Ever increasing needs for sustainable development in the environment, society and economy essentially require dramatic improvements of rapid and on-spot analytical methods for environmental monitoring, social safety guarantee, quality control, clinical diagnostics, and so forth.[1] Among the analytical methods demonstrated so far, electrochemical biosensors remain particularly attractive to meet such requirements because the specific recognition of biomolecules (e.g., enzymes, proteins, and aptamers) towards their targets can be integrated with the technical simplicity and high sensitivity of electrochemical methods. Such integration substantially endows the electrochemical biosensors with excellent properties including good sensitivity, easy adaptability for rapid and on-spot analysis, and relatively cheap instrumentation. [2] However, the pressing need for rapid and on-spot analysis in most cases necessitates great improvements of electrochemical biosensors both in simplifying their fabrication and in minimizing biosensor-to-biosensor deviation. This is because the involvement of multistep surface confinement of all biosensing elements, including biorecognition units (i.e., oxidases and dehydrogenases) and electronic transducers (i.e., cofactors, electron transfer mediators or electrocatalysts) onto conducting solid substrate inevitably renders a complicated and time-consuming process for biosensor fabrication, and more importantly, poor reproducibility with a large biosensor-to-biosensor variation.[3] These limitations unfortunately turn the application of this type of biosensor for rapid and on-spot analysis in a simple way to a challenge.Herein, we report a new strategy for simplifying biosensor fabrication, and thus shorten the analysis time as well as minimize the biosensor-to-biosensor deviation by integrating all the biosensing elements into a single infinite coordination polymer (ICP) nanoparticle. With such bioelectrochemically active ICP nanoparticles as the biosensing units, the biosensors can be simply fabricated by confining the nanoparticles onto the conducting substrate. As a new family of micro-and nanoscaled materials constructed from metal ions or metal ion clusters and polydentate bridging ligands by coordination polymerization, [4] ICPs have attracted increasing attention because of their unique properties including size-and morphology-dependent structural tailorability [5] and potential applications in many fields, such as sensing, catalysis, drug delivery, gas sorption, ion exchange, and bioimaging.[6] More interestingly, the rational inclusion and adaptive encapsulation of functional species into self-supported ICP networks during their self-assembly processes can well-formulate new materials with tailor-made and improved multifunctionalities. [7] This unique property of ICPs inspired us to synthesize bioelectrochemically active ICP nanostructures for simple electrochemical biosensing through efficiently encapsulating all biosensing elements into a single ICP nanoparticle during the c...
