Synthetic biology aims to design novel biological functions by engineering genetic systems of organisms. To achieve sophisticated functional capabilities in the engineered systems, the following questions need to be addressed: "To what level of complexity can we design synthetic genetic networks?" "At the design phase, can we implement biosafety to prevent unexpected genetic mutations?" "Can we computationally quantify the functional behavior of engineered organisms and even their mutants?" For example, in a recent topic of genome-editing, can the genetic technology be applied for therapeutics at the systems level with enhanced biosafety? These questions have been motivating my research. In my talk, in relation to predictable and reliable genetic engineering at the systems level, I will cover three research topics: (1) interplay between stochasticity and nonlinearity, (2) functional stability under mutation pressure, and (3) RNA aptamer probe development and their applications for RNA regulatory circuit characterization.