Nanobody-Based Biotemplating Enables Nanoscale-Precision Metallization of Cellular, Tissue, and Plant Architectures.

Biological organisms possess complex structures that perform specialized functions through their unique structural organization. These structures offer attractive templates for inorganic synthesis that exhibit structural complexity that is difficult to achieve through conventional fabrication methods. As a result, an immunolabeling-integrated biotemplating approach has been developed to achieve selective metal growth along actual protein structures. However, conventional immunolabeling approaches employing Immunoglobulin G (IgG) antibodies face limitations in precisely replicating the intracellular architectures due to the large molecular size of antibodies. Owing to their small size and high affinity, nanobodies serve as effective alternatives for guiding inorganic structure formation through biological templating. Here, we present a nanobody-based biotemplating method that enables the formation of inorganic nanostructures along target proteins with enhanced structural precision and tissue penetration capability. Nanobodies conjugated with 1.4 nm gold seeds specifically bind to fluorescent proteins expressed on target structures, serving as nucleation sites for subsequent metal growth. Using this approach, we demonstrate the synthesis of three-dimensional metal architectures throughout 500 μm-thick brain tissue enabled by the faster diffusion of nanobodies relative to IgG antibodies under identical labeling times. Finally, we extend this strategy to plant tissues to fabricate biotemplated SERS substrates, highlighting the versatility of nanobody-based biotemplating across biological systems.