Friday, 5 August 2016

Postdoc position in UCL Optical Tweezer Group

The Optical Tweezers group at UCL (www.ucl.ac.uk/~ucapphj) is looking to recruit a postdoctoral research associate to work on the British Council-funded project “Manipulation and Destruction of Cancer Cells Using Cavitation Bubbles by Optical and Acoustic Tweezers”. 

The aim of the project is to use optical and acoustic techniques to manipulate microscopic bubbles in the vicinity of cancer cells, with the goal of destroying them either by enhancement of drug uptake, or by physical disruption of the cell membrane.

The project will involve several research visits to our collaborators Dr Burcin Unlu (Bogazici University, Istanbul) and Dr Giovanni Volpe (Bilkent University, Ankara). 

This position is funded for 18 months in the first instance.

The successful candidate should have (or be about to obtain) and PhD in Physics or Medical Physics, and expertise in experimental optics and/or acoustics (including photoacoustics).

Please contact Dr Phil Jones for further detail, or see jobs.ac.uk to apply.

The closing date for applications is 26 August 2016.

Wednesday, 27 July 2016

Paper published in Nano Letters

Our paper on the dynamics of silison nanowires in optical tweezers has been published as A. Irrera et al, 'Photonic torque microscopy of the non-conservative force field for optically trapped silicon nanowires', Nano Letters 16, 4181-4188 (2016).
From the abstract: We measure, by photonic torque microscopy, the nonconservative rotational motion arising from the transverse components of the radiation pressure on optically trapped, ultrathin silicon nanowires. Unlike spherical particles, we find that nonconservative effects have a significant influence on the nanowire dynamics in the trap. We show that the extreme shape of the trapped nanowires yields a transverse component of the radiation pressure that results in an orbital rotation of the nanowire about the trap axis. We study the resulting motion as a function of optical power and nanowire length, discussing its size-scaling behavior. These shape-dependent nonconservative effects have implications for optical force calibration and optomechanics with levitated nonspherical particles.

Monday, 4 April 2016

Paper published in Scientific Reports

Our work on assessing the chage in deformability of red blood cells from patients with the condition diabetic retinopathy has been published as R. Agrawal et al.  'Assessment of red blood cell deformability in type 2 diabetes mellitus and diabetic retinopathy by dual optical tweezers stretching technique', Scientific Reports 6 15873, doi:10.1038/srep15873 (2016).

From the abstract: A pilot cross sectional study was conducted to investigate the role of red blood cells (RBC) deformability in type 2 diabetes mellitus (T2DM) without and with diabetic retinopathy (DR) using a dual optical tweezers stretching technique. A dual optical tweezers was made by splitting and recombining a single Nd:YAG laser beam. RBCs were trapped directly (i.e., without microbead handles) in the dual optical tweezers where they were observed to adopt a “side-on” orientation. RBC initial and final lengths after stretching were measured by digital video microscopy, and a Deformability index (DI) calculated. Blood from 8 healthy controls, 5 T2DM and 7 DR patients with respective mean age of 52.4yrs, 51.6 yrs and 52 yrs was analysed. Initial average length of RBCs for control group was 8.45 ± 0.25 μm, 8.68 ± 0.49 μm for DM RBCs and 8.82 ± 0.32 μm for DR RBCs (p < 0.001). The DI for control group was 0.0698 ± 0.0224, and that for DM RBCs was 0.0645 ± 0.03 and 0.0635 ± 0.028 (p < 0.001) for DR group. DI was inversely related to basal length of RBCs (p = 0.02). DI of RBC from DM and DR patients was significantly lower in comparison with normal healthy controls. A dual optical tweezers method can hence be reliably used to assess RBC deformability.

The movie below shows a red blood cell being stretched using our optical tweezers. 


 

Tuesday, 15 March 2016

Optical Tweezers: Principles & Applications

The textbook Optical Tweezers: Principles and Applications, by P H Jones, O M Marago and G Volpe was published in Europe in 2015, and in the Americas in February 2016.  

Combining state-of-the-art research with a strong pedagogic approach, this text provides a detailed and complete guide to the theory, practice and applications of optical tweezers. In-depth derivation of the theory of optical trapping and numerical modelling of optical forces are supported by a complete step-by-step design and construction guide for building optical tweezers, with detailed tutorials on collecting and analysing data. Also included are comprehensive reviews of optical tweezers research in fields ranging from cell biology to quantum physics. Featuring numerous exercises and problems throughout, this is an ideal self-contained learning package for advanced lecture and laboratory courses, and an invaluable guide to practitioners wanting to enter the field of optical manipulation. The text is supplemented by www.opticaltweezers.org, a forum for discussion and a source of additional material including free-to-download, customisable research-grade software (OTS) for calculation of optical forces, digital video microscopy, optical tweezers calibration and holographic optical tweezers.

"...it is quite simply excellent..." (M Padgett)
"...an amazing Optical Tweezers Software toolbox..." (J J Saenz)
"...a must for all Ph.D. students, researchers, and engineers [...] dealing with optical tweezers..." (M I Mishchenko)

Dr Zhirong Liu joins the group

Dr Zhirong Liu has joined the UCL Optical Tweezers Group as a China Scholarship Council finded visiting researcher.  Dr Liu is an Associate Professor at East China Jiaotong University where his research interests include optical trapping, wave propagation and scattering.  He will be staying with us for one year to work on both experiments and theory of optical tweezers.

Tuesday, 19 January 2016

LCN / Physics / School of Pharmacy "Meet & Greet"

The department of Physics and Astronomy (P&A), the London Centre for Nanotechnology (LCN), and the School of Pharmacy (SOP) have organised a "meet and greet" event to facilitate links between physics / nanotechnology research on one hand, and pharmaceutical research on the other. The main aim of this event is to highlight respective research activities, expertise and facilities, and identify potential for cross-departmental collaborations and funding applications. This will be achieved by a series of short presentations on research questions, expertise, facilities and industrial collaborations, and by ample opportunity to chat over coffee/tea and lunch.

The event is open for UCL academics, postdocs and PhD students working in relevant or potentially relevant areas.

Wednesday 20th January 2016, 10:00am - 3:30pm

LMCB seminar room, UCL Laboratory for Molecular Cell Biology (map)

Programme:

10.00 – 10.15 Welcome and coffee

10.15 – 10.30 Introduction to the morning, with Simon Gaisford (SOP, morning chair), Jon Butterworth (
P&A, Head of Department), Andrew Fisher (LCN, Director)

10.30 – 12:00 Short presentations (15min each)
- Soma Somavarapu (SOP)
- Andela Saric (
P&A)
- Sudax Murdan (SOP)
- Bart Hoogenboom (LCN / P&A)
- TBC (SOP)
- Thanh Nguyen (LCN/
P&A)

12.00 – 1.00 Networking lunch

1.00 – 1.15 Introduction to the afternoon, with Bart Hoogenboom (LCN/P&A, afternoon chair) and Duncan Craig (SOP, Director)

1.15 – 2.45 Short presentations (15min each)
- Duncan Craig (SOP)
- Jochen Blumberger (LCN/P&A)
- Simon Gaisford (SOP)
- Phil Jones (
P&A)
- Gareth Williams (SOP)
- David Bowler (LCN/
P&A)

2.45 – 3:30 Wrap up followed by coffee/tea

Monday, 23 November 2015

COST Visit to IPCF-CNR, Messina

Tom and Onofrio in Messina
UCL Optical Tweezers Group PhD student Tom Smart recently undertook a Short-Term Scientific Mission (STSM) to our colleagues at the NanoSoft Lab, IPCF-CNR (Messina), supported by the COST Action MP1205 Optofluidics.  The aim of Tom's visit was to learn the techniques of Raman spectroscopy on optically trapped particles, which directly addresses the COST action goal of "detection, identification and manipulation of biomolecules and nanomaterials."