Polydimethylsiloxane core–polycaprolactone shell nanofibers as biocompatible, real-time oxygen sensors

Abstract

Real-time, continuous monitoring of local oxygen contents at the cellular level is desirable both for the study of cancer cell biology and in tissue engineering. In this paper, we report the successful fabrication of polydimethylsiloxane (PDMS) nanofibers containing oxygen-sensitive probes by electrospinning and the applications of these fibers as optical oxygen sensors for both gaseous and dissolved oxygen. A protective ‘shell’ layer of polycaprolactone (PCL) not only maintains the fiber morphology of PDMS during the slow curing process but also provides more biocompatible surfaces. Once this strategy was perfected, tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) (Ru(dpp)) and platinum octaethylporphyrin (PtOEP) were dissolved in the PDMS core and the resulting sensing performance established. These new core-shell sensors containing different sensitivity probes showed slight variations in oxygen response but all exhibited excellent Stern-Volmer linearity. Due in part to the porous nature of the fibers and the excellent oxygen permeability of PDMS, the new sensors show faster response (<0.5 s) −4–10 times faster than previous reports – than conventional 2D film-based oxygen sensors. Such core-shell fibers are readily integrated into standard cell culture plates or bioreactors. The photostability of these nanofiber-based sensors was also assessed. Culture of glioma cell lines (CNS1, U251) and glioma-derived primary cells (GBM34) revealed negligible differences in biological behavior suggesting that the presence of the porphyrin dyes within the core carries with it no strong cytotoxic effects. The unique combination of demonstrated biocompatibility due to the PCL ‘shell’ and the excellent oxygen transparency of the PDMS core makes this particular sensing platform promising for sensing in the context of biological environments.

Morphology impact on oxygen sensing ability of Ru(dpp)3Cl2 containing biocompatible polymers

“…The low porosity could be another explanation to the slow response times of the cast films, in addition to the smaller available surface area for the oxygen molecules to access. Other studies show that increasing film thickness of 2D polymer films increases diffusion depth and correlates to greater oxygen response time [14]. An order of magnitude increase in PCL fiber diameter also reduced sensitivity and increased response time, imposing limits on oxygen diffusion through the polymer matrix [13].…”

Emerging Roles of Electrospun Nanofibers in Cancer Research

“…Lannutti et al developed core/shell structured fibers with PCL as shell and oxygen-sensitive probe, tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) (Ru(dpp)) and platinum octaethylpor-phyrin (PtOEP) containing polydimethylsiloxane (PDMS) as the core, for oxygen detection. [124] It was found that the sensor exhibited rapid response within 0.5 s due to the porous structure of the nanofibers and the excellent oxygen permeability of PDMS. Table 2 shows the representative electrospun nanofiber-based biosensors for cancer cell detection.…”

THE STUDY OF EFFECT OF METAL ION Fe(III) ON THE CHLOROPHYLL AS POTENTIAL PHOTOSENSITIZER ON DYE SENSITIZED SOLAR CELL

“…This phenomenon is included in the phenomenon of MLCT. 13 MLCT phenomenon occurs due to ligand has orbital π* with low energy and the presence of MLCT phenomenon on the complex compound cause the complex compound is very well be used as dye sensitizer because it can absorb light with optimal so that it can be converted into electrical energy. When a compound has a lot of electrons in d orbitals and amount of ligand is abundant it cause the compounds are able to suffer the MLCT phenomenon.…”

“…When a compound has a lot of electrons in d orbitals and amount of ligand is abundant it cause the compounds are able to suffer the MLCT phenomenon. 13 In this study, Fe(III)-chlorophyll dissolved in dimethyl sulfoxide (DMSO) as solvent because this solvent has high degree of polarity. In addition DMSO also not liberate hydrogen when met with very electropositive metal.…”