Patterned conducting polymers for all-polymer cell electroporation microsystems

Cancer immunotherapy shows increasing potential for assisting in fighting cancer, based on reinjection of dendritic cells “trained” in the laboratory to recognize a patient’s cancer cells. The training proceeds via transient formation of nanopores in the cell membranes induced by a pulsed high electrical field. Highly defined electroporation of single cells has been demonstrated by a number of methodologies during the past decade. However, none of these techniques may be easily up-scaled in a cost-effective manner to handle the large number of cells required for immunotherapy (10-100 million trained dendritic cells). Furthermore, the initial generation of high numbers of dendritic cells, by chemically induced differentiation of the patient’s blood monocytes in the laboratory, is a labor intensive and costly procedure. The differentiation process and subsequent electroporation procedure are therefore well suited as targets for direct integration in a lab-on-a-chip configuration. We have set out to produce such an integrated microsystem based exclusively on commodity polymers for microchannel structures combined with micropatterned conductive polymers (CP) as active field generators and active components of the microfluidic pumping system. Our technology platform is based on new methodologies, to be presented here, for integrating and patterning CP layers into the surface of bulk polymers: Integration occurs via solvent-induced blending of a nanoscale thickness CP layer into a thermoplastic polymer surface [1]. This results in mechanically highly stable surfaces retaining the conductivity of the CP layer (see Figure 1). Surprisingly, the procedure works equally well for thermoplastic elastomers which may be strained by more than 50% without irreversible change in conductivity [2]. Patterning of the free-standing or integrated CP occurs in a fast parallel micropatterning (<2 micrometer resolution in seconds to minutes) procedure based on spatially selective transfer of an oxidant from a stamp surface relief to CP areas to be deactivated [3] (see Figure 2). We have demonstrated the application of these combined methodologies for the fabrication of an all-polymer electroosmotic microfluidic pumping system (see Figure 3), suitable for the slow controlled release of agents inducing monocyte differentiation [1]. Furthermore, we have manufactured interdigitated gold microelectrode arrays for controlled electroporation of large cell numbers and shown their ability to electroporate and transfect live dendritic cells by messenger-RNA coding for enhanced Green Fluorescent Protein. On-going activities focus on achieving equivalent results by conducting polymer electrode arrays.