The compatibility of hepatocytes with chemically modified porous silicon with reference to in vitro biosensors

Abstract

Porous Si is a nanostructured material that is of interest for molecular and cell-based biosensing, drug delivery, and tissue engineering applications. Surface chemistry is an important factor determining the stability of porous Si in aqueous media, its affinity for various biomolecular species, and its compatibility with tissues. In this study, the attachment and viability of a primary cell type to porous Si samples containing various surface chemistries is reported, and the ability of the porous Si films to retain their optical reflectivity properties relevant to molecular biosensing is assessed. Four chemical species grafted to the porous Si surface are studied: silicon oxide (via ozone oxidation), dodecyl (via hydrosilylation with dodecene), undecanoic acid (via hydrosilylation with undecylenic acid), and oligo(ethylene) glycol (via hydrosilylation with undecylenic acid followed by an oligo(ethylene) glycol coupling reaction). Fourier Transform Infrared (FTIR) spectroscopy and contact angle measurements are used to characterize the surface. Adhesion and short-term viability of primary rat hepatocytes on these surfaces, with and without pre-adsorption of collagen type I, are assessed using vital dyes (calcein-AM and ethidium homodimer I). Cell viability on undecanoic acid-terminated porous Si, oxide-terminated porous Si, and oxide-terminated flat (non-porous) Si are monitored by quantification of albumin production over the course of 8 days. The stability of porous Si thin films after 8 days in cell culture is probed by measuring the optical interferometric reflectance spectra. Results show that hepatocytes adhere better to surfaces coated with collagen, and that chemical modification does not exert a deleterious effect on primary rat hepatocytes. The hydrosilylation chemistry greatly improves the stability of porous Si in contact with cultured primary cells while allowing cell coverage levels comparable to standard culture preparations on tissue culture polystyrene.

Nano‐hydroxyapatite colloid suspension coated on chemically modified porous silicon by cathodic bias: a suitable surface for cell culture

“…Adhesion of cell tissue to biomaterials is a prerequisite for the incorporation of the material in implants or studies of tissue engineering. Cell compatibility studies with unmodified PS [10] or chemically modified PS have been performed [8,[11][12][13]. The studies show the ability to culture mammalian cells directly onto PS.…”

“…This was achieved through use of a highly stable colloidal suspension of Hap and cathodic bias. The colloidal suspension of Hap nanoparticles was formulated in aqueous media by sonication on an ice bath [12], in the same electrolytic cell used to produce PS. All materials were characterized using Scanning Electron Microscope (SEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Energy Dispersive X-Ray (EDX), Grazing Incidence X-Ray Scattering (GIXS), Thermal Gravimetric Analysis (TGA).…”

Surface-Functionalized Porous Silicon Wafers: Synthesis and Applications

“…The tunable porosity of porous silicon (p-Si) and concomitant physical properties such as photoluminescence and electrical conductivity have long been exploited for solar (Menna, 1995;Vitanov, 1997), biomedical (Low, 2009;MacInnes, 2009;Alvarez, 2009), and (bio)sensing (Razi, 2008;Palestino, 2008;Janshoff, 1998) applications. The most common method used to fabricate porous silicon is electrochemical etching (anodization) of a doped Si wafer in an aqueous/ethanolic HF electrolytic solution (Fahlman, 2011).…”

Silicon and Silicon-Related Surfaces for Biosensor Applications

“…Several studies have investigated the use of surface-modified photonic crystals for biosensing applications; in particular, silicon can be used as a material for the fabrication of photonic crystals sensors, when combined with surface modification by hydrosilylation reactions with alkenes. Indeed, alkene-based monolayers can be readily formed onto the surface of porous silicon structures and the attachment and subsequent surface binding events can be monitored by the shift of the crystal optical band-gap [Alvarez, et al, 2009]. Such a silicon photonic crystal was developed to monitor the protease activity of biological samples , by immobilizing the protein angiotensine on the walls of the crystal: the degradation of the protein caused by the presence of a protease induces a shift in the photonic band gap of the crystal.…”