Light-activated Self-delivered Plasmids

Plasmids are circular double-stranded DNA usable by bacteria and have been the workhorse of molecular biology. However, they can also be adopted by more complex organisms to influence how their cells behave. Importantly, this means they can be leveraged to study intricate molecular networks, gene-function relationships, and hold promise as therapeutic devices. Thus, the ability to deliver, and precisely control when and where they are activated will not only advance their utility in research fields such as developmental and molecular biology, but also expedite their translation to the clinical settings. Nevertheless, two outstanding challenges need to be overcome before plasmids can be used for therapy: the inefficient delivery of large negatively charged molecules into cells, and their activity is not tightly controlled. In this regard, light is a convenient stimulus as it is non-invasive, and its properties and application can be adjusted to minimise cellular damage and achieve spatial precision. However, examples of light-controlled plasmid are limited, with the majority displaying poor light-dependent activation. Moreover, their inability to enter the cells remains an unmet challenge.


This project presents a strategy to make chemically modified plasmids that (1) are light-activated with minimal leakiness, (2) can deliver themselves into cells, and (3) are agnostic to the underlying DNA sequence, so adaptable for any plasmid. To achieve this, light-responsive groups will be placed throughout one DNA strand of the plasmid. These groups shall contain functionalities to block transcription and enable cell delivery. Within cells, light activation will restore plasmid function. Towards this goal, a protocol has been developed to reliably create these chemically modified plasmids. I have shown that these modified plasmids can be attached to proteins blockers, and these proteins can be removed cleanly with ultraviolet (UV) irradiation. This strategy has been validated by demonstrating that gene expression from this plasmid was repressed when proteins were appended, and expression was restored following UV irradiation. It is envisaged that the technology developed herein could be used to probe cellular processes at the single-cell level, or as a means for controllable gene therapy


This project falls within the EPSRC "Synthetic Biology", "Clinical Technologies (excluding imaging)", and "Chemical Biology and Biological Chemistry" research areas.

The emerging and dynamic field of Synthetic Biology has the potential to provide solutions to some of the key challenges faced by society, ranging across the healthcare, energy, food and environmental sectors. The UK government has recently a "Synthetic Biology Roadmap", which presents a vision and direction for Synthetic Biology in the UK. The report projects that the global Synthetic Biology market will grow from $1.6bn in 2011 to $10.8bn by 2016. It highlights that there is an urgent need for the UK to develop the interdisciplinary skills required to take advantage of the opportunities provided by Synthetic Biology.

The challenge to the academic and industrial research communities is to develop new translational approaches to ensure that these potential benefits are realised. These new approaches will range across the design and engineering of biologically based parts, devices and systems as well as the re-design of existing, natural biological systems across all scales from molecules to organisms. The techniques will encompass not only individual cells, but also self-assembled biomimetic systems, engineered microbial communities and multicellular organisms, combining multiple perspectives drawn from the engineering, life and physical sciences.

Realising these goals will require a new generation of skilled interdisciplinary scientists, and the training of these scientists is the primary goal of the SBCDT. Our programme will give the breadth of coverage to produce a "skilled, energized and well-funded UK-wide synthetic biology community", who will have "the opportunity to revolutionise major industries in bio-energy and bio-technology in the UK" (David Willetts, Minister for Universities and Science) in their future careers. This will be made possible through genuine inter-institutional collaboration in partnership with key industrial, academic and public facing institutions.

The potential impact of the SBCDT, and its potential national importance, are very therefore high, and the potential benefits to society are significant.