalized with imidazolium and triazolium groups. The physicochemical properties of the dendrimers such as micellar concentration (CMC), size, and solubilization capacity were measured. Novel dendrimers exhibit high binding efficiency with calf thymus DNA (ctDNA) as revealed by fluorescence quenching of the DNA-EtBr complex in the presence of macrocycles. Dendrimers have been used as supports for Pd nanoparticles, which show high catalytic activity for the reduction of nitroaromatic compounds.

Just Soaping Them: The Simplest Method for Converting Metal Organic Frameworks into Superhydrophobic Materials

The incorporation of superhydrophobic properties into metal organic framework (MOF) materials is highly desirable to enhance their hydrolytic stability, gas capture selectivity in the presence of humidity and efficiency in oil-water separations, among others. The existing strategies for inducing superhydrophobicity into MOFs have several weaknesses, such as increased cost, utilization of toxic reagents and solvents, applicability for limited MOFs, etc. Here, we report the simplest, most eco-friendly, and cost-effective process to impart superhydrophobicity to MOFs, involving a rapid (90 min) treatment of MOF materials with solutions of sodium oleate, a main component of soap. The method can be applied to both hydrolytically stable and unstable MOFs, with the porosity of modified MOFs approaching, in most cases, that of the pristine materials. Interestingly, this approach was used to isolate superhydrophobic magnetic MOF composites, and one of these materials formed stable liquid marbles, whose motion could be easily guided using an external magnetic field. We also successfully fabricated superhydrophobic MOF-coated cotton fabric and fiber composites. These composites exhibited exceptional oil sorption properties achieving rapid removal of floating crude oil from water, as well as efficient purification of oil-in-water emulsions. They are also regenerable and reusable for multiple sorption processes. Overall, the results described here pave the way for an unprecedented expansion of the family of MOF-based superhydrophobic materials, as virtually any MOF could be converted into a superhydrophobic compound by applying the new synthetic approach.

The Effect of the Pd Precursors on the Shape of Hollow Ag-Pd Alloy Nanoparticles Using Ag Nanocubes as Seeds

Hollow Ag-Pd nanoparticles have potentially high catalytic performance owing to their larger surface area compared to their corresponding solid nanoparticles. We successfully fabricated hollow Ag-Pd alloy nanodendrites and nanoboxes by using different Pd precursors (H2PdCl4 and Pd(acac)2) to achieve large surface area nanoboxes. Interestingly, the use of a H2PdCl4 precursor led to the formation of hollow nanodendrite structures, whereas the slower reduction of Pd(acac)2 led to the formation of hollow nanoboxes. The microstructure and chemical composition of Ag-Pd nanoparticles and properties of their growth solutions were investigated by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and ultraviolet-visible spectroscopy.

A Systemic Review on the Synthesis, Characterization, and Applications of Palladium Nanoparticles in Biomedicine

Palladium nanoparticles (Pd NPs) have been considered as a potential candidate in the field of biomedical applications due to its unique properties such as huge catalytic, hydrogen storage, and sensing behavior. Therefore, Pd NPs have shown to have a significant potential for the development of antimicrobials, wound healing, antioxidant, and anticancer property in recent days. There are plenty of reports that showed superior properties of noble metals. However, only very few studies have been undertaken to explore the advantage of Pd NPs in the field of biomedical applications. This review reports detailed and comprehensive studies comprising of the synthesis, characterization, and potential applications of Pd NPs in biomedicine. This report provides evidences in the literature documented by early researchers to understand the potential applications of Pd NPs to be explored in various fields.

Noble metal nanodendrites: growth mechanisms, synthesis strategies and applications

Inorganic nanodendrites (NDs) have become a kind of advanced nanomaterials with broad application prospects because of their unique branched architecture. The structural characteristics of nanodendrites include highly branched morphology, abundant tips/edges and high-index crystal planes, and a high atomic utilization rate, which give them great potential for usage in the fields of electrocatalysis, sensing, and therapeutics. Therefore, the rational design and controlled synthesis of inorganic (especially noble metals) nanodendrites have attracted widespread attention nowadays. The development of synthesis strategies and characterization methodology provides unprecedented opportunities for the preparation of abundant nanodendrites with interesting crystallographic structures, morphologies, and application performances. In this review, we systematically summarize the formation mechanisms of noble metal nanodendrites reported in recent years, with a special focus on surfactant-mediated mechanisms. Some typical examples obtained by innovative synthetic methods are then highlighted and recent advances in the application of noble metal nanodendrites are carefully discussed. Finally, we conclude and present the prospects for the future development of nanodendrites. This review helps to deeply understand the synthesis and application of noble metal nanodendrites and may provide some inspiration to develop novel functional nanomaterials (especially electrocatalysts) with enhanced performance.

Maneuvering the Peroxidase-Like Activity of Palladium-Based Nanozymes by Alloying with Oxophilic Bismuth for Biosensing

Engineering the catalytic performance of nanozymes is of vital importance for their broad applications in biological analysis, cancer treatment, and environmental management. Herein, a strategy to boost the peroxidase-like activity of Pd-based nanozymes with oxophilic metallic bismuth (Bi) is demonstrated, which is based on the incorporation of oxophilic Bi in the Pd-based alloy nanocrystals (NCs). To synthesize PdBi alloy NCs, a seed-mediated method is employed with the assistance of underpotential deposition (UPD) of Bi on Pd. The strong interaction of Bi atoms with Pd surfaces favors the formation of alloy structures with controllable shapes and excellent monodispersity. More importantly, the PdBi NCs show excellent peroxidase-like activities compared with pristine Pd NCs. The structure-function correlations for the PdBi nanozymes are elucidated, and an indirect colorimetric method based on cascade reactions to determine alkaline phosphatase (ALP) is established. This method has good linear range, low detection limit, excellent selectivity, and anti-interference. Collectively, this work not only provides new insights for the design of high-efficiency nanozymes, expands the colorimetric sensing platform based on enzyme cascade reactions, but also represents a new example for UPD-directed synthesis of alloy NCs.

Synthesis of highly monodisperse Pd nanoparticles using a binary surfactant combination and sodium oleate as a reductant

This study presents the synthesis of monodisperse Pd nanoparticles (NPs) stabilized by sodium oleate (NaOL) and hexadecyltrimethylammonium chloride (CTAC). The synthesis was conducted without traditional reductants and Pd-precursors are reduced by NaOL. It was confirmed that the alkyl double bond in NaOL is not the only explanation for the reduction of Pd-precursors since Pd NPs could be synthesized with CTAC and the saturated fatty acid sodium stearate (NaST). A quantitative evaluation of the reduction kinetics using UV-Vis spectroscopy shows that Pd NPs synthesized with both stabilizer combinations follow pseudo first-order reaction kinetics, where NaOL provides a faster and more effective reduction of Pd-precursors. The colloidal stabilization of the NP surface by CTAC and NaOL is confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analysis.

Bimetallic Au@Pd nanodendrite system incorporating multimodal intracellular imaging for improved doxorubicin antitumor efficiency

The sufficient accumulation of drugs is crucial for efficient treatment in a complex tumor microenvironment. Drug delivery systems (DDS) with high surface area and selective cytotoxicity present a novel approach to mitigate insufficient drug loading for improved therapeutic response. Herein, a doxorubicin-conjugated bimetallic gold-core palladium-shell nanocarrier with multiple dense arrays of branches (Au@PdNDs.PEG/DOX) was characterized and its efficacy against breast adenocarcinoma (MCF-7) and lung adenocarcinoma (A549) cells were evaluated. Enhanced darkfield and hyperspectral imaging (HSI) microscopy were used to study the intracellular uptake and accumulation of the DOX-loaded nanodendrites A fascinating data from a 3D-CytoViva fluorescence imaging technique provided information about the dynamics of localization and distribution of the nanocarrier. In vitro cytotoxicity assays indicated that Au@PdNDs.PEG/DOX inhibited the proliferative effects of MCF-7 cells at equivalent IC₅₀ dosage compared to DOX alone. The nanocarrier triggered higher induction of apoptosis proved by a time-dependent phosphatidylserine V release, cell cycle arrest, and flow cytometry analysis. Moreover, the cell cycle phase proportion increase suggests that the enhanced apoptotic effect induced by Au@PdNDs.PEG/DOX was via a G2/M phase arrest. Thus, this study demonstrated the potential of dendritic nanoparticles to improve DOX therapeutic efficiency and plasmonic-mediated intracellular imaging as a suitable theranostic platform for deployment in nanomedicine.

A review of the role and mechanism of surfactants in the morphology control of metal nanoparticles

Although great progress has been made in the synthesis of metal nanoparticles, good repeatability and accurate predictability are still difficult to achieve. This difficulty can be attributed to the synthetic method based primarily on observation and subjective experience, and the role of many surfactants remains unclear. It should be noted that surfactants play an important role in the synthetic process. Understanding their function and mechanism in the synthetic process is a prerequisite for the rational design of nanocatalysts with ideal morphology and performance. In this review article, the function of surfactants is introduced first, and then the mechanism of action of surfactants in controlling the morphology of nanoparticles is discussed according to the types of surfactants, and the promoting and sealing effects of surfactants on the crystal surface is revealed. The relationship between surfactants and the morphology structure of nanoparticles is studied. The removal methods of surfactants are discussed, and the existing problems in the current development strategy are summarized. Finally, the application of surfactants in controlling the morphology of metal nanocrystals is prospected. It is hoped that the review can open up new avenues for the synthesis of nanocrystals.

Enriching the branching of Au@PdAu core–shell nanocrystals using a syringe pump: kinetics control meets lattice mismatch

Gold@palladium–gold nanocrystals with a tunable branched shape are prepared via seeded growth, where the use of a syringe pump allows the manipulation over reaction kinetics as coupled by surface diffusion and strain caused by lattice mismatch.

Therapeutic nanodendrites: current applications and prospects

Multidisciplinary efforts in the field of nanomedicine for cancer therapy to provide solutions to common limitations of traditional drug administration such as poor bioaccumulation, hydrophobicity, and nonspecific biodistribution and targeting have registered very promising progress thus far. Currently, a new class of metal nanostructures possessing a unique dendritic-shaped morphology has been designed for improved therapeutic efficiency. Branched metal nanoparticles or metal nanodendrites are credited to present promising characteristics for biomedical applications owing to their unique physicochemical, optical, and electronic properties. Nanodendrites can enhance the loading efficiency of bioactive molecules due to their three-dimensional (3D) high surface area and can selectively deliver their cargo to tumor cells using their stimuli-responsive properties. With the ability to accumulate sufficiently within cells, nanodendrites can overcome the detection and clearance by glycoproteins. Moreover, active targeting ligands such as antibodies and proteins can as well be attached to these therapeutic nanodendrites to enhance specific tumor targeting, thereby presenting a multifunctional nanoplatform with tunable strategies. This mini-review focuses on recent developments in the understanding of metallic nanodendrite synthesis, formation mechanism, and their therapeutic capabilities for next-generation cancer therapy. Finally, the challenges and future opportunities of these fascinating materials to facilitate extensive research endeavors towards the design and application were discussed.