Surface enhanced Raman scattering (SERS)-active bacterial detection by Layer-by-Layer (LbL) assembly all-nanoparticle microcapsules

Polymeric microcapsules composed by the Layer-by-Layer (LbL) approach have been used for various applica-tions including drug delivery into cells and in vivo, conducting enzyme catalyzed reactions, performing sensoric functions. Typically, LbL-assembled microcapsules have been formulated via alternating deposition of positively and negatively charged polyelectrolytes onto sacrificial templates or so-called cores. In this work, we extend the LbL assembly to produce microcapsules solely based on nanoparticles instead of polymers. We have identified that 5 layers of nanoparticles is the minimum number of layers for a stable assembly of capsules on calcium carbonate templates. Subsequently, these capsules comprised of nanoparticles were applied as Surface Enhanced Raman Scattering (SERS) platform, where the nanoparticle-based shell of capsules is shown to enable SERS of both solutes and macromolecular structures such as bacterial cells.

Automated summary

Polymeric microcapsules assembled using the Layer-by-Layer (LbL) approach have various applications such as drug delivery, enzyme catalyzed reactions, and sensing functions. This study extended the LbL assembly to create microcapsules solely composed of nanoparticles, which were then used as a Surface Enhanced Raman Scattering (SERS) platform, enabling detection of solutes and macromolecular structures.