Biological characterization of the modified poly(dimethylsiloxane) surfaces based on cell attachment and toxicity assays

Abstract

Poly(dimethylsiloxane) (PDMS) is a material applicable for tissue and biomedical engineering, especially based on microfluidic devices. PDMS is a material used in studies aimed at understanding cell behavior and analyzing the cell adhesion mechanism. In this work, biological characterization of the modified PDMS surfaces based on cell attachment and toxicity assays was performed. We studied Balb 3T3/c, HMEC-1, and HT-29 cell adhesion on poly(dimethylsiloxane) surfaces modified by different proteins, with and without pre-activation with plasma oxygen and UV irradiation. Additionally, we studied how changing of a base and a curing agent ratios influence cell proliferation. We observed that cell type has a high impact on cell adhesion, proliferation, as well as viability after drug exposure. It was tested that the carcinoma cells do not require a highly specific microenvironment for their proliferation. Cytotoxicity assays with celecoxib and oxaliplatin on the modified PDMS surfaces showed that normal cells, cultured on the modified PDMS, are more sensitive to drugs than cancer cells. Cell adhesion was also tested in the microfluidic systems made of the modified PDMS layers. Thanks to that, we studied how the surface area to volume ratio influences cell behavior. The results presented in this manuscript could be helpful for creation of proper culture conditions during in vitro tests as well as to understand cell response in different states of disease depending on drug exposure.

FIG. 1.

Proliferation of Balb 3T3/c cells on the modified PDMS samples (prepolymer to curing agent ratio—5:1, 10:1, and 20:1). PDMS samples were modified using UV irradiation or oxygen plasma activation and protein adsorption: gelatin, collagen, fibronectin, laminin, and poly-L-Lysine. The red line indicates proliferation for the positive control—polystyrene surface. (n ≥ 3, asterisk indicates p < 0.05).

FIG. 2.

Proliferation of HMEC-1cells on the modified PDMS samples (prepolymer to curing agent ratio—5:1, 10:1, and 20:1). PDMS samples were modified using UV irradiation or oxygen plasma activation and protein adsorption: gelatin, collagen, fibronectin, laminin, and poly-L-Lysine. The red line indicates proliferation for the positive control—polystyrene surface. (n ≥ 3, asterisk indicates p < 0.05).

FIG. 3.

Proliferation of HT-29 cells on the modified PDMS samples (pre-polymer to curing agent ratio—5:1, 10:1, and 20:1). PDMS samples were modified using UV irradiation or oxygen plasma activation and protein adsorption: gelatin, collagen, fibronectin, laminin, and poly-L-Lysine. The red line indicates proliferation for the positive control—polystyrene surface. (n ≥ 3, asterisk indicates p < 0.05).

FIG. 4.

Immunostaining with vinculin of (a) Balb/3T3c, (b) HMEC-1, and (c) HT-29 cells cultured on different PDMS surfaces modified with plasma oxygen and proteins. (d) Immunostaining with vinculin of Balb/3T3c HMEC-1 and HT-29 cultured on polystyrene (green colour—anti-vinculin conjugated with FITC, red colour—NucRed® Dead 647 ReadyProbes® Reagent).

FIG. 5.

Cytotoxicity of celecoxib and oxaliplatin on Balb 3T3/c, HT-29, and HMEC-1 cells. The viability of the cells was determined 24 h after drug exposure. (n ≥ 3, asterisk indicates p < 0.05).

FIG. 6.

(a) Balb 3T3/c, HMEC-1, and HT-29 cell adhesion on the non-modified PDMS surface, glass, and PDMS surfaces modified with gelatin, collagen, and fibronectin. (b) Scheme of the experiments performed in the microsystems. (c) Balb 3T3/c, (d) HMEC-1, and (e) HT-29 cell detachment test performed in the microsystems 48 h after cell seeding. Flow rates in the range of 5–100 μl/min were tested. (n ≥ 3).

FIG. 7.

Balb 3T3/c cell detachment test performed in the microsystems after incubation with 80 μM of oxaliplatin. Flow rates in the range of 5–100 μl/min were tested. (n ≥ 3).