Shourya Dutta Gupta

Optimization of electrical stimulation parameters for enhanced cell proliferation on biomaterial surfaces

From the point of view of biocompatibility of bone analog materials, cell-material interaction is of fundamental importance. In this article, we report the effect of pulse electric field stimulation on cell-material interaction by analyzing cellular functionality and viability. An in-house fabricated pulse electric field setup was used for the application of electric field during cell culture experiments. To optimize voltage/electric field, the first set of exploratory experiments was conducted with varying field strength at fixed frequency, and subsequently, the frequency of the electrical stimulation was varied to study its influence on the proliferation of L929 mouse fibroblast cells on gelatin-coated control disc. Subsequently, L929 cells were cultured on hydroxyapatite (HA) and HA-40 wt % BaTiO₃ composite. Cell-cultured samples were analyzed qualitatively as well as quantitatively using fluorescence microscope and scanning electron microscope. It has been demonstrated that due to the application of electric field during the cell culture experiment, the cell proliferation and the cell spreading on the surface of the biomaterials were enhanced within a narrow window of voltage/frequency of electrical stimulation. At lower field intensities, the energy density is quite low and increases parabolically with field strength. There is no significant increase in the temperature (ΔT ~10⁻⁵ K) of the medium due to the application of short duration pulse electric field. This led us to believe that electric field with appropriate strength and duration can enhance the cell-material interaction.

Critical coupling at oblique incidence

We study critical coupling at oblique incidence and show the suppression of both reflection and transmission in a multilayered system having a two-component metal–dielectric composite film as the top layer. Almost total absorption of the incident electromagnetic energy in the composite film is shown to be possible for both TE and TM polarization of the incident light. Moreover, the scattering profiles for the TM polarization exhibit additional resonances which can be ascribed to the excitation of the bulk plasmons in the composite film.

Signature of strong atom?cavity interaction on critical coupling

We study a critically coupled cavity doped with resonant atoms with metamaterial slabs as mirrors. We show how resonant atom–cavity interaction can lead to a splitting of the critical coupling dip. The results are explained in terms of the frequency and lifetime splitting of the coupled system.