Gold nanotube membranes: fabrication of controlled pore geometries and tailored surface chemistries

This study concerns the fabrication, chemical modification and characterisation of gold nanotube membranes using porous alumina (PA) membranes as templates. Electroless deposition was used to finely coat membranes with gold, forming gold nanotubes within the pores. PA templates were fabricated with straight and shaped pores thus allowing the fabrication of a wide range of gold nanotube geometries. The gold deposition process provides control over the pore size of the membrane, where pore sizes can be reduced to molecular dimensions. Chemical sensitivity was introduced into the membrane through the addition of self assembled monolayers (SAMs) of thiols. Characterisation of thiol assembly within the pores of the membrane was investigated using confocal Raman

Water transport through nanoporous materials: Porous silicon and single walled carbon nanotubes

We report upon the pressure driven water transport through porous silicon (pSi) and single walled carbon nanotube (SWCNT) membranes. Fabrication of the membranes was monitored by AFM and SEM. Water permeability as high as 16926 mm3 cm-2 s-1 atm-1 is found for the pSi membrane. The SWCNT membrane is built upon the pSi membrane and a water permeability of 0.02 mm3 cm-2 s-1 atm-1 is achieved. Performance comparisons to similar CNT membranes are made and future improvements to the system are proposed

Tuneable 2D self-assembly of plasmonic nanoparticles at liquid|liquid interfaces

Understanding the structure and assembly of nanoparticles at liquid|liquid interfaces is paramount to their integration into devices for sensing, catalysis, electronics and optics. However, many difficulties arise when attempting to resolve the structure of such interfacial assemblies. In this article we use a combination of X-ray diffraction and optical reflectance to determine the structural arrangement and plasmon coupling between 12.8 nm diameter gold nanoparticles assembled at a water|1,2-dichloroethane interface. The liquid|liquid interface provides a molecularly flat and defect-correcting platform for nanoparticles to self-assemble. The amount of nanoparticles assembling at the interface can be controlled via the concentration of electrolyte within either the aqueous or organic phase. At higher electrolyte concentration more nanoparticles can settle at the liquid|liquid interface resulting in a decrease in nanoparticle spacing as observed from X-ray diffraction experiments. The plasmonic coupling between the nanoparticles as they come closer together is observed by a red-shift in the optical reflectance spectra. The optical reflectance and the X-ray diffraction data are combined to introduce a new 'plasmon ruler'. This allows extraction of structural information from simple optical spectroscopy techniques, with important implications for understanding the structure of self-assembled nanoparticle films at liquid interfaces.</p

Gold nanotube membranes

Leonora Velleman, Joe G. Shapter, Dusan Losi

Collective modes of self-assembled supercluster metamaterials:Towards label-free sensing

AOP 2019, Lisbon, Portugal, 31 May - 4 June, 2019. -- http://www.aop2019.org/Peer reviewe

Silver nanoparticles prepared by gamma irradiation across metal-organic framework templates

In this study, we demonstrate for the first time the successful fabrication of well-dispersed ultrafine silver nanoparticles inside metal-organic frameworks through a single step gamma irradiation at room temperature. HKUST-1 crystals are soaked in silver nitrate aqueous solution and irradiated with a Cobalt 60 source across a range of irradiation doses to synthesize highly uniformly distributed silver nano-particles. The average size of the silver nanoparticles across the Ag@HKUST-1 materials is found to vary between 1.4 and 3 nm for dose exposures between 1 and 200 kGy, respectively. The Ag@HKUST-1 hybrid crystals exhibit strong surface plasmon resonance and are highly durable and efficient catalytic materials for the reduction of 4-nitrophenol to 4-aminophenol (up to 14.46 &times; 10-3 s-1 for 1 kGy Ag@HKUST-1). The crystals can be easily recycled for at least five successive cycles of reaction with a conversion efficiency higher than 99.9%. The gamma irradiation is demonstrated to be an effective and environmental friendly process for the synthesis of nano-particles across confined metal-organic frameworks at room temperature with potential applications in environmental science

The control of epidermal growth factor grafted on mesoporous silica nanoparticles for targeted delivery

The performance of biomaterials in a biological environment is largely influenced by the surface properties of the biomaterials. In particular, grafted targeting ligands significantly impact the subsequent cellular interactions. The utilisation of a grafted epidermal growth factor (EGF) is effective for targeted delivery of drugs to tumours, but the amount of these biological attachments cannot be easily quantified as most characterization methods could not detect the extremely low amount of EGF ligands grafted on the surface of nanoparticles. In this study, hollow mesoporous silica nanoparticles (HMSNs) were functionalized with amine groups to conjugate with EGFs via carbodiimide chemistry. Time of flight secondary ion mass spectrometry (ToF-SIMS), a very surface specific technique (penetration depth &lt;1.5 nm), was employed to study the binding efficiency of the EGF to the nanoparticles. Principal component analysis (PCA) was implemented to track the relative surface concentrations of EGFs on HMSNs. It was found that ToF-SIMS combined with the PCA technique is an effective method to evaluate the immobilization efficiency of EGFs. Based on this useful technique, the quantity and density of the EGF attachments that grafted on nanoparticles can be effectively controlled by varying the EGF concentration at grafting stages. Cell experiments demonstrated that the targeting performance of EGFR positive cells was affected by the number of EGFs attached on HMSNs