{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T10:07:09Z","timestamp":1784714829595,"version":"3.55.0"},"reference-count":23,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T00:00:00Z","timestamp":1784678400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Science and Technology Research Project of the Education Department of Jilin Province","award":["JJKH20261663KJ"],"award-info":[{"award-number":["JJKH20261663KJ"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>Mid-infrared spectroscopy provides molecular fingerprint information for bacterial biofilm analysis, but the absorption signal of a thin biofilm layer is usually weak. In this work, a metasurface-enhanced mid-infrared biosensor was designed to enhance the fingerprint response of Staphylococcus aureus biofilms. The biofilm transmission spectrum was measured by Fourier-transform infrared spectroscopy, and the film thickness was obtained by atomic force microscopy using an edge step-height method. Based on these measurements, an effective extinction coefficient was extracted and used in finite-difference time-domain simulations. A metal\u2013insulator\u2013metal metasurface was then optimized to cover the main biofilm absorption bands in the mid-infrared region. Two resonator designs were studied: a polarization-dependent structure and a polarization-insensitive structure. The polarization-dependent design showed a strong response under x-polarized incidence and weak coupling under y-polarized incidence. The polarization-insensitive design provided a more balanced response for orthogonal polarizations. At the selected biofilm fingerprint wavelengths, the highest enhancement factors reached 8.57 and 7.24 for the polarization-dependent and polarization-insensitive structures, respectively. Near-field distributions confirmed that the enhancement mainly originated from localized electric fields at the metal resonator edges. These results provide a proof-of-concept design strategy for enhancing weak mid-infrared fingerprint signals from S. aureus biofilms.<\/jats:p>","DOI":"10.3390\/bios16070397","type":"journal-article","created":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T09:20:39Z","timestamp":1784712039000},"page":"397","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Design of a Metasurface-Enhanced Mid-Infrared Biosensor for Fingerprint Signal Enhancement of Staphylococcus aureus Biofilms"],"prefix":"10.3390","volume":"16","author":[{"given":"Bowei","family":"Yang","sequence":"first","affiliation":[{"name":"School of Life Science and Technology, Changchun University of Science and Technology, No. 7186 Weixing Road, Changchun 130022, China"},{"name":"Postdoctoral Research Station of Instrument Science and Technology, Changchun University of Science and Technology, No. 7089 Weixing Road, Changchun 130022, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ang","family":"Zhou","sequence":"additional","affiliation":[{"name":"School of Life Science and Technology, Changchun University of Science and Technology, No. 7186 Weixing Road, Changchun 130022, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuxiang","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Optoelectronic Engineering, Changchun University of Science and Technology, No. 7186 Weixing Road, Changchun 130022, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"Zhao","sequence":"additional","affiliation":[{"name":"Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, No. 3888 Dong Nanhu Road, Changchun 130033, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunying","family":"Pang","sequence":"additional","affiliation":[{"name":"School of Life Science and Technology, Changchun University of Science and Technology, No. 7186 Weixing Road, Changchun 130022, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Kassem, A., Abbas, L., Coutinho, O., Opara, S., Najaf, H., Kasperek, D., Pokhrel, K., Li, X., and Tiquia-Arashiro, S. (2023). Applications of Fourier Transform-Infrared spectroscopy in microbial cell biology and environmental microbiology: Advances, challenges, and future perspectives. Front. Microbiol., 14.","DOI":"10.3389\/fmicb.2023.1342406"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1889","DOI":"10.1038\/s41598-018-20222-6","article-title":"Analysis of Staphylococcus aureus wall teichoic acid glycoepitopes by Fourier Transform Infrared Spectroscopy provides novel insights into the staphylococcal glycocode","volume":"8","author":"Grunert","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1038\/nrmicro2415","article-title":"The biofilm matrix","volume":"8","author":"Flemming","year":"2010","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Peng, Q., Tang, X., Dong, W., Sun, N., and Yuan, W. (2022). A review of biofilm formation of Staphylococcus aureus and its regulation mechanism. Antibiotics, 12.","DOI":"10.3390\/antibiotics12010012"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"100175","DOI":"10.1016\/j.bioflm.2023.100175","article-title":"Staphylococcus aureus biofilm: Formulation, regulatory, and emerging natural products-derived therapeutics","volume":"7","author":"Wu","year":"2024","journal-title":"Biofilm"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Rahman, B.M.A., Viphavakit, C., Chitaree, R., Ghosh, S., Pathak, A.K., Verma, S., and Sakda, N. (2022). Optical fiber, nanomaterial, and thz-metasurface-mediated nano-biosensors: A Review. Biosensors, 12.","DOI":"10.3390\/bios12010042"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Fdez-Sanrom\u00e1n, A., Bern\u00e1rdez-Rodas, N., Rosales, E., Pazos, M., Gonz\u00e1lez-Romero, E., and Sanrom\u00e1n, M.\u00c1. (2025). Biosensor technologies for water quality: Detection of emerging contaminants and pathogens. Biosensors, 15.","DOI":"10.3390\/bios15030189"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"100141","DOI":"10.1016\/j.bioflm.2023.100141","article-title":"Investigating the chemical pathway to the formation of a single biofilm using infrared spectroscopy","volume":"6","author":"Crisp","year":"2023","journal-title":"Biofilm"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1038\/s43586-023-00253-8","article-title":"Surface-enhanced infrared absorption spectroscopy","volume":"3","author":"Kozuch","year":"2023","journal-title":"Nat. Rev. Methods Primers"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Li, D., Xu, C., Xie, J., and Lee, C. (2023). Research progress in surface-enhanced infrared absorption spectroscopy: From performance optimization, sensing applications, to system integration. Nanomaterials, 13.","DOI":"10.3390\/nano13162377"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1103\/PhysRevLett.45.201","article-title":"Enhancement of the infrared absorption from molecular monolayers with thin metal overlayers","volume":"45","author":"Hartstein","year":"1980","journal-title":"Phys. Rev. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"26652","DOI":"10.1021\/acs.jpcc.5b08344","article-title":"Importance of plasmonic scattering for an optimal enhancement of vibrational absorption in SEIRA with linear metallic antennas","volume":"119","author":"Neuman","year":"2015","journal-title":"J. Phys. Chem. C"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"3688","DOI":"10.1021\/ja312694g","article-title":"Surface-enhanced infrared absorption using individual cross antennas tailored to chemical moieties","volume":"135","author":"Brown","year":"2013","journal-title":"J. Am. Chem. Soc."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"11953","DOI":"10.1364\/OE.20.011953","article-title":"Rational design and optimization of plasmonic nanoarrays for surface enhanced infrared spectroscopy","volume":"20","author":"Liberman","year":"2012","journal-title":"Opt. Express"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Pfezer, D., Karst, J., Hentschel, M., and Giessen, H. (2022). Predicting concentrations of mixed sugar solutions with a combination of resonant plasmon-enhanced SEIRA and principal component analysis. Sensors, 22.","DOI":"10.3390\/s22155567"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"11155","DOI":"10.1021\/acsami.9b19719","article-title":"Self-organized nanorod arrays for large-area surface-enhanced infrared absorption","volume":"12","author":"Giordano","year":"2020","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"111939","DOI":"10.1016\/j.colsurfb.2021.111939","article-title":"Gold nanorod arrays enable highly sensitive bacterial detection via surface-enhanced infrared absorption (SEIRA) spectroscopy","volume":"206","author":"Dizaji","year":"2021","journal-title":"Colloids Surf. B Biointerfaces"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"120699","DOI":"10.1016\/j.saa.2021.120699","article-title":"Surface-enhanced infrared absorption spectroscopy for microorganisms discrimination on silver nanoparticle substrates","volume":"268","author":"Yilmaz","year":"2022","journal-title":"Spectrochim. Acta Part A Mol. Biomol. Spectrosc."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Kudryashov, S.I., Nastulyavichus, A.A., Tolordava, E.R., Kirichenko, A.N., Saraeva, I.N., Rudenko, A.A., Romanova, Y.M., Panarin, A.Y., Ionin, A.A., and Itina, T.E. (2019). Surface-enhanced IR-absorption microscopy of Staphylococcus aureus bacteria on bactericidal nanostructured Si surfaces. Molecules, 24.","DOI":"10.3390\/molecules24244488"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"116755","DOI":"10.1016\/j.microc.2025.116755","article-title":"Large-scale cost-effective mid-infrared resonant silicon microstructures for surface-enhanced infrared absorption spectroscopy","volume":"220","author":"Sudha","year":"2025","journal-title":"Microchem. J."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2200039","DOI":"10.1002\/adsr.202200039","article-title":"SERS Detection of Breast Cancer-Derived Exosomes Using a Nanostructured Pt-Black Template","volume":"2","author":"Li","year":"2023","journal-title":"Adv. Sens. Res."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1016\/S0167-7012(00)00236-0","article-title":"Quantification of biofilm accumulation by an optical approach","volume":"44","author":"Bakke","year":"2001","journal-title":"J. Microbiol. Methods"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"31113","DOI":"10.1038\/srep31113","article-title":"Nanometal skin of plasmonic heterostructures for highly efficient near-field scattering probes","volume":"6","author":"Zito","year":"2016","journal-title":"Sci. Rep."}],"container-title":["Biosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/7\/397\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T09:59:15Z","timestamp":1784714355000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/7\/397"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,22]]},"references-count":23,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["bios16070397"],"URL":"https:\/\/doi.org\/10.3390\/bios16070397","relation":{},"ISSN":["2079-6374"],"issn-type":[{"value":"2079-6374","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,22]]}}}