Functional Micrococcus lysodeikticus layers deposited by laser technique for the optical sensing of lysozyme

[Display omitted] •Functional layers of Micrococcus lysodeikticus deposited via MAPLE on glass slides.•Bacterial interfaces sensitive to lysis by lysozyme were used as optical biosensors.•MAPLE-deposited biointerfaces were compared to ones deposited via layer-by-layer.•Lysozyme detected in undiluted serum in the clinical range up to 10μgmL−1. Whole cell optical biosensors, made by immobilizing whole algal, bacterial or mammalian cells on various supports have found applications in several fields, from ecology and ecotoxicity testing to biopharmaceutical production or medical diagnostics. We hereby report the deposition of functional bacterial layers of Micrococcus lysodeikticus (ML) via Matrix-Assisted Pulsed Laser Evaporation (MAPLE) on poly(diallyldimethylamonium) (PDDA)-coated-glass slides and their application as an optical biosensor for the detection of lysozyme in serum. Lysozyme is an enzyme upregulated in inflammatory diseases and ML is an enzymatic substrate for this enzyme. The MAPLE-deposited bacterial interfaces were characterised by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier-Transformed Infrared Spectroscopy (FTIR), Raman and optical microscopy and were compared with control interfaces deposited via layer-by-layer on the same substrate. After MAPLE deposition and coating with graphene oxide (GO), ML-modified interfaces retained their functionality and sensitivity to lysozyme’s lytic action. The optical biosensor detected lysozyme in undiluted serum in the clinically relevant range up to 10μgmL−1, in a fast and simple manner.