title: Towards a subcutaneous optical biosensor based on thermally hydrocarbonised porous silicon.
abstract: Advanced biosensors in future medicine hinge on the evolvement of biomaterials. Porous silicon (pSi), a generally biodegradable and biocompatible material that can be fabricated to include environment-responsive optical characteristics, is an excellent candidate for in vivo biosensors. However, the feasibility of using this material as a subcutaneously implanted optical biosensor has never been demonstrated. Here, we investigated the stability and biocompatibility of a thermally-hydrocarbonised (THC) pSi optical rugate filter, and demonstrated its optical functionality in vitro and in vivo. We first compared pSi films with different surface chemistries and observed that the material was cytotoxic despite the outstanding stability of the THC pSi films. We then showed that the cytotoxicity correlates with reactive oxygen species levels, which could be mitigated by pre-incubation of THC pSi (PITHC pSi). PITHC pSi facilitates normal cellular phenotypes and is biocompatible in vivo. Importantly, the material also possesses optical properties capable of responding to microenvironmental changes that are readable non-invasively in cell culture and subcutaneous settings. Collectively, we demonstrate, for the first time, that PITHC pSi rugate filters are both biocompatible and optically functional for lab-on-a-chip and subcutaneous biosensing scenarios. We believe that this study will deepen our understanding of cell-pSi interactions and foster the development of implantable biosensors.
authors.affiliation: ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Future Industries Institute, University of South Australia, South Australia, Australia.
authors.forename: Wing Yin
authors.initials: WY
authors.lastname: Tong
authors.affiliation: ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Future Industries Institute, University of South Australia, South Australia, Australia.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Sweetman
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, University of South Australia, South Australia, Australia; Faculty of Environmental Agricultural Sciences, Suez Canal University, North Sinai, Egypt.
authors.forename: Ezzat R
authors.initials: ER
authors.lastname: Marzouk
authors.affiliation: South Australian Health and Medical Research Institute, South Australia, Australia.
authors.forename: Cara
authors.initials: C
authors.lastname: Fraser
authors.affiliation: South Australian Health and Medical Research Institute, South Australia, Australia.
authors.forename: Tim
authors.initials: T
authors.lastname: Kuchel
authors.affiliation: ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Future Industries Institute, University of South Australia, South Australia, Australia. Electronic address: Nico.Voelcker@unisa.edu.au.
authors.forename: Nicolas H
authors.initials: NH
authors.lastname: Voelcker
mesh_terms: D016475:3T3 Cells; D000818:Animals; D015374:Biosensing Techniques; D006838:Hydrocarbons / Q000737:chemistry*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D016062:Porosity; D012825:Silicon / Q000737:chemistry*; D012867:Skin
chemical_list: D006838:Hydrocarbons; D012825:Silicon
keywords: Biocompatibility; Biodegradation; Biosensor; Cytotoxicity; Silicon; Subcutaneous implant