tethered-bilayer-lipid-membranes-to-monitor-heat-transfer-between

Tethered Bilayer Lipid Membranes to Monitor Heat Transfer between Gold Nanoparticles and Lipid Membranes

Here we report a protocol to investigate the heat transfer between irradiated gold nanoparticles (GNPs) and bilayer lipid membranes by electrochemistry ...

University of Technology Sydney

This review identifies the ways in which tethered bilayer lipid membranes (tBLMs) can be used for the identification of the actions of antimicrobials against lipid bilayers. Much of the new research in this area has originated, or included researchers from, the southern hemisphere, Australia and New Zealand in particular. More and more, tBLMs are replacing liposome release assays, black lipid membranes and patch-clamp electrophysiological techniques because they use fewer reagents, are able to obtain results far more quickly and can provide a uniformity of responses with fewer artefacts. In this work, we describe how tBLM technology can and has been used to identify the actions of numerous antimicrobial agents.

The Use of Tethered Bilayer Lipid Membranes to Identify the Mechanisms of Antimicrobial Peptide Interactions with Lipid Bilayers.

Plasmon resonance frequency irradiated gold nanoparticles (GNPs) have gained interest as a laser-targeted treatment for infections, tumors and for the controlled release of drugs in situ. Questions still remain, however, as to the efficiency of heat delivery within biological tissues and how this can be reliably determined. Here, we demonstrate how a nanomaterial-electrode interface that mimics cell membranes can detect the localized heat transfer characteristics arising from plasmon resonance frequency-matched laser excitation of GNPs. We demonstrate that the lipid bilayer membrane can be affected by conjugated GNP induced hyperthermia when irradiated with a laser power output as low as 135 nW/μm. This is four orders of magnitude lower power than previously reported. By restricting the lateral movement of the lipids in the bilayer membrane, it was shown that the change in membrane conductance as a result of the heat transfer was due to the creation of transient lipidic toroidal pores within the membrane. We further demonstrate that the heat transfer from the GNPs alters diffusion rates of monomers of the gramicidin-A peptide within the lipid leaflets. This work highlights how targeted low laser power GNP hyperthermia treatments, in vivo, could play a dual role of interfering with both cell membrane morphology and dynamics, along with membrane protein function.

Real-time monitoring of heat transfer between gold nanoparticles and tethered bilayer lipid membranes.

There has been an increasing interest in the development of antimicrobial peptides (AMPs) and their synthetic mimics as a novel class of antibiotics to overcome the rapid emergence of antibiotic resistance. Recently, phenylglyoxamide-based small molecular AMP mimics have been identified as potential leads to treat bacterial infections. In this study, a new series of biphenylglyoxamide-based small molecular AMP mimics were synthesised from the ring-opening reaction of -sulfonylisatin bearing a biphenyl backbone with a diamine, followed by the conversion into tertiary ammonium chloride, quaternary ammonium iodide and guanidinium hydrochloride salts. Structure-activity relationship studies of the analogues identified the octanesulfonyl group as being essential for both Gram-positive and Gram-negative antibacterial activity, while the biphenyl backbone was important for Gram-negative antibacterial activity. The most potent analogue was identified to be chloro-substituted quaternary ammonium iodide salt , which possesses antibacterial activity against both Gram-positive (MIC against  = 8 μM) and Gram-negative bacteria (MIC against  = 16 μM,  = 63 μM) and disrupted 35% of pre-established  biofilms at 32 μM. Cytoplasmic membrane permeability and tethered bilayer lipid membranes (tBLMs) studies suggested that  acts as a bacterial membrane disruptor. In addition, in vitro toxicity studies showed that the potent compounds are non-toxic against human cells at therapeutic dosages.

Amani Alghalayini

School of Life Sciences,
ARC Research Hub for Integrated Devices for End-user Analysis at Low-levels (IDEAL),
Faculty of Science,
ARC Research Hub for Integrated Devices for End-user Analysis at Low-levels (IDEAL), Faculty of Science

University of Technology Sydney

Tethered Bilayer Lipid Membranes to Monitor Heat Transfer between Gold Nanoparticles and Lipid Membranes