Fourier transform pure nuclear quadrupole resonance by pulsed field cycling

We report the observation of Fourier transform pure NQR by pulsed field cycling. For deuterium, well resolved spectra are obtained with high sensitivity showing the low frequency nu0 lines and allowing assignments of quadrupole couplings and asymmetry parameters to inequivalent deuterons. The technique is ideally applicable to nuclei with low quadrupolar frequencies (e.g., 2D, 7Li, 11B, 27Al, 23Na, 14N) and makes possible high resolution structure determination in polycrystalline or disordered materials

“Chocolate” gold nanoparticles - one pot synthesis and biocompatibility

The chemical synthesis of nanoparticles can involve and generate toxic materials. Here, we present for the first time, a one pot direct route to synthesize gold nanoparticles (AuNPs) using natural cacao extract as both a reducing and stabilizing agent. The nanoparticles were characterized by UV-visible spectroscopy (UV-VIS), dynamic light scattering (DLS), and transmission electron microscopy (TEM); and have excellent biocompatibility with human primary dermal fibroblastsNeelika Roy Chowdhury, Allison J. Cowin, Peter Zilm and Krasimir Vasile

Zero-Field Nuclear Magnetic Resonance

In polycrystalline samples, NMR "powder spectra" are broad and much structural information is lost as a result of the orientational disorder. In this Letter Fourier-transform NMR in zero magnetic field is described. With no preferred direction in space, all crystallites contribute equivalently and resolved dipolar splittings can be interpreted directly in terms of internuclear distances. This opens the possiblity of molecular structure determination without the need for single crystals or oriented samples

Spiked nanostructures disrupt fungal biofilm and impart increased sensitivity to antifungal treatment

First published: February 4, 2022There is a globally increasing demand for medically implanted devices, partly spurred by an aging population. In parallel, there is a proportionate increase in implant associated infection. Much focus has been directed toward the development of techniques to fabricate nanostructured antimicrobial biomaterials to mitigate infection. The present study investigates the interaction of the fungal pathogen Candida albicans with an antimicrobial surface bearing nanoscale protrusions. C. albicans cells were observed to be affected by cell wall stress, which impeded its ability to switch to a hyphal phenotype. There are significant differences in the expression of C. albicans virulence-associated genes between the untreated and nanostructured surfaces. To determine whether the observed inhibition of C. albicans would also sensitize it to antifungal drugs, a culture is established for 3 days on the nanostructured surface before being treated with the antifungal drug amphotericin B. The drug was able to kill all cells on the nanostructured surface at sub-clinical concentrations, while remaining ineffective against cultures grown on a smooth control surface. These findings may eventually prove to be impactful in the clinic, as clinicians may be able to reduce antifungal drug dosages and minimize the effects of drug associated toxicity.Andrew Hayles, Richard Bright, Jonathan Wood, Dennis Palms, Peter Zilm, Toby Brown, Dan Barker, and Krasimir Vasile

Bioactive plasma coatings on orthodontic brackets: In Vitro metal ion release and cytotoxicity

The metal ion release characteristics and biocompatibility of meta-based materials are key factors that influence their use in orthodontics. Although stainless steel-based alloys have gained much interest and use due to their mechanical properties and cost, they are prone to localised attack after prolonged exposure to the hostile oral environment. Metal ions may induce cellular toxicity at high dosages. To circumvent these issues, orthodontic brackets were coated with a functional nanothin layer of plasma polymer and further immobilised with enantiomers of tryptophan. Analysis of the physicochemical properties confirmed the presence of functional coatings on the surface of the brackets. The quantification of metal ion release using mass spectrometry proved that plasma functionalisation could minimise metal ion release from orthodontic brackets. Furthermore, the biocompatibility of the brackets has been improved after functionalisation. These findings demonstrate that plasma polymer facilitated surface functionalisation of orthodontic brackets is a promising approach to reducing metal toxicity without impacting their bulk properties.Lasni Samalka Kumarasinghe, Neethu Ninan, Panthihage Ruvini Lakshika Dabare, Alex Cavallaro, Esma J. Dogramacı, Giampiero Rossi-Fedele ... et al

pH-Responsive Biomaterials for the Treatment of Dental Caries - A Focussed and Critical Review

Dental caries is a common and costly multifactorial biofilm disease caused by cariogenic bacteria that ferment carbohydrates to lactic acid, demineralizing the inorganic component of teeth. Therefore, low pH (pH 4.5) is a characteristic signal of the localised carious environment, compared to a healthy oral pH range (6.8 to 7.4). The development of pH-responsive delivery systems that release antibacterial agents in response to low pH has gained attention as a targeted therapy for dental caries. Release is triggered by high levels of acidogenic species and their reduction may select for the establishment of health-associated biofilm communities. Moreover, drug efficacy can be amplified by the modification of the delivery system to target adhesion to the plaque biofilm to extend the retention time of antimicrobial agents in the oral cavity. In this review, recent developments of different pH-responsive nanocarriers and their biofilm targeting mechanisms are discussed. This review critically discusses the current state of the art and innovations in the development and use of smart delivery materials for dental caries treatment. The authors’ views for the future of the field are also presented.Yanping He, Krasimir Vasilev, and Peter Zil

‘Chocolate’ silver nanoparticles: synthesis, antibacterial activity and cytotoxicity

Abstract not availableNeelika Roy Chowdhury, Melanie MacGregor-Ramiasa, Peter Zilm, Peter Majewski, Krasimir Vasile