A microreactor array platform and method for sealing a reagent in microreactors of an array of microreactors are provided. The microreactor array platform includes an array of microreactors, and a sealing film having a first surface and an opposite second surface, the sealing film configured to movably seal the array of microreactors. The microreactor array platform also includes an injector for delivering a reagent into the array of microreactors via a fluid path between the array and the second surface of the sealing film, and an applicator for directing a sealing liquid against the first surface of the sealing film. The microreactor array platform further includes a system for creating a pressure differential between the reagent in the injector and a space between the array of microreactors and the second surface of the sealing film.