Minimalistic metabolite piezoelectric self-assembly for the development of implantable bioelectronics for in vivo monitoring

Amino acid non-centrosymmetric self-assemblies, possessing inherent polarization as well as biocompatibility, can be employed as bioinspired alternatives for the development of implantable piezoelectric bioelectronics. This could enable the harvesting of biomechanical energy for in situ in vivo monitoring and avoid the need for secondary surgeries, potentially overcoming the trade-off between high-efficiency sensing and the biosafety limitations of traditional inorganic or polymeric piezoelectric counterparts. In this regard, the electromechanical coupling behaviors of the minimalistic metabolite self-assemblies are reported. Experimental tests reveal that compared to other natural amino acid crystals, threonine (T) crystals exhibit a high Young’s modulus of up to approximately 80 GPa by forming a denser three-dimensional hydrogen-bonding network, with each molecule interacting with seven adjacent ones. Computational analysis reveals that side-chain entities dramatically affect crystal packing, with polar hydroxyl moieties accounting for the distinct piezoelectric features underlying the macroscopic performance. This highlights the potential of exploiting T crystals to develop biodegradable piezoelectric bioelectronics that exhibit highly sensitive linear responses for tactile sensing and post-implantation in vivo motion monitoring. This study demonstrates the feasibility of exploiting minimalistic metabolite self-assemblies for piezoelectric bioelectronics in bio-machine interface and biomedical engineering applications.