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LL5.6.1

Controlled Electrospray for Tissue Engineering Applications M.D. Paine & J.P.W Stark Department of Engineering, Queen Mary, University of London Abstract The development and status of a novel electrospray system, capable of a variety of applications, including the fabrication of tissue engineered structures is described. The system requirements dictate the following key components: a micro-fabricated silicon electrospray emitter, a mass spectrometer capable of selecting molecules having a charge to mass ratio up to 32,000 with a resolution of 10,000, and an integrated ion optics system permitting depositing the selected molecules ‘softly’ onto a target with a spatial resolution of 0.1µm. One critical feature of the system is the overall efficiency of transferring biomolecules from a buffer solution, typically comprising water, acetonitrile and ammonium acetate, into an ion flux. Commercial ES/MS systems are generally designed with simplicity of operation as a design driver, together with the low probability of transmitting spray droplets directly into the quadrupole mass selection system. This has focused attention onto the detailed design and characterization of the electrospray emitter and the environment into which the spray is launched. This has highlighted the need to evaluate in detail, an electrospray operating into a low pressure environment and to improve our understanding of the interaction between voltage and flow rate in the transition from nanoelectrospray mode, wherein no positive pressure is applied to the fluid and normal electrospray mode, close to minimum flow rate. Early results of this investigation are presented. There is evidence that at reduced ambient pressure there is a small reduction in spray current, however this is offset by improved transmission of the beam into the first quadrupole stage. Introduction Electrospraying, ES, has proved to be a flexible tool directed to a wide variety of applications: from spacecraft propulsion to crop spraying; from ceramic fabrication to macromolecule production. The use of electrospray mass spectrometry ES/MS by Robinson and others in the characterization of proteins and other biological molecules, is notable. There is, however, still much to be understood concerning the electrospray process if this technique is to be fully exploited. We believe that with this understanding it would be possible to use electrospraying as a highly controllable and versatile source, able to produce, in a specific state, nano particles and macromolecules. ES provides a ‘soft’ ionization method which can produce a range of intact biomolecules. The ability for the precise localization and incorporation of functional macromolecular components, during the formation of nano fabricated devices has many applications within the area of the life sciences. In tissue engineering we believe that this technology provides the opportunity to manipulate molecules so that structural definition is possible at the sub-cellular level, with molecules focussed to less than one micron. T