Layer-by-Layer Self-Assembling of Polyelectrolytes—From Ultrathin Ambipolar Capacitors to Wearable Label-Free Biosensors

Layer-by-layer (LbL) assembly is widely recognized for its effectiveness in coating substrates with polymers, colloids, biomolecules, and cells, offering superior control and versatility, especially on micro and nanostructured surfaces.<br/>This presentation explores the application of LbL self-assembling of polyelectrolytes as a versatile technique in two key areas: ultrathin ambipolar capacitors and wearable label-free biosensors.<br/>Polyelectrolytes, due to their charged nature, facilitate the sequential deposition of alternating nm-thick layers with complementary charges onto various substrates. This process ensures self-regulation of the thickness of both single and multilayer films, promoting uniformity and reproducibility, regardless of the hosting materials.<br/>In the field of energy storage, this control has shown to be critical for developing ultrathin capacitors with ambipolar nature capable of operating across extended frequency ranges with high capacitance densities. These advancements are pivotal for advancing flexible electronics and energy storage applications.<br/>In biosensing, LbL assembly has been utilized to functionalize nanostructured materials with biocompatible polyelectrolyte layers engineered with biomolecules and/or emitting dyes, enabling the development of implantable and wearable sensors for real-time, label-free detection of analytes of clinical interest.<br/><br/>References<br/>A. Paghi et al, Adv. Mater. 2024, 2309365<br/>A. Paghi et al, Adv. Mater. Technol. 2023, 2201600<br/>M. Corsi et al., Adv. Sci. 2022, 2202062<br/>S. Mariani et al, Nat Comm. 2018, 9:5256