An international team of researchers from Bristol and China has prepared biocompatible protocells that generate nitric oxide gas a known reagent for blood vessel dilation - that when placed inside blood vessels expand the biological tissue.

In a new study published today in Nature Chemistry, Professor Stephen Mann and Dr Mei Li from Bristols School of Chemistry, together with Associate Professor Jianbo Liu and colleagues at Hunan University and Central South University in China, prepared synthetic protocells coated in red blood cell fragments for use as nitric oxide generating bio-bots within blood vessels.

Coating the protocells led to increased levels of biocompatibility and longer blood circulation times. Critically, the team trapped an enzyme inside the protocells which, in the presence of glucose, produced hydrogen peroxide. This was then used by haemoglobin in the protocell membrane to degrade the drug molecule hydroxyurea into nitric oxide gas.

When placed inside small pieces of blood vessels, or injected into a carotid artery, the protocells produced sufficient amounts of nitric oxide to initiate the biochemical pathways responsible for blood vessel vasodilation.

Although at a very early stage of development, the new approach could have significant benefits in biomedicine, cellular diagnostics and bioengineering.

Professor Stephen Mann, Co-Director of the Max Planck Bristol Centre for Minimal Biology at Bristol, said: This work could open up a new horizon in protocell research because it highlights the opportunities for creating therapeutic, cell-like objects that can directly interface with living biological tissues.

Associate Professor Jianbo Liu at Hunan University added: We are all really excited about our proof-of-concept studies but there is a lot of work still to be done before protocells can be used effectively as bio-bots in therapeutic applications. But the potential looks enormous.

Enzyme-mediated nitric oxide production in vasoactive erythrocyte membrane-enclosed coacervate protocellsby Liu S, Zhang Y, Li M, Xiong L, Yang X, He X, Wang K, Liu J and Mann S. in Nature Chemistry.

Max Planck Bristol Centre for Minimal BiologyThe Max Planck-Bristol Centre for Minimal Biology, a partnership between the University of Bristol and the Max Planck Society for the Advancement of Science (MPG) in Germany, aims to advance the future of health and medicine by understanding the fundamental nature of life.

Minimal biology is a new emerging field at the interface between the physical and life sciences. It aims to design and build artificial cells, minimal genomes, virus-like nanodevices and new cellular scaffolds, and seeks to understand the foundations of life and how it arose from non-living matter.

Led by Bristol ProfessorsImre Berger(Biochemistry),Stephen Mann(Chemistry) andDek Woolfson(Chemistry and Biochemistry), and ProfessorsJoachim Spatz(Heidelberg),Tanja Weil(Mainz) andPetra Schwille(Munich) at Max Planck Institutes in Germany, the Centre is based in theSchool of Chemistryat the University of Bristol. A paramount objective is to train early career scientists in minimal biology and biodesign.

What is Minimal Biology?Minimal biology is an emerging research field at the interface between the physical and life sciences. It applies principles and methods from the former to construct new systems that mimic or augment living cells and organs.

About Bristol BioDesign InstituteBristol BioDesign Institute(BBI) is the University of Bristol's Specialist Research Institute for synthetic biology. With wide-ranging applications from health to food security, BBI combines pioneering synthetic biology approaches with understanding biomolecular systems to deliver the rational design and engineering of biological systems for useful purposes.

This is delivered through multidisciplinary research which brings together postgraduate and postdoctoral researchers, academics, policy makers and industry, whilst also engaging the public with emerging solutions to global challenges.

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