Ramiz A. Boulos

p-Phosphonic acid calix[8]arene assisted exfoliation and stabilization of 2D materials in water

Exfoliated 2D materials including graphene, BN, MoS(2) and WS(2) are accessible in water over a wide range of pH for a synergistic process involving sonication in the presence of p-phosphonic acid calix[8]arene.

Pyrene-conjugated hyaluronan facilitated exfoliation and stabilisation of low dimensional nanomaterials in water

Pyrene-conjugated hyaluronan (Py-HA) facilitates the exfoliation of low-dimensional nanomaterials including graphite, hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS2), and the dispersion of carbon nanotubes (CNTs) and carbon nano-onions (CNOs) in water (and PBS solutions), with the assistance of sonication.

Microfluidic size selective growth of palladium nano-particles on carbon nano-onions

Size selective growth of palladium nano-particles 2-7 nm in diameter on the surface of carbon nano-onions (CNOs) (derived from catalytic cracking of methane) in water involves pretreating the CNOs with p-phosphonic acid calix[8]arene then H(2)PdCl(4) followed by dynamic thin film processing under hydrogen in a vortex fluidic device.

Multifunctional water-soluble molecular capsules based on p-phosphonic acid calix[5]arene

p-Phosphonic acid calix[5]arene forms molecular capsules in water based on two of the molecules, which can be loaded with carboplatin using intense shearing, and attached to single wall carbon nano-tubes. Spin coating of the capsules onto a substrate affords 2 nm fibres of stacked calixarenes, with the self-assembly understood using molecular modelling.

Non-covalently modified graphene supported ultrafine nanoparticles of palladium for hydrogen gas sensing

A facile aqueous based method of decorating p-phosphonic acid calix[8]arene functionalized graphene with well-dispersed ultrafine palladium nanoparticles (∼2 nm) has been developed. The electrocatalytic Pd-NP–graphene nano-composite has been incorporated into a functional hydrogen sensing device using a simple drop casting technique on interdigitated electrodes.

Nitrate uptake by p-phosphonic acid calix[8]arene stabilized graphene

In situ sonic probe exfoliated graphene sheets in the presence of various concentrations of p-phosphonic acid calix[8]arene are effective in removing nitrate from aquatic effluents, with the efficiency increasing for higher ratios of calixarene to graphite. Mild sonication of the nitrate-adsorbed material releases some nitrate ions back to the effluent.

Shear flow assisted decoration of carbon nano-onions with platinum nanoparticles

Aqueous based controlled decoration of platinum nanoparticles on plasma treated carbon nano-onions (CNOs) occurs within the shear flow generated by a vortex fluidic device (VFD), using ascorbic acid as the reducing agent, with the electrocatalytic potential of the resulting Pt-NPs@CNOs nano-composites demonstrated.

A new antibiotic with potent activity targets MscL

The growing problem of antibiotic-resistant bacteria is a major threat to human health. Paradoxically, new antibiotic discovery is declining, with most of the recently approved antibiotics corresponding to new uses for old antibiotics or structurally similar derivatives of known antibiotics. We used an in silico approach to design a new class of nontoxic antimicrobials for the bacteria-specific mechanosensitive ion channel of large conductance, MscL. One antimicrobial of this class, compound 10, is effective against methicillin-resistant Staphylococcus aureus with no cytotoxicity in human cell lines at the therapeutic concentrations. As predicted from in silico modeling, we show that the mechanism of action of compound 10 is at least partly dependent on interactions with MscL. Moreover we show that compound 10 cured a methicillin-resistant S. aureus infection in the model nematode Caenorhabditis elegans. Our work shows that compound 10, and other drugs that target MscL, are potentially important therapeutics against antibiotic-resistant bacterial infections.

Inspiration from old dyes: tris(stilbene) compounds as potent gram-positive antibacterial agents.

Herein we describe the preparation and structure-activity relationship studies on range of stilbene based compounds and their antibacterial activity. Two related compounds, each bearing carboxylic acid moieties, exhibit good activity against several bacterial strains, including methicillin-resistant Staphylococcus aureus MRSA (ATCC 33592 and NCTC 10442). Compound 10 was most active against Moraxella catarrhalis with minimum inhibitory concentrations (MICs) of 0.12-0.25 μg mL(-1) and against Staphylococcus spp. with MICs ranging from 2-4 μg mL(-1). The derivative 17 showed increased activity with MICs of 0.06-0.25 μg mL(-1) against M. catarrhalis and 0.12-1 against Staphylococcus spp. This level of activity is similar to that reported for S. aureus for antibiotics, such as vancomycin, with MICs of ≤2.0 μg mL(-1) and clindamycin with MICs of ≤0.5 μg mL(-1). As an indicator of toxicity, 17 was tested for its ability to lyse sheep erythrocytes, and showed low haemolytic activity. Such results highlight the value of tris(stilbene) compounds as antibacterial agents providing suitable properties for further development.

Antimicrobial dyes and mechanosensitive channels

The search for new and effective antimicrobial agents has never been as important; however, since the discovery of antibiotics, exploring the antimicrobial activity of dyes has been forgotten. Antimicrobial dyes are an untapped resource and have the ability to potentially combat the spread of drug-resistant bacteria either alone or as antimicrobial adjuvants. The mechanosensitive ion channel of large conductance (MscL) is highly conserved and ubiquitous in bacterial species. There is evidence to suggest that at least one triphenylmethane dye acts through the highly conserved MscL channel and combining the two approaches of exploring the mechanism of action of other triphenylmethane dyes or antimicrobial dyes in general and the novel MscL target provides a new opportunity for further exploration.