Bioaffinity detection and tracking of disease biomarkers via dynamic multi-modal surface plasmon enhanced nanoscopy

Lead Research Organisation: University of Strathclyde
Department Name: Pure and Applied Chemistry


The ability to directly monitor biomolecular interactions (e.g. DNA-DNA, RNA-DNA, protein-protein) in real-time is of great importance to many areas of biology and medicine. At the cellular level, very few molecules can be responsible for inducing a significant biological response and there remains an urgent need for highly sensitive optical methods able to both identify and spatially track multiple target biomolecules simultaneously in complex and dynamic biological environments. To address this challenge we propose to develop a unique multi-imaging platform capable of monitoring large numbers of individual, freely moving nanoparticles and monitoring their interactions with target molecules and other nanoparticles. This new technology will initially be applied to the multiplexed detection of microRNAs with the distinct advantage of not requiring either target pre-modification or subsequent amplification steps to achieve the sensitivities necessary for the direct analysis of genomic RNA samples. The research takes advantage of the electronic properties of metallic nanoparticles that are associated with greatly enhancing the intensity of various types of spectroscopic signals such as scattering, Raman and fluorescence. These signals are highly responsive to changes in the immediate environment around each nanoparticle with Raman in particular providing a molecular fingerprint useful for identification. However, typical investigations involve applying only one of these spectroscopic modalities and either looking at select individual particles immobilised on a surface or acquiring an ensemble-averaged spectrum of the bulk sample. Imaging is a particularly powerful and intuitive approach for investigating complex systems. The radically different multi-spectroscopic methodology proposed here enabling the high-throughput visualisation of individual particles along with rapid optical discrimination between different particles sizes and clusters is expected to have a far-reaching impact. In addition to creating a powerful tool for bioanalytical investigation, this research will open up significant new opportunities to physicists, chemists and engineers interested in the functionalisation and assembly of nanoparticles to create next generation materials and devices.

Planned Impact

The development and exploitation of new nanotechnologies is already beginning to have a far-reaching impact at multiple levels of society including governmental, academic, the commercial sector, as well as the wider public. The proposed research into creating new nanoparticle-enhanced methodologies for dynamically detecting and tracking biomolecular interactions at unprecedented sensitivities and spatial resolutions overlaps with several priority areas stipulated by the UK government and funding research councils. These include nanometrology where there remains a real need for quantitative methods for real-time nanoscale measurement in complex wet environments that will facilitate future research in many biotechnological fields such as medical therapeutics, nanotoxicology and drug delivery. In particular, creating new methodologies for the multiplexed direct detection of disease biomarkers at ultralow concentrations will, in the longer term, lead to earlier diagnosis, more effective treatments and better understanding of disease pathways. These important economic and societal benefits, among others, were recently outlined in the EPSRC's Nanotechnology Grand Challenges in Healthcare. At an industrial level, it is imperative that the UK maintains a leading position in discovering and applying new and emerging technologies. A strong focus on application outcomes in combination with a sound fundamental scientific drive has been a consistent theme of my research in recent years, as demonstrated with 3 US patents and the opportunity to work with a company to develop one of these to a commercial product. This awareness continues in the proposed research with the direct involvement of the company Nanosight Ltd who have demonstrated a committed interest in the research outcomes. Prior to publication of any new research, an assessment on its potential for commercialisation will be made and any new IP developed will be handled via the university's Research and Innovation Department. Another significant benefit to the private sector is that students (postgraduate and undergraduate) participating in the proposed research will be exposed to a variety of biological, material and optical related scientific disciplines besides chemistry. Cross-disciplinary skills and broad experience are becoming ever more important as traditional research barriers are removed and are highly sought after by companies seeking a more adaptable workforce. I am a strong proponent of encouraging undergraduate participation in meaningful research having published my first papers at this level and will actively encourage undergraduates to apply for vacation scholarships and bursaries. Dissemination of research activities and outcomes will be performed at multiple levels aimed at maximising research impact and encouraging public interaction. One approach in which I have already become very active is schools liaison with a particular focus on supporting chemistry teachers by creating new research projects for Advanced Higher students. During the funding period, aspects of my research interests will be adapted to create simple and safe investigative projects that will be distributed to a growing number of schools who have expressed an interest in such support materials. I will also encourage pupils as well as teachers to contact me directly and/or visit the Dept as part of the support. Further opportunities to engage the general public such as following the publication of groundbreaking results in leading journals will be exploited by promptly communicating to the university's press office and the EPSRC as well as via personal, academic and professional websites and forums.
Description The central aim of the research was to develop novel nanoparticle-enhanced imaging methodologies which could be used for the ultrasensitive detection of disease biomarkers. This involved successfully working towards achieving several objectives. In particular: (i) the construction of a novel imaging platform capable of the high-throughput tracking of freely moving particles via more than one optical imaging modality (e.g. scattering, fluorescence, Raman) simultaneously; (ii) the design of a novel class of gold nanoparticle-dye conjugate that enables multimodal imaging, and (iii) the biofunctionalisation and application of these new nanomaterials. The first major accomplishment of the project using equipment purchased with the grant was to publish a proof-of-principle study (J. Phys. Chem. C, 2010, 18115) demonstrating an imaging approach capable of dynamically tracking and sizing freely suspended individual nanoparticle clusters based on their surface-enhanced Raman scattering (SERS) signal. This is the first time such an approach has been demonstrated since the SERS signal is often relatively weak. It also provided the basis for further instrument development with the integration of a second highly sensitive CCD for the wide-field monitoring of nanoparticles via two different spectroscopic signals (e.g. Rayleigh scattering and SERS) at the same time. Also added to the instrument platform was a microspectroscopy setup to acquire spectra of individual nanoparticles. Another objective successfully achieved was to demonstrate the potential of the imaging platform to monitor interactions between DNA-functionalised nanoparticles in the presence of a specific target. A novel approach was to look at DNA triplex formation and control the interparticle distance and correlate this between the plasmonic and SERS responses. This work was achieved in collaboration with Prof Duncan Graham and published in the RSC flagship journal (Chemical Science, 2012, 2262). A separate research theme running concurrently was the design of novel gold nanorod-dye nanostructures as promising nanotags for multimodal imaging. The ability to control the self-assembly of these hybrid materials has featured in a series of high-quality journal publications (Chem. Comm. 2011, 3757; PCCP 2013, 18835 and ACS Nano 2014, 8600). The main achievement of these papers is that we were able to develop a new design of functionalised nanorod particles that are optically much brighter than equivalent spherical particles thus allowing individual nanorods to be imaged and tracked at the single particle level via Raman and Rayleigh scattering. As envisioned in the proposal, successful completion of the main objectives would pave the way for exploring new opportunities long after the expiry date of the grant itself. For example, the ACS Nano 2014 paper mentioned above was also partially supported by a "Bridging The Gap" grant with colleagues in biology and engineering at Strathclyde which enabled us to translate our research to cellular measurements and demonstrate that our surface functionalisation chemistries resulted in non-cytotoxic nanoparticles as well as being able to perform multimodal imaging measurements across a wide range of incident wavelengths. A number of other exciting opportunities are also currently being explored utilising the unique dynamic imaging platform established using this funding.
Exploitation Route Our work on the design of new functionalised nanorod-dye conjugates demonstrating very clear methodologies for their fabrication and ensuring their stability and chemical robustness paves the way for the use of these materials in a variety of labelling and sensing applications. Especially attractive is that we have clearly shown that these materials can be imaged at the single particle level using different optical techniques. Furthermore, the ability to perform optical measurements of the nanorod conjugates across a variety of excitation wavelengths and imaging modalities will enable researchers to design new experiments for biosensing and cellular imaging. The technological developments in the design of the nanoparticle imaging platform is of value to researchers who want to perform similar measurements on different materials or provide a reference point from which to further advance the approach that was taken in this work.
Sectors Chemicals,Healthcare,Pharmaceuticals and Medical Biotechnology

Description University of Strathclyde
Amount £11,000 (GBP)
Funding ID EPSRC Bridging the Gap award to Strathclyde 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 01/2012 
End 06/2012
Description Get Your Hands Dirty!: Advanced Higher Investigation Ideas in Practice 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Presenter : Schools engagement : Created and organised a hands-on practical session for 100 teachers introducing new projects aimed at Advanced Higher Chemistry students.

The event was highly appreciated by teachers, many of whom have subsequently used the project ideas presented in their classes.
Year(s) Of Engagement Activity 2012
Description Into the Lab: More Advanced Higher Investigations in Practice 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Presenter : Schools engagement : Created and organised a lab session introducing six newly designed Advanced Higher projects to 100 teachers over two repeat sessions.

The event was highly appreciated by teachers, many of whom have subsequently used the project ideas presented in their classes.
Year(s) Of Engagement Activity 2012