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Posts Tagged ‘Nanoparticles’


Of nanoparticles, cells and polyanions

It is the end of semester 2 so it’s marking season. Since we double mark (a good thing), the final year research projects are marked by both supervisor and an assessor, a member of staff who is not involved in the project. One of the projects I marked was Gemma Carolan’s on “How do SmartFlares RNA detection probes reach the cytosol? Available are the PDF of report, and posts here and here.

I had a sense of déjà vu while reading the project – the clear endosomal location of the SmartFlares, regardless of the DNA sequences brought me back to the days when antisense was the technology of the future for medicine.

While evaluating new technology it is useful to go back and look at other high flying technology. The reality is that it takes decades before we know whether the promise (and hype) were justified; this is true for any hot topic from stem cells to nanoparticles and graphene.

Antisense effects can be mediated by RNAse H, an enzyme that specifically cleaves RNA-DNA duplexes and which protects our cells from RNA viruses. There are other mechanisms, e.g., interference with splicing or translation, but the RNAse-H mediated transcript degradation should be central to many antisense effects. There were many papers reporting specific effects (evidenced by differences between sense, antisense and scrambled oligonucleotides sequences). These certainly contributed to success of individuals and of institutions, e.g., in UK Research Assessment Exercise and grant awards.
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David Paramelle’s paper on using gold nanoparticles stoichiometrically functionalised with a peptide that recognises sphingolipids has just been published in Advanced Healthcare Materials (Publisher’s site; Pubmed)

The paper is the classic “Sunday afternoon” project, which arose through discussions with Rachel Kraut at NTU.

As ever, a lot more than Sunday afternoons ended up being put into the paper, because David had to develop some new approaches. Particularly nice was the purification of nanoparticles functionalised with the sphingomyelin-binding peptide (called “SBD”) from non-functionalised nanoparticles. This is a key step for the preparation of nanoparticles carrying just one functional peptide or group. Hitherto, we have happily had affinity tags as the functional group, which allows for affinity chromatography (examples here, here and here). (more…)

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Sometime last night this blog received its 50,000th page view. I write this blog because I like to. That others find the content worth reading at times is lovely, thank you.

What has been read the most and the least? (more…)

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The question relates to what Langmuir termed “Pathological Science”, simply put “people are tricked into false results … by subjective effects, wishful thinking or threshold interactions“. There is a lot of pathological science and I only use the examples below, because I am most familiar with them; for nanoparticles, I have a personal interest in understanding these materials, since I use them to try to make biological measurements, e.g., here.
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Dan Nieves’ paper on an easy and accessible method to covalently conjugate proteins, sugars and indeed pretty much any biomoleucle onto nanoparticles has just come out in Chem. Commun. (more…)

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On December 31 2013 I posted my New Year’s resolution: to only review manuscripts from open access or learned society journals.

My reasoning was that open access will only be the norm if we stop giving that which is most precious, our time, to closed access journals. I really think the wider community needs to start to be selective in reviewing. It is far easier to implement than the radical re-alignment of library journal subscriptions. (more…)

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The sadly predictable hyping of things nano reached a nadir recently with the promotion of silver nanoparticles (aka “silver bullet”) as a treatment for ebola virus. There has been a great discussion of this and other aspects of silver nanoparticles by Andrew Maynard (here, here for ebola and here for the essential Risk Bites video).

It may surprise some, but until a few weeks ago, there was no simple, direct published method to quantify non-destructively silver nanoparticles. Yet, the non-destructive quantification of silver nanoparticles is essential to any experiment that aims to prepare and use these in a biological context. Without it any experimental work is likely to be qualitative and simple things, such as determining the stoichiometry of functonalisation, become difficult. Indeed, so important is simple quantification of nanoparticles that we validated and published a method for gold nanoparticles in 2007 that has been very well received by the community and which we use daily in the lab. (more…)

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