Australia is the sunniest continent on Earth — which is why it also has the highest rates of skin cancer. But plentiful sunlight is also likely responsible for the lesser known ‘ocular surface cancer’, which occurs when abnormal cells on the eye grow and divide in an uncontrolled way. Continue reading
Pancreatic cancer is one of the most lethal cancers, but difficult to diagnose: few sufferers have symptoms until the cancer has become large or already spread to other organs. Even then, symptoms can be vague and easily misconstrued as more common conditions. Continue reading
For a couple unable to naturally conceive, in vitro fertilisation is often the only option – but it’s one that involves months, even years, of hope intertwined with disappointment. Contributing to the ‘hit and miss’ are the eggs taken from fallopian tubes of hopeful mothers or donors: healthy eggs are essential for healthy embryos to develop into a pregnancy and, ultimately, a baby. Continue reading
How do you measure the tenderness, juiciness and flavour of beef without eating it? It’s a challenge faced by everyone from meat inspectors at abattoirs to consumers looking through a butcher’s window. And they’re all subjective – until now. Continue reading
Pain: we all experience it, but there’s no objective way to measure it. Sure, you can nominate what it feels like on the 10-point ‘pain scale’ used by doctors; but one man’s pain may be another woman’s discomfort. Continue reading
Researchers have found a way to identify multiple cell signalling proteins using a single cell rather than the billions of cells used previously.
The new measurement technology, developed by researchers at the ARC Centre of Excellence for Nanoscale Biophotonics, brings precision medicine a step closer.
“Cells secrete various messenger molecules, such as cytokines. They may indicate the presence of a disease or act as a driver of key therapeutic effects,” says Dr Guozhen Liu, lead author of paper detailing the technology.
The method, termed OnCELISA, uses antibodies attached on specially engineered cell surfaces to capture cytokine molecules before they have a chance to disperse away from the cell.
The secreted messenger proteins such as cytokines are reported, at the single cell level, by using fluorescent magnetic nanoparticles.
Cytokines secreted from cells play a critical role in controlling many physiological functions, including immunity, inflammation, response to cancer, and tissue repair.
The OnCELISA system can be used for ultrasensitive monitoring of cytokine release by individual cells, and it can also help discover cell populations with therapeutic value.
“The ability to identify and select cell populations based on their cytokine release is particularly valuable in commercial cell technologies and it can help develop unique products, such as future non-opioid pain relief” says Dr Liu.
“Importantly, our design uses commercially available reagents only, so it can be easily reproduced by others,” she adds.
While the published work focuses on specific proinflammatory cytokines IL-6 and IL-1β, the method is potentially suitable for a broad range of other secreted proteins and cell types.
The new technique represents an advance on traditional methods such as the enzyme-linked immunosorbent assays (ELISA) that detect average levels of secreted molecules from cell ensembles.
The OnCELISA takes the ELISA approach to its absolute extreme, by detecting cytokines on the surface of individual, single live cells.
The publication has been reported by prestigious iScience journal and can be found at https://www.sciencedirect.com/science/article/pii/S2589004219303578.
Publication Title: A Nanoparticle-Based Affinity Sensor that Identifies and Selects Highly Cytokine-Secreting Cells
Authors: Guozhen Liu; Christina Bursill; Siân P.Cartland; Ayad G.Anwer; Lindsay M.Parker; Kaixin Zhang; Shilun Feng; Meng He; David W.Inglis; Mary M.Kavurma; Mark R.Hutchinson; Ewa M.Goldys
Summary: We developed a universal method termed OnCELISA to detect cytokine secretion from individual cells by applying a capture technology on the cell membrane. OnCELISA uses fluorescent magnetic nanoparticles as assay reporters that enable detection on a single-cell level in microscopy and flow cytometry and fluorimetry in cell ensembles. This system is flexible and can be modified to detect different cytokines from a broad range of cytokine-secreting cells. Using OnCELISA we have been able to select and sort highly cytokine-secreting cells and identify cytokine-secreting expression profiles of different cell populations in vitro and ex vivo. We show that this system can be used for ultrasensitive monitoring of cytokines in the complex biological environment of atherosclerosis that contains multiple cell types. The ability to identify and select cell populations based on their cytokine expression characteristics is valuable in a host of applications that require the monitoring of disease progression.
CNBP researchers have developed a new method of detecting multiple cytokines – the body’s messenger proteins – in very small volume samples, which could lead to earlier diagnosis of diseases such as lymphoma. Continue reading
Friday 16 August:
CNBP researchers have unlocked the potential to transform microscopy at the nanoscale from a costly, complex option to an everyday laboratory tool, available in every lab.
The technique, described in a paper by lead authors Dr Denitza Denkova and Dr Martin Ploschner, which has been dubbed upconversion super-linear excitation-emission – or uSEE – microscopy, can be used not only for observation but also for the activation of biological structures with super-resolution.
This opens new avenues in optogenetics for precise activation of neurons in the brain or for targeted delivery of drugs with increased sub-cellular precision.
Standard optical microscopes can image cells and bacteria but not their nanoscale features which are blurred by a physical effect called diffraction.
Optical microscopes have evolved over the last two decades in order to bypass this diffraction limit; however, these so-called super-resolution techniques typically require expensive and elaborated instrumentation or imaging procedures.
“We have identified a particular type of fluorescent markers, upconversion nanoparticles, which can enter into a regime where light emitted from the particles grows abruptly – in a super-linear fashion – when increasing the excitation light intensity,” Martin says. “Our key discovery is that if this effect is exploited under the right imaging conditions, any standard scanning optical microscope can spontaneously image with super-resolution.”
The discovery addresses a key challenge for microscopy – the so-called diffraction limit. This prevents optical microscopes from seeing very small features clearly as, when the size and distance between the features start reaching the nanoscale range, they begin to blur together and appear as one.
And that is a problem for biologists to observe nanoscale samples – which is what researchers tackling some of our toughest health challenges need to do all the time.
Little wonder then that accessing the world that lies beyond this diffraction limit has become a holy grail for optical microscopy researchers over the past two decades.
In 2014, the Nobel Prize in Chemistry was awarded to three scientists, who developed three different techniques, capable of tricking physics to overcome the diffraction limit.
This landmark work set the scene for an explosion of so-called super-resolution techniques, which have led to revolutionary discoveries.
So far, however, all of these methods have had significant drawbacks. They are far from user-friendly and require either complicated and costly equipment or elaborated image processing, which often leads to imaging artefacts.
When it comes to 3D imaging, there are even more complications.
All the methods until now also require increasing the illumination power to increase the resolution – but that presents particular problems in the world of biology, where excessive light can harm a fragile specimen.
Denitza’s and Martin’s team took a novel approach to the problem. They wanted to make super-resolution possible on a confocal microscope, without set-up modifications or image processing, so that it would be available for use in any lab at practically no extra cost.
Their key discovery was that they could use a standard scanning optical microscope as a 3D super-resolution machine by imaging “upconversion” nanoparticles, potentially bound to the biological structure being studied. Unlike other super-resolution methods, uSEE microscopy offers better resolution at lower powers, and so minimises the damage to biological samples.
But it is not just the amount of light. Its colour also influences the photo-damage and the resolution. For example, UV- light is more harmful, but since it yields a better resolution, most of the super-resolution methods work in the UV and visible wavelengths.
However, in recent years biologists have become increasingly interested in using near-infrared light. It is less harmful and also allows imaging deeper in the tissue. But it does require a sacrifice in resolution, and the field of super-resolution has a very limited pool of fluorophores and techniques which work in the near-infrared regime.
Conveniently, the upconversion nanoparticles, on which the fluorescent markers employed in uSEE microscopy are based, are excited in the desired near-infrared colour spectrum. They are becoming increasingly popular as biological markers as they offer numerous other advantages for biology, including stable optical performance and possibility for multi-colour imaging.
Numerous papers have been published in the recent years about imaging of such particles for bio-applications. However, the effect of spontaneous super-resolution remains overlooked, mainly because the composition of the particles has not been fine-tuned for this application or the particles were not imaged under suitable conditions.
The CNBP team identified a particular nanoparticle composition which provides a strong improvement of the resolution. To make it easier for the end-user, the researchers developed a theoretical framework to optimise the particles and the imaging parameters for their own laboratory setting.
The concept of this method has been around for decades, and several groups have tried to put it into practice, but they either couldn’t identify fluorescent labels with adequate photo-physics, or the imaging conditions were not suitable to achieve bio-imaging in a convenient laboratory setting.
The CNBP team has shown for the first time that the technique can be used in a 3D biological environment, with biologically convenient particles which are both easy to work with and do not harm the samples.
This new methodological toolbox has the potential to go beyond the applications for which it has so far been used. It can be extended to a much broader imaging context, opening new avenues in the research of super-linear emitters and combining them with other imaging modalities to improve their performance.
Journal: Nature Communications
Publication Title: 3D sub-diffraction imaging in a conventional confocal configuration by exploiting super-linear emitters
Authors: Denitza Denkova, Martin Ploschner, Minakshi Das, Lindsay M. Parker, Xianlin Zheng, Yiqing Lu, Antony Orth, Nicolle H. Packer & James A. Piper
Abstract: Sub-diffraction microscopy enables bio-imaging with unprecedented clarity. However, most super-resolution methods require complex, costly purpose-built systems, involve image post-processing and struggle with sub-diffraction imaging in 3D. Here, we realize a conceptually different super-resolution approach which circumvents these limitations and enables 3D sub-diffraction imaging on conventional confocal microscopes. We refer to it as super-linear excitation-emission (SEE) microscopy, as it relies on markers with super-linear dependence of the emission on the excitation power. Super-linear markers proposed here are upconversion nanoparticles of NaYF4, doped with 20% Yb and unconventionally high 8% Tm, which are conveniently excited in the near-infrared biological window. We develop a computational framework calculating the 3D resolution for any viable scanning beam shape and excitation-emission probe profile. Imaging of colominic acid-coated upconversion nanoparticles endocytosed by neuronal cells, at resolutions twice better than the diffraction limit both in lateral and axial directions, illustrates the applicability of SEE microscopy for sub-cellular biology.
A team led by the CNBP’s Dr Guozhen Liu has developed intelligent biodegradable polymer nanoparticles, which can help monitor a cell-signalling protein, or cytokine, widely expressed in cancer cells. The technique can help with earlier diagnostics and even treatment and represents another step towards personalised nanomedicine.
The research integrates a specific fluorogen – a molecule that generates fluorescence and can be used for protein monitoring – with PLGA nanoparticles for the first time.
The fluorogen in question is a so-called “aggregation-induced emission” fluorogen, known as an AIEgen. Aggregation-induced emission (AIE), has become an important area of research since its discovery around 20 years ago. It describes an abnormal phenomenon, in which some compounds show greater fluorescence as they aggregate than when in solution, as is more common. These AIEgens provide superior advantages for biosensing and bioimaging.
The integration of the nanoparticle and the AIEgen could become an important tool in the relatively new field of medicine known as “theranostics” – a combination of “therapy” and “diagnostics” made possible through the use of nanoparticles and an important transition towards personalised medicine.
Dr Liu’s discovery, for example, detects high levels of the cytokine VEGF-A found in tumor cells, and monitors simultaneous photothermal therapy (PTT), in which heat is used to kill cancer cells, and magnetic resonance imaging (MRI) as part of a whole package of early diagnostics and treatment of cancer cells.
It could be used in the future as a smart drug delivery system, with cancer drugs loaded in the nanoparticles for controlled and sustained release targeted precisely to a tumor.
In the future, Dr Liu believes it will be possible to develop the next generation of intelligent nanoparticles which can continually monitor cytokines and cytokine-triggered drug delivery while also carrying out deep tissue imaging.
Dr Liu is an ARC Future Fellow and Senior Lecturer at Graduate School of Biomedical Engineering at UNSW.
You can read the paper here.
Publication Title: AIEgen based poly(L-lactic-co-glycolic acid) magnetic nanoparticles to localize cytokine VEGF for early cancer diagnosis and photothermal therapy
Authors: Ma, K (Ma, Ke); Liu, GJ (Liu, Guo-Jun); Yan, LL (Yan, Lulin); Wen, SH (Wen, Shihui); Xu, B (Xu, Bin); Tian, WJ (Tian, Wenjing); Goldys, EM (Goldys, Ewa M.); Liu, GZ (Liu, Guozhen)
Abstract: Aim: We demonstrated a novel theranostic system for simultaneous photothermal therapy and magnetic resonance imaging applicable to early diagnostics and treatment of cancer cells. Materials & methods: Oleic acid-Fe3O4 and triphenylamine-divinylanthracene-dicyano were loaded to the poly(L-lactic-co-glycolic acid) nanoparticles (NPs) on which anti-VEGF antibodies were modified to form anti-VEGF/OA-Fe3O4/triphenylamine-divinylanthracene-dicyano@poly(L-lactic-co-glycolic acid) NPs. The 1H nuclear magnetic resonance (NMR), mass spectra, fluorescence, UV absorption, dynamic light scattering, transmission electron microscope and inductively coupled plasma mass spectrometry tests were used to characterize the NPs, and the bioimaging was illustrated by confocal laser scanning microscope (CLSM) and in vivo MRI animal experiment. Results: This system was capable to recognize the overexpressed VEGF-A as low as 68pg/ml in different cell lines with good selectivity and photothermal therapy effect. Conclusion: These ultrasensitive theranostic NPs were able to identify tumor cells by fluorescence imaging and MRI, and destroy tumors under near infrared illumination.
Author Keywords: AIEgen; cytokines; MRI; PDT; PLGA nanoparticle; PTT; theranostics
KeyWords Plus: ENDOTHELIAL GROWTH-FACTOR; IN-VIVO; ANGIOGENESIS; THERANOSTICS; NANOSPHERES; APTASENSOR; EXPRESSION; PROGNOSIS; MEDICINE; PROBE
Almost all cells replace themselves by replicating, but when there are errors in DNA-replication, it can lead to diseases including many cancers.
DNA-replication is complex and involves a host of protein machinery. One of the most important is the protein PCNA, which helps orchestrate the process.
Adelaide University postgraduate student Aimee Horsfall, a member of the ARC Centre of Excellence for Nanoscale Biophotonics (CNBP), was part of the team which analysed the structures of a number of proteins interacting with PCNA.
The work suggests that the 3D shape of these proteins defines how strongly this interaction occurs.
The research is important because, if we can understand what makes the interaction with PCNA stronger, and determine the optimal shape, we can develop a drug that mimics it.
This drug could bind PCNA and stop replication in diseased cells, offering a potential treatment for diseases implicated in erroneous DNA-replication, or as a broad spectrum cancer therapeutic.
Publication Title: Targeting PCNA with peptide mimetics for therapeutic purposes.
Authors: Horsfall AJ, Abell AD, Bruning J.
Abstract: PCNA is an excellent inhibition target to shut down highly proliferative cells and thereby develop a broad spectrum cancer therapeutic. It interacts with a wide variety of proteins through a conserved motif referred to as the PCNA-Interacting Protein (PIP) box. There is large sequence diversity between high affinity PCNA binding partners, with conservation of the binding structure – a well-defined 310-helix. Here, all current PIP-box peptides crystallised with human PCNA are collated to reveal common trends between binding structure and affinity. Key intra- and inter-molecular hydrogen bonding networks which stabilise the 310-helix of PIP-box partners are highlighted, and related back to the canonical PIP-box motif. High correlation with the canonical PIP-box sequence does not directly afford high affinity. Instead, we summarise key interactions which stabilise the binding structure that lead to enhanced PCNA binding affinity. These interactions also implicate the ‘non-conserved’ residues within the PIP-box that have previously been overlooked. Such insights will allow a more directed approach to develop therapeutic PCNA inhibitors.
Keywords: PCNA, peptide mimetics, PIP-box, sliding clamp, DNA replication