Tag Archives: Varun Sreenivasan

Nanorubies for targeted bio-imaging

12 October 2017:

Researchers from the CNBP have released a new paper that examines the use of nanorubies for targeted bio-imaging activity. The work (lead author Varun Sreenivasan pictured) is trans-disciplinary in nature, drawing on the Centre’s collective knowledge in physics, pharmacology, chemistry, material science and embryology. The paper, published in ACS Applied Materials and Interfaces is accessible online.

Journal: ACS Applied Materials and Interfaces.

Publication title: Development of Bright and Biocompatible Nanoruby and its Application to Background-free Time-gated Imaging of G-protein Coupled Receptors.

Authors:  Varun K. A. Sreenivasan, Wan Aizuddin W Razali, Kai Zhang, Rashmi R Pillai, Avishkar Saini, Denitza Denkova, Marina Santiago, Hannah Brown, Jeremy Thompson, Mark Connor, Ewa M. Goldys, and Andrei V Zvyagin.

Abstract: At the forefront of development of fluorescent probes for biological imaging applications are enhancements aimed at increasing their brightness, contrast, and photostability, especially towards demanding applications of single molecule detection. In comparison with existing probes, nanorubies exhibit unlimited photostability and a long emission lifetime (3.7 ms), which enable continuous imaging at single-particle sensitivity in highly scattering and fluorescent biological specimens. However, their wide application as fluorescence probes has so far been hindered by the absence of facile methods for scaled-up high volume production and molecularly-specific targeting. The present work encompasses large scale production of colloidally stable nanoruby particles, demonstration of their biofunctionality and negligible cytotoxicity, as well as validation of its use for targeted biomolecular imaging. In addition, optical characteristics of nanorubies are found to be comparable or superior to state-of-the-art quantum dots. Protocols of reproducible and robust coupling of functional proteins to the nanoruby surface are also presented. As an example, NeutrAvidin-coupled nanoruby show excellent affinity and specificity to µ-opioid receptors in fixed and live cells, allowing wide-field imaging of G-protein coupled receptors with single particle sensitivity.

Neurophotonics Summer School

21 June 2017:

This years Neurophotonics Summer School held in Quebec, Canada, June 11-21, was attended by three CNBP members – Vicky Staikopoulos (University of Adelaide, pictured), Antony Orth (RMIT University) and Varun Sreenivasan (UNSW).

The school focuses on teaching physics and biology and how they can merge, and runs for 10 days and includes 14 lectures from world class speakers and 10 workshops that teach the latest technology in the bio-imaging of the central nervous system.

For the last 4 days of the summer school, students are given a project to participate in for direct hands-on experience which is then presented on the last day,  with prizes awarded for the top 3 presentations.

This year, equal second prize was given to Vicky Staikopoulos for her work on Digital Holographic Microscopy in red blood cells.

 

Physics in the pub!

cnbplogosquare120 June 2016:

Attendees at Sydney’s ‘Physics in the pub’ event were treated to a magical light-inspired show by CNBP researchers Martin Ploschner, Denitza Denkova and Varun Sreenivasan. Together they wowed the audience at the Three Wise Monkeys Hotel, using little more than UV light, fluorescent paint and other handy fluorescing materials.

Their act, one of a number on the night, aimed to take science out of the laboratory,  to take it to the public, and to make it educational, entertaining and fun in equal measure!

All three researchers enjoyed the experience of showcasing their science in a relaxed and informal environment, and quickly overcame any potential stage nerves to flaunt their fluro-physics to a full-house of engaged and interested members of the public.

Well done to all three – a short video of the fun-filled show can be viewed online!

Physicsinthepub_photo

Ultrasensitive imaging of unique nanoruby probes

Wan Razali6 June 2016:

Our CNBP researchers describe a wide-field time-gated photoluminescence microscopy system, customised for ultrasensitive imaging of unique nanoruby probes in this latest paper published in the Journal of Biophotonics.

Publication Title: Wide-Field Time-Gated Photoluminescence Microscopy for Fast Ultrahigh-Sensitivity Imaging of Photoluminescent Probes.

Authors: Wan A W Razali (pictured top left), Varun K A Sreenivasan, Carlo Bradac, Mark Connor, Ewa M Goldys and Andrei V Zvyagin.

Abstract: Fluorescence microscopy is a fundamental technique for the life sciences, where biocompatible and photostable photoluminescence probes in combination with fast and sensitive imaging systems are continually transforming this field. A wide-field time-gated photoluminescence microscopy system customised for ultrasensitive imaging of unique nanoruby probes with long photoluminescence lifetime is described. The detection sensitivity derived from the long photoluminescence lifetime of the nanoruby makes it possible to discriminate signals from un-wanted autofluorescence background and laser backscatter by employing a time-gated image acquisition mode. This mode enabled several-fold improvement of the photoluminescence imaging contrast of discrete nanoru-
bies dispersed on a coverslip. It enabled recovery of the photoluminescence signal emanating from discrete na-norubies when covered by a layer of an organic fluorescent dye, which were otherwise invisible without the use of spectral filtering approaches. Time-gated imaging also facilitated high sensitivity detection of nanorubies in a biological environment of cultured cells. Finally, we monitor the binding kinetics of nanorubies to a functionalised substrate, which exemplified a real-time assay in biological fluids. 3D-pseudo colour images of nanorubies immersed in a highly fluorescent dye solution. Nanoruby photolumines-cence is subdued by that of the dye in continuous  excitation/imaging (left), however it can be recovered by time-gated imaging (right). At the bottom is schematic diagram of nanoruby assay in a biological fluid.

The paper is available online.

 

Supporting Science Experience 2016

Varun Sreenivasan_web15 January 2016:

CNBP researchers  Varun Sreenivasan and Denitza Denkova extended their outreach skills in support of the ConocoPhillips Science Experience program that took place at Macquarie University 13-15th January 2016.

The national program, focused on  Year 9 and 10 students who have an interest in science, is rolled-out across universities and tertiary institutions across Australia. Students who attend are provided with the opportunity to engage in a wide range of fascinating science activities under the guidance of scientists who love their work.

As a part of this program, Varun and Denitza contributed to the ‘Physics and Chemistry Magic Show’ which ran for an hour at Macquarie University’s Science Faculty. Demonstrated were concepts such as the ‘Stroboscopic effect’, the physics behind a ‘singing wineglass’ and the fun that can be had with Sulfur Hexafluoride.

“Through this event, we were able to share our excitement of science with youngsters, hopefully motivating them to do science as they grow up,”said Varun.

“We also improved our presentations and quick problem solving skills too!”

 

CNBP at International Nanomedicine Conference

cnbplogosquare18 July 2015:

CNBP was certainly well represented at the 6th Annual International Nanomedicine Conference, at Sydney’s Coogee Beach, July 6-8, 2015.

Targeting both researchers and clinicians, the conference saw a large number of CNBP personnel in attendance, with oral and poster presentations undertaken by the following CNBP researchers –

Oral Presentations
Dr. Andrew Care – Building a platform technology for the self-assembly of functional upconversion nanoparticles

Prof. Ewa Goldys – Nanorubies For Ultrasensitive Biomolecular Imaging

Dr. Guozhen Liu – Covalent Functionalization of Gold Nanoparticles as Electronic Bridges and Signal Amplifiers Towards an Electrochemical Immunosensor for Botulinum Neurotoxin Type A

Dr. Annemarie Nadort – Blood circulation of nanoparticles in a chick embryo model

Poster Presentations
Mrs. Sandhya Clement – X-ray induced singlet oxygen generation by nanoparticle-photosensitizer conjugates: direct determination of singlet oxygen quantum yield

Dr. Varun Sreenivasan – Large scale production, characterisation and functionalisation of nanorubies

Dr. Kai Zhang – Study on Porous Silica Nanoparticles to co-Delivery of Drug and siRNA

Further information on the conference, attendees and abstacts can be found from the event web site – http://www.oznanomed.org/

Nanorubies talk at EMN conference, China

Varun Sreenivasan_web15 June 2015

Varun Sreenivasan, affiliate CNBP researcher has updated the international nanobiophotonics community on his nanorubies research after providing an invited talk at the Energy Materials and Nanotechnology (EMN) conference in Qingdao, China (14-17th June 2015).

The talk titled, ‘Production and surface engineering of nanorubies for ultrasensitive biomolecular imaging’, provided an overview of nanorubies as new generation photoluminescent probes – their mass production, functionalisation and demonstrated biomolecular labeling in vitro.

 

Monthly Macquare seminars

Biju Cletus28 May 2015:

CNBP Macquarie node undertook its monthly seminar series today, with Dr. Varun Sreenivasan and Dr. Biju Cletus presenting for 30 minutes on the following abstract topics, each followed by a short Q&A session:

Title: Nanorubies for Biomolecular Imaging
Contributors: Varun Sreenivasan, W. A. Wan Razali, Carlo Bradac, Mark Connor, Ewa Goldys, Andrei Zvyagin

Abstract: Nanorubies were introduced as promising probes for biological fluorescence microscopy by our group in 2013. They possess unique photoluminescence properties including, broad excitation spectra (350-570 nm), sharp emission (692+/-3 nm), large quantum yield (~30%), long emission lifetime (~4 ms), extreme photostability and biocompatibility. However, their uptake into the bio-imaging community has been limited due to low production yield and high cost. Therefore, we developed a large scale nanoruby production approach to produce large quantities (several grams) of nanorubies in the size range of 10-200 nm. Results of its characterisation, biofunctionalization, and specific and sensitive imaging of G-protein coupled receptors in mammalian cells will be presented.

Title: Hyperspectral Autofluorescence Fundus Camera
Contributors: Biju Cletus, Martin Gosnell, Ayad Anwer, Ewa Goldys

Abstract: Hyperspectral imaging (HSI) is an emerging diagnostic imaging modality for bio- medical applications. The current research presented here is in the field of hyperspectral autofluorescence imaging, which combines spectroscopy and imaging. This research project intends to modify a Fundus camera to get hyperspectral fluorescence images of the eye. The hyperspectral fluorescence camera will be capable of imaging different sections of the eye from lens to retina providing tissue information that is not available from usual Fundus images. Here we present some preliminary experimental results from the modified Fundus camera.

 

CNBP-themed Research Conference at Macquarie University

Andrei and Igor12 December 2014: They just could not stop talking!

Finishing 2014 on a high note the Macquarie CNBP node organized a CNBP-themed  MQ BioFocus Research Conference on 10 December.

An ECR-led Conference Committee comprising Dr Wei Deng, Ms K. Drozdowicz-Tomsia, and Dr Varun Sreenivasan put together an exciting program of talks and posters, covering disciplines from medicine to laser physics.

Rarely have we seen more lively discussions!

The meeting was attended by 70 staff and students from CNBP and Macquarie MQ BioFocus Research Centre led by Professor Ewa Goldys (Deputy Director, CNBP).

CNBP Associate Investigators (pictured above) A/Prof Igor Aharonovich (right) and Andrei Zvyagin (left) have presented their research.

MQ BioFocus Research Centre was established in 2010 and it laid the foundation for the CNBP node at Macquarie.

Macquaire BioFocus Research Centre Conference

fromjimpiper7 December 2014: Upcoming event

The Macquarie BioFocus Research Centre is organising a conference in bringing together academics from Physics, Chemistry, Biology and Medicine from within Macquarie and other local institutions.

See http://biofocus.science.mq.edu.au/eventsandnews/events/2014-conference/ for details.

Registration is free, and all are welcome to attend.