Comparative biological effects of spherical noble metal nanoparticles (Rh, Pd, Ag, Pt, Au) with 4-8 nm diameter

In vitro and in vivo study of antibacterial and anti-encrustation coating on ureteric stents

OBJECTIVES

To investigate the ability of propolis-coated ureteric stents to solve complications, especially urinary tract infections (UTIs) and crusting, in patients with long-term indwelling ureteric stents through antimicrobial and anti-calculus activities.

MATERIALS AND METHODS

Polyurethane (PU) ureteric stents were immersed in the ethanol extract of propolis (EEP), a well-known antimicrobial honeybee product, and subjected to chemical, hydrophilic, and seismic tests. The antimicrobial activity of the EEP coating was then examined by in vitro investigation. Proteus mirabilis infection was induced in rats within uncoated and EEP-coated groups, and the infection, stone formation, and inflammation were monitored at various time points.

RESULTS

The characterisation results showed that the hydrophilicity and stability of the EEP surface improved. In vitro tests revealed that the EEP coating was biocompatible, could eliminate >90% of bacteria biofilms attached to the stent and could maintain bacteriostatic properties for up to 3 months. The in vivo experiment revealed that the EEP-coating significantly reduced the amount of bacteria, stones, and salt deposits on the surface of the ureteric stents and decreased inflammation in the host tissue.

CONCLUSIONS

Compared with clinically used PU stents, EEP-coated ureteric stents could better mitigate infections and prevent encrustation. Thus, this study demonstrated that propolis is a promising natural dressing material for ureteric stents.

Interactive Effects of Copper-Doped Urological Implants with Tissue in the Urinary Tract for the Inhibition of Cell Adhesion and Encrustation in the Animal Model Rat

The insertion of a ureteral stent provides acute care by restoring urine flow and alleviating urinary retention or dysfunction. The problems of encrustation, bacterial colonization and biofilm formation become increasingly important when ureteral stents are left in place for a longer period of time. One way to reduce encrustation and bacterial adherence is to modify the stent surface with a diamond-like carbon coating, in combination with copper doping. The biocompatibilities of the Elastollan^® base material and the a-C:H/Cu-mulitilayer coating were tested in synthetic urine. The copper content in bladder tissue was determined by atomic absorption spectroscopy and in blood and in urine by inductively coupled plasma mass spectrometry. Encrustations on the materials were analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. A therapeutic window for copper ions of 0.5–1.0 mM was determined to kill bacteria without affecting human urothelial cells. In the rat animal model, it was found that copper release did not reach toxic concentrations in the affecting tissue of the urinary tract or in the blood. The encrustation behavior of the surfaces showed that the roughness of the amorphous carbon layer with the copper doping is probably the causal factor for the higher encrustation.

Polydimethylsiloxane nanocomposite macroporous films prepared via Pickering high internal phase emulsions as effective dielectrics for enhancing the performance of triboelectric nanogenerators

Polydimethylsiloxane (PDMS) nanocomposite (NC) macroporous films were prepared by a Pickering high internal phase emulsion (HIPE) templating technique and used as effective dielectrics for enhancing the performance of triboelectric-nanogenerators (TENGs). HIPEs were formulated using commercial PDMS and water as the continuous and dispersed phase, respectively. The formation and solidification of PDMS-based HIPEs were possible through stabilization with silver-nanoparticles (Ag-Nps) and surfactant (Span 20) mixtures. The resulting PDMS-NC-polyHIPE films presented an interconnected 3D macroporous structure with Ag-Nps on their porous surface. The addition of different amounts of Ag-Nps (0, 4, 20, 28, 36 wt%) in HIPE formulations allowed modification of the pore size, total pore volume and dielectric properties of the tribo-materials. Results revealed that both the porosity and dielectric properties of these materials play an important role in enhancing the output performance of TENGs. Thus, the best TENG based on the PDMS-NC-polyHIPE film was achieved with 20 wt% of Ag-Nps, with voltage, current and power values of 4.88 V, 0.433 μA and 2.1 μW, respectively, which gives over 3.28-fold power enhancement compared with the reference TENG (based on a PDMS film without porosity or Ag-Nps). Therefore, the preparation of tribo-materials through a Pickering HIPE templating technique provides a novel, effective and easy way for the improvement of the TENG's performance.

Laser-Based Synthesis of Au Nanoparticles for Optical Sensing of Glyphosate: A Preliminary Study

Nowadays, gold nanoparticles Au nanoparticles (AuNPs) capture great interest due to their chemical stability, optical properties and biocompatibility. The success of technologies based on the use of AuNPs implies the development of simple synthesis methods allowing, also, the fine control over their properties (shape, sizes, structure). Here, we present the AuNPs fabrication by nanosecond pulsed laser ablation in citrate-solution, that has the advantage of being a simple, economic and eco-sustainable method to fabricate colloidal solutions of NPs. We characterized the stability and the absorbance of the solutions by Ultraviolet-Visible (UV-Vis) spectroscopy and the morphology of the AuNPs by Transmission Electron Microscopy. In addition, we used the AuNPs solutions as colorimetric sensor to detect the amount of glyphosate in liquid. Indeed, glyphosate is one of the most widely used herbicides which intensive use represents a risk to human health. The glyphosate presence in the colloidal AuNPs solutions determines the aggregation of the AuNPs causing the change in the color of the solution. The variation of the optical properties of the colloidal solutions versus the concentration of glyphosate is studied.

Noble Metals Based Bimetallic and Trimetallic Nanoparticles: Controlled Synthesis, Antimicrobial and Anticancer Applications

Noble bimetallic and trimetallic nanoparticles (NBT-NPs) have superior biomedical applications as compared to their monometallic counterparts. The performance of these nanomaterials depends on their composition, shape and size. Hence, the controlled-synthesis of these nanomaterials is a hot area of research. Till date, no review article in the literature accounts regarding the controlled-synthesis and biomedical applications related to morphology, optimum composition, biocompatibility and versatile chemistry of NBT-NPs. Taking this into contemplation, an effort was made to provide a clear insight into the morphology-controlled synthesis and size/shape-dependent anticancer and bactericidal applications of NBT-NPs. Chemical reduction method for the controlled-synthesis of NBT-NPs is reviewed critically. Furthermore, the potential role of various reaction parameters such as time, reducing agents, stabilizing/capping agents, nature/concentration of precursors, temperature and pH in the shape/size-controlled synthesis of these nanomaterials are discussed. In the second part of this article, anticancer and bactericidal applications of the NBT-NPs are reviewed and the influences of optimum composition, size, surface structure, versatile chemistry and synergism are studied. Finally, the current challenges in the controlled-synthesis and biomedical applications of these nanomaterials, and prospects to resolve related issues are discussed. HighlightsChemical reduction method for the synthesis of NBT-NPs is reviewed.The influences of parameters on the control synthesis of NBT-NPs are discussed.Antibacterial and anticancer applications and cytotoxicity of NBT-NPs are reviewed.Possible solutions for the key challenges are discussed.Outlooks about the synthesis and biomedical applications of NBT-NPs are discussed.

Enhanced dissolution of silver nanoparticles in a physical mixture with platinum nanoparticles based on the sacrificial anode effect

A strategy to reduce implant-related infections is the inhibition of the initial bacterial implant colonization by biomaterials containing silver (Ag). The antimicrobial efficacy of such biomaterials can be increased by surface enhancement (nanosilver) or by creating a sacrificial anode system for Ag. Such a system will lead to an electrochemically driven enhanced Ag ion release due to the presence of a more noble metal. Here we combined the enlarged surface of nanoparticles (NP) with a possible sacrificial anode effect for Ag induced by the presence of the electrochemically more noble platinum (Pt) in physical mixtures of Ag NP and Pt NP dispersions. These Ag NP/Pt NP mixtures were compared to the same amounts of pure Ag NP in terms of cell biological responses, i.e. the antimicrobial activity against Staphylococcus aureus and Escherichia coli as well as the viability of human mesenchymal stem cells (hMSC). In addition, Ag NP was analyzed by ultraviolet-visible (UV-vis) spectroscopy, cyclic voltammetry, and atomic absorption spectroscopy. It was found that the dissolution rate of Ag NP was enhanced in the presence of Pt NP within the physical mixture compared to a dispersion of pure Ag NP. Dissolution experiments revealed a fourfold increased Ag ion release from physical mixtures due to enhanced electrochemical activity, which resulted in a significantly increased toxicity towards both bacteria and hMSC. Thus, our results provide evidence for an underlying sacrificial anode mechanism induced by the presence of Pt NP within physical mixtures with Ag NP. Such physical mixtures have a high potential for various applications, for example as antimicrobial implant coatings in the biomedicine or as bactericidal systems for water and surface purification in the technical area.

Nanotechnological Applications Hold a Pivotal Position in Boosting Stem Cells Osteogenic Activity: In Vitro and In Vivo Studies

This approach was constructed to appraise the therapeutic effectiveness of a single i.v. dose of osteoblasts generated from co-culturing BM-MSCs with nano-HA, Pt-NPs, or Pt-HA-nanocomposite in osteoporotic rats. MSCs were grown, propagated in culture, and characterized. The effect of the suggested nanoplatforms on the survival, osteogenic differentiation, and mineralization of BM-MSCs was assessed by MTT assay, real-time PCR analysis, and Alizarin red S staining, respectively. Thereafter, the generated osteoblasts were employed for the treatment of ovariectomized rats. Our results revealed that the selected nanoplatforms upregulate the expression of osteogenic differentiation related genes (Runx-2 and BMP-2) significantly and enhance calcium deposition in BM-MSCs after 7 and 21 days, respectively, whereas the in vivo study validated that the infusion of the generated osteoblasts considerably downturn serum BALP, BSP, and SOST levels; upswing OSX level; and regain femur bone mineralization and histoarchitecture. Conclusively, the outcomes of this work provide scientific evidence that transplanting osteoblasts derived from differentiation of BM-MSCs in the presence of nanoplatforms in ovariectomized rats restores bone remodeling balance which constitutes a new hope for the treatment of osteoporosis.

Bimetallic silver-platinum nanoparticles with combined osteo-promotive and antimicrobial activity

Bimetallic alloyed silver-platinum nanoparticles (AgPt NP) with different metal composition from Ag₁₀Pt₉₀ to Ag₉₀Pt₁₀ in steps of 20 mol% were synthesized. The biological effects of AgPt NP, including cellular uptake, cell viability, osteogenic differentiation and osteoclastogenesis as well as the antimicrobial activity towards Staphylococcus aureus and Escherichia coli were analyzed in comparison to pure Ag NP and pure Pt NP. The uptake of NP into human mesenchymal stem cells was confirmed by cross-sectional focused-ion beam preparation and observation by scanning and transmission electron microscopy in combination with energy-dispersive x-ray analysis. Lower cytotoxicity and antimicrobial activity were observed for AgPt NP compared to pure Ag NP. Thus, an enhanced Ag ion release due to a possible sacrificial anode effect was not achieved. Nevertheless, a Ag content of at least 50 mol% was sufficient to induce bactericidal effects against both Staphylococcus aureus and Escherichia coli. In addition, a Pt-related (≥50 mol% Pt) osteo-promotive activity on human mesenchymal stem cells was observed by enhanced cell calcification and alkaline phosphatase activity. In contrast, the osteoclastogenesis of rat primary precursor osteoclasts was inhibited. In summary, these results demonstrate a combinatory osteo-promotive and antimicrobial activity of bimetallic Ag₅₀Pt₅₀ NP.

X-ray powder diffraction to analyse bimetallic core–shell nanoparticles (gold and palladium; 7–8 nm)

A comparative X-ray powder diffraction study on poly(N-vinyl pyrrolidone) (PVP)-stabilized palladium and gold nanoparticles and bimetallic Pd–Au nanoparticles (both types of core–shell nanostructures) was performed.

Synthesis and biological characterization of alloyed silver–platinum nanoparticles: from compact core–shell nanoparticles to hollow nanoalloys

Bimetallic nanoparticles consisting of silver and platinum were prepared by a modified seeded-growth process in water in the full composition range in steps of 10 mol%. The particles had diameters between 15–25 nm as determined by disc centrifugal sedimentation (DCS) and transmission electron microscopy (TEM). Whereas particles with high platinum content were mostly spherical with a solid silver core/platinum shell structure, mostly hollow alloyed nanoparticles were observed with increasing silver content. The internal structure and the elemental distribution within the particles were elucidated by high-resolution transmission electron microscopy (HRTEM) in combination with energy-dispersive X-ray spectroscopy (EDX). The particles were cytotoxic for human mesenchymal stem cells (hMSC) above 50 mol% silver. This was explained by dissolution experiments where silver was only released at and above 50 mol% silver. In contrast, platinum-rich particles (less than 50 mol% silver) did not release any silver ions. This indicates that the presence of platinum inhibits the oxidative dissolution of silver.

Bimetallic nanoparticles consisting of silver and platinum were prepared by a modified seeded-growth process in water in the full composition range in steps of 10 mol%.