A novel biosensor based on chemiluminescent-DNA nanomachine for life biomarker detection in planetary exploration

Several studies reported the presence of organic compounds in extraterrestrial environments, thus one of the main objectives of the research in the field of exobiology is the search for organic molecules and compounds in planetary exploration missions and the identification of their biological or non-biological origin. To reach this goal, devices capable of analyzing in-situ material samples searching for organic molecules, amino acids, nucleic acids, polysaccharides and other biological systems molecules are under development. An important example is given by the on-going development of the Life Marker Chip (LMC) [1], which scientific aim is the detection of organics in the form of biomarkers that might be associated with extinct life, extant life or abiotic sources. The increasing development of extremely compact systems relying on microfluidics, commonly known as lab-on-chip (LOC) devices, has gained much attention thanks to their favorable characteristics in terms of reduced size, weight and power requirements, amenability to automation, very low sample and reagent consumption, reduced analysis time and, often, superior achievable performances in terms of limits-of-detection. Thus, LOC devices are extremely suitable for space missions and are under investigation in view of future planetary exploration. Among bioassays, aptamer-based one appear to be particularly suited for space applications, exploiting the higher stability of DNA-based bioreceptors, with respect to antibodies. Herein we report about the design and optimization of a DNA switch based on chemiluminescent (CL) detection for the identification of Adenosine triphosphate (ATP), which is commonly accepted as a high-ranking biomarker of extant life in extraterrestrial environments. Indeed, CL-based detection allows developing bioassays characterized by high detectability and sensitivity and it is also particularly suited for miniaturized analytical devices, as it avoids the need for external radiation sources and complex optical systems combining filters and lenses [2]. The DNA switch will be implemented into a portable device comprising a microfluidic network based on capillary forces for the handling of samples and reagents, a set of functionalized detection sites where DNA nanomachine-based assay will be carried out and an array of thin-film hydrogenated amorphous silicon (a-Si:H) photosensors for the detection of the analytical CL signal [3]. The implementation of the CL bioassay into the compact and fully-integrated device will provide a new analytical platform for the multiparametric detection of bio-organic molecules outside of the Earth.